Scientists think modest amounts, such as 15 minutes a few times a week without sunscreen, are enough to let light-skinned people absorb the ultraviolet rays needed to produce vitamin D.

Some scientists believe that people should spend a little more time in the sun -- without sunscreen -- so that their skin can absorb this helpful vitamin. Obviously, that's a controversial notion, given all the warnings about the risk of skin cancer. Here are some answers about this confusing topic:

Q: For years, we've been told to use sunscreen. Shouldn't we be worried about skin cancer?

A: Cancer experts say the risks posed by other cancers is far greater than that of skin cancer, which is rarely fatal. Melanoma, the deadliest kind, is expected to account for just 1.4 percent of the 570,000 cancer deaths in the United States this year.

Q: How much sun should I get?

A: Recommending sun is controversial, and no major health agencies do it outright. But scientists think modest amounts, such as 15 minutes a few times a week without sunscreen, are enough to let light-skinned people absorb the ultraviolet rays needed to produce vitamin D. They are not encouraging long periods in the sun without sunscreen.

Q: Why can't I just take a vitamin pill?

A: The form of D in most vitamin pills and multivitamins isn't that potent. It's also possible to overdose on vitamin D from pills, but not from sunshine.

Q. Don't foods contain vitamin D?

A. Oily fish like salmon, mackerel and tuna do, and milk is fortified with it. But diet accounts for little of the vitamin D that circulates in the blood.

Q: I'm black. Does my skin absorb enough UV rays to produce sufficient vitamin D?

A: In most cases, no. And some experts believe this may be one reason blacks have higher rates of cancer than whites. Nutrition specialists think vitamin D-3 supplements may be especially helpful for dark-skinned people.

Q: How much do I need?

A: Scientists think adults may need 1,000 international units (IUs) a day, possibly 1,500 for cancer prevention. The government says 2,000 IUs is the upper daily limit for anyone over a year old. Any more can cause the body to retain dangerous amounts of calcium.