The association of dietary flavonoids, magnesium and their interactions with the metabolic syndrome in Chinese adults: a prospective cohort study

The aim was to systematically analyse the association of the specific flavonoids, Mg and their interactions from different food sources with the metabolic syndrome (MetS) and its components in a cohort study. A total of 6417 participants aged 20 to 74 years from the Harbin Cohort Study on Diet, Nutrition and Chronic Non-communicable Diseases were included. Multivariate logistic regression analyses, forest plot and restricted cubic spline were performed in the study. After a 5 center dot 3-year follow-up, 1283 incident cases of the MetS were reported. Those with a higher total flavonoid intake had a lower risk of the MetS (fourth v. first quartile, relative risk (RR) 0 center dot 58; 95 % CI 0 center dot 37, 0 center dot 93; P = 0 center dot 024) and central obesity (RR 0 center dot 56; 95 % CI 0 center dot 33, 0 center dot 95; P = 0 center dot 032). Further analysis showed that the specific flavonoids quercetin, kaempferol, isorhamnetin, luteolin, and flavonoids from fruits, potatoes and legumes had the similar associations with risk of the MetS and central obesity (P < 0 center dot 05 for all). A higher intake of total flavonoids, quercetin and luteolin combined with a high level of Mg was more strongly associated with a lower risk of the MetS (RR 0 center dot 60; 95 % CI 0 center dot 45, 0 center dot 81 for total; RR 0 center dot 61; 95 % CI 0 center dot 45, 0 center dot 82 for quercetin; RR 0 center dot 52; 95 % CI 0 center dot 38, 0 center dot 71 for luteolin; all P (for interaction) < 0 center dot 01). Dose-response effects showed an L-shaped curve between the total intake of five flavonoids and the risk of the MetS. A higher flavonoid intake is associated with a lower risk of the MetS and central obesity; their combination with Mg helps to strengthen their negative association with the MetS.