Higher Vitamin D Levels May Greatly Lower Breast, Colon Cancer Risk
Even more research evidence just out reinforcing the importance of adequate vitamin D levels for avoiding the development of breast and colon cancers.
In the first paper published in the Journal of Steroid Biochemistry and Molecular Biology, researchers pooled data from two previous studies and found that individuals with the highest vitamin D levels (greater than 50 ng/mL) had one-half the risk of developing breast cancer versus individuals with the lowest vitamin D levels (less than 10 ng/mL).
“The data were very clear, showing that individuals in the group with the lowest blood levels had the highest rates of breast cancer, and the breast cancer rates dropped as the blood levels of 25-hydroxyvitamin D increased,” said study co-author Cedric Garland, Dr.P.H. “The serum level associated with a 50 percent reduction in risk could be maintained by taking 2,000 international units of vitamin D3 daily plus, when the weather permits, spending 10 to 15 minutes a day in the sun.”
In the second paper published in the American Journal of Preventive Medicine, researchers found that individuals with the highest vitamin D levels had the lowest colon cancer risk.
“Through this meta-analysis we found that raising the serum level of 25-hydroxyvitamin D to 34 ng/ml would reduce the incidence rates of colorectal cancer by half,” said co-author Edward D. Gorham, Ph.D. “We project a two-thirds reduction in incidence with serum levels of 46ng/ml, which corresponds to a daily intake of 2,000 IU of vitamin D3. This would be best achieved with a combination of diet, supplements and 10 to 15 minutes per day in the sun.”
Sources
The primary source of vitamin D is sunshine (UVB rays) hitting the skin, converting cholesterol-based molecules there into a molecule called cholecalciferol, which is then converted by two more reactions in the liver and kidneys into the final, active form of vitamin D (calcitriol).
Interestingly, researchers have learned in recent years that the final conversion that takes place in the kidneys can also take place in other cells in the body, such as breast, colon, prostate, and skin cells, four cell types that are prone to cancer.
Food is a poor source of vitamin D. Only fortified dairy really contains significant amounts, and then, only about 100 IU in an 8 oz. glass of milk. Not much.
If you get vitamin D through sun exposure, you want to avoid getting too much exposure and damaging the skin. You don’t want the skin to change color. 10 to 15 minutes per day of noontime sun on a clear day three or four times a week for a fair-skinned person should be fine. Dark-skinned people need significantly more exposure, e.g., 25 to 30 minutes exposure each time out.
In Northern latitudes during the winter months, the sun isn’t strong enough to generate adequate vitamin D, even during mid-day sun. Supplementation is the preferred source.
Getting 2000 IU/day of vitamin D through supplementation is both easy and inexpensive (less than $15 a year). As long as people aren’t getting regular, significant sun, such an intake level year-round is likely to be safe and promote healthful vitamin D levels that may:
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reduce the risk for several types of cancer
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improve calcium utilization and bone density
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strengthen immunity and reduce susceptibility to the flu
As the evidence continues to mount, last month’s appeal by leading researchers for an increase in the vitamin D upper intake level, as well as higher daily recommended intake levels for optimal health, needs to be taken seriously.
