Filed under: Vitamin D
Vitamin D is an integral part of your immune system, and not having enough could put you at higher risk of respiratory tract infections (RTIs) such as the flu and the common cold. Unfortunately, results are mixed when it comes to taking vitamin D supplements for the prevention and treatment of RTIs. People who are deficient in vitamin D may experience the most immune-protecting effects from vitamin D supplements, but the evidence is limited.
Even though vitamin D supplements may not stop a cold in its tracks, getting enough vitamin D does help optimize your immune system. For best results, strive to get the Recommended Dietary Allowance of vitamin D (600 IU) on a daily basis, not just when an illness is coming on. "Vitamin D, the sunshine vitamin," can be harder to obtain in winter, when it’s cold and cloudy and most people spend more time indoors, but you can get vitamin D from foods such as fatty fish and fortified milk, yogurt, and juice. Ask your doctor to test your vitamin D status before you take vitamin D supplements.
Vitamin D is actually a hormone that your body produces when your skin is exposed to sunlight, earning it the nickname “sunshine vitamin.” It plays key roles in reducing your risk of many health conditions, including depression, cancer, heart disease, osteoporosis, and others. Spending 10 to 15 minutes outside on a sunny day with your arms and legs uncovered can provide nearly all the vitamin D most people need—challenging when you’re wearing a long-sleeved uniform or working inside all day—but you can also get some vitamin D in your diet from fatty fish (such as salmon), mushrooms, and many fortified foods.
The Recommended Dietary Allowance for most individuals is 600 IUs. People who have a vitamin D deficiency or certain medical conditions might require supplemental vitamin D but only under the supervision of their healthcare provider. That’s because excess vitamin D can be stored in your body, putting you at risk for toxicity. Over time, too much vitamin D can lead to irregular heart rhythms, kidney damage, and other serious health problems. If you take large doses of supplemental vitamin D and eat foods that are fortified with it, you could easily obtain more than recommended amounts.
Despite the risk for toxicity, nearly one-fourth of people living in the U.S. have low vitamin D levels, so all adults and children should have their vitamin D status checked by their healthcare provider. For more information about vitamin D, read this fact sheet from the Office of Dietary Supplements.