Investigating the links between habitual diet, the gastrointestinal microbiota, and cardiovascular disease risk factors in healthy weight, overweight, and obese men and women
Authors: Bailey Melisa A. , Beals Joseph W. , Skinner Sarah K. , Paluska Scott A. , Burd Nicholas A. , Holscher Hannah D. 
Published: June 2021

BackgroundThe connection between diet and the gastrointestinal (GI) microbiota is an area of intense interest as the microbiota is increasingly linked to a growing list of not only gastrointestinal, but also metabolic diseases. Dietary factors including saturated fat, added sugars, and dietary fiber are all related to cardiometabolic health. However, the relationship between the human GI microbiota, blood lipids, and habitual diet remains under‐investigated.ObjectiveWe aimed to determine the relationships among bacterial taxa, blood lipids, and dietary intake patterns in healthy weight, overweight, and obese men and women.MethodsBlood and fecal samples were collected from adults (n=68, 31 males; 25–45 years of age) without physician diagnosed metabolic or gastrointestinal diseases. Dietary intake patterns were assessed using the Diet History Questionnaires (DHQII, Past Year and Past Month with Portion Size) and Healthy Eating Index (HEI‐2010) scores were calculated to assess diet quality. Following DNA isolation, bacterial (V4 region of 16S rRNA), fungal (ITS1‐4), and archaeal amplicons were generated using a Fluidigm Access Array followed by high‐throughput sequencing on an Illumina MiSeq. Sequences were quality filtered, then operational taxonomic units (OTUs) were picked against the Greengenes 13‐8 reference database using QIIME versions 1.8 and 1.9. Total cholesterol, low density lipoprotein (LDL) cholesterol, very low density lipoprotein (VLDL) cholesterol, high density lipoprotein (HDL) cholesterol, non‐HDL‐cholesterol (nHDLc), and triglycerides were measured using a chemical analyzer. Body composition was assessed using dual energy x‐ray absorptometry. Data were analyzed using SAS 9.4.ResultsBivariate correlations revealed positive associations between Phascolarctobacterium and nHDLc (r=0.28, p=0.03) and refined grains (r=0.34, p=0.01). However, these relationships were mitigated by age and whole body percent fat. Dorea spp were positively related to nHDLc (r=0.38, p=0.003), total cholesterol (r=0.40, P=0.001), LDL‐cholesterol (r=0.34, p=0.007), and total dairy intake (p=0.35, p=0.01). The positive association between Dorea spp. and total cholesterol remained significant after controlling for whole body percent fat, age, total HEI‐2010 score and dietary intake of saturated fat/kcal and total dairy. Total dairy intake tended to positively relate to nHDLc (r=0.26, p=0.07).ConclusionsThese results suggest potential relationships between microbial, metabolic, and dietary factors. Specifically, Dorea is independently related to increased cardiometabolic disease markers and dietary components such as total dairy intake in US adults. Future directions include assessments of additional dietary factors including types of fat, bile acids, and inflammatory markers to better define the interconnections between the gut microbiota composition, habitual diet, and human health.Support or Funding InformationSupported in part by the USDA National Institute of Food and Agriculture, Hatch project ILLU‐668‐902 and Haas Avocado Board.