Vitamin D in infancy prevents childhood food allergy

What the research found

A randomised trial of 975 infants in 2019 compared 400 IU with 1200 IU of vitamin D daily. Food sensitisation at 12 months did not differ between the groups. Milk allergy was more common in the higher-dose group, though the result was borderline.

A smaller 2014 randomised trial gave mothers 800 IU of vitamin D daily while breastfeeding. Doctor-diagnosed food allergy up to age 2 was more common in the vitamin D group. The authors noted many families were lost to follow-up, so this is weak evidence.

A 2018 systematic review found very low certainty evidence. Vitamin D supplementation may not reduce allergic disease. It found no studies on preventing allergy in children, and the food allergy finding was for pregnant women.

A 2023 meta-analysis of ten case-control studies found children with low vitamin D were more likely to have food allergy. These studies only show a link. They cannot show that low vitamin D caused the allergy or that supplements would prevent it.

What it doesn’t mean

• This does not mean infants should skip vitamin D. It is still important for bone health, and deficiency in infancy can cause rickets.
• The trials compared doses or used mothers' supplements, so they do not settle whether a standard infant dose has any effect on food allergy. Higher doses are not shown to be better.
• Talk to your GP or child health nurse about whether your baby needs a vitamin D supplement and how much, especially if you have a family history of allergy.