Vitamin D is one of those nutrients that I highly recommend for just about everyone. Vitamin D levels are being found to be insufficient or deficient in people all over the world, including in the United States. By conventional medical standards, a vitamin D level (25-hydroxy vitamin D) of less than 12 ng/mL is considered deficient, and 20 ng/mL or higher is considered adequate. Many health experts disagree, however, stating that levels of at least 30 ng/mL (up to 50 ng/mL or more) are adequate for optimal health.
A number of studies have linked low vitamin D levels to increased risk of development of upper respiratory infections like cold and flu. A recent study published in the Journal of the American Medical Association found that supplementation with high doses of vitamin D (200,000 iu once a month for two months followed by 100,000 iu per month for 16 months) was not protective against the development of upper respiratory infections. The headlines, as you can imagine, sound like, “Vitamin D No Match for Common Cold” and “Trying to Avoid a Cold? Skip the Vitamin D Supplements.”
Please, please—I urge you to not toss your vitamin D supplements because of the headlines you read about this study. What these misleading headlines don’t tell you is that the people in this study started out with vitamin D levels at 29 ng/mL—sufficient levels. You can see that the study was set up to fail from the start. What might the researchers have found if they started with people who had lower vitamin D levels, and thus, higher risk of upper respiratory infection? Perhaps they would have found what other studies that included participants who were deficient in vitamin D found—a reduction in upper respiratory infections.
In fact, a study published in the same journal found that patients with tuberculosis who were deficient in vitamin D experienced a decrease in upper respiratory infections with vitamin D supplementation over two months. Certainly, more studies are needed to clear up the confusion before people write off the immune health benefits of vitamin D, which have been extensively documented. Optimizing your vitamin D level should be a priority, no matter your health status. If you haven’t had your vitamin D level tested, it’s time you did. Ask your doctor about it, or request an at-home test on your own.