Fish oil in pregnancy linked to increase in child’s lean and bone mass

Fish oil supplements in the later stages of pregnancy is associated with an increase in total lean and bone mass at six years of age, but with no increase in fat mass, according to a new study.

A team of researchers based in Denmark and the UK 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 from the Copenhagen Prospective Studies on Asthma in Childhood study who were randomised to receive fish oil (n-3 long-chain polyunsaturated fatty acids) or olive oil (control) daily from week 24 of pregnancy until one week after birth.

Height, weight, head and waist measurements were assessed 11 times from birth to age 6 years and adjusted for age and sex. These revealed a sustained higher BMI from one year to six years of age.

Body composition was assessed using scans at 3.5 and six years of age and demonstrated 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 age six, 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.

The researchers concluded that 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.

Access the full study, published in the BMJ, here.