Abstract P222: Consuming a Vegan Diet Compared to Omnivore Diet Leads to No Significant Changes in Serum TMAO, Fasting Glucose, Insulin, or Vitamin B12: The Twins Nutrition Study (TwiNS) Randomized Controlled Trial

Abstract

Introduction: Vegan diets are often encouraged for a myriad of health reasons, traditionally for control of blood lipid, cholesterol, and lipoprotein values. We proposed looking at other markers of health, including serum trimethylamine N-oxide (TMAO), fasting glucose, fasting insulin, or vitamin B12 in identical twins assigned to either a vegan or omnivore diet. Hypothesis: We hypothesized that the healthy vegan diet would lead to lower TMAO, fasting glucose, and fasting insulin (better), and lower vitamin B12 (worse) than the healthy omnivore diet. Methods: Identical twins were recruited and randomized to a healthy vegan or healthy omnivore diet. All twins consumed an omnivorous diet before enrollment. Meals were provided via a meal delivery service from baseline through week 4, with participants supplementing the delivered meals with their own diet adherent snacks. For delivered meals, both the healthy vegan and healthy omnivore diets were designed to consist of whole grains, legumes, and produce, with the main difference being omnivore diets provided ~1/3 of energy intake from animal-sourced foods. Participants prepared their own meals and snacks from weeks 5-8. Participants received nutrition education at baseline via orientation and were encouraged to choose “healthy” snacks, which for those on the vegan diet included legumes, nuts, seeds, and produce, and for those on the omnivore diet included dairy, nuts, seeds and produce. To assess compliance and intake, 24-hour dietary recalls were taken at weeks 0, 4, and 8. Clinical labs were collected at baseline, week 4, and week 8 through Stanford Medicine and analyzed both onsite and at Washington University St. Louis. Results: No significant differences between baseline and 4 or 8 weeks were seen in serum TMAO, fasting glucose, fasting insulin, or vitamin B12 between vegan and omnivorous twins (n=44). Conclusions: Vegan diets are often encouraged for their health promoting benefits; however, a healthy omnivorous diet can lead to comparable clinical lab outcomes. Funding: This study was supported by a generous donor, by the National Heart, Lung, and Blood Institute (NIH 5T32HL007034), and the Stanford Clinical and Translational Science Award (NIH UL1TR001085).