Polyunsaturated fatty acids and risk of anorexia nervosa: A Mendelian randomization study

Observational studies have suggested that polyunsaturated fatty acids (PUFAs) decrease the risk of anorexia nervosa (AN). In the present study, we examined this hypothesis using a Mendelian randomization analysis.We used summary statistics for single-nucleotide polymorphisms associated with plasma levels of n-6 (linoleic acid and arachidonic acid) and n-3 PUFAs (alpha-linolenic acid, eicosapentaenoic acid, docosapentaenoic acid, and docosahexaenoic acid) and the corresponding data for AN from a genome-wide association meta-analysis of 72,517 individuals (16,992 diagnosed AN cases and 55,525 controls).None of the genetically predicted PUFAs were significantly associated with the risk of AN; odds ratios (95 % confidence interval) per 1 standard deviation increase in PUFA levels were 1.03 (0.98, 1.08) for linoleic acid, 0.99 (0.96, 1.03) for arachidonic acid, 1.03 (0.94, 1.12) for alpha-linolenic acid, 0.98 (0.90, 1.08) for eicosapentaenoic acid, 0.96 (0.91, 1.02) for docosapentaenoic acid, and 1.01 (0.90, 1.36) for docosahexaenoic acid.Only two types of fatty acids (LA and DPA) can be used for pleiotropy tests using the MR-Egger intercept test.This study does not support the hypothesis that PUFAs decrease the risk of AN.