A meta-analysis of 5 studies found that higher blood vitamin D is associated with a 50% lower risk of colorectal cancer.
A larger daily dose of vitamin D could reduce the incidence of colorectal cancer with minimal risk, according to a new review that pools results from five studies.
The analysis found that maintaining a specific target blood level of vitamin D was associated with a 50 percent lower risk of colorectal cancer than that seen in people with consistently lower blood levels.
Previous studies had shown that lower blood levels of vitamin D did not protect against colorectal cancer, according to lead author Edward Gorham, Ph.D., a research epidemiologist with the Naval Health Research Center in San Diego. However, a meta-analysis pools the data from several studies, thus increasing the strength of the results.
I've been telling my regular readers about the benefits of vitamin D for years. A few of you are even acting on this information. Okay, what's with the rest of you? What are your excuses?
The researchers found that a blood serum vitamin D level of 33 nanograms per milliliter or higher was associated with a 50 percent lower risk of colorectal cancer than that seen with blood levels of 12 nanograms per milliliter or lower.
You would need to get between 1000 and 2000 IU of vitamin D per day to get this benefit. You can get there with a supplement or with daily sunbathing.
The amount of dietary vitamin D needed to reach the serum levels that appear to be protective against colorectal cancer — 1,000 to 2,000 international units a day — would not pose any risk, according to Gorham: “The Institute of Medicine has set a ‘No Adverse Effect Level’ of 2,000 IU per day for vitamin D intake, so this recommendation would be safe for most people.”
There is no official recommended dietary allowance for vitamin D, but an adequate dietary intake per day for most adults is currently considered to be 200 to 400 IU.
If you spend alot of time out in the sun during the summer you might only need the supplement during the colder months with the shorter days.
Small amounts of sun exposure would also help people boost their vitamin D levels. Fifteen to 20 minutes per day without sunscreen is enough for the body to synthesize 10,000 IU of vitamin D with minimal risk of sunburn or skin cancer, Gorham said.
Vitamin D will probably lower your risk of Multiple Sclerosis and your incidence of colds and flu too. I believe it is the vitamin that we'd get the most benefit from if we got more of it. Not saying there aren't people out there with plenty of D but not enough iron or zinc or folic acid or C. But for most people more D would deliver the biggest benefit.
The breast cancer study, published online in the current issue of the Journal of Steroid Biochemistry and Molecular Biology, pooled dose-response data from two earlier studies - the Harvard Nurses Health Study and the St. George's Hospital Study - and found that individuals with the highest blood levels of 25-hydroxyvitamin D, or 25(OH)D, had the lowest risk of breast cancer.
The researchers divided the 1,760 records of individuals in the two studies into five equal groups, from the lowest blood levels of 25(OH)D (less than 13 nanograms per milliliter, or 13 ng/ml) to the highest (approximately 52 ng/ml). The data also included whether or not the individual had developed cancer.
"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."
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