Human Auto-ethanol Formation and Acetate Signaling

The HotFacets study is a randomized, controlled, cross-over meal study that investigates the acute effects of alcohol consumption on short-chain fatty acids dynamics, energy metabolism, and biomarkers.

Despite the negative health consequences of chronic alcohol abuse, observational and cohort studies associate moderate alcohol consumption with a 20-30 % lower risk of cardiovascular diseases (CVD) and Type 2 Diabetes Mellitus (T2DM), compared to abstainers. Based on the J-shaped relationship between alcohol intake and the risk of cardiometabolic diseases, ½-2 standard drinks/day can be considered as moderate alcohol consumption. The interpretation of the J-shaped relationship has been criticized mainly due to potential confounding from the selected reference group and uncontrolled lifestyle factors. Longer, well-designed randomized controlled trials are lacking to infer causality and to clarify the mechanism of action for the acute and chronic effects of moderate alcohol consumption on cardiometabolic health and energy homeostasis. However, some aspects of alcohol metabolism and biomarker validation could inform such a study.

HotFacets is set to generate insight into the effects of acute alcohol intake on SCFA dynamics in blood, urine, and faeces; into the dose-response relationship with REE, thermogenesis, substrate oxidation, and alcohol biomarkers; and to explore potential low levels of alcohol produced in the gut.

A randomized, controlled, four times cross-over, single-blinded, meal study with 24 healthy fasting subjects will be conducted with a) placebo (water), b) a metabolic acetate generator (triacetin), and c) a half or d) one unit of isotope labelled ethanol, provided in a randomized order. Volunteers will be confined in a metabolic chamber overnight before each test drink (in 250mL water with lemon and juniper taste) and energy production and expenditure will be measured initially using seven ventilated hood measurements. After the test drinks and ventilated hood measurements an ad libitum lunch will be served before the participants will be admitted to the metabolic chamber, where metabolic measurements will be continued until the following day. Participants will go through a 2-week run-in period before each test drink and a 2-week wash out period afterwards, both with alcohol abstention. From two days before the test day in each period until one day after the test days, standardized foods will be provided. Anthropometrics, DXA, heart rate, blood pressure and all movements will be recorded before and/or during the test days. Before, during, and after the test day repeated biological samples (i.e., urine, blood, feces, hair) will be collected. The study will be divided into a pre-trial (8 subjects, 50-75y) and a main trial (16 subjects, 25-75y).

Eligibility Criteria:
Subjects will be recruited to the trial in two seasons. First, eight healthy men and post-menopausal women 50-75 years will be recruited for the pre-trial during autumn/winter 2021. Secondly, 16 healthy men and women with an age-range of 25-75 years will be recruited for the main trial during late spring/summer 2022.

Age-specific inclusion criteria for the pre-trial:

* Healthy men and healthy, post-menopausal women (12 consecutive months without menstrual period)
* Age: 50-75 years old
* BP ≤ 140/90 (systolic/diastolic)
* Plasma glucose \<7 mmol/l
* BMI: 18.5-27 kg/m2
* Subjects with a good command of both written and verbal English

Age-specific inclusion criteria for the main-trial:

* Healthy men and women
* Age: 25-75 years old
* BP ≤ 140/90 (systolic/diastolic)
* Plasma glucose \<7 mmol/l
* BMI: 18.5-27 kg/m2

Inclusion criteria for the pre- and main-trial:

* Willing to provide registration of compliance during the run-in period and follow-up periods
* Willing to avoid drinking alcohol for 2 weeks before the first test day and between test days
* Willing to stay in the respiration chamber the night before and after each test day
* Owning a smartphone

Exclusion Criteria:

* Alcohol naïve or has not consumed alcohol within the last year
* Any history of alcohol or substance abuse or a high alcohol intake, defined as:

  * An Alcohol Use Disorders Identification Test (AUDIT, appendix 1) score \> 5 at screening
  * Drinking on average \>14 alcoholic beverages a week during the past 6 months
  * Yale-Brown Obsessive Compulsive Scale-heavy drinking (Y-BOCS-hd, appendix 2) total score of ≥6 on questions 1, 2, and 3
* Intolerance or allergy to alcoholic beverages, juniper or citrus
* Diagnosed with any CVD event (MI, revascularization procedure or stroke) within the past six months
* Diagnosed with any known or past severe chronic disease including liver diseases (e.g., active hepatitis B and C infections, liver cirrhosis, hepatitis, cancer), T2DM, prediabetes, hypertension, severe psychiatric illness or frequent use of medication (except over-the-counter drugs or mild anti-depressants) or any other clinical condition that makes the subject ineligible according to the clinically responsible medical doctor (self-reported).
* Cancer - active malignant cancer or history of malignancy within the last 5 years (with exception of non-melanoma skin cancer).
* Previous breast cancer diagnosis or at high risk of breast cancer defined as:

  * Breast Cancer Risk Assessment Tool (BCRAT) risk score \> 5 % (https://bcrisktool.cancer.gov/calculator.html)
  * Close relatives with diagnosed breast cancer (mother, sister, daughter)
* A Patient Health Questionnaire (PHQ-9, appendix 3) ≥15 at screening or a positive response on question 9 (thoughts about suicide)
* Diagnosed with atrial fibrillation
* Hemoglobin (Hb) levels below 7.3 mmol/L for women and 8.3 mmol/L for men.
* Chronic use of any type of medication, except for mild antidepressants or contraceptives
* Any use of contraindicated medication for alcohol intake, such as disulfiram, dual antiplatelet therapy, metronidazole, warfarin or hormone replacement therapy
* Hypersensitive to plasters
* Use of any type of antibiotics within two month before the first test day
* Unintentional weight loss \>20% during the last 6 months
* Any type of gastrointestinal problems or prior surgery expected to influence gut health and absorption.
* Estimated glomerular filtration rate (eGFR) \< 30 ml/min/1.73 m2 or end-stage renal disease
* Liver function tests \>2 times the upper limit of the normal range according to current limits at "sundhed.dk": alanine transaminase (ALT), aspartate aminotransferase (AST), and gamma-glutamyltransferase (GGT).
* Blood donations within the past three months before the recruitment
* Having no hair on the head (bald-headed)
* Current participation in another trial
* Not willing to sign the Informed consent form (ICF)
* Not willing to comply with the all the trial procedures including completion of the two-week run-in periods without drinking alcohol as well the two-week wash-out periods
* Unable or unwilling to follow the safety procedures related to Covid19
* Any other issue that makes the project responsible researcher doubt the eligibility of the volunteer