Vitamin D helps build strong bones and teeth - that's long been known. Exposure to sunlight is the easiest way to get your daily dose of vitamin D. It's unusual not to look to diet to get adequate nutrients but sunlight triggers the conversion of a natural compound in the skin into vitamin D and is a better source than most foods. More recently, attention has been focused upon the effect of vitamin d on asthma, breast cancer, diabetes, high blood pressure and Multiple Sclerosis. Some experts have suggested it is time for daily recommendations to be revised upwards to protect not just bones and teeth but to promote general health and avoid chronic disease.
A paper in the September issue of the Annals of Allergy, Asthma & Immunology has found a possible cause-and-effect link between vitamin D deficiency and asthma. Researchers Manbir Sandhu and Thomas Casale, from Creighton University, Nebraska, USA, looked back at almost 60 years of research on the effect of vitamin d on asthma.
So it wasn't exactly a new study, but these reviews often uncover previously hidden connections and evidence - and can be really useful in pointing the way for future studies and possible asthma treatment. They found that vitamin D deficiency is linked to increased airway hyper-responsiveness - the clinical hallmark of asthma - as well as to poorer lung function and worsened asthma control. This does not amount to evidence that you should add a vitamin D supplement to your regular asthma treatment. First of all, even if there is an effect of vitamin d on asthma and vitamin D deficiency was confirmed as a genuine cause of asthma, it is not the only cause. And, second, you wouldn't know you had a vitamin D deficiency unless you were tested for it. However, the Creighton researchers do make a cautious recommendation that people with asthma might consider vitamin D - but, if you want to do this, it's best to discuss it with your allergy specialist first.
What's needed now is fresh, forward-looking studies to find the exact effect of vitamin d on asthma and to see whether taking vitamin D can help prevent asthma or help control it better if you already have it. In the meantime, if the sun's out, take advantage and get outside. You only need 20 minutes exposure to the sun (without sunscreen) to start building up long-term supplies of vitamin D in your body.
To learn more about asthma visit our asthma information page.