In a nationally representative population, plasma elaidic acid, a major trans fatty acid (TFA), 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. Researchers included 2,136 non-pregnant participants aged ≥20 years from the National Health and Nutrition Examination Survey 2009–2010. 4 major TFAs, including palmitelaidic acid, elaidic acid, vaccenic acid, and linoelaidic acid, were measured in fasting plasma using gas chromatography/mass spectrometry. Depressive symptoms were assessed using the validated Patient Health Questionnaire-9. They found:

• 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).
• 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 for total TFAs.
• For each individual type of TFA, the corresponding OR was 1.78 (1.03–3.07) for elaidic acid, 1.23 (0.76–2.00) for linoelaidic acid, 1.19 (0.75–1.87) for palmitelaidic acid, and 1.20 (0.75–1.94) for vaccenic acid.