Association between plasma concentrations of elaidic acid, a major trans fatty acid, and depression in a nationally representative sample of U.S. adults

Previous studies on health effects of trans fatty acids (TFA) have focused mainly on cardiovascular health. Little is known about the association of TFA with brain or mental health. In this study, we examined the associations of objectively-measured plasma TFA concentrations with depression in a large population-based cross-sectional study among U.S. adults.We included 2136 non-pregnant participants aged 20 years or older from the National Health and Nutrition Examination Survey 2009-2010. Four major TFAs, including palmitelaidic acid (C16:1n-7t), elaidic acid (C18:1n-9t), vaccenic acid (C18:1n-7t), and linoelaidic acid (C18:2n-6t, 9t), were measured in fasting plasma using gas chromatography/mass spectrometry. Depressive symptoms were assessed using the validated Patient Health Questionnaire-9.Participants with depressive symptoms had a higher plasma concentration of total TFA compared with those without depressive symptoms (6.6 vs 6.0 μmol/g lipids, P = 0.046). After adjustment for other major risk factors, the odds ratio (OR) of depressive symptoms comparing the highest with lowest tertile of TFAs was 1.44 (95% CI, 0.86-2.39) for total TFAs (P for trend 0.15). For each individual type of TFA, the corresponding OR was 1.78 (1.03-3.07) for elaidic acid (P for trend 0.049), 1.23 (0.76-2.00) for linoelaidic acid (P for trend 0.37), 1.19 (0.75-1.87) for palmitelaidic acid (P for trend 0.46), and 1.20 (0.75-1.94) for vaccenic acid (P for trend 0.43).The cross-sectional study design limited causal inferences of the findings.In a nationally representative population, plasma elaidic acid, a major trans fatty acid, was positively associated with depressive symptoms in adults. A positive but non-significant association of depressive symptoms was observed for total TFAs, linolelaidic acid, palmitelaidic acid, and vaccenic acid.