- The Washington Times - Saturday, May 21, 2005


Fifteen minutes of sun every few days may keep the oncologist away.

Doctors and researchers are reconsidering the impact of vitamin D, nicknamed the “sunshine vitamin” because the skin makes it from ultraviolet rays, and are questioning the long-standing advice to use sunscreen, as it blocks the vitamin’s production.

If the research bears out, it will challenge one of medicine’s most fundamental beliefs: that people need to coat themselves with sunscreen whenever they’re in the sun. Doing that actually may contribute to far more cancer deaths than it prevents, some researchers think.

The reason is that vitamin D increasingly seems important for preventing and even treating many types of cancer. In the past three months alone, four separate studies found it helped protect against lymphoma and cancers of the prostate, lung and, ironically, the skin. The strongest evidence is for colon cancer.

Many people aren’t getting enough vitamin D, and it is hard to get from food and fortified milk; the effect of supplements is questionable. So the thinking is this: Even if too much sun leads to skin cancer, which is rarely deadly, too little sun may be worse.

No one is suggesting that people fry on a beach, but many scientists believe that “safe sun” — 15 minutes a few times a week without sunscreen — is a healthy thing to do. One is Dr. Edward Giovannucci, a Harvard University professor of medicine and nutrition who laid out his case in a recent lecture at a major cancer research meeting.

His research suggests that vitamin D might help prevent 30 deaths for each one caused by skin cancer. “I would challenge anyone to find an area or nutrient or any factor that has such consistent anti-cancer benefits as vitamin D,” Dr. Giovannucci told the cancer scientists. “The data are really quite remarkable.”

The talk so impressed the American Cancer Society’s chief epidemiologist, Dr. Michael Thun, that the society is reviewing its sun-protection guidelines. “There is now intriguing evidence that vitamin D may have a role in the prevention as well as treatment of certain cancers,” Dr. Thun said.

The dilemma, Dr. Allan Halpern, dermatology chief at Memorial Sloan-Kettering Cancer Center in New York, said is a lack of consensus on how much vitamin D is needed or the best way to get it. Even if sunshine were to be recommended, the amount needed would depend on the season, time of day, where a person lives, skin color and other factors.

Others worry that folks might overdo it. “People tend to go overboard with even a hint of encouragement to get more sun exposure,” Dr. Thun said, adding that he’d prefer people get more of the nutrient from food or pills.

How vitamin D works is still under study, but there are lots of reasons to think it can.

• Lab and animal studies show that vitamin D stifles abnormal cell growth, helps cells die when they are supposed to, and curbs formation of blood vessels that feed tumors.

• Cancer is more common in the elderly, and the skin makes less vitamin D as people age.

• Blacks have higher rates of cancer than whites and more pigment in their skin, which prevents them from making much vitamin D.

• Vitamin D gets trapped in fat, so obese people have lower blood levels of D. They also have higher rates of cancer.

• People in the northeastern United States and northerly regions of the globe such as Scandinavia have higher cancer rates than those who get more sunshine year-round.

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