Vitamin D significantly reduces the risk of cancer

Scientists say most people in North America are not taking enough vitamin D, and that could increase their risk for developing cancer quite significantly.

In a study conducted by researchers at Creighton University School of Medicine, researchers followed 1,179 healthy, postmenopausal women from rural eastern Nebraska for a four-year period between 2000 and 2005.

The women were all 55 years or older and free of known cancers for at least 10 years prior to entering the Creighton study; they were randomly assigned to take daily dosages of 1,400-1,500 mg supplemental calcium, 1,400-1,500 mg supplemental calcium plus 1,100 IU of vitamin D3, or placebos.

The research team found that those taking calcium, as well as a quantity of vitamin D3, at nearly three times the U.S. government's Recommended Daily Amount (RDA) for middle-age adults, showed a 60 percent or greater reduction in cancer risk than women who did not get the vitamin.

Lead investigator Joan Lappe, Ph.D., R.N., Creighton professor of medicine says vitamin D is a critical tool in fighting cancer as well as many other diseases.

Dr. Lappe believes the findings confirm what many have suspected for some time and supports a growing body of evidence that a higher intake of vitamin D may be helpful in the prevention and treatment of cancer, high blood pressure, fibromyalgia, diabetes mellitus, multiple sclerosis, rheumatoid arthritis and other diseases.

As a rule people make their own vitamin D3 when they are exposed to sunlight and just 10-15 minutes a day in a bright summer sun creates large amounts of the vitamin.

The researchers found that over the course of four years, women in the calcium/vitamin D3 group experienced a 60 percent decrease in their cancer risk than the group taking placebos.

Working on the premise that some women entered the study with undiagnosed cancers, the researchers then eliminated the first-year results and looked at the last three years of the study and the results appeared even more dramatic with the calcium/vitamin D3 group showing a remarkable 77 percent cancer-risk reduction.

In the three-year analysis, there was no statistically significant difference in cancer incidence between participants taking placebos and those taking just calcium supplements.

Through the course of the study, 50 participants developed non skin cancers, including breast, colon, lung and other cancers.

Lappe says more research is needed to determine whether the research results apply to other populations, including men, women of all ages, and different ethnic groups as all the study participants were Caucasian.

Where you live in the world as well as your ancestry influences the body's ability to convert sunlight into vitamin D; dark skinned people have more difficulty making the vitamin and those living at latitudes north of the 37th parallel are unable to get their vitamin D naturally during the winter months because of the shortage of sunlight.

There is agreement amongst experts that doses of vitamin D need to be increased in some situations, but debate persists on the amount.

Supplements are available in two forms, vitamin D2 and vitamin D3 and the researchers recommend vitamin D3, because it is more active and thus more effective in humans.

The study has prompted the Canadian Cancer Society to advise all Canadian adults to take large doses of vitamin D during the sun-poor winter months, and says the elderly and those with dark skins should take the supplements year round.

The Canadian Cancer Society says the Canadian population is at greater risk because of its latitude.

The society recommends that adults take 1,000 international units of vitamin D a day during fall and winter, while the elderly, dark-skinned people, or those who don't go outside often, should consider supplements year round.

The National Institutes of Health funded the study and the results are published in the June 8, 2007 online edition of the American Journal of Clinical Nutrition.