MADISON, Wis., Nov. 23 (UPI) -- Previous studies have shown that children with asthma have low levels of vitamin D, with studies mounted to find whether increasing levels of the vitamin would help ease the chronic condition. Researchers at the University of Wisconsin were surprised to find it had no effect on decreasing colds or asthma symptoms.
Researchers at Wisconsin had previously published research showing patients whose vitamin D levels were returned to normal had a 40 percent reduction in asthma exacerbations, however the new study did not find vitamin D reduced the number or severity of colds in adults with the condition.
"Other studies of vitamin D and colds have produced mixed results," said Dr. Laura Denlinger, an associate professor of medicine at the University of Wisconsin, in a press release. "Most of those studies were conducted among healthy patients. We wanted to ask the same question of a patient population in which the impact of a cold carries greater risk."
The researchers enrolled 408 adults with mild to moderate asthma whose vitamin D levels either were insufficient or deficient. Participants were randomly given either daily doses of vitamin D or a placebo for 28 weeks.
Of the participants, about 82 percent of patients given vitamin D supplements reached proper levels in about 12 weeks, and roughly half of all participants had at least one cold during the study. Researchers reported, however, there was no difference in the number of colds or their severity among people who were given a supplement rather than placebo.
While researchers said vitamin D is useful for other health risks that can affect asthma patients, Denlinger said "we can't recommend vitamin D for the prevention of colds."