Nutritional supplements and allergy prevention

Research into the use of nutritional supplements during pregnancy and infant allergy prevention remains inconclusive. Focus has been placed on the potential benefits of maternal vitamin and mineral intake however studies thus far have found no clear evidence of an effect on infant allergy or eczema risk. At present there is insufficient evidence to recommend maternal intake of routine probiotics during pregnancy to prevent food allergy. There continues to be a lack of good understanding of the mechanisms through which probiotics might prevent allergic outcomes. 

In their position paper on primary prevention of food allergy, The European Academy of Allergy and Clinical Immunology (EAACI) concluded that there is currently a lack of evidence to support any recommendation that pregnant or breastfeeding women should take probiotic supplements in order to prevent food allergies. Evidence does however suggest that there may be beneficial effect of omega-3 fatty acid ingestion during pregnancy in relation to the reduction in risk of eczema and development of allergy antibodies (allergic sensitisation) in early life. Pregnant women should continue to limit oily fish intake to twice per week, as the benefits of omega-3 fatty intake are however outweighed by the risk of possible toxicity if eaten in larger amounts.  Further research is required in this area.

General health recommendations in pregnancy continue to advise the following;

• Folic acid and vitamin D supplementation during pregnancy.
  • Folic acid supplementation (400 micrograms/day) when planning a pregnancy and up to 12 weeks gestation, is advised to help reduce the risk of neural tube defects (NTDs).
  • Vitamin D helps the absorption of calcium and therefore is important for bone health. Vitamin D supplementation (10 micrograms/day) is recommended during pregnancy and when breastfeeding. Women who are at higher risk of vitamin D deficiency, such as those with reduced sunlight exposure or increased skin pigmentation, will require additional provision of vitamin D (25 micrograms/day).

• Women who are following a vegetarian or vegan diet may need to take additional supplementation of iodine, omega-3 fatty acids and vitamin B12.

NHS Website ‘Vitamins, supplements and nutrition in pregnancy’

The use of a non-cow’s milk based formula (such as soya) or a specialist ‘low allergy’ or hypoallergenic formula, when breastfeeding if not possible has not been consistently shown to prevent food allergy or allergic disease in infants.

In summary, currently there is no recommendation for or against the following: use of vitamin supplements, fish oil, prebiotics, probiotics or synbiotics in pregnancy, when breastfeeding or in infancy; altering the duration of exclusive breastfeeding; and use of hydrolysed infant formulas in allergy prevention. Strategies to prevent food allergy remains unclear, and further multinational research is required.

EAACI guideline: Preventing the development of food allergy in infants and young children, 2020 update