Vitamin D is essential for building bone and maintaining skeletal structure, promoting calcium absorption, aiding immune function, and helping to reduce inflammation. The challenge is finding it -- it doesn't naturally occur in many foods like other vitamins and minerals. Fortunately, there are plenty of easy ways to get the recommended dietary allowance of this necessary nutrient: 600 international units, or IU, each day.
Getting out in the sun is perhaps the easiest way to boost vitamin D, which is created when ultraviolet B rays strike the skin. The best time is midday during the warmer months, when the sun's rays are strongest. (Keep in mind that glass blocks UVB, so sitting behind a window doesn't work.) Sitting outside for as little as 10 minutes is sufficient for many people. A host of other outdoor activities, including gardening, biking, and sports, are just as effective.
Fish are one of the few natural food sources of vitamin D, and fatty fish are the best bets. For example, a 3-ounce portion of rainbow trout boasts about 645 IU, according to the U.S. Department of Agriculture's National Nutrient Database. The same size serving of Atlantic herring delivers 182 IU of vitamin D, or about 30 percent of the recommended amount.
Cod liver oil is another excellent source of naturally occurring vitamin D, but the taste is unpalatable to many. Try some tips and tricks to help the medicine go down, such as mixing cod liver oil into homemade salad dressing or stirring it into yogurt. And if that doesn't work, capsules containing cod liver oil are just as effective -- and more convenient.
Although dairy products aren't a natural source of vitamin D, nearly all milk sold in the United States is fortified with about 100 IU of vitamin D in an 8-ounce serving. This applies to all types of milk -- full-fat, 2 percent, 1 percent, and skim -- but generally not milk products such as cheese and ice cream.
Likewise, vitamin D isn't naturally present in oranges, but some brands of orange juice are fortified with varying amounts of vitamin D, along with calcium, as an alternative for those who don't -- or can't -- consume milk products. Think of it as juiced-up juice.
Three ounces of cooked beef liver supplies about the same amount of vitamin D found in an egg yolk -- about 40 IU. You can't rely on liver for a full complement of vitamin D, of course, but it helps to know that an occasional meal helps boost your daily intake.
Many brands of ready-to-eat breakfast cereal contain added vitamin D, along with other vitamins and minerals. Fortified cereal alone isn't a significant source of vitamin D -- it supplies about 10 percent of the daily requirement. But adding milk raises the amount of vitamin D to 25 percent of the recommended amount. Note: Some non-GMO cereals aren't fortified with vitamin D, likely due to the difficulty of sourcing vitamins from non-genetically modified sources.
While vitamin supplements can be expensive, vitamin D can be bought cheaply. A 600-count bottle of Kirkland Signature vitamin D3 softgels from Costco with 2,000 IU (about half the upper limit for adults, according to the National Institutes of Health) costs about $11.50, or less than 2 cents a tablet. Big-box retailers such as Walmart and Target offer similarly priced products -- but be sure to compare the dosage, which can vary considerably from product to product.