Dietary intake and adipose tissue content of long-chain n-3 PUFAs and subsequent 5-y change in body weight and waist circumference

Background: Adding long-chain n-3 (omega-3) polyunsaturated fatty acids (PUFAs) to a rodent diet reduces fat mass and prevents the development of obesity, but evidence of a similar effect in humans is rather limited. Objectives: We investigated the associations between dietary intake and adipose tissue content of long-chain n-3 PUFAs and subsequent 5-y change in body weight and waist circumference in humans. Effect modification by the carbohydrate: protein ratio and glycemic index was also investigated. Design: A total of 29,152 participants included in the Diet, Cancer, and Health cohort were followed. Dietary intake was assessed with the use of a validated 192-item semiquantitative food-frequency questionnaire. Adipose tissue content of fatty acids was determined by gas chromatography in a random sample of the cohort (n = 1660). Anthropometric measurements were taken at baseline and 5 y later. Associations were investigated with the use of a linear regression model. Results: For high (1.22 g/d) compared with low (0.28 g/d) total n-3 PUFA intake, the difference in 5-y weight change was 147.6 g (95% CI: -42.3, 337.5 g); P-trend = 0.088. No associations between the individual n-3 PUFAs eicosapentaenoic acid, docosapentaenoic acid, and docosahexaenoic acid were observed. Intake of n-3 PUFAs was not associated with a 5-y change in waist circumference. For high (0.16%) compared with low (0.06%) adipose tissue content of EPA, the difference in 5-y weight change was -649.6 g (95% CI: -1254.2, -44.9 g); P-trend = 0.027. No associations between total n-3 PUFA, docosapentaenoic acid, and docosahexaenoic acid and 5-y weight change were observed. Adipose tissue content of n-3 PUFAs was not associated with 5-y change in waist circumference. No effect modification by carbohydrate: protein ratio or glycemic index was found. Conclusion: Dietary intake and adipose tissue content of long-chain n-3 PUFAs were neither consistently nor appreciably associated with change in body weight or waist circumference.