n -3 Fatty acid intake and circadian syndrome in US adults: evidence from the National Health and Nutrition Examination Survey 2005–2018

Abstract Circadian syndrome (CircS) appears to be a better predictor for CVD than metabolic syndrome, and n -3 fatty acids are generally suggested to alleviate negative health outcomes. This study aims to investigate the association between n -3 intake and CircS and examine the effect modification by sociodemographic and lifestyle factors. In this cross-sectional study, data from the National Health and Nutrition Examination Survey 2005–2018 were analysed ( n 12 028). Survey-weighted multivariable logistic regression was applied to analyse the associations of n -3 intake with CircS and its components. Subgroup analyses examining the effect modification by sociodemographic and lifestyle factors were followed by a restricted cubic spline investigating the non-linear associations between n -3 intake and CircS by race. The weighted prevalence of metabolic syndrome and CircS was 45·8 and 37·3 %, respectively. Overall, no significant associations were found between the intake of total n -3, EPA or DHA and CircS. However, n -3 intake was associated with a lower risk of depression – a component of CircS. Comparing extreme quartiles of n -3 intake (highest v . lowest), the OR (95 % CI) for depressive symptoms was 0·77 (0·64, 0·90). Among the Black, those in the highest quartile of n -3 intake were more likely to have CircS, with the OR (95 % CI) of 1·36 (1·02, 1·82). No association between n -3 intake and CircS in the total study population was observed. However, n -3 intake was inversely associated with depressive symptoms in American adults. Interactions between race and n -3 intake in relation to CircS were also identified.