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As a crucial part of the symbiotic system, the gut microbiome is metabolically connected to many diseases and conditions, including cardiovascular diseases (CVD). Trimethylamine (TMA) is produced by gut bacteria from dietary choline, betaine, or L-carnitine, and is then converted in the liver to Trimethylamine N-oxide (TMAO), which in turn affects hepatic and intestinal lipid metabolism. Circulating TMAO is positively associated with CVD risk. Because eggs are rich in choline, it has been speculated that their consumption may increase plasma TMAO. In this study, we hypothesized that 2 eggs per day increases plasma TMAO level by altering gut microbiome composition in mildly hypercholesterolemic postmenopausal women. In this randomized, cross-over study, 20 overweight, postmenopausal women were given 2 whole eggs and the equivalent amount of yolk-free substitute as breakfast for 4 weeks, in randomized order, with a 4-week washout in between. Fasting blood draws and stool were collected at the beginning and end of each treatment period. Plasma TMAO, choline, betaine and other metabolites were analyzed using LC/MS, while gut microbiome composition was analyzed using 16S amplicon sequencing. Plasma choline and betaine were significantly increased after whole egg but not yolk-free substitute, however TMAO level was not significantly affected by treatments. Gut microbiome composition showed large inter-individual variability at baseline and in response to the treatments. The consumption of 2 eggs per day in overweight, postmenopausal mildly hypercholesterolemic women significantly increased plasma choline and betaine, but did not increase plasma TMAO or alter gut microbiome composition.

OBJECTIVES: To determine if equivalent amounts of carbohydrate ingested in the form of whole grapes or grape juice have differential effects on glucose, insulin, gene expression, protein content, and microRNA profiles following ingestion. METHODS: Following an overnight fast, subjects consumed equivalent amounts of carbohydrate from whole grapes, grape juice, or glucose standard in randomized order. Blood was collected at fasted baseline and at 15, 30, 45, 60, 90, 120, and 180 minutes following ingestion of the test food. Glucose was quantified enzymatically and insulin was measured through radioimmunoassay and AUC was calculated. Peripheral blood mononuclear cells were isolated at baseline, 60, 120, and 180 minute time points and stored at −80°C for later analysis of gene expression, protein content, and microRNA profiles. Gene expression and mircoRNA will be measured using qtPCT. Protein expression will be determined using Western blots. Folin-Ciocalteu was used to determine total polyphenol counts of grapes and grape juice. Glucose and insulin responses between three treatments was analyzed using repeated measures ANOVA with Tukey's posthoc. RESULTS: Fourteen subjects (64.3% female) participated in the study; 12 had complete data. Glucose and insulin dropped below baseline in some subjects, so the absolute value of AUC was calculated for each treatment. The absolute value of glucose was significantly different when comparing whole grapes to grape juice (1189.03 vs. 2787.38, p > 0.001) and significant differences were also seen in the absolute value of insulin (1399.93 vs 2732.34, P = 0.002). As a secondary analysis, we will investigate whether these differences manifest in upregulation of pathways related to inflammation. Gene expression, protein expression, and microRNA analyses are ongoing. CONCLUSIONS: Healthy adults have intra-individual variation in glycemic response to equivalent amounts of carbohydrate, depending on the matrix in which the carbohydrate is delivered. This response may result in differences in inflammatory processes, which should be considered in dietary recommendations. FUNDING SOURCES: This research was supported through internal funds at the University of California, Davis, as well as Jastro-Shields and Kirvin Knox Fellowships.

Cardiovascular disease is a leading cause of death around the world. Overall diet quality and dietary behaviors are core contributors to metabolic health. While therapeutic targets have traditionally focused on levels of lipoprotein cholesterol when evaluating cardiovascular risk, current perspectives on high-density lipoprotein (HDL) have shifted to evaluating the functionality of this lipoprotein particle. Effects of diet on cardiovascular health are mediated through multiple pathways, but the impact on HDL composition and function deserves greater attention. Potential areas of investigation involve changes in particle characteristics, distribution, microRNA cargo, and other functional changes such as improvements to cholesterol efflux capacity. Various dietary patterns like the Mediterranean diet and Dietary Approaches to Stop Hypertension (DASH) diet have beneficial effects on cardiovascular health and may prevent cardiovascular events. These healthful dietary patterns tend to be rich in plant-based foods, with cardiovascular benefits likely resulting from synergistic effects of the individual dietary components. The purpose of this review is to summarize current perspectives on selected functions of HDL particles and how various dietary patterns affect cardiovascular health biomarkers, with a focus on HDL functionality.