Vitamin Mineral Research

Vitamin D for Your Allergies?

The data behind vitamin D for asthma, eczema, and atopic conditions

More than 50 million Americans have an allergy of some kind. If you or a family member has allergies, you know how irritating they can be (literally). Allergies occur when the immune system overreacts to one or more allergens by producing antibodies called immunoglobulin E (IgE).[1],[2] Symptoms may include red eyes, an itchy rash, sneezing, a runny nose, shortness of breath, and/or swelling, any of which can range from mild to severe.

The incidence and severity of allergic reactions is influenced by genetics, the microbiome, the route of exposure, age at exposure, and nutritional status. [3],[4],[5] Recent studies show that vitamin D helps modulate IgE responses[6] and that a deficiency of vitamin D exacerbates allergies.[7],[8],[9] Let’s examine the connection between sunlight, vitamin D, and allergies.

Sun, vitamin D, and allergies

Individuals with low UVB exposure have an increased risk of vitamin D deficiency and of allergies.

Vitamin D is known as the sunshine vitamin because it is generated within the skin when it is exposed to ultraviolet B (UVB) rays, the rays responsible for suntans.[10] Vitamin D formation is diminished in people who live in northern latitudes, work indoors, or have greater skin pigmentation (since melanin acts as a natural sunscreen). Individuals with low UVB exposure have an increased risk of vitamin D deficiency and of allergies.[11],[12],[13],[14]

This connection is dramatically illustrated by the case of a 14-year-old girl who presented with severe atopic dermatitis (eczema), asthma, and food allergies (egg, fish, and shellfish).[15] Due to her condition, she avoided eating fish and going out in the sun. Her serum level of 25-hydroxy-vitamin D (25[OH]D, the best indicator of vitamin D status) was very low at 12 nmol/L, so severely deficient that she was diagnosed with rickets, a softening of bones caused by inadequate vitamin D. Supplementation with vitamin D3 (cholecalciferol) for six months corrected the deficiency and dramatically improved her skin condition.[15]

The authors state, “We advise a high index of suspicion of vitamin D deficiency rickets in children of all ages with atopic dermatitis, particularly during accelerated growth periods and in the presence of other risk factors such as darker skin, living at high latitude, sun avoidance, and low intake of vitamin D-rich foods [such as fatty fish and eggs].”[15]

Although rickets is relatively rare, vitamin D insufficiency is widespread.[16] Growing evidence suggests that insufficient vitamin D plays a role in allergies, as discussed below.

Atopic dermatitis

In the U.S., atopic dermatitis (AD) affects 9.6 million children and 16.5 million adults.[17],[18] Serum 25(OH)D levels are lower in AD patients than in healthy controls, and low 25(OH)D levels are associated with more severe symptoms.[19],[20],[21],[22] This may explain why controlled UVB light treatment is effective for AD: it increases 25(OH)D.[23],[24]

In a randomized placebo-controlled trial (RCT), adults with AD received either vitamin D3 (5000 IU per day) or a placebo for three months.[21] The participants continued standard treatments with topical corticosteroids. Vitamin D supplementation restored serum 25(OH)D to near-adequate levels and “strongly favored” remission of AD.[21] Positive results were also seen in children with AD who were supplemented with a lower dose of vitamin D3 (1000 IU daily for one month.)[22],[25] A meta-analysis of several RCTs reported that vitamin D supplementation may reduce the extent and severity of AD by 50%.[20]

Food allergy

Food allergy affects 5.6 million children and 26 million adults in the U.S.[26],[27] Milk, egg, peanut, tree nuts, wheat, soy, fish, and shellfish are responsible for the majority of IgE-mediated reactions,[26] requiring complete avoidance of the trigger food(s) in susceptible individuals. A study of 3,136 children and adolescents found that sensitization to 11 of 17 allergens, assessed with skin prick tests, was more common in children with vitamin D deficiency than in those with adequate levels.[28] In children with food allergy, low 25(OH)D levels are associated with stronger allergic responses.[29],[30],[31] Thus vitamin D may be an important protective factor for food allergy, at least in children.

Allergic rhinitis

As with atopic dermatitis and food allergy, allergic rhinitis is more common in people with low 25(OH)D levels.

Allergic rhinitis affects up to 60 million people in the U.S.,[32] and its presence increases the risk for asthma.[33],[34] As with atopic dermatitis and food allergy, allergic rhinitis is more common in people with low 25(OH)D levels.[35],[36],[37],[38] In children with allergic rhinitis due to grass pollen, supplementation with vitamin D3 (1000 IU daily) significantly reduced the symptoms.[39] The administration of vitamin D3 also improved symptoms in animal models of allergic rhinitis, suggesting that vitamin D has direct anti-allergic effects.[40],[41]

Asthma

Asthma affects nearly 26 million people in the U.S., including seven million children.[42] Low 25(OH)D levels are associated with greater asthma severity.[43],[44],[45] In a four-year study of children with mild-to-moderate asthma, the group with low 25(OH)D (≤ 30 ng/mL) had a 50% greater risk of any hospitalization or emergency department visit.[46]

Insufficient or deficient 25(OH)D levels were associated with increased asthma severity, frequent flare ups, and the need for a higher inhaled corticosteroid dose.

In a study of adult asthma patients in Italy, 75% of the individuals had a clear vitamin D deficiency (≤20 ng/mL).[44] Insufficient or deficient 25(OH)D levels were associated with increased asthma severity, frequent flare ups, and the need for a higher inhaled corticosteroid dose.[44] Individuals with vitamin D deficiency were supplemented with an initial injection of vitamin D3, followed by oral supplementation with 5000 IU weekly plus 400 IU daily for one year. Those who followed the supplementation protocol experienced a significant decrease in flare ups (from 2.6 to 1.6 per year) and a significantly decreased need for oral corticosteroids.[44]

A review of seven clinical trials involving 955 participants concluded that vitamin D supplementation reduced the number of asthma flare ups requiring oral corticosteroids.[47] In one study, severe adult asthmatics with proven resistance to oral corticosteroids showed an improved response after only four weeks of supplementation with 1,25-dihydroxyvitamin D3.[48]

The effect of maternal vitamin D on childhood allergies

Adequate maternal vitamin D levels during pregnancy and breastfeeding may help reduce the risk of allergic diseases in infants and children.[49],[50],[51] Although the optimal level is a subject of debate, two clinical trials suggest that maternal 25(OH)D of ≥ 40 ng/mL (100 nmol/L) may be needed to decrease asthma risks.[52],[53],[54] Women entering pregnancy with circulating 25(OH)D concentrations ≥ 30 ng/mL (75 nmol/L) who were given 4,000 IU/d vitamin D starting at 10 to 18 weeks’ gestation achieved the maximum protection against asthma development in their infants.[52],[53] The authors of a recent review state: “Careful attention to maternal asthma control, monitoring vitamin D status, and correcting insufficiency at early pregnancy and maintaining the sufficiency status throughout pregnancy have potential preventive roles in offspring asthma.”[55]

How much vitamin D is enough?

The only way to assure you are getting enough vitamin D is to have your blood level of 25(OH)D tested. The Institute of Medicine (IOM) guidelines suggest that serum 25(OH)D levels of 20 ng/mL (50 nmol/L) are adequate for good health.[56] However, compelling evidence suggests that higher levels of 30 ng/mL (75 nmol/L) or even 40 ng/mL (100 nmol/L) may be optimal.[57],[58],[59],[60] This requires approximately 1,000 to 2,000 IU per day of supplemental vitamin D and even higher doses if deficiency exists.[57],[61],[62],[63],[64],[65]

Summary

Although low levels of vitamin D have a strong association with increased incidence of allergic conditions, the data also suggest that by restoring levels to an adequate state these conditions may improve. Thus, in addition to supplementation with vitamin C and other supportive nutrients, making sure vitamin D levels are sufficient should be a primary consideration for individuals who experience allergies and asthma.

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