Kate Johnson

March 21, 2012

March 21, 2012 (Orlando, Florida) — One-year-old children with low levels of serum vitamin D are more likely to have food allergies than those with normal levels, according to a study presented here at the American Academy of Allergy, Asthma and Immunology 2012 Annual Meeting.

This finding gives rise to the question of whether the correction of vitamin D levels might be associated with the resolution of allergic symptoms, said Katie Allen, MD, from Murdoch Childrens Research Institute at the University of Melbourne, and the Royal Children's Hospital in Parkville, Australia.

In the observational study, Dr. Allen and colleagues wanted to determine whether those who eventually develop tolerance do so because their vitamin D deficiency has resolved.

The researchers used data from the population-based HealthNuts study, which screened more than 5000 one-year-old infants for food allergy, first with skin prick tests and then with oral food challenge.

Serum 25-hydroxy vitamin D levels from 165 children with challenge-proven food allergy to peanut, egg, and/or sesame were compared with those from 104 nonallergic control subjects.

The analysis found that children with vitamin D insufficiency (serum levels between 26 and 50 nmol/L) or deficiency (serum levels below 26 nmol/L) were more likely to be food allergic than children with vitamin D levels above 50 nmol/L.

Specifically, 25.5% of allergic children had vitamin D insufficiency and 3% had deficiency, whereas 10.6% of nonallergic children vitamin D insufficiency and 1% had deficiency.

After adjustment for breast or formula feeding, the consumption of raw egg, the presence of siblings or a pet dog, and the time of year that blood was drawn for vitamin D measurement, the adjusted odds ratios for any food allergy with vitamin D insufficiency and deficiency were 3.23 and 4.57, respectively (P = .003); for egg allergy were 3.65 and 3.41, respectively (P = .002); and for peanut allergy were 4.0 and 9.04, respectively (P = .007).

Dr. Allen said the researchers are going back to look at the children's heel stick blood to see whether vitamin D status at birth is predictive of the subsequent development of food allergy, and whether normalization of vitamin D with age corresponds with the resolution of food allergy.

"This is a very rich line of inquiry. It is going to be very revealing," said Michael Wein, MD, chief of allergy and immunology at the Florida State University College of Medicine in Tallahassee, when asked to comment by Medscape Medical News.

"We're looking for the reason for the increase in atopic disease in the United States, and actually worldwide, and vitamin D is one of the leading culprits," he said. "This is an amazing study because it's a huge cohort, it's a population-based study, and the data are showing that there's a correlation between vitamin D deficiency and allergy to food.... It gives clinicians a test to measure and an intervention that can change the natural history of the disease."

"If we find someone with vitamin D deficiency, regardless of their atopic status, we should correct it. Maybe I should be checking vitamin D more regularly in my patients who have atopic disease. Most clinicians don't check vitamin D deficiency."

Others at the meeting were more cautious.

"It's still evolving," said Audreesh Banerjee, MD, from the airways biology initiative in the pulmonary, allergy, and critical care medicine division at the University of Pennsylvania in Philadelphia. "I think the cardiac effects of vitamin D are still being looked at, and the neurological effects, and we're still trying to understand the effects on the immune system."

Vitamin D behaves very much like a steroid, he said. "It's not something benign enough that we can just supplement everybody.... It's important to look at kidney function because we know it affects the kidneys, and to look at serum calcium and magnesium levels because we know that vitamin D affects calcium and magnesium metabolism. There might be some patients who are more susceptible to vitamin D toxicity. The other thing we don't know about is levels. We know that below 2 nmol/L, the skeleton is affected, but we don't know if there are effects at 30, 40, or 50 nmol/L on other organs."

The speakers have disclosed no relevant financial relationships.

American Academy of Allergy, Asthma and Immunology (AAAAI) 2012 Annual Meeting: Abstract 535. Presented March 5, 2012.

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