A Mediterranean Diet and Low-Fat Vegan Diet to Improve Body Weight and Cardiometabolic Risk Factors: A Randomized, Cross-over Trial.

Abstract

Objective: Evidence suggests that both Mediterranean and vegan diets improve body weight and cardiometabolic risk factors, but their relative efficacy has not been compared in a randomized trial. Methods: In a randomized crossover trial, 62 overweight adults were randomly assigned to a Mediterranean or vegan diet for a 16-week period. Body weight, plasma lipids, blood pressure, and body composition (dual X-ray absorptiometry) were measured. Secondary measures included insulin resistance (Homeostasis Model Assessment, HOMA-IR), oral glucose insulin sensitivity (OGIS), and predicted insulin sensitivity (PREDIM) indices. Thereafter, participants were asked to return to their baseline diets for 4\u2009weeks, after which they began the opposite diet for 16\u2009weeks. The same parameters were measured before and after this 2nd 16-week period. Results: Overall net weight changes were 0.0 (Mediterranean) and -6.0\u2009kg (vegan), (treatment effect -6.0\u2009kg [95% CI -7.5 to -4.5]; p\u2009<\u20090.001). HOMA-IR decreased and OGIS increased on the vegan diet with no significant change on the Mediterranean diet (treatment effect -0.7 [95% CI, -1.8 to +0.4]; p\u2009=\u20090.21; and +35.8\u2009mL/min/m2 [95% CI, +13.2 to +58.3]; p =\u20090.003, respectively). PREDIM did not change significantly in either group. Among participants with no medication changes, total and LDL-cholesterol decreased 18.7\u2009mg/dL (0.5\u2009mmol/L) and 15.3\u2009mg/dL (0.4\u2009mmol/L), respectively, on the vegan diet, compared with no significant change on the Mediterranean diet (treatment effect -15.6 [-24.6 to -6.6]; p =\u20090.001 and -14.8 [-23.5 to -6.2]; p =\u20090.001, respectively); systolic and diastolic blood pressure decreased 9.3 and 7.3\u2009mmHg on the Mediterranean diet, compared with 3.4 and 4.1\u2009mmHg on the vegan diet (treatment effect +5.9 [95% CI +1.0 to +10.9]; p =\u20090.02; and +1.8 [95% CI -4.6 to +8.1]; p =\u20090.58, respectively). Conclusions: A low-fat vegan diet improved body weight, lipid concentrations, and insulin sensitivity, both from baseline and compared with a Mediterranean diet. Blood pressure decreased on both diets, more on the Mediterranean diet. Clinical trial registration: ClinicalTrials.gov number, NCT03698955 https://clinicaltrials.gov/ct2/show/NCT03698955?term=NCT03698955&draw=2&rank=1.