February 10, 2007
Vitamin D Cuts Colorectal Cancer Incidence

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?

50%!

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.

Higher blood vitamin D also reduces breast cancer risk 50%.

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."

Share |      Randall Parker, 2007 February 10 12:34 PM  Aging Diet Cancer Studies


Comments
Peter said at February 11, 2007 3:59 PM:

Randall,
Too bad we don't fortify foods with more vitamin D. The public heath benefit would be enormous, and cumulative. Most people don't realize that the current dairy fortification is with the weaker form of vitamin D (D2). If we switched to D3 and upped the level, we could increase serum levels across the board. As far as dangerous levels, there is no evidence of any toxicity until daily levels exceed 10,000 units daily. The 2000 IU level has be talked about for so long as a danger level that people just accept it a conventional wisdom. The overblown fear of an overdose needs to be weighed against the very real risks of not getting enough.

Doug said at February 16, 2007 4:23 PM:

I continue to take about 10,000 I.U. per day of vitamin D3 during the winter; I even tend to take make-up doses when I've missed a dose. I've been taking 5,000 I.U./day in the summer and 10,000 I.U./day in the winter for about two years now. It's important to note that my exposure to the summer sun is low. Also, no one has gone so far as actually to recommend 10,000 I.U. per day, not even John Cannell, M.D., the best friend vitamin D3 ever had. I'm relying on what I've read about the body's daily production when exposed to the noon-time, summer sun for a few minutes each day.

I encourage readers to see John Cannell's site, http://www.vitamindcouncil.com , for more information about vitamin D3, more than you can consume even in several sittings.

JoAnne said at March 19, 2007 7:55 PM:

Our company has Vitamin D3 in 10,000 IU USP, PHARMACEUTICAL quality CHOLECALCIFEROL 0.25mg
It is meant for once a week dosing and does not require a prescription. Getting a baseline D3 level is recommended so you and your MD can decide how much you need to take to get your D3 level where it belongs before you go to maintenance dosing.
It is called Maximum D3 and is at www.vitd3.com

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