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Vitamin D Supplements: FAQ


What it does: Experts agree on the basics. Vitamin D helps the body absorb calcium, and that is good for bone health. Vitamin D also helps reduce inflammation in our cells. Inflammation can trigger disease.

What are the main areas of disagreement about Vitamin D?

How much is needed: At the center of the debate is how much vitamin D is enough. "We need more vitamin D than what we are getting [from diet and sun exposure]," Recker says. "What is not agreed upon is how much more."

The Institute of Medicine recommends that most Americans need no more than 600 international units (IU) of vitamin D a day. People 71 and older may need 800 IU, it says. This level is enough for bone health, it says.

Vitamin D is found in some foods, including fatty fish like salmon and tuna, beef liver, fortified dairy products, cheese, and egg yolks. Except for those, getting enough vitamin D from your diet isn’t easy. As examples, a 3-ounce serving of salmon provides 447 IU, and 3 ounces of tuna fish offer 154 IU.

Meanwhile, our skin makes vitamin D when exposed to natural sunlight. This helps vitamin D levels in our blood. But Recker says only people who live at the equator get a large amount of D from sunlight.

Testing: Experts disagree on whether healthy people need routine testing to detect low vitamin D blood levels.

How much is enough: Experts also disagree on how much vitamin D we need in our blood to be healthy.

Which groups of people might benefit more from higher levels of D?

Older adults who are frail, Campos-Outcalt says. Getting 800 IU a day may help them prevent falls and fractures.

Recker says older people who are healthy can also benefit from the higher levels, ''because the skin loses the ability to make vitamin D" as people age. Some older people also stay indoors more as they age, he says.

Other people may also need to pay close attention to vitamin D in their foods. Among them are people on corticosteroids and other medications that can affect bone health, Recker says.

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