Effect of reducing the n-6:n-3 long-chain PUFA ratio during pregnancy and lactation on infant adipose tissue growth within the first year of life: an open-label randomized controlled trial

Background: The composition of long-chain PUFAs (LCPUFAs) in the maternal diet may affect obesity risk in the mother's offspring. Objective: We hypothesized that a reduction in the n-6 (omega-6): n-3 (omega-3) LCPUFA ratio in the diet of pregnant women and breastfeeding mothers may prevent expansive adipose tissue growth in their infants during the first year of life. Design: In a randomized controlled trial, 208 healthy pregnant women were randomly assigned to an intervention (1200 mg n-3 LCPUFAs as a supplement per day and a concomitant reduction in arachidonic acid intake) or a control diet from the 15th wk of pregnancy to 4 mo of lactation. The primary outcome was infant fat mass estimated by skinfold thickness (SFT) measurements at 4 body sites at 3-5 d, 6 wk, and 4 and 12 mo postpartum. Secondary endpoints included sonographic assessment of abdominal subcutaneous and preperitoneal fat, fat distribution, and child growth. Results: Infants did not differ in the sum of their 4 SFTs at <= 1 y of life [intervention: 24.1 +/- 4.4 mm (n = 85); control: 24.1 +/- 4.1 mm (n = 80); mean difference: -0.0 mm (95% CI: -1.3, 1.3 mm)] or in growth. Likewise, longitudinal ultrasonography showed no significant differences in abdominal fat mass or fat distribution. Conclusions: We showed no evidence that supplementation with n-3 fatty acids and instructions to reduce arachidonic acid intake during pregnancy and lactation relevantly affects fat mass in offspring during the first year of life. Prospective long-term studies are needed to explore the efficacy of this dietary approach for primary prevention. This trial was registered at clinicaltrials.gov as NCT00362089. Am J Clin Nutr 2012;95:383-94.