The children of women who take fish oil supplement during pregnancy gain healthy weight quicker for the first six years of life, according to a new study.
Taking the supplements in the later stages of pregnancy are linked with a higher body mass index (BMI) which is explained by an increase in total lean and bone mass but with no increase in fat up to the age of six.
Studies in animals have shown that supplementing the diet with fish oil during pregnancy affects adipogenesis – the development of fat cells.
But while trials in humans have shown pregnant women with a higher intake of fish oil give birth to higher birth weight babies, the impact on children later in life has been unclear.
Professor Hans Bisgaard of Copenhagen University said: “Diet during pregnancy and infancy is an important determinant for children’s development and health.
“In particular, intake of fish containing n-3 long chain polyunsaturated fatty acids
(LCPUFA) is important for adequate development.
“In humans, both observational studies on dietary intake of fish and randomised controlled trials of n-3 LCPUFA (fish oil) supplementation in pregnancy and during lactation have consistently shown higher birth weight in children born to women with higher n-3 LCPUFA intake; this is mainly explained by an increase in gestational age, but an increase in size for gestational age has not been excluded.
“However, the long term effect on anthropometry during childhood is uncertain.”
So researchers based in Britain and Denmark set out to examine the effect of taking fish oil supplements during pregnancy on the growth and body composition of children later in life.
The trial involved 736 pregnant women who received either fish oil or olive oil daily from week 24 of pregnancy week until one week after birth.
Height, weight, head and waist measurements were assessed 11 times from birth to age six and adjusted for age and sex.
The findings, published in The BMJ, revealed a sustained higher BMI from 12 months old to six years of age.
Body composition was assessed using dual-energy X-ray absorptiometry (DXA) scans at 3.5 and six years of age.
The scans showed that the higher BMI was not the result of a higher fat percentage, but reflected a proportional increase in lean mass, bone mass, and fat mass, suggesting that the fish oil supplementation had a general growth stimulating effect.
At six years of age, DXA scans showed children whose mothers had taken fish oil supplements while pregnant had a 395g higher total mass, 280.7g higher lean mass, 10.3g higher bone mineral content and 116.3g higher fat mass compared with children of mothers who took the control oil.
Prof Bisgaard said: “The body composition at age six in children given fish oil supplementation was characterised by a proportional increase in lean, bone, and fat mass suggesting a general growth stimulating effect.
He concluded: “Fish oil supplementation from the 24th week of pregnancy led to a higher BMI in the offspring from 0 to six years of age but not an increased risk of obesity at age six.
“The body composition at age six years in children given fish oil supplementation was characterised by a proportional increase in lean, bone, and fat mass suggesting a general growth stimulating effect of n-3 long chain polyunsaturated fatty acid.”