The prevalence of food allergy has increased dramatically over the past decade and has now reached epidemic levels in Western countries like Australia and the United States, with up to 10 percent of 12-month-old infants having a clinically confirmed food allergy . As food allergies have increased, vitamin D levels in the population appear to have concurrently decreased. Estimates suggest that up to 50% of people in Western countries are vitamin D insufficient and up to 10% are vitamin D deficient [2, 3].
The Sunshine Vitamin
Vitamin D, sometimes called the ‘sunshine vitamin,’ is a nutrient essential for good health. It plays a major role in the maintenance of healthy bones by helping the body to absorb calcium and also has an essential role in immune system function.
Vitamin D is produced in the body through sunshine on the skin, or it can be consumed in the diet through food or supplements. Oily fish—salmon, tuna and sardines—and fish oils are the richest sources of dietary vitamin D. Other good sources are eggs (vitamin D is in the yolk), liver and vitamin D fortified foods including dairy products, margarine or infant formulas.
Vitamin D and Food Allergy – What Does the Research Say?
Areas further away from the equator (and thus with lower ambient ultraviolet radiation [UVR]) have been shown to have higher rates of childhood food allergy-related hospital admissions , epinephrine autoinjector prescriptions [4, 5], and peanut allergy (up to six times the risk)  than areas closer to the equator. Season of birth (being born in autumn or winter when there is less UVR exposure) has also been associated with higher risk of anaphylaxis  and food allergy .
A link between late introduction of egg, one of the few common dietary sources of vitamin D in the infant diet, and food allergy has been observed in a large Australian study . Infants who were first given egg earlier (that is between four and six months) had significantly less food allergy than infants first given egg later (that is, after six months of age).
Research using direct measures of vitamin D from blood samples have also shown an association between low vitamin D and increased risk of allergic sensitization in children and adolescents  and food allergy in infants . In this Australian study, infants with low vitamin D were more likely to have egg or peanut allergy and were more likely to have multiple allergies compared to infants with normal vitamin D levels.
What Does This Mean for You?
It’s too early to say whether vitamin D can reverse food allergies. Future research is needed to answer that question. However, research is beginning to support the idea that vitamin D can protect against food allergies and vitamin D is important for overall good health.
For most people, the best way to ensure you have enough vitamin D is a combination between sensible sun exposure and adequate intake of foods containing the vitamin. Your doctor can assess your vitamin D status with a simple blood test and recommend a supplement if necessary. Supplements should only be taken under the advice of a healthcare professional, like an allergist / immunologist.
If you’re pregnant, ensuring you have adequate vitamin D (particularly in late pregnancy) is essential to ensuring your child will have adequate levels. Infants’ vitamin D stores in the first year of life rely on the mother’s stores before birth.
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This article has been reviewed by Thanai Pongdee, MD, FAAAAI