Purpose: 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.
Methods: 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).
Results: 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.
Limitation: Only two types of fatty acids (LA and DPA) can be used for pleiotropy tests using the MR-Egger intercept test.
Conclusion: This study does not support the hypothesis that PUFAs decrease the risk of AN.
Keywords: Anorexia nervosa; Eating disorder; Epidemiology; European ancestry; Mendelian randomization; Polyunsaturated fatty acids.
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