Periodic veganism in healthy individuals improves blood lipids, reduces low-grade inflammation, but impairs bone health: the FastBio study

ABSTRACT Background Dietary restriction (DR) is gaining ground as a means to prevent and treat a range of conditions and diseases, but possible negative effects on health remain unclear. In our study we address the impact of DR, in the form of periodic abstinence from animal products (periodic veganism), on markers of health. Methods We profiled a unique group of 200 periodic vegan (PV) individuals who alternate between an omnivorous and a vegan diet for religious reasons. PV individuals practice veganism for a total of 180-200 days annually, in a temporally structured and highly consistent manner, and have adhered to this diet for at least ten years. We also profiled 211 non-vegan (NV), omnivorous individuals. Traits were measured at two timepoints, the first capturing a period of omnivory for both groups, the second capturing a period during which PV individuals only had followed a vegan diet for three to four weeks. We report results on blood lipids (total, LDL, and HDL cholesterol, triglycerides), glucose metabolism (glucose, insulin, HBA1c), renal function (urea, uric acid, creatinine), liver function (AST, ALT, γ-GT), bone/liver function (ALP), thyroid function (TSH), inflammation (CRP), complete blood counts, anthropometric traits and blood pressure. We used linear mixed effects models to report changes in measured traits across timepoints for each dietary group, and differences of measured traits between dietary groups at each timepoint. Results Following three to four weeks of veganism, PV individuals display reduced levels of total and LDL cholesterol [both β=-0.3, 95% CI:(-0.4, -0.2) mmol/L] and of CRP [β=-1.3, 95% CI:(-2.1, -0.5) mg/L] which decreases by 28%. Compared to NV, PV individuals display consistently lower counts of total white blood cells (WBC) [β=-0.4, 95% C.I:(-0.6,-0.3) K/μL] and neutrophils [β=-0.4, 95% C.I:(-0.5,-0.2) x10³/μl], but higher levels of ALP [β=5.9, 95% C.I:(2.7,9.1) U/L]. Conclusions Abstinence from animal products improves cardiovascular health and reduces low-grade inflammation, but periodic veganism has long-term, detrimental effects on bone health. FastBio is the first highly comprehensive study to unveil the impact of long-term, periodic DR on health and can help inform public health policies on how to harness dietary intake to prevent and treat disease.