Sparks fly in debate on sunshine vitamin
Posted on Tuesday, May 13, 2008
URL: http://www.nwanews.com/adg/News/225599/
The discovery by researchers that at least 30 percent of the U. S. population is vitamin D deficient has led to a burst of interest in the vitamin long known to help strengthen bones and boost the immune system.
“It was a total surprise,” said Dr. Stavros C. Manolagas, chief of endocrinology and metabolism at the University of Arkansas for Medical Sciences.
“In retrospect, it turns out to be the way we dress, the way we eat, the way we avoid the sun based on the advice of our dermatologists... that has brought an epidemic of vitamin D deficiency.”
Nicknamed the “sunshine vitamin,” vitamin D is a fat-soluble vitamin that allows the body to absorb calcium. The body produces vitamin D when skin is exposed to ultraviolet rays from the sun.
People can also get vitamin D from select foods and vitamin supplements.
Doctors have known the benefits of vitamin D to skin, muscles and bones for more than 50 years. But a growing body of research suggests it may also benefit heart health, reduce high blood pressure, help prevent certain forms of cancer, and curb depression and pain disorders.
“This is probably the hottest topic in nutrition right now from a scientific research standpoint,” said Todd Whitthorne, president and chief operating officer of Cooper Concepts Inc., part of the Cooper Aerobics Clinic in Dallas. “The last three or four years, the research has just exploded.”
But doctors say much of the research remains inconclusive, and a lot is still unknown about vitamin D.
As a result, there is an ongoing conflict between vitamin D experts who say a certain amount of sun exposure is essential to life, and skin-cancer experts who warn about the dangers of sun exposure.
“We’re very concerned about reports that link the health benefits of vitamin D to unprotected ultraviolet exposure, because ultraviolet exposure is a known cause of skin cancer,” said Dr. Andrew Kaufman, a dermatologic surgeon in Thousand Oaks, Calif., and a fellow of the American Society for Dermatologic Surgery.
As many as 90 percent of skin cancers are caused by sun exposure, with more than 1 million new cases expected to be diagnosed this year, he said.
Vitamin D deficiency was called a “pandemic with a heavy public health burden,” in a Jan. 15 British Medical Journal article by Gregory Plotnikoff, medical director of the Institute for Health and Healing at Abbott-Northwestern Hospital in Minneapolis.
Manolagas said at least 30 percent to 40 percent of the population is vitamin D deficient. Others have estimated that as much as 70 percent of the population is deficient.
People who are vitamin D deficient are at increased risk for diabetes, hypertension, infectious and auto-immune diseases, and developing osteomalacia, or a softening of the bones, Plotnikoff wrote.
Harvard Medical School researchers said people who are vitamin D deficient are twice as likely to experience heart trouble, including a heart attack, heart failure or stroke within a five-year period compared with people with normal levels, in a Jan. 8, 2007, report published in Circulation: A Journal of the American Heart Association.
Other studies show that people who are vitamin D deficient are at an increased risk of certain types of cancer such as breast, ovarian, prostate and pancreatic cancer, Whitthorne said. An article this month in Cancer Epidemiology Biomarkers and Prevention, a publication of the American Association for Cancer Research, said studies are inconclusive so far, but that maintaining sufficient levels of vitamin D might be a “promising approach” to preventing or treating cancer. Overall research linking vitamin D deficiency to different diseases is “still under big debate,” Manolagas said. “Unfortunately, I don’t think the proof is there yet,” Manolagas said. “Is it possible that vitamin D may be good for other things ? Perhaps, but we don’t have definitive proof.”
MEASURING DEFICIENCY Eight years ago, Lauren Hill began having sharp pain in her feet. Her doctor said a lack of calcium had weakened her bones and led her to have stress fractures in two major foot bones.
“My feet hurt me so bad,” said Hill, who spends a lot of time on her feet as manager of the bariatric program at Baptist Health Medical Center-Little Rock.
Hill was diagnosed as vitamin D deficient about a decade after having gastric bypass surgery. She was directed to wear an orthopedic boot to allow her foot to heal and to take more vitamin D.
“Back then we didn’t know to look for vitamin D,” she said.
Today, Baptist Health tests vitamin D levels in all gastric bypass patients. Many patients who have the surgery are found to be vitamin D deficient because their bodies have a difficult time absorbing vitamins, Hill said. The surgery makes the stomach smaller and allows food to bypass part of the small intestine.
About a year ago, the Cooper Clinic began routine testing of clients’ vitamin D levels from blood samples. People with less than 30 nanograms per millimeter of vitamin D are considered deficient.
“Well over 50 percent of our patients are vitamin D deficient,” he said. The clinic sees about 10, 000 patients annually.
Part of the problem with addressing vitamin D deficiency is that it isn’t routinely measured, so many people don’t know they’re deficient, Whitthorne said.
In the 1930 s, the U. S. government began requiring producers to fortify milk with vitamin D to combat rickets, a softening of the bones in children that could lead to fractures and deformity, according to the Office of Dietary Supplements, part of the National Institutes of Health.
Rickets was a major public health problem at the time but has since been virtually eliminated, according to the federal office. Today, about 99 percent of milk supplies in the United States are fortified with vitamin D.
Vitamin D is also found in cod liver oil, margarine, pudding, fortified ready-to-eat cereals, eggs, liver, beef, Swiss cheese and several types of fish including salmon, mackerel, tuna and sardines.
Vitamin D helps the body maintain normal blood levels of calcium and phosphorus, an essential element of living cells. It helps the body maintain a healthy immune system and reduce inflammation, according to the office.
The amount of sun exposure needed for the body to synthesize vitamin D varies depending on the season, location, time of day, weather conditions and a person’s skin tone.
The darker the skin and the farther north a person lives, the more sun exposure it takes for the body to produce vitamin D.
A person is more likely to become vitamin D deficient as he gets older and his body has a harder time absorbing it.
Whitthorne said vitamin D deficiency is easy to correct. Vitamin D supplements are readily available and inexpensive.
But just how much vitamin D people need to stay healthy remains a matter of debate.
The U. S. Food and Drug Administration recommends 400 international units of vitamin D each day. Cooper Concepts, which has three varieties of adult multivitamins, recommends at least 1, 000 international units of vitamin D daily.
At UAMS, doctors recommend elderly people have 50, 000 international units of vitamin D a month, Manolagas said.
THE SUNLIGHT QUESTION The National Institutes of Health’s Office of Dietary Supplements Web site says experts suggest five to 30 minutes of sun exposure between 10 a. m. and 3 p. m. at least twice a week to the face, arms, legs or back without sunscreen is enough to maintain adequate vitamin D levels. But the federal agency also warns it is “important to routinely use sunscreen to help prevent skin cancer or other negative effects.” Dr. Daniel Davis, dermatopathologist at the UAMS, said he spends every day correcting the ravages of skin cancer, including removing people’s noses, eyes and ears.
While there is excitement over the possibility that vitamin D might help fight cancer, it’s important to remember the known dangers of sun exposure, he said.
“Is the sun is important to human beings ? Yes, we couldn’t survive without it,” Davis said. “Does sun cause skin cancer ? It’s indisputable. So where is the happy medium ?”
People should limit their sun exposure and use supplements, Davis said.
Kaufman said 1. 35 million new cases of skin cancer were diagnosed in 2006, more than all other types of cancer. Sun damage builds up slowly over time, he said, so it could be as long as 20 years before a person develops skin cancer.
“Is it safe to get a little bit of color; is it safe to get tan ? The answer is no,” Kaufman said. “A tan, or freckles or a sunburn are all signs of damage from the sun to a person’s skin.”
Manolagas recommends people use common sense.
“Certainly sunbathing for hours after hours in the Caribbean is one extreme, and going outside with short sleeves in the summer for half an hour or one hour of work is a completely different thing,” he said.
While people who are greater risk of developing skin cancer should take precautions, “covering every part of your body and hiding from the sun is certainly not the way we humans were made,” Manolagas said.