The long-term association of different dietary protein sources with metabolic syndrome.

Due to scarce epidemiologic data linking dietary protein intakes and metabolic syndrome (MetS), we aim to determine the longitudinal association of different types of dietary protein with the incidence of MetS among Iranians adults. The study was conducted in the framework of the Isfahan Cohort Study (ICS) on 6504 adults, aged ≥ 35 years, and free of MetS at baseline. A validated food frequency questionnaire was used for assessing usual dietary intakes. MetS was defined according to the Joint Scientific Statement. Mixed-effects logistic regression was applied to examine the associations between changes in weekly frequency consumption of protein and MetS status. After a median follow-up of 11.25 years, in multivariate-adjusted model, each additional frequency consumption of total protein intake (OR 0.83; 95% CI 0.81-0.85), animal protein (OR 0.80; 95% CI 0.77-0.83), plant protein (OR 0.70; 95% CI 0.64-0.76), red meat (OR 0.74; 95% CI 0.70-0.78), poultry (OR 0.73; 95% CI 0.68-0.78), egg (OR 0.79; 95% CI 0.72-0.88) and nuts and seeds (OR 0.77; 95% CI 0.71-0.84) was associated with reduced risk of MetS. No significant association was found for processed meat (OR 0.96; 95% CI 0.87-1.01) and legumes and soy (OR 0.96; 95% CI 0.86-1.07) with MetS. Our results suggest an independent inverse association between total protein, animal and plant protein and the risk of MetS. These associations did not differ by sex. Although our results can be considered to be a strategy to reduce MetS risk by dietary guidelines, randomized clinical trials are required to confirm our findings.