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Orthomolecular Medicine News Service, October 21, 2008
Vitamin B6 Reduces Colon Cancer
Intake is Often "Inadequate" Even When it Exceeds the RDA
by Andrew W. Saul
(OMNS, October 21, 2008) A study of almost 5,000 persons has shown that consuming more vitamin B6 means less colon cancer. (1) The researchers described the connection as "moderately strong." Any nutrient that has a "moderately strong" influence on reducing colon cancer risk is very important indeed. Almost 150,000 Americans are annually diagnosed with colon cancer; nearly 55,000 die every single year. Other authors, reviewing previous studies, have said the same thing: B6 substantially reduces colon cancer risk. (2,3)
Many of us are not getting nearly enough B6 from our diets. The American Journal of Clinical Nutrition (May, 2008) published a study of nearly 8,000 people showing that B6 inadequacy is common throughout the United States. "Across the study population," the authors said, "we noticed participants with inadequate vitamin B6 status even though they reported consuming more than the Recommended Daily Allowance of vitamin B6, which is less than 2 milligrams per day." Three out of four women using oral contraceptives are vitamin B6 deficient, unless they also take vitamin B6 supplements. Smokers and the elderly are also especially likely to be at risk. Remarkably, even among people who take B6 supplements, one in ten is still B6 deficient. (4)
This indicates that we might better take more B6. But many won't. This is because the public has been warned off of supplementing with this vitamin. So irrational is this fear that, at one point, a so-called "Safe Upper Limit" for daily B6 intake was set at only 10 mg. (6) That was only about six times the US RDA/DRI. Who set such a "limit"? Not the voters, that's for sure. An unelected committee did it, one created by the National Academy of Sciences, Institute of Medicine's Food and Nutrition Board. (5) They have, in a manner of speaking, recently admitted that they were wrong. The "Safe Upper Limit" is now 100 mg.
That is more like it, but still too low. Alan Gaby, M.D., in reviewing B6 toxicity, wrote that adverse effects from B6 (pyridoxine) were occurring in people taking "2,000 mg/day or more of pyridoxine, although some were taking only 500 mg/day. There is a single case report of a neuropathy occurring in a person taking 200 mg/day of pyridoxine, but the reliability of that case report is unclear. The individual in question was never examined, but was merely interviewed by telephone after responding to a local television report that publicized pyridoxine-induced neuropathy." Dr Gaby adds that there have been no reports of B6 side effects at under 200 mg/day. (6)
Modern processed, low-nutrient diets are not providing anything close to 200 milligrams. In fact, they typically provide less that 1% of that amount. You can get some B-6 from food, if you really like to eat whole grains, seeds and organ meats. A goodly slice of beef liver contains a whopping 1.2 mg of B-6. Chicken liver is only 0.6 mg per serving, and most other foods contain less. Avocados (0.5 mg each) and bananas (0.7 mg each) lead the pyridoxine league for fruits. Potatoes (0.7 mg each) and nuts (especially filberts, peanuts and walnuts) are fairly good vegetable sources.
But people are not eating nuts, seeds, vegetables, and liver. What they are eating is way too many nutrient-poor junk foods. Our diets are low in B6, yet B6 reduces risk of colon cancer. Clearly supplementation is the way to go.
(1) Theodoratou E, Farrington SM, Tenesa A et al. Dietary vitamin B6 intake and the risk of colorectal cancer. Cancer Epidemiol Biomarkers Prev. 2008 Jan;17(1):171-82.
(2) Matsubara K, Komatsu S, Oka T, Kato N. Vitamin B6-mediated suppression of colon tumorigenesis, cell proliferation, and angiogenesis (review). J Nutr Biochem. 2003 May;14(5):246-50. See also: Komatsu S, Yanaka N, Matsubara K, Kato N. Antitumor effect of vitamin B6 and its mechanisms. Biochim Biophys Acta. 2003 Apr 11;1647(1-2):127-30. "Epidemiological studies have reported an inverse association between vitamin B(6) intake and colon cancer risk." http://www.ncbi.nlm.nih.gov/pubmed/12686121
(3) Zhang SM et al. Folate, vitamin B6, multivitamin supplements, and colorectal cancer risk in women. Am J Epidemiol. 2006 January 15; 163(2): 108-115. http://aje.oxfordjournals.org/cgi/content/full/163/2/108 .
(4) Morris MS, Picciano MF, Jacques PF, Selhub J. Plasma pyridoxal 5'-phosphate in the US population: the National Health and Nutrition Examination Survey, 2003-2004. Am J Clin Nutr. 2008 May;87(5):1446-54. See also: http://www.lef.org/whatshot/2008_05.htm#Vitamin-B6-RDA-questioned
(6) Gaby AR. "Safe Upper Limits" for nutritional supplements: one giant step backward.
J Orthomolecular Med, 2003, Vol 18, No 3&4, p 126-130.
http://findarticles.com/p/articles/mi_m0ISW/is_243/ai_109946551 and http://www.iahf.com/20040127.html
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