Studies have shown that vitamin D helps to reduce inflammation, decrease asthma severity, and improve treatment success in asthmatics.

Asthma is an immune system disorder marked by excessive levels of inflammation in the bronchial tubes. Vitamin D is a safe and highly effective anti-inflammatory that is helpful for all sorts of immune system problems. A recent study involving 308,000 adults aged between 22 and 50 years found that asthmatics with vitamin D deficiency were 25 percent more likely to experience asthma attacks compared to asthmatics with normal vitamin D levels.

Asthma attacks are more common in winter, and vitamin D deficiency is also more prevalent in winter. This is because sunshine exposure helps your skin to manufacture vitamin D. In many parts of the world, even if it is sunny in winter, the sun may not be strong enough to stimulate vitamin D production.

Very few foods are a source of vitamin D; egg yolks, oily fish, and butter provide small amounts. It’s a good idea to get a blood test to check your vitamin D level in winter, as that’s the only way to know for sure if you’re getting enough of this nutrient. If your blood level is low, a vitamin D supplement can help to bring it into the normal range.

Confino-Cohen R, Brufman I, Goldberg A, et al. Vitamin D, asthma prevalence and asthma exacerbations: a large adult population-based study. Allergy. 2014 Dec;69(12):1673-80.