Recommendations around vitamin D intake are a little confusing. While the recommended dietary allowance (RDA) from the National Academies for vitamin D is 600 IU for most healthy adults, some research7 suggests that you need a minimum of 3,000 IU of vitamin D3 a day to get a total serum 25(OH)D (the clinical biomarker of your body’s vitamin D status) of 30 ng/ml, aka clinical sufficiency. Some leading wellness experts suggest that 30 ng/ml is still well below truly optimal vitamin D levels (ie, 50 ng/ml).
“There’s a lot of information suggesting that 600 IU—the current RDA for vitamin D—isn’t enough to optimize your vitamin D status,” says Samantha Cassetty, MS, RD, a nutrition and wellness expert and co-author of Sugar Shock. It’s possible to get vitamin D from salmon, egg yolks, certain mushrooms, and fortified milk, but many plant-based milks aren’t fortified to the same degree as cow’s milk. As a result, “vegans and vegetarians are at higher risk for vitamin D insufficiency,” Cassetty says. Even if you eat animal products, it’s hard to get enough vitamin D from food and exposure to sunlight (another vitamin D source) alone.
Ultimately, “most people tend to need a supplement for vitamin D,” says Jessica Cording, MS, RD, CDN, registered dietitian and author of The Little Book of Game-Changers. When selecting a vitamin D supplement, Cording recommends looking for one with vitamin D3. “It’s the most absorbable form,” she says, adding that she especially likes formulations that include plant-based fats, like olive oil, avocado oil, or flax oil.
As for dosage? Leading health experts recommend 5000 IU daily to reach truly optimal vitamin D status. “Factor in the vitamin D you’re getting from all sources, such as your multivitamin and calcium supplements,” Cassetty says. (To find a supplement that meets all of these criteria, check out mindbodygreen’s roundup of best vitamin D supplements.)