Vitamin D does not protect infants from allergies

If children get enough sunlight in the first three months of life, they later have lower levels of certain lab values indicative of allergies than children who do not get much sun.
Children who received enough sunlight also rarely developed eczema. However, supplemental vitamin D had no influence on the development of eczema.

These were the findings from a study by Australian immunologist Kristina Rueter from Perth Children’s Hospital. She presented the initial results of her study at the European Academy of Allergy and Clinical Immunology (EAACI) Congress in July 2021.

What was the study about?

The incidence of allergic diseases has continued to rise in recent decades. Research has still not revealed why this is occurring, says Rueter.
Vitamin D is believed to protect against allergies and has been the focus of scientific studies in this context. It stands to reason that patients who receive supplemental vitamin D will not be deficient in vitamin D. This would also mean that children would develop fewer allergies. Rueter investigated whether this hypothesis was actually correct.

How did the researchers conduct their study?

The researchers recruited 195 babies shortly after birth with a high risk of allergies and divided them into two groups:

One group got received 400 IU (international units) of vitamin D per day.
The second group was given a placebo.

Neither the doctors nor the parents knew which group received vitamin D and which did not. The children followed this treatment until the age of sixth months.

In addition, all of them were given a dosimeter that measures the direct UV radiation of the sun. It was positioned on the children’s clothing in such a way that it was not covered by the baby blanket.

The research team then regularly tested the children’s blood to determine their vitamin D levels and other lab values indicative of allergies. They also regularly checked for signs of food allergies, eczema and wheezing in the children.

What’s new?

Although vitamin D levels in the blood were higher in children who had also received vitamin D, there were no differences in terms of food allergies, eczema, wheezing or allergic rhinitis.

Children exposed to little sunlight developed eczema more frequently in the first six months of life, regardless of vitamin D supplementation. They also had higher lab values indicative of allergies.

Why is this important?

Supplemental vitamin D does nothing to prevent allergies in infants and toddlers. But sunlight does. However, the right amount is critical, since too much UV radiation damages the skin. “We absolutely must conduct more studies in order to determine the right balance”, says Rueter. She recommends that parents follow the advice of specialist associations to ensure that their children are adequately protected from the sun.