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Vitamin D and Cancer
A May 2008 Canadian study found that breast cancer patients with low levels of vitamin D are much more likely to die of the disease or have it spread than patients getting enough of the nutrient - adding to evidence the "sunshine vitamin" has anti-cancer benefits. This is additional evidence about the importance of the role of vitamin D in cancer prevention.
The skin makes vitamin D from sun light. Too much sunlight can raise the risk of skin cancer, but small amounts - 20 minutes or so a few times a week without sunscreen - is beneficial plus taking Vitamin D supplements.
Research published in the June 2007 issue of the American Journal of Clinical Nutrition, is the first time that scientists significantly boosted — and measured — blood levels of vitamin D and then followed identical groups of patients from start to finish.
The new research strengthens the case made by some specialists that vitamin D may be a powerful cancer preventive and most people should get more of it. Building hope for one pill to prevent many cancers, vitamin D cuts the risk of several types of cancer by 60 percent.
“The findings ... are a breakthrough of great medical and public health importance,” according to Cedric Garland, a vitamin D researcher at the University of California-San Diego. “No other method to prevent cancer has been identified that has such a powerful impact.”
The study was originally designed to monitor how calcium and vitamin D improve bone health. It takes an important step in extending several decades of research that began with observations that cancer rates among similar groups of people were lower in southern latitudes than in northern ones. Scientists reasoned that had to do with more direct sunlight in southern regions.
Supplements put to the test
The skin makes vitamin D when exposed to sunlight’s ultraviolet rays. This study used that same form of the vitamin, known as D3 or cholecalciferol. Multivitamins usually carry a much weaker variant known as D2, but D3 is available in stand-alone dietary supplements.
Earlier research has shown that vitamin D helps regulate cell growth, a fundamental biological process that goes haywire in cancer. Most other supplements have tended to target specific types of disease in early testing, like selenium or vitamin E for prostate cancer.
The researchers at Creighton University in Omaha focused on 1,179 seemingly healthy women with an average age of 67. The women were divided into three groups: 446 got calcium and vitamin D3 supplements, a similar number got calcium alone, and 288 took a placebo.
The research team gave 1,000 daily international units of vitamin D, more than current guidelines calling for 200 to 600 units depending on a person’s age.
The researchers intended to check mainly for the effects of calcium on bone health. Their interest in cancer risk was secondary. However, the lower cancer risk stood out. Only 13 women, or 3 percent, developed cancer over four years of calcium and vitamin D supplements. With calcium alone, 17 women, or 4 percent, got cancer. With a placebo, cancer appeared in 20 women, or 7 percent.
That shows a 60 percent lower cancer risk over four years in the group taking both supplements, compared to patients taking placebos. And when the first-year cancers were excluded — the ones mostly likely present before the study began — the findings were stronger still: a 77 percent lower risk for the combo group.
While the calcium-only group lowered its four-year cancer risk by 47 percent compared to the untreated group, it did no better when early cancers were excluded. That suggests calcium alone may have done little in this experiment, the researchers said.
Experts reviewing the study focused on vitamin D as the powerful agent in the combo group, but it can’t be ruled out that calcium might somehow amplify the effect of vitamin D.
While numbers were limited, these women developed a broad range of cancers, including disease of the breast, colon, lungs and blood. Dr. Michael Holick, of Boston University Medical Center, who sat on the professional panel that issued the 1997 guidelines for vitamin D, said this study shows that enough vitamin D “markedly reduces the risk of developing the most serious deadly cancers.”
How much vitamin D?
Dr. Holick supports raising the recommended amount of the vitamin and said 1,000 daily units of vitamin D3 would now be reasonable for most people. The research adds to the great bunch of evidence that we need to have better vitamin D nutrition. Some foods carry the vitamin, like salmon, tuna and fortified milk, but diet accounts for little of the vitamin circulating in the body. Overexposure to the sun can cause skin cancer, especially in the southern latitudes.
The Canadian Cancer Society announced that all adults should start taking vitamin D supplements. It is the first time a major public health organization endorsed daily use of the vitamin as a cancer-prevention therapy for an entire population.
The society recommends that:
- Adults should consider taking 1,000 international units (IU) of vitamin D supplements a day during the fall and winter.
- Adults at higher risk of having vitamin D deficiency should consider taking the 1,000 IU supplement year round.
Factors that increase the risk for vitamin D deficiency include:
- Getting older, since the skin is less capable of producing vitamin D from exposure to the sun with age. No precise age cutoff has been determined.
- Darker skin.
- Not going outside often.
- Wearing clothing that covers most skin.
"We're recommending 1,000 IUs daily because the current evidence suggests this amount will help reduce cancer risk with the least potential for harm," said Heather Logan, the society's director of cancer control policy.
87-8 A & D Vitamins 10,000 / 1000 IU 120 gel caps $12.95 Ingredients: Vitamin A, Vitamin D. The vitamin content is entirely derived from natural fish liver oil with no chemicals or additives.
58-1 Calcium Citrate with Minerals 100 Tablets $14.95
85-3 Liquid Calcium and Magnesium 12 fl oz $16.00
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