Life Extension Update Exclusive
Review finds vitamin D could prevent significant number of cancers...
In a review that will appear in the February 2006 issue of The American Journal of Public Health vitamin D researcher Michael F. Holick and colleagues concluded that improved vitamin D status could significantly cut the risk of colon, breast, ovarian and prostate cancer. A previous review conducted by the team, published in the October 2005 Journal of Steroid Biochemistry and Molecular Biology found that consuming 1000 international units (IU) or more of vitamin D per day cut the risk of colon cancer in half.
The team reviewed 63 studies of oral intake or serum levels of vitamin D as related to the risk of cancer published between January 1966 and December 2004. The majority revealed a protective effect for the vitamin. The authors attribute vitamin D’s benefits to its abilities to inhibit the formation of new blood vessels by tumors, stimulate mutual adherence of cells, and enhance intercellular communication. They also note that having higher serum vitamin D levels is associated with reduced proliferation of high-risk epithelial cells in the colon and that the vitamin helps prevent breast epithelial cell mitosis.
The authors observed that vitamin D doses of up to 1000 IU per day are unlikely to produce toxicity and comment that this dose would be consistent with maintaining serum vitamin D levels at or above 30 nanograms per milliliter. Serum levels of vitamin D lower than 30 ng/mL have been associated with double the risk of colon cancer than that experienced by individuals with higher levels.
The review concludes that “Supplemental vitamin D intake could address the high prevalence of vitamin D deficiency in the United States... The cost of a daily dose of vitamin D3 (1000 IU) is less than 5 cents, which could be balanced against the high human and economic costs of treating cancer attributable to insufficiency of vitamin D.”
Coauthor Cedric F. Garland, who is a professor at the University of California, San Diego School of Medicine’s Department of Family and Preventive Medicine, commented, “A preponderance of evidence, from the best observational studies the medical world has to offer, gathered over 25 years, has led to the conclusion that public health action is needed. Primary prevention of these cancers has largely been neglected, but we now have proof that the incidence of colon, breast, and ovarian cancer can be reduced dramatically by increasing the public's intake of vitamin D."
"Many people are deficient in vitamin D,” he added. “A glass of milk, for example, has only 100 IU. Other foods, such as orange juice, yogurt and cheese, are now beginning to be fortified, but you have to work fairly hard to reach 1,000 IU a day. Sun exposure has its own concerns and limitations . . . The easiest and most reliable way of getting the appropriate amount is from food and a daily supplement.
Comment: It seems clear that anyone who is not paying attention to vitamin D status, either for themselves or for patients, is indeed ignoring the evidence. While much research remains to be done, and not all studies have provided positive results, the number of health issues that appear to relate to vitamin D status provides a strong incentive for being concerned. It should be clear that: (a) there is considerable evidence of rather widespread vitamin D deficiency; (b) numerous studies indicate the importance of maintaining high levels of serum 25(OH)D in order to optimize health; and (c) the importance of vitamin D transcends its role in bone health and calcium metabolism. The government mandated fortification of dairy products and cereals is indicative of a general awareness in public health circles of the importance of this vitamin, at least as regards to bone health. But because of the variation in eating patterns, geographical location of residence, sun exposure, and fear of skin cancer, becoming deficient may merely involve following the path of least resistance, since the alternative is to estimate intake from food and supplements, pay attention to levels of fortification, and estimate generation from sunlight, actions that take effort and some knowledge. Furthermore, there is a common opinion among health care professionals that since rickets is rare, there is no vitamin D problem. There is also the commonly held opinion that we get everything we need from food. Neither of these positions appears defensible. If you would like a source of D3 in capsule form, providing 1000 IU's per capsule - email me.
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