Allergies can also be termed as ‘allergic diseases’, which are a couple of conditions caused by hypersensitivity (intolerance caused by a set of undesirable reactions produced by the normal immune system. Such reactions may be damaging, uncomfortable, or occasionally fatal).
Such condition may include hay fever, food allergies, atopic dermatitis, allergic asthma, and anaphylaxis/ acute allergic reaction. Related symptoms may include red, watery eyes, an itchy rash, runny nose, shortness of breath, or swelling.
Through the scientific research, it has been observed that low vitamin D levels are associated with most types of allergies. There exist about 5 to 10 times higher risk of food allergy with insufficient levels of vitamin D. People living in cities or having dark skins/more melanin content generally have low vitamin D levels and thus are prone to more allergies.
There is an overwhelming evidence that vitamin D reduces allergies.
Allergy involves an overstated response of the immune system, often associated to common substances such as foods or pollen.
The immune system is a complex system that generally defends our body against any foreign invaders, such as bacteria and viruses. It also surveys for conditions such as cancer and autoimmunity.
Allergens are typically the substances that are foreign to the body and are responsible for causing an allergic reaction. IgE- Immunoglobulin type E is the allergic antibody.
Although many individuals have the capacity to outgrow allergies over a period of time, allergies can also develop at any age, including during adulthood and can recur.
While the environment plays a major role in the development of allergy, there is a greater risk of developing allergic conditions if a person has a family history of allergy, especially in parents or siblings- genetics.
A number of research studies that have been carried out have suggested that Vitamin D deficiency may play a role in the development of allergy.
Research studies carried out in Australia have exhibited that childhood food allergies are more common in the south of the country (where there is less sunlight) than in the north, indicating that less sun exposure could be a critical factor in deciding the role of developing an allergy. Sunlight is an important source of Vitamin D.
Allergy expert Dr Ray Mullins conducted a study in Australia to study behavioural patterns of the allergic conditions across the continent. He started off with 36,000 children in Australia-wide who had been prescribed “allergy-safe” infant formula. He also mapped the locations of 69,000 children and prescribed emergency adrenaline to be used in case of a food allergy event. He added the locations of 11,000 cases, over five years, of children who were taken to hospital suffering an allergic reaction to food.
Though there were many factors that could skew the results, such as differences in population and access to doctors across the country, it showed a significant gathering in Australia’s south, where there is less sunlight.
He although warned that the research should not be the sole base to see as an encouragement to stop wearing sunscreen, as a person’s required level of vitamin D could be obtained in just 20 minutes of mid-morning sun exposure.
Another research in USA found that more people with food allergy are born in autumn and winter than in the sunnier months of the year.
Over 1,000 food-allergic patients in Boston were recruited for the study.
Months of birth in patients with food allergy were compared with those of patients visiting the emergency departments for reasons other than food allergy. There have been numerous other “month of birth” studies showing higher rates of all allergies for those born in the autumn. But, there could be many explanations independent of sunlight exposure to explain this.
Another group of researchers examined the blood samples of African-American youths with persistent asthma appearing in an urban paediatric medical centre.
The results showed that most were Vitamin D deficient or insufficient. The study team stated that given the emerging associations between low vitamin D levels and asthma, strong consideration should be given to routine Vitamin D testing in urban African American youths, particularly those with asthma.
What can be observed is that we do have a very high rate of Vitamin D deficiency in our community, which has the tremendous potential to have antagonistic effects on health irrespective of any effect on allergy. Low sunlight exposure is clearly a major reason for this. In people with food allergy the problem is increased because of their dietary avoidance. It is routine practice for allergy clinics to measure Vitamin D levels and prescribe supplements if they are insufficient.
Discussion: The above studies all recognize an association between low levels of vitamin D and risk of allergy. However, this does not necessarily point that this is a cause-and-effect relationship. The only way to establish this is to set up controlled intervention studies. A number are currently in progress.