Vitamin D protects against severe asthma attacks

Taking a supplement of vitamin D in combination with your prescription asthma medicine may halve your risk of an asthma attack that would require hospitalization, according to a new meta-analysis from Queen Mary University in London (QMUL). A vitamin D deficiency alone, which is rather common at northern latitudes, can increase the risk of asthma. Therefore, it is vital to make sure to have sufficiently high levels of this nutrient all year round to protect your respiratory tract.

Around 300 million worldwide are affected by asthma. The disease is a chronic inflammatory lung condition, and the bronchial constriction causes symptoms such as breathing difficulty, coughing, and chest tightness. Asthmatics are more prone to fatigue and poor sleep because of having breathing difficulty and coughing. Also, they are more vulnerable to respiratory tract infections that are able to trigger an acute asthma attack. Asthma can affect all age groups and is believed to be the cause of around 400,000 deaths annually around the globe.

Did you know that during the whole winter period, the sun sits too low in the sky for us to be able to synthesize vitamin D?

Vitamin D has several mechanisms against asthma

The primary function of the immune system is to fight bacteria and virus, and it is vital that it does not overreact and cause chronic inflammatory conditions such as asthma. Vitamin D works by boosting the immune response against microbes, while at the same time making sure to put the brakes on the immune system, once the microbes have been tackled. That way, harmful reactions are avoided. In other words, vitamin D protects against respiratory tract infections and asthma at the same time.
The researchers from Queen Mary University in London gathered data from seven controlled studies with a total of 955 patients, whose vitamin D intake had been tested. The meta-analysis found that supplementary use of vitamin D resulted in a:

• 50 percent reduction in asthma attacks that require treatment of hospitalization
• 30 percent reduction in the rate of asthma attacks that require medical attention with corticosteroids or injections

The scientists found that supplements of vitamin D are generally safe and easy to administer. No cases of elevated calcium levels or kidney stones were registered, which may otherwise occur if vitamin D is overdosed. For the record, the amount of vitamin D contained in a regular vitamin D supplement is far below the amount that we humans produce in our skin on a hot summer’s day, and it is also far below the EFSA (European Food Safety Authority) upper safe intake level of 100 micrograms daily.
Lead author of the study, Professor Adrian Martineau, says that the meta-analysis supports the increasing amount of scientific evidence of vitamin D’s vital role in the immune defense.

Supplements work best for those patients who lack vitamin D to begin with

The QMUL meta-analysis also found, which groups of patients are most likely to benefit from taking vitamin D. It turned out that vitamin D supplementation has a very positive and statistically significant effect on those who had low levels in the blood, to begin with. These individuals experienced a 55 percent drop in the rate of asthma attacks that require treatment with corticosteroids. The study was funded by the National Institute for Health Research (NIHR) and is published in The Lancet Respiratory Medicine. According to Hywel Williams, Director of NIHR, the meta-analysis produces evidence from several global studies that confirms how vitamin D can help asthma patients.
The study mainly included adults with mild to moderate asthma, which means that they experienced symptoms at least twice per week. Children and adults with severe asthma were underrepresented in the data material, which makes is more difficult to say if vitamin D benefited these patients.

A good idea to take high-dosed supplements

As it turns out, asthma patients (and many others) benefit the most from taking high-dosed vitamin D, at least if the supplement is expected to boost the immune defense. This was seen in a previous meta-analysis, which Professor Adrian Martineau carried out in collaboration with a group of researchers from Cochrane, a global, non-profit network that focuses on public health.
In this meta-analysis, the scientists analyzed several studies with a total of 435 children and 658 adults. The participants came from different parts of the world, and most of them suffered from mild to moderate asthma. During the study period, the majority of study participants continued using asthma medication. The researchers observed that taking a daily 25-50 microgram vitamin D supplement helped lower by around 50 percent the risk of several asthma attacks that require special attention and hospitalization.
Vitamin D supplements also reduced the patients’ need for corticosteroid therapy, which is associated with numerous side effects.

British health authorities recommend more vitamin D

Since July 2016, the British health authorities have officially recommended that everyone from the age of one year take a daily 10 microgram supplement of vitamin D – especially during the winter period where to sun sits too low in the sky for us to be able to synthesize the vitamin.
In Denmark, the reference intake level (RI) is 10 micrograms for children aged 1-10 years but only 5 micrograms from 11 years and older. In other words, the RI level for Danish adults is only half of the British recommendations.
As mentioned earlier, the scientists observed that daily supplementation with 25-50 micrograms of vitamin D lowered the risk of severe asthma attacks. That intake level is far beyond the official recommendations, in Great Britain as well as in Denmark.

Threshold levels in the blood

When measuring vitamin D levels in the blood, the official threshold value is 50 nmol/L. Many scientists believe that this is insufficient and say that levels as high as 75-100 nmol/L are required for optimal disease prevention.

Vitamin D, supplements, and absorption

Vitamin D is a lipid-soluble nutrient. Therefore, we can best absorb and utilize it when it is contained in some kind of oil in capsules.

References

David A Jolliffe et al. Vitamin D supplementation to prevent asthma exacerbations: systematic review and meta-analysis of individual participant data. The Lancet Respiratory Medicine 2017
http://www.thelancet.com/journals/lanres/article/PIIS2213-2600(17)30306-5/fulltext

Queen Mary University of London. Vitamin D protects against severe asthma attacks. ScienceDaily October 3, 2017
https://www.sciencedaily.com/releases/2017/10/171003202923.htm

Adrian R Martineau et al. Vitamin D for the management of asthma. Cochrane Library 2016
http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD011511.pub2/abstract

https://www.theguardian.com/society/2016/sep/05/vitamin-d-supplements-could-halve-risk-of-serious-asthma-attacks

http://www.netdoktor.dk/sygdomme/fakta/astma.htm#