People fighting off winter colds and bouts of the flu typically reach for a glass vitamin C-packed orange juice, but new research suggests that vitamin D may be a better protector. People with low levels of the vitamin, which is often called the sunshine vitamin because sun exposure triggers its production in the body, are more likely to catch colds, the flu, and even pneumonia, a broad new study reports. The effect was magnified in people with asthma or other lung diseases.
Vitamin D deficiency is quite common in the United States — particularly in winter…. “People think that if they have a good, balanced diet that they will get enough vitamin D, and that’s actually not true,” said Dr. Michal Melamed…. “Unless you eat a lot of fish and drink a lot of milk, you can’t get enough vitamin D from diet” [CNN].
In the new study, published in the Archives of Internal Medicine, researchers studied data from almost 19,000 participants in a national health and nutrition survey. They found that people with the worst vitamin D deficiency were 36 percent more likely to suffer respiratory infections than those with sufficient levels…. Among asthmatics, those who were vitamin D deficient were five times more likely to get sick than their counterparts with healthy levels [Scientific American]. While the study didn’t prove a cause and effect relationship, experts say the correlation is quite striking.
As a next step, the research team plans to supplement high-risk populations during winter months with high doses of vitamin D to see if those people have reduced infection rates compared with untreated people [Science News].
Evidence has been piling up that vitamin D plays an important role in maintaining the immune system.
Lab work has shown that lack of vitamin D is associated with weaker production of an antimicrobial peptide called hCAP-18, a protein that works with immune-system cells to kill pathogens. “We think that if you’re exposed to a virus [and] you have sufficient vitamin D, those cells will be better equipped to fight off that organism so you don’t get an infection” [Scientific American], says study coauthor Adit Ginde. Higher levels of vitamin D have also recently been linked to reduced risks of heart disease, diabetes, and cancer.
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