The main purpose of the study was to examine whether fish oil supplementation of lactating mothers affect infant development during first year of life, focusing on visual and mental development. A follow-up studies are conducted in order to see if early intake of long-chain n-3 polyunsaturated fatty acids (n-3 LCPUFA) have any long-term effects on health, primarily immun function and markers of cardiovascular risk.

Background:

Studies indicate that infants, who are fed formula without n-3 LCPUFA, have slower visual development than those, who receive n-3 LCPUFA in breast-milk. The mental development seems also to depend on whether infants are breast-fed or not. Long-term health has also been proposed to be affected (The infant origin of adult disease hypothesis). It is not clear whether these differences is due to dietary LCPUFA as comparison of breast-fed and formula-fed infants are complicated by the socio-demographic differences that exist between mother, who choose to breast-feed or not. Recent studies indicate that LCPUFA supplementation of formulas has beneficial effects on the visual acuity and mental abilities of infants. The LCPUFA content of breast-milk varies and this could potentially be of importance for infant development.

Methods:

211 pregnant women with a high (>80 percentile) or low (< mean) fish intake were recruited. After birth mother with low fish intake were randomized to receive 4 g/day of fish oil or olive oil for the first 4 months of the lactation period. 150 mother-infant pairs were followed for 1 year gathering information on maternal n-3 LCPUFA intake and infant development (growth, developmental milestones, visual acuity, cognitive functions and language acquisition). Milk samples were collected at 0, 2, 4 and 9 months and blood samples were taken from the mother and the infant at 4 months of age in order to determine the biochemical effect of the supplementation.

The children were followed-up at 2½ years of age and around 7 years of age. The study is performed in association to the National Birth Cohort.

Inclusion Criteria:

• Pregnant women with uncomplicated singleton pregnancy
• No metabolic disorders and prepregnancy BMI < 30 kg/m2
• Intention to exclusively breast-feed for 4 mo
• Fish intake below the Danish mean or above 80th percentile (reference group)

Exclusion Criteria:

• Pre- or post term delivery (< 37 or > 43 wks of gestation)
• Abnormal weight for gestation (outside 10th-90th percentile range)
• Apgar score 5 min after delivery < 8
• Infant admission to a neonatal department
• If supplementation did not begin within 2 wks after delivery