Interaction between maternal dietary fat intake, breast milk omega‐3 fatty acids and infant growth during the first year of life

Abstract Background Long chain fatty acids (LCFA) of human milk (HM) might be associated with different patterns of weight gain in infancy. This study aims to examine the interaction between maternal dietary fat intake, breast milk content of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) with infant growth during the first year of life. Methods This longitudinal study was conducted among 215 Iranian mother–infant pairs. The infants were followed up from birth to 12 months of age. Trained healthcare providers measured infant anthropometrics including weight, length and head circumference at birth, 2, 4, 6 and 12 months of age. Breast hind milk samples were collected in the morning through hand expression between 6 and 12 weeks postpartum. Maternal dietary intake was assessed using a 3‐day dietary record. Linear mixed effects models were performed to determine the interaction between maternal dietary fat intake, the breast milk content of EPA and DHA with infant growth. Further adjustments were applied for potential confounders. Results Mean and standard deviation (SD) of maternal age and body mass index were 29.70 (5.24) years and 24.47 (4.42) kg/m 2 , respectively. Mean (SD) of infant birth weight was 3177.50 (413.20) g, and 50% were boys. An inverse interaction existed between maternal dietary fat intake and breast milk EPA with infant 4‐month weight ( β : −366.2, P‐ value: 0.01). We found a significant association of maternal dietary fat intake and infant 6‐month weight ( β : 22.5, P‐ value: 0.04). An inverse interaction was documented between maternal dietary fat intake and breast milk DHA with infant weight at 12‐month of age ( β : −95.3, P‐ value: 0.02). We found a significant association between maternal dietary fat intake and infant length at 12‐month ( β : 0.06, P‐ value: 0.02). Conclusion We found an inverse interaction between maternal dietary fat intake and breast milk omega‐3 fatty acids with infant weight at 4 and 12 months of age. Although longer follow‐up of growth indices is recommended, these findings suggest functional relevance of HM composition to infant growth.