Can you wear sun block and still get vitamin D from solar rays? According to conventional wisdom, sunscreen blocks all D production, but a recent review by Chiu and a colleague suggests it’s not that simple. “Most people don’t apply enough or reapply if they’re spending a lot of time in the sun,” he says. Even so, if you’re a regular sunscreen user (and you should be), you can’t count on producing enough D to maintain healthy levels. Enter the supplements.
How much to take? Most experts agree that 1,000 to 2,000 IU per day is safe, but the bottom end of that range probably isn’t enough to boost those who are low on D into the adequate level. “Only half of people who have insufficient amounts of D will get to 30 nanograms per milliliter by taking a dose of 1,200 IU a day,” Norman says. To be cautious, start with a 1,000-IU dose and see where you are in two months; if you’re still low, bump it up to 2,000. “Two thousand should bring most people into the desirable range,” Willett says.
Look for a D3 supplement, which provides the kind of D created when skin is exposed to the sun. It raises blood levels more effectively than D2, the plant-based form. You can improve vitamin absorption by as much as 50 percent if you down your pill with your biggest meal of the day, a Cleveland Clinic study reports. “Most people take D with orange juice or toast in the morning, but it doesn’t seem to be well absorbed unless you also eat some fat, because D is fat soluble,” says Angelo Licata, MD, an endocrinologist who worked on the study.
Don’t expect the so-called sunshine vitamin to leave the spotlight anytime soon. “This is probably the hottest topic in nutrition research,” Willett says. “Stay tuned for further details.”
Originally published in the September 2010 issue of More.