June 23, 2009
Major Study To Examine Benefits Of Vitamin D, Fish Oil
For years, vitamin D and fish oil have been two of the most popular over-the-counter dietary supplements in U.S. Now, an extensive, government-funded study will test the benefits of both in the prevention of cancer, heart disease and strokes to determine whether they will get the official thumbs up.
What's more, the study is one of but a small handful of health experiments to ever look into the ethnic-specific effects of nutrients on the human body.
In humans and most other mammals vitamin D is synthesized naturally when UVB rays from the sun penetrate the skin and stimulate its production in the basal levels of the epidermis. In dark-skinned people however"”particularly those of African descent"”large quantities of the pigment melanin in the upper layers of skin serve as a filter, blocking most of the UVB light and significantly reducing the amount of vitamin D that the body is able to produce.
A number of scientists have hypothesized that this lower production of vitamin D may be an important piece of the puzzle in understanding why African Americans, for example, suffer from such high rates of cancer, stroke and heart disease.
"If something as simple as taking a vitamin D pill could help lower these risks and eliminate these health disparities, that would be extraordinarily exciting," said Dr. JoAnn Manson of Harvard-affiliated Brigham and Women's Hospital in Boston, who, along with Dr. Julie Buring, will be co-leader of the research project.
"But we should be cautious before jumping on the bandwagon to take mega-doses of these supplements," she cautioned. "We know from history that many of these nutrients that looked promising in observational studies didn't pan out."
For a time, a there was a tremendous buzz in the medical community over the tremendous potential of Vitamins C, E, beta carotene, folic acid and others to lower the risk of a number of chronic health problems. After rigorous testing, however, mega-doses of these supplements were shown to carry just as many health risks as benefits.
Others have simply proven ineffective. In October of 2008, federal funding for a major long-term study examining the role of vitamin E in preventing certain forms of cancer was abandoned after researchers failed to produce results that even remotely hinted at statistically significant benefits of the supplement.
Vitamin D is one of the last well-known nutrients to be put through the scientific ringer.
Scientists and nutritionists have known for some time that a large number of people have vitamin D deficiencies. In addition to blacks, health experts have also detected higher rates of cancer in people inhabiting northern regions, where longer winters and reduced exposure to sunlight means that their bodies have less opportunity to produce sufficient quantities of the "sunshine vitamin."
Further complicating the problem for both northerners and those with dark skin is the fact that vitamin D is not as readily available in dietary sources as a number of other vitamins. Nutritionists say that it's difficult to eat enough dairy and fish products to compensate for a lack of naturally-produced vitamin D.
While scientists are already quite certain about several of the health benefits of the vitamin D"”such as its role as a regulator of calcium and phosphorous levels in the blood"”they are also eager to take a more in depth look at some of the less-understood physiological effects of the fat-soluble compound.
"Vitamin D and omega-3s have powerful anti-inflammatory effects that may be key factors in preventing many diseases. They may also work through other pathways that influence cancer and cardiovascular risk," explained an optimistic Manson.
The expansive new study will include some 20,000 subjects over the age of 60 who have no history of heart disease or stroke. Because of difficulties that the body often has utilizing vitamins from a pill, some of the participants will be randomly assigned to take vitamin D pills, while others will take natural fish oil supplements, both nutrients or placebo pills.
For a five year period, the patients will receive 2,000 international units of vitamin D-3 a day. Also known to researchers by its scientific name, cholecalciferol, this version is known to be the most active form of the nutrient.
The subjects receiving fish oil will get about one gram a day"”roughly 10 times more than what the average American consumes.
"We're hoping to see a result during the trial, that we won't have to wait five years," said Manson.
Besides the vitamin's potential effect on heart disease, stroke and cancer, the researchers will also be looking for possible benefits in reducing memory loss, depression, diabetes, osteoporosis and other problems, explained Buring.
National Cancer Institute, in collaboration with the National Heart, Lung and Blood Institute and other federal agencies will be funding the $20 million project. Pharmavite LLC of Northridge, Calif., is providing the vitamin D pills, and Ocean Nutrition Canada Ltd. of Dartmouth, Nova Scotia, is providing the omega-3 fish oil capsules.
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