Effects of hypocaloric very-low-carbohydrate diet vs. Mediterranean diet on endothelial function in obese women.

Abstract

Background Obesity is a cardiovascular risk factor associated with endothelial dysfunction, but the effect of dif- ferent weight loss strategies on endothelial function is not known. The effect of diet on endothelial function in two hypocaloric diets, a very-low-carbohydrate diet (A) and a Mediterranean diet (M), was measured by brachial artery flow-mediated dilation (FMD). Design Using a longitudinal, randomized, open study design, subjects were engaged in a 2-month weight loss diet. FMD, inflammatory cytokines [interleukin-6 (IL-6) and tumour necrosis factor-a] and a marker of oxidative stress [8-iso-prostaglandin F2a (8-iso-PGF2a)] were measured in subjects on three occasions: before initiating the diet (T0), after 5–7 days of dieting (T5) and after 2 months of dieting (T60). The very short- and medium-term time points were established to discriminate respectively the effect of the diet itself (T5) from that of weight loss (T60). Twenty overweight ⁄ obese but otherwise healthy women (BMI: 27–34.9 kg m)2; age 30–50 years) completed the study. Results Group A lost more weight (mean ± SEM; )7.6 ± 0.8 kg) than group M ()4-9 ± 0.6 kg, P = 0.014) at T60. The FMD was not significantly different between the two groups at T0 (group A: 12.2 ± 2.9% vs. group B: 10.3 ± 2.3%, P = ns). In group A, FMD was significantly reduced at T5 and returned to baseline at T60; in group M, FMD increased at T5 and returned to baseline at T60 (P = 0.007 for diet · time interaction). Serum concentrations of IL-6 and 8-iso-PGF2a were not significantly different between the two groups at T0 and increased significantly at T5 only in group A (P < 0.001 and P < 0.005 respectively). Conclusion As endothelial dysfunction is known to be associated with acute cardiovascular events, this study suggests that the cardiovascular risk might be increased in the first days of a very-low-carbohydrate diet.