Are you getting enough vitamin D in your diet? This nutrient is important for growing healthy cells, keeping your immune system humming to ward off illness, and aiding in calcium absorption so your bones stay strong. It also helps prevent the bone disease rickets in children, and along with calcium, the so-called sunshine vitamin guards against osteoporosis in older adults, according to the National Institutes of Health (NIH). All these benefits explain why the U.S. Food and Drug Administration (FDA) began requiring food manufacturers to include it on nutrition labels in 2018.
Vitamin D is produced in your body when the sun’s ultraviolet rays hit your skin, and the recommended daily allowance (RDA) of vitamin D is 600 international units (IU), which is 15 micrograms (mcg) for most adults, according to the NIH. For those older than 80, the RDA is 800 IU (20 mcg).
Yet most people don’t get enough vitamin D via sunlight, nor is food a good source of the nutrient, says Lori Zanini, RD, a Los Angeles–based dietitian. According to data from the 2013–2016 National Health and Nutrition Examination Survey (NHANES), average daily intake from diet was 204 IU for men and 168 IU for women. Even if you drink whole milk fortified with vitamin D (whole milk has slightly more vitamin D than reduced-fat or skim), 8 fluid ounces (oz) contain just 95.6 IU, per the United States Department of Agriculture (USDA) — one-eighth the amount that you need daily. No wonder an estimated 24 percent of Americans have a vitamin D deficiency, per a review published in January 2020 in Nature. A vitamin D deficiency means you have less than 20 nanograms per milliliter of the nutrient in your blood, per the NIH. If you are nonwhite, obese, or do not get sufficient sun exposure, you may be at greater risk for being vitamin D deficient according to the NIH. Your healthcare provider can test your blood to find out for sure.
How to Get More Vitamin D
As with most nutrients, it’s best to get vitamin D the natural ways — through safe sun exposure and, when possible, diet. If, however, your doctor confirms a deficiency, supplements might be a good option. There are two main types: vitamin D2 and D3. Zanini recommends vitamin D3 (cholecalciferol), which is found in animal sources of food and has been shown to more effectively increase levels and sustain them for a longer period of time. Those who eat a plant-based diet, however, may prefer vitamin D2 (ergocalciferol) supplements, which are manufactured using UV irradiation of ergosterol in yeast, per the NIH.
If you’re not deficient, recent research says your bone health likely won’t benefit from a pill. A study published July 28, 2022, in the New England Journal of Medicine examined the effects of 2,000 IU of vitamin D3 supplements versus a placebo in over 25,000 healthy, nondeficient volunteers older than 50. Researchers aimed to see if the supplement would limit risk of bone fractures over the course of five years, and found that, compared to placebo, it did not.
Few foods naturally contain vitamin D, so it is important to make sure you are getting as many of them in your diet as possible, along with D-fortified foods. “Getting vitamin D from food is a priority,” says Zanini. Make sure your diet is rich in the following fare, so you can get what you need.