By Uniformed Services University Human Performance Resource Center Staff
Winter is no longer coming, everyone – it’s here.
If you live in the northern Hemisphere, you’re well aware that it’s cold and dark outside a lot now. Dec. 21 is the shortest day of the year, and about now is the time when our bodies start to crave Vitamin D, that an essential nutrient that your body produces when your skin is exposed to sunlight.
Vitamin D helps your body absorb calcium, promotes bone growth, strengthens immunity and helps in reducing the risk of many health conditions. But aside from the sun, you can also get it from foods.
How Much Sun Exposure Do I Need?
Fair-skinned people can get enough from as little as 15 minutes in the sun; the darker your skin, the longer it will take, but it is still less than it would take for your skin to burn. For many reasons, however, that can be challenging when you’re wearing a long-sleeved uniform, working inside all day or in the middle of winter.
How to Get Vitamin D From Foods
Vitamin D is in foods such as cod liver oil, swordfish, salmon, tuna, sardines, beef liver and egg yolks.
Not a big fan of those things? Unfortunately, vitamin D doesn’t naturally occur in many other foods. That’s why some foods are “fortified” with vitamin D, meaning it’s added later. The most common is milk, but some cereal products, yogurt, orange juice, margarine and other foods are also fortified.
How Much Vitamin D Do I Need a Day?
The recommended daily allowance of vitamin D is 600 International Units (exceptions: infants under 1 year need only 400 IU, and adults 70+ need 800 IU).
On fortified food labels, look for “DV” (Daily Value) to make sure you get some in your diet if you don’t get enough sun on your skin. NOTE: The 100% DV is only 400 IU because it assumes you get some vitamin D from sun exposure and foods with natural vitamin D content.
Foods fortified with vitamin D are required to list the amount on their label’s Nutrition Facts panel. However, natural vitamin D content isn’t required on food labels. If you want to find out the natural content in various foods, you can use the USDA Food Composition Databases.
Using Vitamin D Supplements
Another way to get vitamin D is through supplements, especially for people who are deficient in this nutrient or have special medical needs. However, it’s important to consult a healthcare provider before taking supplemental vitamin D because excess amounts of it 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 get more than the recommended amount.
The Bottom Line
Despite the availability of vitamin D from all these sources, nearly one-fourth of people living in the U.S. have low vitamin D levels, which can lead to osteoporosis, autoimmune diseases, type 2 diabetes, certain types of cancer and more. For more information about vitamin D, read this fact sheet from the Office of Dietary Supplements.
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