Taking Vitamin D supplements to improve breathing only assists asthma sufferers who can get enough of the vitamin in their blood, a new study by Washington University has found.
The researchers studied 408 patients with asthma and low levels of Vitamin D and gave half of this group large doses of the supplement.
They found no differences in all major measures of asthma control, but patients who already had sufficient levels of the vitamin in their blood did exhibit improved asthma control.
Read more at Washington University School of Medicine