Little is known about the demographics of people who use cannabis, including how use trends within population subgroups have evolved over time. It is therefore challenging to know if the demographics of participants enrolled in cannabis clinical trials are representative of those who use cannabis. To fill this knowledge gap, data from the National Survey on Drug Use and Health (NSDUH) on “past-month” cannabis use across various population subgroups in the United States was examined from 2002 to 2021. The most notable increases in “past-month” cannabis use prevalence occurred in those aged 65 and older  and 50–64-year-olds (472.4%). In 2021, people reporting “past-month” cannabis use were 56.6% male and 43.4% female. Distribution across self-reported race and ethnicity was 64.1% White, 14.3% Black, 14.1% Hispanic, and 3.1% more than one race. And many ages were represented as 24.4% were 26–34, 24.1% were 35–49, 22.4% were 18–25, and 17.6% were 50–64 years old. To understand if these population subgroups are represented in cannabis clinical trials, participant demographics were extracted from peer-reviewed clinical trials reporting on pharmacokinetic and/or pharmacodynamic models of cannabis or cannabinoids. Literature was grouped by publication year (2000–2014 and 2015–2022) and participant prior exposure to cannabis. Results identified that cannabis clinical trial participants are skewed toward overrepresentation by White males in their 20s and 30s. This represents structural discrimination in the research landscape that perpetuates social and health inequities. Cannabis and cannabinoid pharmacology and epidemiology are the focus of several federal Requests for Proposals and Notices of Special Interest. Despite renewed pharmacological research interest, little is known about the demographics of people who currently or have recently used cannabis, including how use trends have evolved over time. In 2018, an extensive review on national trends in adult cannabis use was published5, considering data from 2002 through 2014 in participants aged 18–25 and those aged 26 and older7. It was noted that increases in cannabis use occurred across sex, region, educational level, and employment status8. However, the detailed demographics of people who use cannabis was not critically assessed nor reported. In 2019, Cerdá et. al. found that recreational cannabis legalization was associated with increases in frequent cannabis use among adults9. However, impacts of demographic variables beyond age were not assessed. Also in 2019, Hasin et. al. published a narrative review on cannabis use trends by sociodemographic subgroups, summarizing data from several national surveys and a literature review10. They concluded that cannabis use had increased across all sociodemographic subgroups including age sex, race, ethnicity, educational level, and location10. While this work was comprehensive and complete, survey results through 2015 were considered, and an update is required. In 2022, Waddell et. al. reported on the age, sex, and race-varying rates of cannabis use in veterans and non-veterans11. Although the demographic characteristics of these populations were assessed, this work focused on interactions of demographic details and veteran status as risk factors for alcohol and cannabis use11.The shifting legal status of cannabis in the United States (US) and internationally is resulting in increased research interest into cannabis and cannabinoid pharmacokinetics and pharmacodynamics12. Cannabis effects may be moderated by a wide range of factors such as sex, age, race, and ethnicity. For example, preclinical work from rodent ∆9-tetrahydrocannabinol (∆9-THC) dosing studies demonstrates that metabolism and bioaccumulation of ∆9-THC and psychoactive metabolites are significantly impacted by rodent sex. Human studies have also identified sex differences in subjective cannabis effects16, although additional exploration is needed. Similarly, aging is associated with metabolic changes, morbidities, and an overall decline in functioning17, likely impacting cannabis pharmacology. However, only a few studies have evaluated the pharmacology of cannabis in older adults21. The authors were unable to find literature describing demographics of people who currently or have recently used cannabis. However, two recent reviews and meta-analysis of published works on cannabis use disorder and behavioral health found that approximately 70% of study participants were male, 72% were non-Hispanic White, and the median participant age (SD) was 29.9 (9)24. However, balanced clinical trial participant pools must be demographically representative of those who use cannabis to gather generalizable results translatable to public policy. We hypothesize that cannabis clinical trial participants do not represent the sex, race, ethnicity, and age characteristics of people who use cannabis. One may argue that most fundamental pharmacokinetics and pharmacodynamics assessments of cannabis or cannabinoids do not aim to inform statutory or policy language. However, the lack of knowledge surrounding cannabis pharmacokinetics and impairment forces policy makers, enforcement officials, and other stakeholders to apply any available works to their immediate public health and safety needs. That is, results from any cannabis pharmacokinetics or pharmacodynamics studies in humans are likely to be read by and applied to those tasked with crafting evidence-based policies, recommendations, or assessments. This begs the question, what are the demographics of cannabis clinical trial participants, and do they reflect those of people who use cannabis? To begin answering this question, we will consider two data sources: (1) participant demographics extracted from a systematic review of cannabis pharmacokinetics and/or pharmacodynamics studies and (2) results from the United States National Survey on Drug Use and Health (NSDUH) from years 2002–2021. To the best of our knowledge, this is the first study comparing the demographics of cannabis clinical trial participants to those of people who use cannabis.It is well known that cannabis pharmacokinetics and pharmacodynamics vary intra- and inter-personally25. It is a key source of national and state-level data on the prevalence of substance use and health in the US.The National Survey on Drug Use and Health (NSDUH) is a nationally representative and cross-sectional survey of individuals aged 12 years or older living in households or non-institutional group housing  or with no permanent housing . The NSDUH uses a multistage area probability sample for each US state and the District of Columbia and an audio computer-assisted interviewing method to support confidential and private responsesSelf-reported “past-month” cannabis use was examined by demographic characteristics within the 2002–2021 NSDUH data. All analyses used the Substance Abuse & Mental Health Data Archive (SAMHDA) Public-use Data Analysis System (PDAS) to query the NSDUH data. Self-reported “past-month” cannabis use  was considered as a function of respondent sex . Similarly, other variables were considered such as reported race and ethnicity . This included the following options: non-Hispanic White, non-Hispanic Black/African American, non-Hispanic Native American or Alaskan Native, non-Hispanic Native Hawaiian or Other Pacific Islander, non-Hispanic Asian, non-Hispanic more than one race, or Hispanic. A combined sex by race variable was also used  for those who identify as non-Hispanic White, non-Hispanic Black, or Hispanic. Similarly, age was considered  in the ranges of 12–17, 18–25, 26–34, 35–49, 50–64, and 65 + years old. Prior to 2005, the 6-Level age category was not available. Therefore, CATAG5  was used for years 2002 through 2004 for the age ranges of 12–17, 18–25, 26–34, and 35–49 years old. A combination of sex and age category was also used  which identified the distribution of males and females within 12–17 and 18–25 age groups.“Past-month” cannabis use was reported in eSupplement Table 26.Our study was exempt from IRB approval per the University of Wisconsin-Madison’s policy on publicly available, de-identified data sets. We followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guidelines for cross-sectional studies 27. Regression lines were fitted to prevalence estimates using linear regression fits in which the dependent variable was the annual prevalence estimates. Linear regression models include slope (β), y-intercept (α), and their standard errors. Results from linear regression models are included as eSupplement Table 2) values. Residual standard error was found as the standard deviation of residuals using 18 degrees of freedom. A right-tailed F-test was used to identify model significance through the F-statistic (F) and p-value (p). Due to methodological changes in the 2005 NSDUH, the 6-level age category was not available for the 50–64 and 65 and older age ranges in years 2002 through 2004.Weighted crosstab analysis was used to identify and extract self-reported “past-month” cannabis use by age, sex, and race and ethnicity from 2002 through 2021. Results were displayed as weighted count, prevalence, and distribution Both authors independently extracted the following data from each article: (1) participant type , (2) previous cannabis exposure , (3) total number of participants, (4) administration route, (5) time of last plasma sample, (6) pharmacokinetics model (yes/no), (7) pharmacodynamics model (yes/no), (8) pharmacodynamics indicator reported, (9) participant sex, (10) participant age, and (11) participant race and ethnicity. Not all articles reported participant sex, age, race, and ethnicity.30. This striking proportion of the population using cannabis recently and/or regularly is the culmination of a steady increase in societal acceptance of cannabis and cannabis use. Linear regression analysis identified trend directionality, and detailed results are provided in eSupplement Table In 2021, NSDUH estimates 12.9% of Americans  used cannabis in the “past-month”Increasing cannabis use is also observed, although unevenly, across sex and racial and ethnic groups, Fig. The demographics of people who have recently used cannabis was identified from 2021 NSDUH data. In 2021, a total of 69,850 US residents completed the NSDUH. Weighted demographics of respondents, as shown in eSupplement Table Overall, 12.9% of the 2021 respondents reported “past-month” cannabis use. Considering all people engaging in “past-month” cannabis use, demographic distributions were 43.4% female, 64.1% White, 14.3% Black or African American, 1.3% Native American or Alaskan Native, 2.5% Asian, 3.2% two or more races, and 14.1% Hispanic  and females . Only 20 publications70 reported at least some participant race information, see eSupplement Table 70 (11.9%), including 139 (16.4%) total participants and 14 (10.1%) who identified as Hispanic.Results of the literature search and selection process are detailed in Fig. 63 including 155 participants. Those works included participants in the following age ranges: 14–15 , 16–17 , 18–19 , 20–29 , 30–39 , 40–49 , 50–59 , and 60–69 . In addition, 37 publications70 reported age ranges including 907 participants. The minimum age considered was 15 and maximum was 79 years old. Considering the minimum age, the mean was 23.9, the median was 21, and the range was 15–52 years old. Considering the maximum age, the mean was 44.3, the median was 43, and the range was 25–79 years old.Detailed participant age information was available in 6 publications42 were published in 2000–2014 that met the inclusion criteria of this work. These studies included 187 participants of which most  were male. When race was reported, 100.0% of participants were White. Conversely, 29 manuscripts70 were published in 2015–2022 and met the inclusion criteria of this work. These studies included 780 participants of which 429 (65.0%) were male. Race was reported for 338 participants, including While , Black , Asian  Asian, two or more races , Native American , or "other"  participants. In this cohort (2015–2022), ethnicity was reported for 139 participants, with 14 (10.1%) identifying as Hispanic. Minimum and maximum age ranges were similar, when reported, for these works.To assess for shifts in cannabis clinical trial participant demographics over time, the above described data was partitioned into works published in 2000–2014 and those published in 2015–2022. Summaries of participant demographic characteristics for each literature analysis subgroup are included in eSupplement Table 67 including 715 participants of which 430 (72.3%) were male. Race was reported for 240 of these participants, including White , Black , Asian , two or more races , Native American , or other . Ethnicity was reported for 78 participants and 10 (12.8%) were Hispanic.When applying cannabis clinical trial results to people who use cannabis, readers must consider if the clinical trial participants were patients or healthy and if they have prior experience with cannabis. To that end, we also considered cannabis clinical trial participant demographic characteristics (published in 2000-2022) when all “patients” and “no prior cannabis exposure” participants were removed, see eSupplement Table 67 and 545 participants that should be most similar to the demographic characteristics of NSDUH “past-month” cannabis use survey results. Within this group, 297 (69.9%) participants were male. Race was reported for 187 participants including those who identified as White , Black , Asian , two or more races , Native American , or "other" . The distribution of racial groups (when available) included in cannabis clinical trials reporting pharmacokinetics and/or pharmacodynamics models are shown in Fig. 60 reported the participant’s ethnicity, including 78 total participants and 10 (12.8%) who identified as Hispanic. Participant ages were primarily reported as minimum to maximum age ranges. The range of minimum ages was 15–29 years old, with an average minimum age of 21.2 years old. The range of maximum ages was 25–52 years old, with an average maximum age of 35.7 years old.Within the above described “prior cannabis exposure” cohort, 10 manuscripts were published between 2000 and 2014. Removing those, a final subgroup was created including “prior cannabis exposure” participants that were published between 2015 and 2022, see eSupplement Table Asian 7, .7%, two Asian 7, .7%, two 71. Therefore, any pharmacokinetics or pharmacodynamics models generated from these cannabis clinical trials may not be generalizable to the increasingly diverse population of people who use cannabis.This is the first study to compare the NSDUH demographics of people reporting “past-month” cannabis use to cannabis clinical trial participants. The main finding of this study is that demographics of those reporting “past-month” cannabis use are quite diverse, with significant prevalence increases between 2002 and 2021 in older Americans, women, and historically underrepresented groups. However, cannabis clinical trial participants continue to be majority White males in their 20s and 30s. Literature published recently (2015–2022) have included more women and racial minorities compared to literature from 2000–2014. However, this chasm between the demographics of people reporting recent cannabis use and clinical trial participants is concerning. It is well known that demographic differences are an important factor in interpersonal variability in the pharmacokinetics and pharmacodynamics of a substance74. In cannabis clinical trials, age ranges were reported for most participants (94.0%), but detailed age information down to the decade was only reported on some (15.6%) participants. Furthermore, removal of patient participant works reduced the overall age range of participants included in studies. Pharmacokinetics and pharmacodynamics clinical trials are inherently limited by small sample size and stringent inclusion and exclusion criteria. Despite these limitations, the rapid expansion of “past-month” cannabis use by adults aged 50 and older warrants additional clinical investigation.Over the past 18 years, the prevalence of “past-month” cannabis use increased across all age categories except 12–17-year-olds. While decreasing prevalence of “past-month” cannabis use in the pediatric population is encouraging, significant increases in other age groups warrants increased awareness and scientific inquiry. Increases in “past-month” cannabis use prevalence was not evenly distributed across all age groups considered. For example, “past-month” cannabis use prevalence increased 50.9% in 18–25-year-olds from 2002 to 2021 whereas the increase was 224.9% in 26–34 and 148.0% in 35–49-year-olds. Increases were even larger for 50–64-year-olds at 472.4% and use by those aged 65 and older increased an astonishing 2,066.1%. Significant increases in “past-month” cannabis use by older Americans has not received a commiserate increase in research interest and clinical investigationTo understand how cannabis clinical trial participant demographic characteristics have changed over time, data extracted from the literature was divided into several subgroups. These subgroups were: works published in 2000–2014, works published in 2015–2022, works including healthy participants with prior cannabis experience, and works including healthy participants with prior cannabis experience which were published from 2015 to 2022. With respect to publication date, promising improvements in participant demographic characteristics are apparent. Works published in the years 2015–2022 included more women and historically underrepresented racial and ethnic groups than those published in 2000–2014. Including participant eligibility criteria  alongside publication years of 2015–2022 boosted the racial and ethnic diversity of participants, but decreased female representation. Furthermore, removal of patients (studies assessing cannabis for therapeutic applications) reduced the age range of included participants.Cannabis clinical trial participant demographic information was significantly lacking in the works considered here. Participant sex was commonly (87.9%) reported, but race (39.1%) and ethnicity (14.0%) details were deficient. When participant demographic data is missing, the reader is unable to critically assess the translatability of reported results to “real world” cannabis use. Even when available, race and ethnicity data is oversimplified and incomplete. For example, NSDUH crudely aggregates all those identifying as Hispanic together, limiting our ability to consider how ethnicity overlaps with different racial groups in those who report “past-month” cannabis use. However, cannabis clinical trial participant demographics largely failed to capture any ethnicity information. This represents structural discrimination in the research landscape that perpetuates social and health inequities. Overall, there needs to be greater transparency and reporting of participant demographics.This study had several limitations. Cannabis clinical trial participant data was derived from peer-reviewed literature, which introduces publication bias. That is, this work fails to capture any studies that were completed but not published, for whatever reason. Additionally, cannabis clinical trials often include intentionally stringent participant eligibility and ineligibility criteria. For example, females of reproductive potential may be ineligible due to teratogenicity risk. Additionally, the small sample sizes used in pharmacokinetics and pharmacodynamics studies may result in narrow eligible age ranges, preventing consideration of older adults. This is exemplified by studies on therapeutic potential of cannabis and cannabinoids  for certain indications which tended to include older adults.https://pdas.samhsa.gov/). Therefore, demographic details on people reporting cannabis use, including “past-month”, “past-year”, or “lifetime” cannabis use, is available. This data and online data exploration tool was chosen to promote its use when designing future cannabis clinical trials. As shown in this work, the demographics of people reporting “past-month” cannabis use has changed over time. These changes across age, sex, and race and ethnicity necessitate annual reconsideration of the demographics of people who use cannabis. However, cannabis clinical trials seeking to generate pharmacokinetics and/or pharmacodynamics models of cannabis or cannabinoids do not include participants whose demographics are representative of those who use cannabis. This disconnect is problematic for those seeking translatable data to inform public policy on cannabis use and cannabis products. Well-crafted clinical trials should consider the demographics described in this work and updated annually through the Substance Abuse and Mental Health Data Archive. Funding agencies should also consider this data when evaluating funding proposals and crafting Requests for Proposals and Notices of Special Interest announcements.Significant investments have facilitated the wide availability of NSDUH results and datasets to the public through the Substance Abuse and Mental Health Data Archive (Supplementary Tables.


Non-alcoholic fatty liver disease (NAFLD) and alcohol-related liver disease (ALD), both of them accounting for fatty liver disease (FLD), are among the most common chronic liver diseases globally, contributing to substantial public health burden. Both NAFLD and ALD share a similar picture of clinical presentation yet may have differences in prognosis and treatment, which renders early and accurate diagnosis difficult but necessary. While NAFLD is the fastest increasing chronic liver disease, the prevalence of ALD has seemingly remained stable in recent years. Lately, the term steatotic liver disease (SLD) has been introduced, replacing FLD to reduce stigma. SLD represents an overarching term to primarily comprise metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as non-alcoholic fatty liver disease (NAFLD), as well as alcohol-related liver disease (ALD), and MetALD, defined as a continuum across which the contribution of MASLD and ALD varies. The present review discusses current knowledge on common denominators of NAFLD/MASLD and ALD in order to highlight clinical and research needs to improve our understanding of SLD. Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide and shows a continuously increasing global prevalence of 38% in recent years, driven by the obesity pandemic ,2. In coNAFLD is closely linked to obesity and the metabolic syndrome and represents the most rapidly increasing cause for chronic liver failure, hepatocellular carcinoma (HCC), and the need for liver transplantation (LT) . While tThe nomenclature of NAFLD has been a matter of debate in recent years. It is perceived that the term NAFLD may have contributed to the trivialization of the disease, prolonging patient journeys until adequate treatment was offered . AdditioThus, joint efforts of international scientific societies and patient associations have been made to rename and redefine NAFLD to destigmatize patients, improve diagnostic accuracy, and raise awareness . SupportSince progression of hepatic steatosis to cirrhosis and HCC is an important feature of both NAFLD and ALD, it is relevant to identify potentially harmful alcohol consumption and metabolic risk factors for FLD early in order to offer adequate treatment.This review summarizes current knowledge on common denominators and specific differences between NAFLD/MASLD and ALD in clinical presentation, pathogenesis, diagnosis, and treatment in order to uncover hitherto unresearched fields and catalyze our understanding of unmet medical need.Throughout this review article, the previous nomenclature will be used where appropriate to allow for an accurate reflection of the published literature.NAFLD is the most rapidly growing indication for liver transplantation in the US and has become the most common indication for liver transplantation in the US elderly population ,14.According to a recent systematic review, global NAFLD prevalence in the general population increased by ≈50% from 25% in the time period of 1990–2006 to 38% in 2016–2019. Its prevalence has been estimated at 31% in North America and Australasia, 44% in Latin America, 25% in Western Europe, 37% in the Middle East/North Africa, 34% in South Asia, 33% in Southeast Asia, and 28% in Asia-Pacific countries .The prevalence of NAFLD is rising in parallel with the global obesity epidemic. Among metabolic risk groups, prevalence of NAFLD is even higher, with >70% in patients with type 2 diabetes mellitus (T2DM) and 90% in patients with severe and morbid obesity undergoing bariatric surgery ,17. Currently, about 13% of children and adolescents are affected by NAFLD . The shaALD accounts for 5.1% of all disease and injury globally, 5.3% of deaths are attributed to alcohol consumption exceeding those caused by diabetes, and the main cause of death among men aged 25–45 years is alcohol consumption . In contCurrently available data on NAFLD and ALD epidemiology need to be interpreted with caution given that underlying databases largely did not account for systematic testing for alcohol consumption or systematic screening for alcohol use disorder (AUD) in NAFLD patients. Thus, the continuous increase in NAFLD prevalence might be biased by undetected harmful alcohol consumption .Within NAFLD/MASLD, two stages are discerned: (i) non-alcoholic fatty liver (NAFL) or metabolic dysfunction-associated steatotic liver (MAFL) which shows low liver-related morbidity, and (ii) non-alcoholic steatohepatitis (NASH) or metabolic dysfunction-associated steatohepatitis (MASH) which has a higher risk for progressive hepatic fibrosis and shows substantial liver-related mortality . ImportaAs in other etiologies of chronic liver disease, fibrosis stage emerged as a major determinant of prognosis. Angulo et al. identified the superior prognostic value of fibrosis stage as compared to presence or absence of NASH on liver histology . This fiOn the other hand, prognosis is also limited by extrahepatic factors, such as cardiovascular risk and non-hepatic malignancies. A diagnosis of NAFLD should, therefore, prompt screening for cardiovascular disease, e.g., by exercise testing or cerebrovascular sonography. It should be noted that the presence of NAFLD may indicate the cardiovascular manifestations of the underlying metabolic syndrome. Recently, in a retrospective study on 460 patients with stroke, we could show an association of mortality with increased FIB-4 values on admission .Similar to NAFLD/MASLD, ALD encompasses a spectrum of simple hepatic steatosis, steatohepatitis, fibrosis, cirrhosis, and HCC. Additionally, patients may suffer from severe alcoholic steatohepatitis (ASH) that may present as acute-on-chronic liver failure associated with high liver-related short-term mortality . NotablyBesides the well-known impact of abstinence during follow-up, prognosis of ALD, similarly to NAFLD, is mainly determined by fibrosis stage. In a large multinational cohort of 450 patients with ALD of varying severity, SALVE fibrosis stage (SFS) at baseline was found to be an excellent predictor of outcome after 10 years  31]..31].However, alcohol consumption not only increases liver-related morbidity and mortality but affects numerous extrahepatic organs. Similar to NAFLD, diabetes, cardiovascular disease, and obesity are highly prevalent in patients with ALD. According to a recent meta-analysis by Theodoreson et al., major causes of extrahepatic morbidity and mortality comprise cardiovascular disease, non-hepatic malignancies, as well as infection associated with increased risk of death, with a relative risk of 2.4, 2.2, and 8.2, respectively . NAFLD/MASLD and ALD share a common picture of clinical presentation, have large overlaps in associated comorbidities, such as cardiovascular disease, obesity, and cancer, and also share fibrosis as determinant of prognosis. However, longitudinal long-term studies on the natural history of NAFLD/MASLD and ALD are needed to better understand the dynamic of both diseases as well as to facilitate public health initiatives to improve prevention and therapy. Recently, using a Delphi process, a multidisciplinary panel defined a global research priority agenda to enhance public health responses to SLD . This paNAFLD pathogenesis is multifactorial and seems to be mainly driven by lipotoxicity, insulin resistance, and inflammatory pathways. It remains unclear why only 20% of NAFLD patients progress to NASH .Overload of free fatty acids leads to increased fat accumulation from de-novo lipogenesis as well as impaired lipolysis, resulting in lipotoxicity. The latter leads to hepatocellular injury, which provokes inflammation and activation of hepatic stellate cells to myofibroblasts, resulting in enhanced fibrogenesis.Multiple hits stressing the liver, including gut-derived pathogen-associated molecular patterns (PAMPs) and or damage-associated molecular patterns (DAMPs) enhance the transition of NAFL to NASH .In addition, genetic factors, such as patatin-like phospholipase domain-containing protein 3 (PNPLA3) variants, but also altered gut microbiota (dysbiosis), may contribute to the progression to NASH. Interestingly, a recently proposed hypothesis suggests that saccharomyces and candida species contained in the gut mycobiome are an important source of endogenous EtOH generation from ingested fructose (“autobrewery syndrome”) . AdditioBased on current knowledge of pathogenetic factors, potential therapeutic targets have been identified, such as a reduction in fat accumulation, improvements in insulin signaling, suppression of inflammatory response, a reduction in oxidative stress, and the inhibition of fibrogenic signaling  37]..37].Development of ALD and associated mortality is largely dependent on the amount of alcohol consumed. As shown by a meta-analysis by Rehm et al., >2 standard drinks per day for women and >3 standard drinks per day for men is associated with a significantly increased risk for liver cirrhosis morbidity . In a moAlcohol consumption leads to cell injury via direct and indirect toxic effects of EtOH and its even more toxic metabolite acetaldehyde. EtOH is metabolized to acetaldehyde predominantly via ADH (oxidative pathway), which is mainly expressed in the cytosol of hepatocytes  . Via the2O2 and O2−), DNA damage or lipid peroxidation of cell membranes, and increased endotoxin generation and inflammation. During chronic heavy drinking, the continuous reduction of NAD+ to NADH in the reactions catalyzed by ADH and acetaldehyde dehydrogenase (ALDH) during EtOH and acetaldehyde metabolism causes a significant metabolic shift towards fatty acid synthesis as well as increased production of lactate causing metabolic acidosis (REF). Structural mitochondrial alterations caused by acetaldehyde lead to decreased ATP generation and the production of reactive oxygen species causing oxidative stress  , which can be induced by increasing amounts of alcohol as EtOH protects CYP2E1 from being degraded by the ubiquitin proteasome system . This leEtOH and acetaldehyde also show direct toxic effects onto the gastric and intestinal mucosa which may lead to maldigestion and malabsorption of nutrients, vitamins, and trace elements. In the small and large intestine, EtOH is metabolized by the residing microbiota leading to an additional increase in acetaldehyde, cellular damage, and dysbiosis, including changes in the mycobiome and virome (mainly bacteriophages) . Despite the toxic effects of alcohol, only up to 20% of patients with continued excessive alcohol consumption develop alcohol-related liver cirrhosis, pointing to additional protective and risk factors in ALD pathogenesis. As well as the amount of alcohol consumed, the time period of continued alcohol consumption and the drinking pattern are important contributors: daily alcohol consumption, drinking while being fasted and binge drinking have been identified as determinants of increased risk ,9. Although conflicting data exist, the type of alcohol may also be associated with the risk of ALD development. While beer and red wine have been found to be associated with less harm to the liver in animal models and human studies, others did not confirm these findings ,48,49,50Additionally, genetic ancestry and sex modify the risk and severity of ALD and may predispose individuals to AUD ,52. PatiSimilar to NAFLD, several single nucleotide polymorphisms (SNP) have also been identified as modifiers of the risk and severity of ALD ,56. BaseFurthermore, cultural influences, environmental factors, and diet are factors contributing to the development and severity of ALD ,54,60,61As well as epidemiology and clinical presentation, NAFLD/MASLD and ALD have several pathogenetic determinants in common. However, pathogenesis of NAFLD and ALD is still incompletely understood. Elucidating the interaction of EtOH and food intake/weight, as well as the role of microbiota, including the intestinal barrier, might help identify biomarkers for early diagnosis and new therapeutic targets. Due to the high prevalence of NAFLD risk stratification by simple noninvasive tests, it is of utmost importance to provide optimal linkage to care for those patients with high risk of liver-related events. Previous studies have identified advanced fibrosis (F ≥ 3) as the major prognostic factor in NAFLD ,27,62. TWhile there is currently no approved biomarker for the presence of NASH, several noninvasive tests are available for the estimation of fibrosis stage in NAFLD. Simple tests based on routine clinical and laboratory parameters are readily available and are, therefore, useful for broad risk stratification in primary care. NAFLD fibrosis score (NFS), using a combination of the parameters of age, fasting glucose, body mass index (BMI), platelet count, albumin, and AST/ALT ratio , as wellIn addition, several proprietary liver fibrosis panels have been developed. The enhanced liver fibrosis (ELF™) test is based on three extracellular matrix proteins including hyaluronic acid (HA), procollagen-3 N-terminal peptide (P3NP), and tissue inhibitor of metalloproteinase-1 (TIMP-1), and has been studied in adult and pediatric patient populations with NAFLD ,69,70,71®) has shown accurate fibrosis staging ability in liver diseases of various etiologies including NAFLD [Vibration-controlled transient elastography  followed by a detailed noninvasive staging by the ELF test or VCTE. These sequential strategies are cost-effective as the high NPV of FIB-4 < 1.30 for advanced fibrosis allows researchers to reserve the costlier proprietary tests for those patients above this cut-off. In a recent individual patient data meta-analysis on 5735 patients from 37 studies, Mozes et al. validated the FIB-4 followed by VCTE algorithm, indicating high NPV for FIB-4 < 1.30 and reasonable PPV for FIB-4 > 2.67 or LSM > 10 kPa . ImportaUnfortunately, ALD is mostly detected in very advanced stages presenting with decompensated cirrhosis. Nevertheless, noninvasive fibrosis tests may be well-suited in screening for early ALD, e.g., during or shortly after alcohol detoxification treatment.Thiele et al. evaluated and compared 10 different noninvasive fibrosis tests in a Danish cohort of 289 patients with ALD attending an outpatient liver clinic or rehabilitation and demonstrated good to excellent diagnostic accuracy for the prediction of F3-4 stage on histology using FIB-4 (AUROC 0.85), ELF score (AUROC 0.92), and VCTE by FibroScan  [It should be noted that liver stiffness measured by VCTE depends not only on fibrosis but also inflammation, cholestasis, and/or congestion. During alcohol withdrawal, a rapid decline in LSM has been observed within 2 weeks after admission . In ordeAn individual patient data meta-analysis of 10 studies comprising the VCTE data of 1026 patients with ALD revealed an optimal LSM cut-off of 12.1 kPa for the prediction of F ≥ 3, which, however, varied from 8.8 kPa to 16.1 kPa depending on AST and bilirubin levels .Histological NASH is defined by the presence of >5% macrovesicular steatosis, lobular inflammation, and hepatocellular ballooning, typically with a predominantly centrilobular distribution . ActivitAccording to Yip et al., histological ASH is defined by the presence of steatosis (any degree), lobular inflammation, and hepatocellular ballooning . GradingAlongside the increasing burden of obesity and T2DM, alcohol consumption has become a major public health concern given that 55.5% of the world population, 76.5% of the European population, and 83.1% of the American population consume alcohol  ,93.Lifestyle modification resulting in weight loss currently represents the cornerstone of NAFLD treatment as its beneficial effects have been demonstrated in multiple studies. In a small randomized study, Promrat et al. tested the effect of intensive lifestyle intervention vs. structured education only on NASH and reported a significant improvement in ALT and a reduction in NAS on liver histology in parallel to weight loss of 9% in the intervention group . These fThe Western diet, containing high amounts of saturated fat and carbohydrates, should be replaced by Mediterranean diet rich in polyphenols and omega-3 polyunsaturated fatty acids . Low-fatAs the above-mentioned lifestyle changes are achieved in a minority of NAFLD patients only, effective drug therapy is highly desirable, especially in patients with active fibrotic NASH. Pharmacologic treatment of NASH aims to improve various pathophysiologic pathways, including metabolic , anti-inflammatory, and anti-fibrotic targets . To date2). A French study with serial liver biopsies at the time of surgery, 1 year later, and 5 years later has demonstrated resolution of NASH without worsening of fibrosis at 5 years in 84% and improvement of fibrosis by ≥1 stage at 5 years in 70% of patients [Bariatric surgery, using the Roux-en-Y gastric bypass or sleeve gastrectomy, is a very effective treatment option in patients with morbid obesity , psychosocial intervention, and pharmacological therapy . AlthougIn order to support abstinence, pharmacological treatment options in patients with ALD are limited. Baclofen is currently the only pharmacological treatment (off-label use) that has been tested in randomized-controlled trials in patients with AUD and advanced ALD, and its safety in patients with advanced liver disease has been supported by several additional observational studies ,107,108.Future treatment options for liver fibrosis in ALD might include rifaximin-α, which has recently been evaluated in an investigator-initiated, randomized, double-blind, placebo-controlled, single-center, phase 2 trial at Odense University Hospital in Denmark. The trial showed a lesser fibrosis increase after 18 months in the treatment arm . FindingAccording to the new nomenclature and definition, patients with MetALD present with features of both MASLD and ALD, including hepatic steatosis, ≥1 cardiometabolic risk factor out of 5, plus average daily alcohol consumption of 20–50 g  and 30–60 g , respectively . This neIt is well known that concurrent alcohol consumption worsens the prognosis of NAFLD/MASLD and ALD. However, the pathogenesis of NAFLD/MASLD and ALD is multifactorial, incompletely understood, and the true impact of alcohol consumption on the development and progression of SLD has remained unclear. Further research is needed to delineate the relative risk conferred by metabolic factors, various amounts (and type) of alcohol, and further pathomechanistic factors that might influence disease development, progression, as well as treatment targets. Importantly, current treatment of SLD should aim for both correction of cardiometabolic factors and alcohol abstinence. The designs of future clinical trials on the treatment of MASH, MetALD, and ALD need to consider characteristics of both MASLD and ALD.Understanding that there might be a huge overlap between NAFLD/MASLD and ALD, including the new entity of MetALD, requires further clarification of disease-contributing factors. Moving forward, a systematic screening for alcohol consumption and AUD as well as cardiometabolic risk factors is needed in patients presenting with (suspected) chronic liver disease. This should include the assessment of the amount of alcohol consumed with application of alcohol biomarkers to understand the true burden of disease, allow early diagnosis, and improve access to accurate treatment. Improving our understanding of the decisive drivers of NAFLD/MASLD and ALD, as well as their mutual interaction, will support further refinement of the MetALD definition and allow for a personalized treatment approach.


Non-Alcoholic Fatty Liver Disease (NAFLD) is a prevalent extraintestinal manifestation in patients with Inflammatory Bowel Disease (IBD). Liver fibrosis is the determinant long-term prognostic marker in patients with NAFLD because it is associated with progression to liver cirrhosis and hepatocellular carcinoma. In fact, NAFLD is already the most common liver disease worldwide and is becoming a leading cause of liver-related mortality. In this article, we systematically reviewed the available evidence regarding the prevalence and risk factors of liver fibrosis in patients with NAFLD and IBD, and we discussed the role and pathways of progression from liver fibrosis to hepatocellular carcinoma.The aim of the systematic review is to assess the prevalence and risk factors of liver fibrosis in patients with Inflammatory Bowel Disease (IBD) and Non-Alcoholic Fatty Liver Disease (NAFLD) and to discuss the role of liver fibrosis in the progression to hepatocellular carcinoma (HCC). We performed a structured search in PubMed, Web of Science, Embase, and Scopus up to 3 March 2023 to identify observational studies reporting liver fibrosis in patients with NAFLD and IBD. Quality of studies was assessed using the Newcastle-Ottawa Scale (NOS) score. A total of 23 studies met our inclusion criteria, including 629,781 patients. A total of 10 cross-sectional, 3 case-control, and 10 cohort studies were included. Fourteen studies had a NOS score ≥ 7 points. NAFLD was diagnosed in 2162/6332 (34.1%) IBD participants. However, NAFLD diagnosis was established in 924/2962 (31.2%) healthy individuals without IBD. Advanced liver fibrosis was found in 116 (11.6%) of 992 IBD patients with NAFLD. Most studies found an association between NAFLD and classic cardiovascular risk factors such as older age, male sex, higher BMI, diabetes, hypertension and dyslipidemia. In addition, metabolic syndrome features were also associated with an increased risk of significant and advanced liver fibrosis. Although no strong association between NAFLD and IBD therapy was reported, some studies associated NAFLD with IBD diagnosis, Crohn’s Disease, a complicated course of IBD, disease activity, and IBD duration. Advanced liver fibrosis was also associated with Crohn’s disease in several studies. In conclusion, NAFLD and advanced liver fibrosis are prevalent and clinically relevant extraintestinal manifestations, so its diagnosis and potential progression to HCC should be carefully considered in daily clinical practice. Non-Alcoholic Fatty Liver Disease (NAFLD) is defined as the presence of more than 5% of steatosic hepatocytes in patients without significant alcohol intake . Recentlp < 0.001) and the presence of IBD was a risk factor for developing MAFLD [The worldwide burden of NAFLD is increasing with a global prevalence of approximately 25% and it is becoming a leading cause of chronic liver disease and liver transplantation in the United States ,6. The png MAFLD .Obese patients have an increased risk of developing NAFLD in the general population but also in IBD ,13,14. Np < 0.001) and IBD was an independent risk factor for advanced fibrosis [Beyond cardiovascular risk, NAFLD is a clinically relevant condition due to the potential progression to NASH, advanced fibrosis, cirrhosis, and HCC . About 1fibrosis . The potfibrosis .Due to the higher risk of NAFLD in IBD and the complex interaction between the two diseases, the aim of this systematic review is to assess the prevalence and risk factors of liver fibrosis in patients with IBD and NAFLD and to discuss the role of liver fibrosis in the progression to HCC.This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines . InstituWe performed a comprehensive literature search in PubMed, Web of Science, Scopus and Embase up to 3 March 2023. Only human studies were included but no language or time restrictions were applied. Database searches were performed independently by three authors  using the following terms: inflammatory bowel disease OR IBD OR ulcerative colitis OR UC OR Crohn’s disease OR CD. The Boolean operator “AND” was used to combine these terms with: NAFLD OR non alcoholic fatty liver disease OR NAFL OR non alcoholic fatty liver OR steatosis OR NASH OR steatohepatitis OR hepatosteatosis OR MAFLD OR metabolic associated fatty liver disease OR liver fibrosis OR liver cirrhosis. All references were imported into an EndNote 20.5 reference manager software file. Duplicate references were electronically removed and subsequently reviewed manually. Titles and abstracts were independently assessed by three authors . Later, full-text articles were reviewed for inclusion by three authors , and any disparities were discussed and resolved by consensus (F.G). Finally, references from eligible studies were also reviewed to identify potential studies missed by the electronic search.The following inclusion criteria were applied: (1) studies including patients with established diagnosis of IBD; (2) studies assessing prevalence and/or risk factors of liver fibrosis in patients with NAFLD or MAFLD; and (3) observational studies, with or without control group.Studies were excluded in case of: (1) absence of original data ; (2) conference communications; (3) non-human studies; (4) studies involving only non-IBD patients or when IBD population data could not be identified; (5) absence of data regarding liver fibrosis in participants with NAFLD or MAFLD; and (6) studies focusing on patients with IBD receiving hepatotoxic drugs.Each included study was critically reviewed by three authors  and disparities were resolved by consensus among all authors. The following data was extracted from the selected studies: first author, year of publication, study location, study design, sample size, age, gender, Body Mass Index (BMI), IBD type, IBD therapy, prevalence of NAFLD and liver fibrosis, and risk factors for NAFLD and liver fibrosis.NAFLD was defined as the presence of liver steatosis after exclusion of significant alcohol consumption and secondary causes of fat accumulation in the liver . MALFD wThe prevalence of NAFLD and liver fibrosis was calculated, including all studies with available information. Absolute frequencies were estimated when only relative frequencies were reported. Data from longitudinal studies were obtained from the beginning or end of follow-up depending on the study design and the available information  by three authors . Disagreements were solved thorough discussion among all authors. Studies were considered to have low risk of bias if they achieved at least 7 stars. NOS for cohort and case-control studies is compound by 8 items: 4 items for the selection of exposed/non-exposed group or cases/controls groups, 1 item for the comparability of the groups, and 3 items for outcome evaluation/ascertainment of exposure. A maximum of 1 star can be assigned to each item except for comparability, which can be assigned 2 stars  . NOS scaThe flow diagram of study retrieval for the systematic review is detailed in All the included studies were observational, including 10 43.5%) cross-sectional studies ,40,46,48.5% crossRegarding the diagnostic method for NAFLD, 3 performed a retrospective review of database records ,35,42, 22, except participants included by Bessisow 2016, Veltkamp 2022, and Yen 2021 [A total of 629,781 participants were included, 220,128 35%) with IBD and 409,653 (65%) without IBD at enrolment. CD was the most frequent IBD type with 218,162 (99.1%) participants, followed by UC with 1907 (0.9%) patients. Sample size ranged from 35 (0.01%) patients  to 405,4Yen 2021 ,48,49. DYen 2021 ,40. ThioYen 2021 ,45,46,48Yen 2021 ,39,45,48Yen 2021 ,35,37,41% with IBNOS scores for risk of bias assessment are shown in NAFLD was diagnosed in 2162 34.1%) patients of a total of 6332 IBD participants included in 18 studies .1% patie,47,48,49Data on liver fibrosis were reported heterogeneously in the different studies. Advanced liver fibrosis was found in 116 (11.6%) of 992 IBD patients with NAFLD included in six studies ,33,42. TMost studies found an association between NAFLD and classic cardiovascular risk factors such as older age, male sex, higher BMI, type 2 diabetes, arterial hypertension, and dyslipidemia. In fact, Spagnuolo (2019) demonstrated that weight gain is a predictor of steatosis worsening . RegardiIn parallel, metabolic syndrome features were also associated with an increased risk of significant liver fibrosis ,36,40,46This systematic review reported the prevalence and risk factors associated with NAFLD and liver fibrosis in patients with IBD. In the last few months, several articles focused on NAFLD and IBD ,38,46,48Due to the heterogeneous report of liver fibrosis status, we estimated a prevalence of advanced liver fibrosis of 11.6% including information from six studies ,32,33,42Unfortunately, we did not find studies reporting the prevalence and/or risk factors of HCC specifically performed in the IBD population. However, a recent study assessed the effect of immune checkpoint in patients with pre-existing IBD, finding that approximately 40% patients experienced relapse of IBD with a rate of discontinuation of 35% . ConversMany studies have investigated the elements involved in fibrosis progression . In thisGenetic factors can also influence the risk of disease progression, fibrosis and HCC. The polymorphism p.I148M of the PNPLA3 gene has been linked to an increased risk of NAFLD, NASH, HCC, and liver-related mortality . It is oThe development of HCC in non-cirrhotic patients with NASH suggest that other pathogenic ways independent of fibrosis can lead to carcinogenesis, so some studies have investigated the role of the microbiota, metabolic changes, and immune and fibrotic cells . There iBile acids are produced in the liver through cholesterol oxidation, secreted into the duodenum and conjugated by gut microbiota in order to facilitate the absorption of fatty acids and also to activate the Farnesoid X Receptor (FXR) of the enterocytes, which regulates the enterohepatic circulation and play an important role in the glucose metabolism . DysbiosConcerning the role of metabolic changes, the development of NASH is secondary to the accumulation of free fatty acids in the liver with an increase in the gluconeogenesis, which leads to higher levels of glucose and more conversion to fatty acids ,71. WhenInnate but also adaptive immunity seem to play an important role in the development of fibrosis and HCC, since in NAFLD the continuous inflammatory response ends up producing dysregulation of the immune system with immunosuppression and tumor tolerance. Monocyte-derived macrophages form complexes with dead steatotic hepatocytes triggering a pro-fibrotic response, which could be involved in carcinogenesis . NeutropIn conclusion, liver fibrosis is an independent risk factor for HCC but NAFLD HCC can also occur in absence of cirrhosis, so other elements should be considered in this population ,76,77. MFinally, we acknowledge the following limitations of our study. First, the different study designs of included studies and the high rate of uncontrolled studies. Second, the heterogeneity of diagnostic methods and cut-offs used for NAFLD and liver fibrosis diagnosis. Third, the variability of data reported by each study, especially for liver fibrosis. Fourth, the absence of solid evidence on the prevalence and specific risk factors of HCC in patients with concomitant IBD and NAFLD. Nevertheless, the strengths of the study are its large sample size, the high rate of recently published articles and that, on average, the quality of the included studies was high. Our findings are clinically relevant as they reveal the magnitude of a comorbidity, whose adequate prevention and treatment could improve the prognosis and quality of life of the IBD population.NAFLD is a prevalent extraintestinal manifestation in patients with IBD and it can promote HCC thorough liver fibrosis development, although not exclusively. The presence of advanced liver fibrosis is not rare in the IBD population with NAFLD, especially in those suffering from Crohn´s Disease. Therefore, the presence of NALFD should be considered in patients with IBD, especially in association with additional risk factors. After diagnosis, hygienic-dietary measures should be initiated and evolution should be monitored to prevent complications, such as cirrhosis or HCC. Future studies are needed to evaluate the prevalence and specific risk factors of HCC in IBD population with NAFLD.


Nonalcoholic fatty liver disease (NAFLD), the most widespread chronic liver disease worldwide, confers a significant burden on health systems and leads to increased mortality and morbidity through several extrahepatic complications. NAFLD comprises a broad spectrum of liver-related disorders, including steatosis, cirrhosis, and hepatocellular carcinoma. It affects almost 30% of adults in the general population and up to 70% of people with type 2 diabetes (T2DM), sharing common pathogenetic pathways with the latter. In addition, NAFLD is closely related to obesity, which acts in synergy with other predisposing conditions, including alcohol consumption, provoking progressive and insidious liver damage. Among the most potent risk factors for accelerating the progression of NAFLD to fibrosis or cirrhosis, diabetes stands out. Despite the rapid rise in NAFLD rates, identifying the optimal treatment remains a challenge. Interestingly, NAFLD amelioration or remission appears to be associated with a lower risk of T2DM, indicating that liver-centric therapies could reduce the risk of developing T2DM and vice versa. Consequently, assessing NAFLD requires a multidisciplinary approach to identify and manage this multisystemic clinical entity early. With the continuously emerging new evidence, innovative therapeutic strategies are being developed for the treatment of NAFLD, prioritizing a combination of lifestyle changes and glucose-lowering medications. Based on recent evidence, this review scrutinizes all practical and sustainable interventions to achieve a resolution of NAFLD through a multimodal approach. Before the middle of the last decade, the worldwide prevalence of non-alcohol fatty liver disease (NAFLD) was approximately 25% in adult individuals. NAFLD is currently defined as an ectopic accumulation of lipids in the liver in the absence of secondary causes or other etiologies of liver disease ,2. It isIn the 21st century, among other metabolic diseases, diabetes mellitus has become the main concern for societies and health care systems. In particular, T2DM is mentioned to affect 1 in 11 adults and up to 463 million people worldwide . This tyThe development of NAFLD is an intricate process and is not completely understood. The liver, as is widely known, promotes many functions through the mobilization, regulation, and storage of nutrients. Hepatocytes play an essential role as regulators of amino acid, triglyceride and lipoprotein metabolism, gluconeogenesis, and ketogenesis . InteresIn a small percentage of patients, NAFLD is associated with infectious pathologies that can lead to the appearance of liver steatosis, such as hepatitis C and the human immunodeficiency virus (HIV). In some cases, it is related to medications  and specific toxins or acquired/inherited metabolic diseases such as cachexia, lipodystrophy, or even gastrointestinal surgery ,18.The development of NASH has been reported to be divided into two phases. The first is fatty deposition in the liver combined with an increase in insulin resistance. The second phase is related to cellular and molecular changes, including primarily oxidative stress and oxidation of fatty acids through lipid peroxidation, hyperinsulinemia, energy homeostasis, variation in the extracellular matrix, and changes in immune system function ,20. ConsRobust evidence suggests that there is a strong and bidirectional relationship between the progression of NAFLD and T2DM. High levels of diacylglycerol or ceramides can affect liver–insulin signaling, leading to an abnormal increase in liver insulin resistance . FurtherIt should be noted that several studies have shown that improvements in insulin sensitivity have been positively associated with histological improvements in NAFLD/NASH and regression of fibrosis . In 2013The purpose of this narrative review is to summarize the current literature on modern therapeutic approaches to NAFLD in patients with and without diabetes, focusing on the targeting of metabolic disturbances. Another purpose is to discuss future potential treatments and knowledge gaps in the therapy of NAFLD.The therapeutic quiver of NAFLD consists of several levels, of which lifestyle, pharmaceutical, and surgical approaches are the main treatments. A multimodal intervention with multiple aspects, such as lifestyle modification, weight loss, specific diets, and medication, is the most appropriate and holistic approach for most people with NAFLD.Robust evidence supports the crucial role of lifestyle changes as primary options for the treatment of NAFLD. These approaches, which include diet, exercise, or physical activity, mainly aim to control metabolic status . LookingWeight loss is a gold standard therapy for most patients with NAFLD and can regress liver disease, along with the reduction of cardiovascular disease and the risk of T2DM . Some reA clinical trial by Holmer et al., which recruited 74 patients with NAFLD, indicated that intermittent calorie restriction and a low carbohydrate high fat diet (LCHF) are more effective in reducing liver steatosis and body weight compared to general lifestyle modification. Participants were randomized into 3 groups: intermittent calorie restriction, including 500 kcal/day for women and 600 kcal/day for men; LCHF, with an average daily calorie intake of 1600 kcal/day for women and 1900 kcal/day for men; and general lifestyle advice . FurtherIn addition to the above, it should be noted that some studies reported the beneficial effect of diabetes remission on NAFLD and pancreatic morphology. In 2020, a post hoc analysis of the DiRECT trial showed changes in the gross morphology of the pancreas 2 years post T2DM remission. The size of the pancreas had increased in patients who achieved remission and weight loss, compared to those who did not respond to the weight loss intervention. Intrahepatic fat and levels of FGF-21 and FGF-19 also decreased. However, it is notable that there is no significant increase in pancreas volume after 6 months of reversal of type 2 diabetes . AdditioNumerous studies have corroborated the pivotal role of certain macronutrients in the initiation and progression of NAFLD, regardless of caloric intake. In particular, macronutrients such as saturated fatty acids (SFA), trans fats, simple sugars such as sucrose and fructose, and animal proteins are known to inflict damage on the liver through the accumulation of triglycerides and impaired antioxidant activity, compromising insulin sensitivity and postprandial triglyceride metabolism . In contFurthermore, Halima et al. conducted a study investigating the impact of apple cider vinegar on rats with diabetes and demonstrated that in addition to its potent antihyperglycemic properties, it also exhibited a crucial hepatoprotective effect. In particular, indicators of liver toxicity, namely ALT, AST, total and direct bilirubin, as well as levels of TC, TG, and LDL-c, demonstrated a significant reduction, which was particularly prominent after four weeks of treatment, together with an elevation in HDL-c . These f2) [The potential effects of bariatric surgery on liver fat disease may extend beyond weight loss. In fact, serum concentrations of glucagon-like peptide-1 (GLP-1) increase after metabolic surgery, leading to decreased appetite, slower gastric emptying, and improved insulin sensitivity . Further2) ,79. Alth2) .The most common bariatric surgery procedures include adjustable gastric band (AGB), biliopancreatic diversion (BPD), vertical sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB). Consequently, different methods might induce variable biological effects depending on the surgical procedure. The most common metabolic operations are SG and RYGB. In the first, about 80% of the stomach portion is removed along the gastric greater curvature and the small dimensions of the stomach, along with the changes in the hormonal environment, reduce hunger and delay gastric emptiness. In the second procedure, the stomach is separated into a smaller pouch in the smaller curvature (through stapling) and anastomosed with the jejunum ,82. In fIt is well established that fatty liver and T2DM are the two sides of the same coin, sharing common pathogenic pathways and factors such as insulin resistance. Although the coexistence of fatty liver and T2DM is increasing, the treatment is not adequate. Due to this close link between T2DM and NAFLD, various glucose-lowering drugs have been used as NAFLD therapeutics. Numerous clinical trials have shown the beneficial effects of GLP-1 receptor agonists, insulin-sensitizing thiazolidinediones, and sodium-glucose cotransporter 2 (SGLT2) inhibitors on liver fat content. GLP-1 binds to a specific GLP-1 receptor, whose activation can promote the reduction of liver steatosis by improving insulin signaling pathways, hepatocyte lipotoxicity, and mitochondrial function ,96. On tIt is significant to mention that a multitude of studies have recently elucidated the efficacy of SGLT2 inhibitors in alleviating liver steatosis. Of particular interest, in 2018, Shibuya et al. revealed, for the first time, the statistically significant and advantageous impact of luseogliflozin, compared to metformin, on NAFLD and weight loss . The resThiazolidinediones increase peripheral insulin sensitivity by stimulating adipokines, promoting triglyceride storage in adipose tissue, and improving the suppressive action of insulin on lipolysis . In thisRecently, semaglutide and tirzepatide have been added to the therapeutic quiver against T2DM and obesity. Semaglutide is a GLP-1 analogue, and tirzepatide is a dual analogue of GLP-1 and GIP (glucose-dependent insulinotropic polypeptide) . Both deRealizing that NALFD is strongly related to metabolic syndrome, there is a need for an integrated approach for individuals with a high liver fat content. The definition of metabolic syndrome includes the following criteria: abdominal obesity, with waist circumference of ≥90 cm in men or ≥85 cm in women; low high-density lipoprotein (HDL) cholesterol with HDL-cholesterol of <40 mg/dL in men and <50 mg/dL in women; hypertriglyceridemia with triglyceride (TG) of ≥150 mg/dL; high systolic blood pressure (BP), with systolic BP of ≥130 mmHg and/or diastolic BP of ≥85 mmHg; or hyperglycemia, with fasting plasma glucose (FPG) of >100 mg/dL ,126. ConFurthermore, the category of omega-3 polyunsaturated fatty acids (n-3 PUFAs), such as a-linolenic acid (a-ALA), stearidonic acid (SDA), eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA), has a beneficial effect on peripheral insulin sensitivity and on triglycerides levels, leading to a lower deposition of liver fat . A randoAlthough statins have long been used as a widely accepted method for reducing cholesterol and minimizing the risk and mortality associated with cardiovascular disease, recent years have seen increasing scrutiny of their potential side effects. It should be noted, in particular, the increasing evidence linking prolonged statin use with diabetes progression and ectopic fat deposition, particularly in the kidneys of patients with diabetic nephropathy . RecentlMore recently, new potential drugs for NAFLD have been studied. The most common treatment targets are the farnesoid X receptor (FXR), a nuclear receptor, and obeticholic acid (OCA), which is a synthetically modified analogue of chenodeoxycholic acid . These a2 or >27 kg/m2 in the presence of at least one metabolic comorbidity, because it can lead to the remission of diabetes and improves the progression of fatty liver disease [During recent years, weight loss pharmacotherapy has been an attractive option for patients with NAFLD, with or without T2DM and with a BMI > 30 kg/m disease ,146. Τhe disease . In 2005 disease . In cont disease .As previously stated, two recently approved drugs, tirzepatide, a dual analogue of GIP/GLP-1, and semaglutide, a GLP-1 analogue, were added to the therapeutic arsenal of NAFLD . A phaseTirzepatide is associated with a significant reduction in liver fat content (LFC), subcutaneous abdominal adipose tissue (ASAT), and volume of visceral adipose tissue (VAT) ,153. A mIn 2020, Hartman et al. determined the result of tirzepatide on the biomarkers of NASH and fibrosis in people with diabetes. A reduction in ALT, AST, keratin-18 (K-18), and N-terminal pro-peptide of type III collagen (Pro-C3) levels was revealed, combined with a significant increase in adiponectin levels that was dose-dependent . It is aSemaglutide has also been effective in improving liver biochemistry. A prospective study by Volpe et al. showed a significant decrease in glucometabolic parameters, liver enzymes, and laboratory indicators of liver steatosis during therapy, as well as a reduction in fat mass and VAT. Interestingly, liver steatosis improved in 70% of participants after 52 weeks of treatment . FurtherRecently, an open-label phase 2 trial by Alkhouri et al. reported that the combination of semaglutide with cilofexor and firsocostat achieved greater improvements in liver steatosis and biochemistry profile than monotherapy . Based oFuture studies are expected to add additional evidence on the effects of new antidiabetic agents on NAFLD progression and clarify whether the benefits are driven primarily by weight loss or by the pleiotropic actions of the drugs.The review of available evidence supports the notion that NAFLD is an important risk factor for the development of T2DM, but also underlines the bidirectional relationship between these conditions. Despite many advances in our knowledge on the epidemiology and pathogenesis of NAFLD, the most established treatment so far is intensive weight loss. The importance of weight reduction is highlighted in people with NASH, where weight loss greater than 7% is associated with a clinically significant regression of disease status . ExercisToday, the question is no longer whether lifestyle modification is an effective clinical therapy, but how we implement lifestyle as a therapy in daily clinical care. However, most studies indicate several barriers to maintaining a healthy lifestyle in the long term and that weight regain is very common among people with diabetes and/or obesity, making the use of pharmacotherapy a necessity in most cases. In this context, a better understanding of the mechanisms linking NAFLD and T2DM will help design targeted therapies that can stop or reverse disease progression.


A characteristic of nonalcoholic fatty liver disease (NAFLD) is the buildup of excess fat in the liver which encompasses various clinical phases, including steatosis, inflammation, ballooning, fibrosis, and liver cirrhosis. Nonalcoholic steatohepatitis (NASH) represents a severe form of NAFLD. The prevalence of NAFLD, particularly NASH, is notably high among Hispanics and those with morbid obesity. Diabetes, obesity, and dyslipidemia are significant risk factors in patients with NAFLD. The pathogenesis of NAFLD involves complex interactions between hormonal, nutritional, and genetic factors. Different clinical trials have been conducted to determine if there are any supplements that could help patients with NASH. Evidence has shown that vitamin E decreased the NAFLD activity score but not fibrosis. Our review summarizes the influence of supplementation on patients with NAFLD and NASH, focusing on the use of different clinical trials, systematic reviews, and meta-analyses. In the future, patients and physicians will play crucial roles in exploring diverse approaches and finding effective solutions to address this growing issue. Nonalcoholic fatty liver disease (NAFLD) is a condition in which excess fat is stored in the liver . The livObesity and related ailments, such as cardiovascular diseases and type 2 diabetes mellitus (T2DM), have been linked to oxidative stress, which has been recognized as a major contributing factor in NAFLD . ThroughSearch strategyUsing NAFLD, NASH, supplement use in NASH and NAFLD, epidemiology, risk factors, and pathophysiology of NASH and NAFLD as research keywords, articles were reviewed to illustrate and analyze the role of supplements in the improvement of NAFLD, NASH, and liver function tests. Studies published between 2011 and 2023 were considered for inclusion in this review. Medline was used as the primary database. Data were collected from literature reviews, systematic reviews, meta-analyses, and several types of clinical trials, cohort studies, and retrospective studies. There were no age or ethnicity limitations to the search. Only articles published in the English language were included in this review.This section will discuss the epidemiology, risk factors, and pathophysiology of NAFLD and NASH; the role of multiple kinds of supplements in both diseases; and how supplements can benefit NASH patients and improve their liver function tests.Epidemiology of NAFLDThe incidence and prevalence of NAFLD are increasing quickly around the globe, ranging from 13% in Africa between 1989 and 2015 to 40% in Southeast Asia between 1999 and 2019 . The preRisk factors of NAFLDDiabetes and obesity are major risk factors in patients with NAFLD . T2DM haPathophysiology of NAFLD and NASHThe pathogenesis of NAFLD and NASH is multifactorial, and many mechanisms have been proposed as possible causes of fatty liver infiltration . In receRole of supplements in NAFLD and NASHSilybum marianum), can mitigate lipid peroxidation and free radical injury [Curcuma longa Linn, has reportedly been effective in reducing oxidative stress and inflammatory cascades [Vitamin E is a naturally occurring fat-soluble vitamin with the reputation of being a crucial antioxidant . The PIVl injury . Five mel injury . Curcumicascades . In a plcascades . Hepaticcascades . Omega-3cascades . A meta-cascades . In a 12cascades . Improvecascades .Synbiotics are formulas containing probiotics plus prebiotics . A probiNASH is rapidly rising worldwide and is the fastest-growing cause of liver cancer death globally, especially in the Spanish community. Lifestyle plays a significant role according to new data. Therefore, it is important to study the role of supplements and how they benefit patients with NAFLD and NASH. According to numerous studies published in the last 10 years, supplementation plays a role in helping NAFLD and NASH patients by improving liver function tests and other factors; however, no significant improvement has been reported in the level of fat in the liver or improvement in any scarring tissue. Both physicians and patients should be educated about the disease and lifestyle changes, encouraging patients to participate in ongoing pharmaceutical clinical trials worldwide to help find a new solution.


Nonalcoholic fatty liver disease (NAFLD), recently renamed metabolic dysfunction-associated steatotic liver disease (MASLD) affects ~70% of patients with type 2 diabetes (T2D), with ~20% showing signs of advanced liver fibrosis. Patients with T2D are at an increased risk of developing cirrhosis, liver failure, and hepatocellular carcinoma and their liver-related mortality is doubled compared with non-diabetic individuals. Nonetheless, the condition is frequently overlooked and disease awareness is limited both among patients and among physicians. Given recent epidemiological evidence, clinical practice guidelines recommend screening for NAFLD/MASLD and advanced liver fibrosis in patients with T2D. While many drugs are currently being tested for the treatment of NAFLD/MASLD, none of them have yet received formal approval from regulatory agencies. However, several classes of antidiabetic drugs  have shown favorable effects in terms of liver enzymes, liver fat content and, in some occasions, on histologic features such as inflammation and fibrosis. Therefore, diabetologists have the opportunity to actively treat NAFLD/MASLD, with a concrete possibility of changing the natural history of the disease. In the present narrative review, we summarize evidence and clinical recommendations for NAFLD/MAFLD screening in the setting of T2D, as well as on the effect of currently available glucose-lowering drugs on hepatic endpoints. Nonalcoholic fatty liver disease (NAFLD), recently renamed metabolic dysfunction-associated fatty liver disease (MAFLD)  or metabIn a recent study in patients with NAFLD/MASLD studied with paired liver biopsies, even after adjustment for potential confounders, the presence of T2D was associated with a 70% increase in the relative risk of fibrosis progression . While pImportantly, the degree of liver fibrosis is the most important histologic predictor of future development of liver-related events, as shown by several cohort studies and meta-analyses ,17. The In the present narrative review, we will provide the reader with a practical summary of available evidence and guideline recommendations on screening, diagnosis, and treatment of NAFLD/MASLD in patients with T2D. We will also focus on the effect of currently available and future antidiabetic medication on liver-related endpoints.Liver biopsy remains the established and most reliable method for assessing the severity of NAFLD/MASLD as it allows for a comprehensive evaluation of the three histologic aspects of the disease: steatosis, inflammation, and fibrosis. Nonetheless, this procedure is invasive and not well-received by patients  and it cInternational guidelines recommend the use of a conventional liver ultrasound as a first-line diagnostic technique to be applied in clinical practice for the diagnosis of steatosis (and therefore NAFLD/MASLD itself) and suggest that all patients with T2D, independently from liver enzymes levels, should be screened for steatosis with an ultrasound examination ,27,28. EWhile magnetic resonance spectroscopy (MRS) or magnetic resonance imaging-Proton Density Fat Fraction (MRI-PDFF) have higher accuracy in identifying and quantifying intrahepatic fat compared with ultrasound , their uFinally, Controlled Attenuation Parameter (CAP), a measure that can be obtained concomitantly with the liver stiffness measurement (LSM) using vibration-controlled transient elastography (VCTE), has gained attention as a rapid and inexpensive technique to detect and quantify liver fat . The CAPGiven the prominent role of liver fibrosis in determining the prognosis of patients with NAFLD/MASLD and the difficulties encountered in the development of accurate biomarkers of inflammation, efforts have been made to identify accurate and readily available non-invasive methods to detect and stage liver fibrosis. Ideally, biomarkers should possess more than just diagnostic capabilities when compared to the current gold standard technique of liver biopsy. They should also have the ability to predict future liver-related events, facilitate disease monitoring over time, and indicate the effectiveness of a specific intervention . RegrettNonproprietary algorithms utilizing common clinical and biochemical variables (indirect markers of fibrosis) are simple blood tests easily accessible in routine clinical practice, and they are correlated with histologic identification of advanced fibrosis. The most validated and applied are the FIB-4  (based oProprietary blood tests are designed with specific markers directly related to various elements of the extracellular matrix (ECM). In contrast to simple blood tests, these proprietary tests provide a more accurate representation of the dynamic processes involved in ECM deposition (fibrogenesis) and reorganization (fibrolysis). Many of these scores , commercially available as Fibroscan by Echosens, was the first to be introduced and is currently the most extensively validated . AlthougFollowing that, elastography methods have been integrated into ultrasound devices using distinct technologies, such as point shear wave elastography (p-SWE) and two-dimensional shear wave elastography (2D-SWE) . DespiteMost of these limitations can be addressed through the application of magnetic resonance elastography (MRE). MRE employs specific hardware to generate a pulse sequence, and the acquired data are then processed by dedicated software to create a color elastogram of the entire liver . Althougn = 3202) [Several studies investigated whether combining either simple scores with patented ones or simple scores with imaging modalities could increase the accuracy in identifying the minority of patients with NAFLD/MASLD and advanced liver fibrosis, in order to facilitate referral to hepatologists for adequate management. For instance, a baseline analysis of the STELLAR trials, which evaluated the efficacy of selonsertib in patients with NASH, evaluated possible concomitant or sequential combinations of several noninvasive methods in a large population of patients evaluated by liver biopsy ( = 3202) . The autThe first guidelines to recommend generalized screening for NAFLD/MAFLD in patients with T2D were published in 2016 by EASL, the European Association for the Study of Diabetes (EASD) and the European Association for the Study of Obesity (EASO) . This muWhile these guidelines represent a fundamental effort to achieve a systematic approach to the problem, several reports have underlined a potential for over-referral of patients in the setting of T2D or obesity clinics ,57. MoreIn the following years, data have accumulated on the performance of combining different methodologies and on the high prevalence of advanced fibrosis and cirrhosis in patients with T2D ,8,44,56.The first step is FIB-4 calculation, and if a value ≥ 1.3 is obtained, VCTE should be performed. If the LSM value is ≥8 kPa, the patient should be referred to the hepatologist, while advanced fibrosis can safely be excluded if a lower value is obtained .This strategy has generally been implemented in other recent guidelines from several international hepatologic and endocrinologic societies. In 2023, AASLD published new guidelines in which they recommended screening for advanced fibrosis in all patients with T2D, which was considered a condition facilitating progression towards cirrhosis . SimilarAs a summary, agreement on the need for systematic screening for NAFLD/MASLD, but most importantly for advanced liver fibrosis, has increased progressively in the last decade. Most international societies also recommend similar two-step algorithms in which a simple inexpensive blood test is performed first and more specialized tests are only performed in the case of uncertainty on the first. Our data on patients with T2D suggest that FIB-4 excludes advanced fibrosis in 55–60% of patients , leavingThe important favorable effect of lifestyle interventions and bariatric surgery on histologic features of NAFLD/MASLD were demonstrated in multiple observational studies . As a coNonetheless, diabetologists are in a position of favor, as some drugs currently used to treat T2D itself have shown some efficacy on liver disease endpoints as well. Here, we report results with drug classes currently used for the treatment of T2D that were studied in RCTs on different NAFLD/MASLD endpoints. A summary of current evidence is also provided in The rationale for employing pioglitazone is based on its activation of peroxisome proliferator-activated receptor gamma (PPARγ), which can exert a significant impact on the pathophysiology of NAFLD/MASLD. By ameliorating insulin resistance, modulating lipid and glucose metabolism in a favorable manner, and reducing hepatic and gastrointestinal inflammation, pioglitazone contributes to a reduction in portal hypertension, splanchnic inflammation, angiogenesis, and porto-systemic shunts .Based on a post-hoc analysis involving 55 patients with biopsy-proven NASH, treatment with pioglitazone appears to result in changes in body fat distribution, specifically a decrease in the visceral-to-subcutaneous fat ratio, and biochemical alterations, including an increase in plasma adiponectin levels, when compared to the control group. These changes reflect the mechanism by which this drug contributes to the reduction of steatosis and necroinflammation in NASH patients .In the literature there are several randomized controlled trials (RCTs) conducted in different parts of the world  which involve patients with or without T2D and biopsy-proven NAFLD/MASLD. A phase 2 meta-analysis published by Musso et al. encompasses eight RCTs, involving approximately 500 patients with biopsy-proven NASH, who were treated with thiazolidinediones . These tAccording to the European guidelines (EASL-EASD-EASO), pioglitazone may be used in the treatment of NAFLD/MASLD in individuals with type 2 diabetes (off-label in those without type 2 diabetes). On the other hand, the American guidelines (AASLD), in line with UK guidelines (NICE), suggest the use of pioglitazone only in diabetic individuals with NAFLD/MASLD . The recThe GLP-1 receptor agonists (GLP-1 RAs) play a direct and indirect role in the pathophysiology of NAFLD/MASLD. They increase insulin levels, thereby reducing hepatic gluconeogenesis. Additionally, GLP-1 RAs decrease lipolysis and the influx of free fatty acids in the liver. These agents may also contribute to reducing inflammation and apoptosis, promoting tissue remodeling, and increasing adiponectin levels. However, most importantly, they induce weight loss .p = 0.019). Moreover, two (9%) of twenty-three patients in the liraglutide group versus eight (36%) of twenty-two patients in the placebo group had progression of fibrosis  [The first RCT conducted to evaluate the effect of a GLP1-RA on histologic liver endpoints was the Phase 2 LEAN trial, in which 26 patients were randomly assigned to receive liraglutide and 26 to placebo. This relatively small study showed positive results as nine (39%) of twenty-three patients who received liraglutide had NASH resolution, compared with two (9%) of twenty-two in the placebo group  .2 value of 0.791. This supports the idea that the effect of GLP-1 RAs on NAFLD/MASLD endpoints is mostly driven by their capacity to promote weight loss [The effectiveness of GLP-1 RAs has been recently summarized in a meta-analysis that included 11 placebo-controlled or active-controlled phase-2 RCTs involving a total of 936 middle-aged individuals . These tght loss .n = 3) or vildagliptin (n = 1) to specifically treat NAFLD/MASLD [The role of DPP4 inhibitors (DPP4-i) in NAFLD/MASLD is considered minimal. Although these drugs can reduce HbA1c levels, they have a neutral effect on weight. There are four placebo-controlled or active-controlled RCTs that used either sitagliptin (LD/MASLD . These RSGLT2 inhibitors (SGLT2-I) induce a series of modifications that have the potential to improve the liver condition in individuals with NAFLD/MASLD: they improve glycemic profile, reduce visceral adipose tissue, increase plasma adiponectin levels, and decrease uric acid levels; they also diminish oxidative stress and systemic inflammation and increase glucacon levels .n = 6 RCTs), empagliflozin (n = 3 RCTs), ipragliflozin (n = 2 RCTs), and canagliflozin (n = 1 RCT), administered for a median period of 24 weeks. The subjects included in these studies were predominantly diabetic (≃90%), and NAFLD/MASLD was diagnosed through imaging. From the meta-analysis of these studies, it is evident that SGLT2-I, compared to the control group (placebo or reference therapy), led to a significant reduction in the percentage of hepatic fat as evaluated by MRI. Currently, there are no published RCTs that utilize histological hepatic endpoints. According to most international guidelines, SGLT2-I are considered safe for patients with liver diseases, but their specific use for the treatment of NAFLD/MASLD is not yet recommended.Twelve RCTs involving the use of these drugs for the specific treatment of NAFLD/MASLD were conducted in different parts of the world  . The SGLMetformin is the first-line drug in the treatment of diabetes and can reduce gluconeogenesis and liponeogenesis, lower systemic inflammation, increase GLP1 levels, and modify intestinal microbiota, all of which have potential beneficial effects on the liver .In the literature, there are trials conducted in various parts of the world that involve the use of metformin in diabetic, non-diabetic, or prediabetic patients with NAFLD/MASLD diagnosed through biopsy or imaging. It has been observed that metformin can reduce liver steatosis, leading to a significant decrease in transaminase levels . However, it does not have a significant effect on fibrosis and resolution of NASH . The AISTirzepatide, a dual glucose-dependent insulinotropic polypeptide (GIP) and GLP-1 receptor agonist, has demonstrated superiority compared with GLP1-RA on both glycemic control and weight loss, and achieved favorable effects on hepatic endpoints. In a substudy of the SURPASS-3 trial, which enrolled exclusively patients with T2D, tirzepatide showed a significantly greater reduction in liver fat content (LFC), volume of visceral adipose tissue (VAT), and abdominal subcutaneous adipose tissue (ASAT) compared to insulin degludec . These rRetatrutide (RETA), a once-weekly injectable triple hormone agonist of the GIP, GLP-1, and glucagon receptors, has also shown promise in the treatment of obesity. In a phase 2 obesity trial, RETA treatment resulted in substantial reductions in body weight (up to 24%) . In a suRecommendations of international societies on screening and pharmacological treatment of NAFLD/MASLD in patients with T2DM are summarized in NAFLD/MAFLD and T2D are tightly linked in a strong, bidirectional relationship. Given the extremely high disease prevalence, referral of all affected patients to hepatologists is not feasible or cost-effective. Diabetologists are therefore called to actively screen and risk-stratify patients to identify those that are at higher risk of clinically relevant liver-related outcomes. Current guidelines recommend a two-step strategy in which a simple blood-based score such as FIB-4 is followed (if advanced fibrosis cannot directly be excluded) by an imaging technique (most commonly VCTE). This screening procedure does not only aim to identify patients to refer to the hepatology clinic, but also to inform treatment. Indeed, while no specific agent has been approved with the indication to improve NAFLD/MASLD outcomes, several glucose-lowering agents showed some efficacy on hepatic endpoints in dedicated RCTs. In particular recent guidelines recommend pioglitazone or GLP1-RA in patients with T2D and biopsy-proven NASH or those at a high risk of advanced liver fibrosis. We believe that diabetologists are currently in a privileged position to actively treat patients with T2D not only to reduce their risk of developing micro- and macro-vascular complications, but also to reduce the disease burden associated with cirrhosis and hepatocellular carcinoma.