Maternal Fish Oil Supplementation in Lactation and Growth during the First 2.5 Years of Life

Fish oil addition to infant formulas has raised concern on whether increased intake of n-3 long-chain polyunsaturated fatty acid (n-3LCPUFA) affects infant growth. The objective of this study was to determine whether maternal fish oil supplementation during 0–4 mo of lactation influences growth in infancy and early childhood. In a randomized, blinded intervention trial, lactating Danish mothers with a fish intake below the population median were randomized to 4.5 g/d fish oil or olive oil. A reference group of 53 mothers with a fish intake in the highest quartile of the population and their infants were included in the study. Head circumference, weight, length, skinfold thickness, and waist circumference of children were measured at 2, 4, and 9 mo and at 2.5 y. One hundred children completed the intervention trial, and 72 were followed up at 2.5 y together with 29 from the reference group. Growth in weight, length, and head circumference did not differ between the randomized groups up to 9 mo, but at 2.5 y, body composition differed significantly. Children in the fish oil group had larger waist circumference body mass index (BMI; 0.6 kg/m2; p = 0.022), and head circumference compared with those in the olive oil group. Adjusted for sex, ponderal index at birth and current energy intake, BMI at 2.5 y was associated with docosahexaenoic acid in maternal erythrocytes after the intervention. In conclusion, the n-3LCPUFA intake of lactating mothers may be important for growth of young children. The long-term effect on weight and BMI remains to be investigated.