The researchers found that giving an oral vitamin D supplement reduced the risk of severe asthma attacks requiring hospital admission or emergency department attendance from 6% to around 3%. They also found that vitamin D supplementation reduced the rate of asthma attacks needing treatment with steroid tablets. These results are based largely on trials in adults. They also found that vitamin D did not improve lung function or day-to-day asthma symptoms, and that it did not increase the risk of side effects at the doses that were tested.
A version of this article appears in print on October 13, 2013, on page A 1 of the New York edition with the headline: The Soaring Cost of a Simple Breath. Get Free Email Alerts on These Topics Asthma Drugs (Pharmaceuticals) Prices (Fares, Fees and Rates) Series Inside Health » Too Hot to Handle Arts » The Harmony of Liberty Opinion » Should Beach Privatization Be Allowed? Room for Debate asks whether shorefront homeowners should have to open their land to all comers.