Some animal products, like cheese, egg yolks, and fatty meats, also have small amounts of vitamin D. For example, you can find 88 IU of vitamin D in a three-ounce serving of braised pork spareribs and 44 IU in a large hard-boiled egg, according to the USDA.
Another good source is some varieties of mushrooms, which are sometimes even treated with UV light to produce more vitamin D, according to the ODS. According to the USDA, morel, chanterelle, maitake, and UV-treated portabella mushrooms tend to contain the most vitamin D, although levels vary based on growing and storage conditions. For instance, chanterelle mushrooms have about 114 IU per cup, according to the USDA.
Most of the vitamin D in the American diet, though, comes from foods that are fortified with vitamin D. Almost all dairy milk sold in the U.S. is fortified with vitamin D, according to the ODS. (You can get 117 IU per cup of 1% milk with added vitamin D, for example.) Yogurt, plant-based milks (like soy, almond, or oat milk), cereal, and orange juice are also commonly fortified. For example, Cheerios have 60 IU of vitamin D in each 1.5-cup serving. Adding more of these foods that are naturally rich in vitamin D or fortified with it can help increase your vitamin D intake.
It’s possible to get enough vitamin D in your diet, but it’s not always easy. “If people aren’t eating a variety of foods, especially cereals, milks, yogurt, and fish, then a supplement might be needed,” says Spence.
It’s always smart to check with your doctor before starting a new supplement, and to do your homework before buying, as SELF has reported. If a blood test reveals deficiency, your doctor can give you a prescription supplement or recommend an over-the-counter supplement in a dose to restore your levels to normal, Dr. Shapses says. If you work with a registered dietitian, they may also recommend a supplement, Spence says, as well as counsel you on dietary sources of vitamin D.
In general, doses of 600 IU to 1,000 IU of vitamin D per day are pretty safe, says Dr. Shapses. (Many multivitamins contain about 1,000 IU of vitamin D, she says.) Spence typically recommends 600 IU for women up to age 70 from a brand that is USP-verified. (This certification means the product contains the ingredients listed on the label in the declared potency and amounts, does not contain harmful levels of specified contaminants, will break down and release into the body within a specified amount of time, and has been made according to the U.S. Food and Drug Administration’s Good Manufacturing Practices, according to USP. But keep in mind that the FDA doesn’t regulate the actual supplements.)
You should only take higher doses of 5,000 IU to 10,000 IU per day if recommended by your doctor, Dr. Shapses says. If your doctor diagnoses you with a vitamin D deficiency, they may prescribe a special high-dose supplement for you to take for a short time, about 8 to 10 weeks. This can bring your levels up into the normal zone fast.
Again, speak to your doctor, and play it safe. There is a risk of excessive vitamin D supplementation—due to mistakes in manufacturing the supplement, an incorrect doctor’s prescription, or simply taking a lot more than directed. This can lead to extremely high levels of vitamin D (greater than 125 nmol/L or 50 ng/mL), which have been linked to adverse health effects, the ODS says.
If you’ve been diagnosed with low or deficient vitamin D or are trying to get more vitamin D into your life, talk to your health-care provider about these various ways to increase the levels of vitamin D in your body—whether through time in the sun, diet, or supplements. And if you want to know whether your efforts are working, there’s only one way to find out: That’s right, you’re going to need to get that blood test.