More than 20 studies of probiotics and prevention of allergy. No safety concerns. 15 found supplementation during pregnancy and lactation may reduce eczema, but no effect in asthma, food allergy, rhinitis.
Fish oil supplementation during pregnancy may reduce risk of allergic sensitisation to egg.
Cochrane 2013 review of prebiotics concluded “promising results in high risk populations”, WAO find in favour (probiotics too), but others institutions have not!
Other dietary exposures, including maternal allergenic food avoidance, vitamin, mineral, fruit and vegetable intake did not appear to influence risk of allergic or autoimmune disease.
There is limited evidence to suggest that supporting mothers to breastfeed for longer reduces risk of eczema in the first year
Longer exclusive breastfeeding duration reduces risk of type 1 diabetes.
2 previous systematic reviews suggested extensively hydrolyzed formula may be protective against milk allergy in high risk babies. Partially hydrolysed found to possibly protect in 2 systematic reviews. Certainly some studies with no effect. Soya does not help! EAACI have recommended hypoallergenic formula (“one with documented preventive effect”) for 4/12 (Grade I, evidence A-B), but Cochrane have withdrawn their 2017 review, which was also in favour, “due to data entry error”.[PLoS Med metanalysis 2018]