(The Associated Press) -- Evidence is growing that vitamin D, which the skin makes from sunshine, is linked to lower risk of breast cancer and other cancers. But that doesn't mean it's good to get a golden tan -- and certainly not a sunburn.

Vitamin D also is in certain foods and supplements, though the effectiveness varies. Here's the lowdown:

Q: How much sun should I get?

A: Many experts believe just 15 minutes a few times a week without sunscreen is sufficient and safe for most light-skinned people, but this is controversial.

Q: I'm black. Does my skin absorb enough ultraviolet 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. But you'll have to read the label to find D-3 - most multivitamins don't contain it.

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.

Q. What about food sources?

A. Vitamin D is in salmon, tuna and other oily fish, and is routinely added to milk. But diet accounts for very little of the vitamin D circulating in blood.

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

A: Sunscreen is advised for longer periods outdoors, to prevent skin cancer. Skin cancer is rarely fatal. Melanoma, the deadliest kind, accounts for less than 2 percent of cancer deaths. The risks posed by other, more common cancers is far greater.

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