Did you know that vitamin D deficiency is extremely common even in the US? It is estimated that 50% of the world’s population is vitamin D–deficient. And this deficiency is sneaky—you may not have any symptoms, but low blood levels of vitamin D (25-hydroxyvitamin D) can lead to low bone density, brittle bones, osteoporosis and more.
The current Recommended Dietary Allowance (RDA) for vitamin D is 600 international units (IU)* for most children and adults…800 IU after age 70. But Michael F. Holick, PhD, MD, the country’s preeminent researcher on vitamin D, says these amounts are just not enough. Based on the Endocrine Society Practice Guidelines, he recommends the following to keep your D levels in the healthy zone…
Infants: 400 IU to1,000 IU
Children: 600 IU to 1,000 IU
Teens and adults: 1,500 IU to 2,000 IU
Note: If your body mass index (BMI) is over 30, you need two or three times this amount because vitamin D is diluted when stored in large amounts of body fat and very slow to be released.
Problem: It is just not possible to get enough vitamin D through diet and/or sun exposure—especially if you live north of Atlanta or Los Angeles, where the angle of the sun is too low from November through March to produce vitamin D in the skin…and the temperature is too cold in the early spring and late fall for you to comfortably expose enough skin. So your first step to keeping your vitamin D levels healthy is to supplement. All adults should take a 2,000-IU vitamin D supplement every day—any national brand that contains either vitamin D-2 or D-3 will do, and it can be a tablet, liquid or capsule, taken on an empty or full stomach.
Even better: You can help keep your vitamin D levels strong by eating the right foods. Dr. Holick explains which are the best choices to keep your vitamin D levels in the safe zone…
Two foods are standouts…
Wild-caught salmon. The typical advice is to eat a range of oily fish, including trout, char, herring, anchovies, sardines, bluefish, mackerel, swordfish and tuna—but of these, salmon is the best choice. While swordfish has more vitamin D in a three-ounce serving, you should eat it very infrequently—no more than once a month—because of its toxic mercury content. For the same reason, you should have tuna no more than once a week. Salmon is the closest to ideal with 446 IU of vitamin D per three-ounce serving. And because D remains stable to 200°C (about 400°F), you can cook it any way you like—poached, grilled, pan-seared, etc. Best: Wild-caught salmon, which can be fresh, frozen or canned. Farm-raised salmon (and other farm-raised fish) have only about 10% to 25% of the vitamin D in wild-caught.
Mushrooms. Until recently it was thought that fungi that naturally grow in sunlight, such as chanterelles and morels, have more vitamin D than mushrooms grown under other conditions. Recent finding: Just about any type of mushroom can produce appreciable amounts of D when sun-dried or otherwise exposed to UV light. The mushrooms convert ergosterol, a precursor to vitamin D, into ergocalciferol, commonly known as vitamin D-2. While D-2 is different from the vitamin D-3 found in animal products, your body still absorbs it well—an important consideration if you’re vegan. You can do a Google search to find producers that expose their mushrooms to UV light. Oyster, cremini, portabella, shiitake and ubiquitous white button mushrooms enhanced with UV light or sun-dried all are available.
Egg yolks and beef liver provide incremental amounts of vitamin D, about 40 IU per yolk or three ounces of liver.
The list of fortified foods is growing. Example: In India, cooking oil is being fortified with vitamin D-2. It doesn’t get destroyed with cooking and is appropriate for that country’s large vegan population.
Here are the most commonly D-fortified foods in the US. The amounts of D they contain are relatively small but can add to your daily intake…
Milk. While milk is not a natural source of vitamin D, it has been added in most US milk products since the 1930s. An eight-ounce glass delivers between 115 IU and 125 IU.
Nondairy milks. Almond, oat and other nondairy milks usually are fortified with 100 IU of D per eight-ounce glass as well as calcium (look for at least 300 mg of calcium). Avoid blends with added sugars. In addition to soy milk, some tofu is fortified, too.
Yogurt. Some brands are fortified with about 80 IU of vitamin D. Best: Low-fat and sugar-free varieties.
Fortified orange juice. You’ll get an average of 100 IU in an eight-ounce glass. Look for brands with added calcium. Caution: Avoid orange juice if blood sugar is a concern.
Cereals are commonly fortified with vitamin D (as well as other nutrients), but usually a scant 40 IU per cup. Best: Pick cereals that also have some whole grains for their fiber and that don’t have (or have minimal) added sugar.
