Despite being readily available through sunlight, some foods, and supplementation, many Americans are still getting inadequate amounts of vitamin D—according to the most recent information from the Centers for Disease Control and Prevention, two-thirds of the population had sufficient vitamin D, defined by the Institute of Medicine as a serum 25-hydroxyvitamin D (25OHD) value of 50–125 nmol/L. Because you can’t necessarily find out if you a vitamin D deficiency on your own, the best thing to do is to consult a medial expert, says Cynthia Sass, RD, MPH, contributing nutrition editor for Health. “Ideally the best approach is to have your blood vitamin D level tested to find out if your blood vitamin D level is within the adequate range,” she explains. “This determines if a supplement is needed in order to achieve adequate blood vitamin D status, and if so, the proper dosage of supplemental vitamin D.”
If you find out you are deficient or lacking in vitamin D intake, there are a few key ways you can up your daily dosage—staring with getting around 20 minutes of sunlight several times a week, according to Newgent. “The major cause of vitamin D deficiency is inadequate exposure to sunlight, an increasing feature in modern life,” says Dr. Boyd. But remember: You still need to wear sunscreen whenever you step outside—even to get vitamin D.
Aside from the sun, you can also get extra vitamin D through a few (albeit very few) foods, like fatty fish (including salmon, tuna, mackerel, and sardines) and mushrooms (some of which are exposed to ultraviolet (UV) light to increase vitamin D levels), says Drs. Nasrallah and Newgent. Foods like milk, orange juice, yogurt, and breakfast cereals can also be fortified with vitamin D. And of course, you can always go the supplement route, in the form of vitamin D3, if your doctor thinks it’s necessary. According to Dr. Boyd, many doctors now consider a daily dose of 1000-2000 IU of D3 safe and will assure optimal levels for most adults. As for when to take it, because vitamin is fat soluble, he suggests pairing it with your largest meal of the day, “containing fat to assure maximal absorption.” But again, check in with your doctor before you decide to try vitamin D in supplement form