Vitamin D Deficiency Called Major Health Risk

beyond bone and muscle problems, some evidence suggests a dearth of vitamin D may be associated with an array of more serious illnesses, including many forms of cancer, high blood pressure, depression, and immune-system disorders such as multiple sclerosis, rheumatoid arthritis and diabetes.

In response, many scientists have begun pushing to sharply boost the official recommendations for how much vitamin D everyone should get daily, either by taking supplements, by eating more food that contains the nutrient or from the sun -- a major source of vitamin D.

Suggestions that people get more sun exposure, however, have sparked an unusually intense, and sometimes bitter, debate. Skin cancer experts are alarmed that people will disregard warnings about unprotected sun exposure, making them more vulnerable to what is the most common malignancy.

With people spending more time indoors, covering up and slathering on sunblock when they are outside, and smog obscuring the sun on many days, the amount of vitamin D people create naturally is probably very low, many scientists say.

"Imagine you're a space alien looking down on Earth. You have these humans who evolved in the Horn of Africa, as nudists living around the equator. They would have been getting lots of vitamin D through their skin. Then they suddenly . . . move north and put on lots of clothes and block out most of their capacity to make vitamin D," said Reinhold Vieth, a University of Toronto vitamin D researcher. "For me it's a no-brainer. We're not getting enough."

many cancers, most notably breast, colon and prostate cancer, seem to increase the farther you get from the equator, where exposure to ultraviolet light from the sun is greatest.

"The highest rate of prostate cancer is among African Americans, followed by countries in northern Europe. How are blacks like Scandinavians? They don't look alike, but in some important ways they have to be alike," said Gary G. Schwartz, a cancer researcher at Wake Forest University School of Medicine. "One way that they are alike is both groups have very low levels of vitamin D."

While there could be many other explanations, the idea that vitamin D may help prevent malignancies has been buttressed by animal and laboratory studies indicating it can act as a brake on cell growth, preventing the uncontrolled cell division that is cancer.

Similarly, vitamin D appears to damp down the immune system, and researchers have also found associations among sun exposure, vitamin D levels and the incidence of "autoimmune diseases" such as multiple sclerosis, lupus and diabetes, in which the immune system attacks the body.

Some studies suggest vitamin D can reduce blood pressure, which would cut the risk for heart disease and strokes -- the nation's leading causes of death. Others suggest that low vitamin D levels may contribute to depression and other psychiatric conditions.

"There's no question that chronic, excessive exposure to sunlight and sunburning incidents markedly increases your risk for skin cancer. But there's little evidence out there that if you practice safe sun exposure, it would increase your risk for skin cancer or wrinkling," Holick said.

But dermatologists and skin cancer experts argue that those recommendations are irresponsible and have little firm scientific support.

"Dr. Holick says vitamin D is a cure-all magic pill. If everyone took vitamin D, there would be no more cancer. But there's no evidence that is true," said James Spencer, vice chairman of dermatology at Mount Sinai School of Medicine in New York.

"Ultraviolet light contained in sunlight causes skin cancer and wrinkles. That's beyond dispute," Spencer said. "We already have an epidemic of skin cancer in this country."

Barbara Gilchrest, who chairs the dermatology department at the Boston University School of Medicine, said she asked Holick to resign his position in her department in February because of his views and because he receives some funding from the tanning-parlor industry. "He has, in my opinion, an enormous conflict of interest that he refuses to acknowledge," Gilchrest said.

Holick, who kept his other academic positions at the university, acknowledges he receives funding from the tanning industry, but he says it is a small portion of his budget and comes with no strings attached. "The dermatologists get a lot of money from the sunscreen industry and no one ever questions them about that," he said.

Many experts who believe vitamin D deficiencies play an important role in a range of diseases say people can get enough safely by taking vitamin D supplements, sidestepping the contentious sunlight debate.

An informative article regardless of the ongoing confrontation between the darmatologist who get paid by the sunscreen industry and the vitamin D proponent getting paid by the tanning-parlor industry.