Fish Oil and Probiotics Consumed During Pregnancy May Reduce Childhood Allergies

In one of the largest ever research reports that fish oil and probiotics consumed during pregnancy affects her baby’s allergy and eczema risk, scientists from Imperial College London assessed over 400 studies involving 1.5 million people.

  • As part of the study, they found that when pregnant women took a daily fish oil capsule from 20 weeks pregnant, and during the first three to four months of breastfeeding, risk of egg allergy in the child was reduced by 30 per cent.
  • The team, who were commissioned by the Food Standards Agency (UK), also found that taking a daily probiotic supplement from 36-38 weeks pregnant, and during the first three to six months of breastfeeding, reduced the risk of a child developing eczema by 22 per cent.

The researchers, who published their meta-analysis in the journal PLOS Medicine, found no evidence that avoiding potentially allergenic foods such as nuts, dairy and eggs during pregnancy made a difference to a child’s allergy or eczema risk.

Dr Robert Boyle, lead author of the research from the Department of Medicine at Imperial College London, explained: “Food allergies and eczema in children are a growing problem across the world. Although there has been a suggestion that what a woman eats during pregnancy may affect her baby’s risk of developing allergies or eczema, until now there has never been such a comprehensive analysis of the data.”

“Our research suggests probiotic and fish oil supplements may reduce a child’s risk of developing an allergic condition, and these findings need to be considered when guidelines for pregnant women are updated.”

More research is now needed to understand how fish oil and probiotics may reduce allergy and eczema risk, said Dr Vanessa Garcia-Larsen, co-author of the study from the National Heart and Lung Institute at Imperial: “Despite allergies and eczema being on the rise, and affecting millions of children, we are still hunting for the root causes of these conditions, and how to prevent them.” Dr Garcia-Larsen, who is also based at John Hopkins University, added: “This study has provided clues, which we now need to follow with further research.”

Fish Oil, Egg and Peanut Allergies

The team also assessed around 19 trials of fish oil supplements during pregnancy, involving around 15,000 people. These studies revealed a 30 per cent reduction in risk of egg allergy by age one, which equates to a reduction of 31 cases of egg allergy per 1000 children.

  • In the studies using fish oil supplements, the capsules contained a standard dose of omega-3 fatty acids (another type of fatty acid, called omega-6, was not found to have any effect on allergy risk).
  • Most of the trials used supplements, although one involved eating oily fish, and a few others used non-fish oils such as nut oils. The Department of Health advises women to eat no more than two portions of oily fish a week, and to avoid shark, swordfish or marlin as these contain high levels of mercury.
  • The team also found that taking fish oil supplements during pregnancy reduced the child’s risk of peanut allergy by 38 per cent. However they caution this finding was based only on two studies, and not as reliable as the egg allergy and eczema results.

Probiotics and Allergy Risk

The team assessed 28 trials of probiotic supplements during pregnancy, involving around 6,000 women. In the research, probiotics were taken during pregnancy and breastfeeding as a capsule, powder or drink (most yogurts do not contain enough probiotic). They were found to reduce the risk of a child developing eczema — between the ages of six months to three years — by 22 per cent. This is the equivalent of 44 cases of eczema per 1000 children.

The scientists added that the probiotics, which mostly contained a bacterium called Lactobacillus rhamnosus, were not used in early pregnancy. The study also revealed some evidence for links between longer duration of breast feeding and a reduced risk of eczema, and breastfeeding was also linked with a lower risk of type one diabetes.

Source: Diet during pregnancy and infancy and risk of allergic or autoimmune disease: A systematic review and meta-analysis. PLOS Medicine, 2018; 15 (2): e1002507 DOI: 10.1371/journal.pmed.1002507