How To Get The Vitamin D You Need: The Truth About Sunlight, Foods & Supplements

Vitamin D is an essential nutrient—but it's rare to get enough of it from food and sunshine alone without being very intentional. In fact, research has shown that 931 to 100%2 of Americans fail to consume just 400 IU from their diet each day, and many experts say 5,000 IU per day is needed for optimal health. Further, almost half the population3 in the U.S. is insufficient in the sunshine vitamin (considering all inputs from sun, diet, etc.!), which just really isn't great news for our overall health.

Vitamin D is a fat-soluble vitamin and hormone4 (in its active form) that helps your body absorb and maintain homeostasis of calcium and phosphorus, major building blocks needed to create and maintain strong bones and teeth5.* Ample vitamin D also allows these minerals to function properly in your muscles so they can contract and relax properly.*

That's not all, either. The sunshine vitamin also supports the body's response to inflammation, promotes cell growth, and is critical for immune function.*

Vitamin D needs are more nuanced than you might think. As mbg's vice president of scientific affairs Ashley Jordan Ferira, Ph.D., RDN, explains: "The question of daily vitamin D needs is directly informed by your vitamin D status, measured via serum 25-hydroxyvitamin D from a blood test, or for short, 25(OH)D."

The National Academies recommend a cutoff of 20 ng/ml for sufficiency, while The Endocrine Society more recently vetted the science and recommended a 30 ng/ml cutoff. As Ferira expounds, "to be clear, these cut points are numbers to avoid. In other words, you want to exceed 30 ng/ml daily for most of your life to reap the full benefits of vitamin D for health."* In fact, a vitamin D supplement less than 20 or 30 ng/ml is associated with suboptimal bone density (not something to mess with).

To support your personal health, you'll want to get familiar with your 25(OH)D levels, which means asking your health care provider for this simple blood test6₆. This is the clinical measure of your whole-body vitamin D status—and necessary information if you want to track your baseline status and watch how optimizing your vitamin D intake makes a significant impact.*

Brittany Henderson, M.D., a board-certified endocrinologist who specializes in hormones (including vitamin D) in her clinical practice, shares that "achieving optimal serum 25(OH)D levels in the 50+ ng/ml range is imperative for immune health, bone health, and more."*

"Vitamin D is found in very few foods—and the foods that it is found in do not have amounts that will move the needle much in terms of total amount humans need for health," says integrative dietitian Whitney Crouch, RDN, CLT.

Sina Gallo, Ph.D., R.D., associate professor of nutritional sciences at the University of Georgia, agrees: "It's difficult to meet the requirement for this vitamin through diet alone."

The reason vitamin D is called the sunshine vitamin? You can get it from sunlight. "Cutaneous [skin] production of vitamin D occurs when the sun is higher in the sky, as in summer, and the skin is exposed as long as it is not too heavily pigmented," says Connie Weaver, Ph.D., a professor in the Department of Nutrition Science at Purdue University.

One major caveat here: Getting enough vitamin D from sunlight risks exposing you to unsafe skin practices. "You can try to get some [vitamin D] naturally by being exposed for five minutes before applying sunscreen, but the length of time can be affected by individual differences," Gallo says. (Read: Depending on your skin tone, you may need more sun exposure than is ultimately safe in order to produce the amount of vitamin D you're after.)

Now, if meeting that optimal vitamin D intake means eating 18 ounces of trout each day (i.e., six servings of this fish) and relying on the sun is a bit of a crapshoot, what options does that leave you with if you want to ensure you're getting enough of the sunshine vitamin (every day for decades) to feel your best? Well...supplements.*

Here's what to look for: First, go for vitamin D3 (cholecalciferol), which, as Gallo explains, is the form our skin produces from sun exposure. It's also been shown to be the most effective at raising and maintaining our 25(OH)D levels (your status biomarker). Next, look for a high-potency option that provides at least 5,000 IU so that you're getting enough to hit that 50 ng/ml+ goal for 25(OH)D. Folks with more fat tissue (i.e., overweight or obese), will require two to three times more vitamin D99 to achieve the same serum status, according to science and clinical consensus.