Associations between metabolic syndrome and Plant-Based diet Indices in the NutriNet-Santé study

BACKGROUND: Prior studies have shown that plant-based diets are associated with lower risk of cardiovascular diseases but the risk seems to differ according to the nutritional quality of plant food intakes. We aimed to investigate the cross-sectional association between metabolic syndrome (MetS) and healthful and unhealthful Plant-Based diet Indices (hPDI and uPDI). METHODS: This study included 16,358 participants from the NutriNet-Santé study who underwent a clinical visit, allowing to collect blood samples for the measure of total cholesterol, LDL and HDL, triglycerides and anthropometric measurements. The MetS was assessed following the joint interim definition. The consumption of food such as fruits and whole grains to the diet compared to animal food can be reflected by hPDI, and its opposite uPDI reflecting the consumption of food such as refined grains and desserts were estimated using data from 24-h dietary records. The association between these plant-based diet indices and MetS were estimated by multivariable robust Poisson regression models with robust errors. RESULTS: In both women and men, a higher contribution of healthy plant food to the diet was associated with a lower prevalence of MetS (women: PR hPDI 0.74; 95% CI: 0.69, 0.80, men: PR hPDI 0.82; 95% CI: 0.76, 0.89). Similar trends were observed for all the MetS components (abdominal obesity, elevated blood pressure, elevated triglyceridemia, low HDL and elevated glycaemia) and BMI, except for low HDL and elevated glycaemia in men. Only in women, a higher contribution of unhealthy plant food to the diet was positively associated with the prevalence of MetS (PR uPDI: 1.12; 95%CI: 1.03, 1.21) and elevated triglyceridemia (PR uPDI: 1.21; 95%CI: 1.09, 1.33). CONCLUSIONS: In this large scale observational study, we observed that it is necessary to consider the nutritional quality of plant food: healthy vs. unhealthy plant food, to promote plant-based diets in prevention of cardiovascular diseases. KEY MESSAGES: • In men and women, a higher contribution of healthy plant food to the diet was associated with a lower prevalence of MetS and all its components only in women. • An increase in the contribution of unhealthy plant food was associated with a higher prevalence of MetS and elevated triglyceridemia but only in women.