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Adrian Martineu of Queen Mary University said that he was taken aback by the findings, adding that while earlier studies had failed to recognize this effect, their thorough analysis showed that the protective effect of vitamin D was “statistically and clinically significant.”
Fewer severe attacks
It has been long known that vitamin D has a critical role in maintaining bone health, but in the 1980s researchers found that vitamin D receptors are found throughout the body, especially in white blood cells and the epithelial layer of the respiratory system. This finding sparked an interest in whether vitamin D potentially plays a role in respiratory and immune health.
Since then, many studies have confirmed that it does play a role in immune regulation. Lack of vitamin D in the body has been associated with many autoimmune diseases, which all share the same characteristics with asthma and allergies. Additionally, observational studies also found that asthma patients with lack of vitamin D are more prone to asthma attacks.
For newer studies, researchers studied 81 separate studies into the link between vitamin D and asthma attacks. They spotted nine that were double-blind, placebo-controlled, randomized trials, considered as the gold standard in medical research.
The team of researchers looked at various asthma-related outcomes, including worsening of symptoms to the extent of requiring hospital admission or oral corticosteroid treatment; exhaled nitric oxide, biomarkers of airway inflammation, and lung function.
It has been concluded that those taking vitamin D supplements were 50% less likely to suffer from asthma attacks severe enough to require hospital admission. In addition, they lowered the risk of oral corticosteroid treatment.
Vitamin D fights infection, inflammation
The design of the earlier studies is the reason for the researchers` inability to determine whether taking vitamin D supplements helped all patients or those who were deficient in vitamin D before the beginning of the study. Consequently, they partnered with the investigators of the nine studies in order to review individual patient data.
Even though it is difficult to say why vitamin D lowered the risk of attacks, earlier studies offer a few possibilities. For instance, some studies have shown that vitamin D is able to suppress inflammatory responses, including the ones that produce asthma attacks.
It has been also shown that vitamin D helps induce immune responses when the body identifies infection with an upper respiratory virus, such as flu or cold, both of which are the major causes of asthma attacks.
Martineau pinpoints two major cautions in regard to this research. First, he noted that only half of asthma patients suffer from a form severe enough to be at risk of the attacks. It is not clear how vitamin D affects those with more mild forms of the disease. Second, he noted that vitamin D supplementation was used in addition to regular treatment in all the trials, not as a replacement.
source: http://besthealthyguide.com