Vitamin D may prevent colorectal cancer
By David Liu, PHD
Thursday Oct 25, 2012 (foodconsumer.org) -- Taking vitamin D supplements or sufficient exposure to sun rays often to prevent vitamin d insufficiency or deficiency may help prevent colorectal cancer, according to a study in Journal of Steroid Biochemistry and Molecular Biology.
The mouse study showed that mice chemically treated to induce preneoplastic lesions or dysplasia, a precursor to colorectal cancer, were less likely to develop the preneoplastic lesions if they were treated with a vitamin d supplement.
Doris. M. Hummel at Department of Pathophysiology and Allergy Research, Medical University of Vienna in Vienna, Austria conducted the study to examine whether increased dietary vitamin D intake would prevent or delay the formation of chemically induced preneoplastic lesions in mice.
A total of 28 6-week old female mice were fed a diet with vitamin D(3) at doses of 100, 400, 1000, 2500IU/kg diet. Mice were treated with carcinogen azoxymethance intraperitoneally (10mg/kg) to induce dysplasia and then treated with 2% dextran sodium sulfate salt, a tumor promoter, three times in the drinking water.
Dietary vitamin D intake was correlated inversely with dysplasia score and positively with serum vitamin D(3) concentrations. This means having high intake of dietary vitamin d can help prevent vitamin d insufficiency and dysplasia.
But increasing dietary vitamin D intake beyond 1000 IU/kg did not further increased circulating 25-D(3) levels, while the dysplasia score leveled out at greater than 2500IU/kg vitamin D.
The researchers found high dietary vitamin D intake increased renal mRNA expression of the vitamin D-catabolizing enzyme called cyp24a1 and decreased the expression of vitamin D-activating enzyme cyp27b1, preventing the body from exposure to toxic levels of serum vitamin D metabolite 1,25-dihydroxyvitamin D(3).
The researchers concluded that "increased dietary vitamin D intake is able to prevent chemically induced preneoplastic lesions. The maximum impact was achieved when the mice consumed more than 2500IU vitamin D/kg diet."
The study suggests that high dietary intake of vitamin D may help prevent colorectal cancer.
Other modifiable risk factors for colorectal cancer prevention include a diet high in fat, low in calcium, folate, and fiber, and smoking cigarette. This means eating more fruit and vegetables and less meat products may help prevent polyps and colorectal cancer.
The Western diet is often low in vegetables, which means the intake of natural folate and fiber may be deficient. A variety of dietary fiber are available as dietary supplements. It is believed that intake of 30 to 35 grams of dietary fiber daily is needed for adults.
Colorectal cancer is diagnosed in about 144,000 men and women each year (103,000 cases of colon cancer and 40,300 cases of rectal cancer) in the United States and 51,700 patients die annually because of this disease, according to the National Cancer Institute.
Vitamin D deficiency has been associated with more than 100 health conditions including heart disease, type 2 diabetes mellitus, depression, 17 types of cancer, obesity, and metabolic syndrome among others.
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