Several studies show the importance of vitamin D in immune health.
John J. Cannell, MD, executive director of the Vitamin D Council, observed a flu epidemic at a prison hospital. As various wards next to his got the flu, none of those in his ward did, even though patients and nurses intermingled. The only difference between wards was that those in Dr. Cannell’s unit had been taking 2,000 IU of vitamin D per day for several months prior to the flu outbreak.
In a tuberculosis (TB) study, 67 men and women with lung tissue damage from TB took a single 10,000 IU dose of vitamin D or a placebo in the sixth week of standard TB treatment. Doctors found that 100 percent of those in the vitamin D group had no sign of TB in lung mucus compared to 77 percent for placebo. Chest X-rays also improved more in the vitamin D group than for placebo.
In an English TB study, 131 participants who had been exposed to TB took a single 100,000 IU dose of vitamin D or a placebo. Six weeks later, those who had taken vitamin D had better TB immunity than placebo. Doctors noted that in most TB cases in London, people were previously infected but the disease was inactive and that those most at risk are often deficient in vitamin D. The scientists believe that vitamin D may prevent the TB bacteria from reactivating and recommend everyone take a vitamin D supplement.
In a cold study, researchers measured the blood levels of vitamin D in 800 young Finnish military men. Those whose vitamin D levels fell below half the average were absent from duty due to lung infection far more than those with higher vitamin D levels. Doctors noted that non-smokers and exercisers had higher vitamin D levels.
In a study of newborns with severe lung infection, 25 sick babies and their moms had about half the amount of vitamin D in the blood compared to 15 healthy babies and their moms.
In light of these and other findings, in June 2008 the American Medical Association encouraged the U.S. Food and Drug Administration to update its Daily Reference Intake Value for vitamin D.
Reference: European Journal of Clinical Nutrition; November, 2007, electronic pre-publication.