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Vitamin D3 supplements fight prostate cancer, breast cancer - study confirms

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By David Liu, PHD

Saturday Aug 25, 2012 (foodconsumer.org) -- It's breakthrough news!  David Feldman of Stanford University School of Medicine and colleagues conducted a study that suggests taking vitamin D3 supplements may effectively prevent or treat both breast cancer and prostate cancer.

Serum vitamin D levels have been inversely associated with risk of breast cancer and prostate cancer.  This animal study confirmed that vitamin D3 is effective in killing these malignancies that together hit half a million American men and women each year.

The study showed immunosuppressed mice bearing breast cancer xenografts experienced greater than 50 percent shrinkage in the tumor after ingestion of a vitamin D3 supplemented diet (5000 IU/kg), compared to a control diet (1000 IU/kg).  And a similar result was found in mice bearing PC-4 prostate cancer treated with vitamin D3 supplements.

It has been known that 1,25-dihydroxyvitamin D3 [1,25(OH)2H3 or calcitriol], the hormonally active metabolite of vitamin D produced in the kidney has anticancer action in animal models of breast cancer and prostate cancer.

The current study reported in Endocrinology demonstrated vitamin D3 supplements are as effective as calcitriol.  Dietary vitamin d3 inhibition of tumor growth at 5000 IU/kg was similar to that of administered calcitriol at doses of 0.025, 0.05 and 0.1 ug per mouse, three times a week.

One advantage with vitamin D3 supplementation is that it in a high dose did not cause high calcium or hypercalcemia in the blood, as the researchers found. Calcitriol, on th eother hand, at 0.05 and 0.1 ug per mouse three times a week, caused a modest yet significant increase in serum calcium, which is undesirable.  

Evidence from this study suggests vitamin d3 was converted not only in the kidney, but also in the cancer mass to calcitriol that exerts autocrine/paracrine anticancer action against breast cancer and prostate cancer.

Dietary vitamin d3 supplements increased calcitriol but not serum calcium. It did not alter CYP27B1 mRNA (for 1α-hydroxylase, the enzyme catalyzing calcitriol formation) in the kidney, but was converted in the tumor to calcitrol, which fights breast cancer and prostate cancer. 

Additionally, both calcitrol and dietary vitamin d3 were found equally effective in suppressing estrogen synthesis and signaling and other proinflammatory signaling pathways, according to the study. Estrogen is a cancer promotor in the case of breast cancer and it may also play a role in prostate cancer.

The researchers concluded "These preclinical data demonstrate the potential utility of dietary vitamin D3 supplementation in cancer prevention and therapy."

Many vitamin D researchers and cancer researchers know that calcitriol is a potent anticancer agent.  The problem is, it can cause hypercalcemia at an effective dose.  The current study suggests that vitamin d3 does not cause this problem, but exert the same efficacy against both breast cancer and prostate cancer, making the dietary supplement a perfect candidate as a chemotherapy or a cancer preventative.

Vitamin D3 is fairly safe at relatively high doses even though it is oil-soluble.  Canadian Cancer Society has already recommended healthy individuals use 1000 IU per day while in the U.S., resistance is strong against a high dose recommendation.   Regardless, it is generally believed that up to 10,000 IU of vitamin d3 per day is safe for a person to take.  Exposure of bare hands and face to the sun at the hottest hours of the day can get a person 10,000 IU easily.  So there is no reason to doubt the safety of vitamin D at this level. 

Remember that to prevent and treat breast cancer and prostate cancer, a high dose is needed.  Also remember that those who are using high doses of vitamin D to treat cancer should be monitored for their serum calcium levels and adjust intake of the vitamin accordingly.

Early studies suggest vitamin D supplementation may reduce cases of breast cancer by 75 percent.  It can also cut risk of prostate cancer drastically.

Breast cancer and prostate cancer are expected to be diagnosed in 230,000 women and 230,000 men each year in the United States, each disease kills about 40,000 a year in the country, according to the National Cancer Institute.

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