Known as the ‘sunshine vitamin’ because we get it primarily through the sun’s UVB rays, vitamin D is crucial for our health in a number of ways. Thing is, research suggests approximately 40 percent of the U.S. population is deficient. That’s why many of us turn to supplements to meet our daily needs.
Like any other supplement, how much, what form, and when we take vitamin D all matter. Use this comprehensive guide to maximize its benefits.
Why Vitamin D Matters
You may already know that vitamin D is important for bone health, but it’s also crucial for immune system resilience, insulin function, and energy. It may also even boost athletic performance, mood, and our ability to lose weight.
Our Intended Source Of Vitamin D: The Sun
Our skin is designed to produce vitamin D when exposed to the sun. However, very few of us catch enough rays to meet our needs.
In the winter, the sun’s UVB rays aren’t strong enough to trigger production of the vitamin, putting anyone who lives far from the equator at risk for falling short, says Khalid Saeed, D.O. Plus, most of us spend the vast majority of our days working indoors. According to a Clinical Laboratory study, this pretty much guarantees us low vitamin D levels.
Even people who spend lots of time outside likely miss out on the nutrient, since sunscreen interferes with vitamin D production, says Jonathan Valdez, R.D.N., owner of Genki Nutrition and spokesperson for the New York State Academy of Nutrition and Dietetics. In fact, SPF 15 blocks up to 93 percent of UVB rays.
Oh, and did we mention that your skin’s ability to help convert sunlight into vitamin D decreases with age? Not an ideal set of circumstances for healthy vitamin D status.
What’s At Stake With Vitamin D Deficiency
Given these factors, older adults, people who spend little time outside or live far from the equator, people with darker skin, and people with digestive issues are at the greatest risk for a deficiency of vitamin D, says Monisha Bhanote, M.D., F.A.S.C.P., F.C.A.P.
However, vegans, vegetarians, nursing mothers, folks with depression, and people who take certain prescription medications are at risk, too.
Unsurprisingly, deficiency comes with some serious consequences. “Vitamin D deficiency has been associated with increased risks of cancer, autoimmune diseases, hypertension, osteoporosis, heart disease, and depression,” says Saeed. It’s also been associated with weight gain and greater susceptibility to infectious disease.
How Much Vitamin D We Really Need
The trouble doesn’t end there. Many experts disagree about how much vitamin D we truly need to be at our healthiest.
While The National Institutes of Health Office of Dietary Supplements recommends that adults (including pregnant and breastfeeding women) get 600 IU of vitamin D per day, other organizations recommend aiming higher—much higher. The Endocrine Society, for example, suggests up to 2,000 IU per day, while the The Vitamin D Council recommends 5,000 IU.
“Most registered dietitians and doctors think the government’s recommendation is outdated and too low,” explains Bhanote. (She personally recommends 2,000 to 4,000 IU a day.)
And while a few foods—like liver, fatty fish, egg yolks, and mushrooms—contain some vitamin D, you can’t rely on your diet alone to meet your nutrient needs, says Jennifer Dennis-Wall, Ph.D., science writer at research organization Biorasi.
When Supplements Can Help
If you’re vitamin D deficient (which a simple blood test can reveal), your doctor will likely recommend a supplement in the form of vitamin D3. (Research suggests D3 more effectively raises overall vitamin D levels long-term than vitamin D2, the other form of vitamin D.)
Most people will take somewhere between 500 and 2,000 IU per day, says Valdez. However, if your levels are incredibly low, your doctor may recommend as much as 10,000.
From there, check your levels in a few months to make sure you’re absorbing the D you’re taking.
The Right Time To Take Vitamin D
To reap the most benefits from supplementing with vitamin D, you’ve got to consider when and how you take it.
Because vitamin D is a fat-soluble vitamin, which means it needs fat to be fully absorbed and used by the body, Bhanote recommends taking it with a meal that contains healthy fats. You don’t have to go out of your way to eat extra fat, just make sure your meal contains some healthy fats, like avocado, eggs, nuts, coconut oil or olive oil, or chia seeds.) “I recommend taking it with your largest meal to be safe,” says Bhanote.
“However, if dinner is your largest meal and you eat late, your supplement may affect your sleep,” she says. You see, the sunshine vitamin has an inverse relationship with melatonin—the sleep hormone.
This inverse relationship means two things: First, that low levels of vitamin D overall are associated with higher rates of sleep disturbances, lower sleep quality, and reduced sleep duration. Second, that taking vitamin D supplements at night, when melatonin levels are naturally high, may interfere with melatonin production and affect sleep quality.
As of right now, the latter connection is mostly anecdotal. However, Bhanote suspects that because our bodies associate vitamin D with daytime—it is the sunshine vitamin, after all—taking the nutrient at night tricks our body into thinking we should be awake.
Given that, experiment with when you take your vitamin D and stick to whenever works for you. “Usually the morning is more convenient, and easier to remember,” says Saeed. That’s especially true if you go out to dinner or work in an office. To be safe, stick to the first half of the day.