May 16, 2008 in Nation/World

Vitamin D deficiency linked to cancer spread

Marilynn Marchione Associated Press
 

From dietary sources, sun

» Vitamin D is found in many dietary sources such as fish, eggs, fortified milk and cod liver oil. The sun also contributes significantly to the daily production of vitamin D. The term “vitamin D” refers to several different forms of this vitamin. Two forms are important in humans: ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). Vitamin D2 is synthesized by plants. Vitamin D3 is synthesized by humans in the skin when it is exposed to ultraviolet-B rays from sunlight. Foods may be fortified with vitamin D2 or D3.

» The major biologic function of vitamin D is to maintain normal blood levels of calcium and phosphorus. Vitamin D aids in the absorption of calcium, helping to form and maintain strong bones. Recently, research also suggests vitamin D may provide protection from osteoporosis, hypertension, cancer, and several autoimmune diseases.

Mayo Clinic

Breast cancer patients with low levels of vitamin D were much more likely to die of the disease or have it spread than patients getting enough of the nutrient, a study found – adding to evidence the “sunshine vitamin” has anti-cancer benefits.

The results are sure to renew arguments about whether a little more sunshine is a good thing.

The skin makes vitamin D from ultraviolet light. Too much sunlight can raise the risk of skin cancer, but small amounts – 15 minutes or so a few times a week without sunscreen – may be beneficial, many doctors believe.

While the vitamin is found in certain foods and supplements, most don’t contain the best form, D-3, and have only a modest effect on blood levels of the nutrient. That’s what matters, the Canadian study found.

Only 24 percent of women in the study had sufficient blood levels of D at the time they were first diagnosed with breast cancer. Those who were deficient were nearly twice as likely to have their cancer recur or spread over the next 10 years, and 73 percent more likely to die of the disease.

“These are pretty big differences,” said study leader Dr. Pamela Goodwin of Mount Sinai Hospital in Toronto. “It’s the first time that vitamin D has been linked to breast cancer progression.”

But people shouldn’t start downing supplements, she warned. Experts don’t agree on how much vitamin D people need or the best way to get it, and too much can be harmful. They also don’t know whether getting more vitamin D can help when someone already has cancer.

“We have no idea whether correcting a vitamin D deficiency will in any way alter these outcomes,” said Dr. Julie Gralow, a cancer specialist at the University of Washington in Seattle.

The study was released Thursday by the American Society of Clinical Oncology and will be presented at the group’s annual meeting later this month.

Lots of earlier research suggests vitamin D may help prevent prostate, breast and especially colon cancer. In lab and animal tests, vitamin D stifles abnormal cell growth, curbs formation of blood vessels that feed tumors and has many other anti-cancer effects.

Other evidence: People who live in northern regions of the world have higher cancer rates than those living closer to the equator, possibly because of less sunshine and vitamin D.

© Copyright 2008 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

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