Vitamin D Dosage and Cancer Chemoprevention

The Durk Pearson & Sandy Shaw®
Life Extension NewsTM
Volume 9 No. 2 • April 2006


Vitamin D Dosage and Cancer Chemoprevention

A new paper1 in the Journal of the National Cancer Institute performs an analysis of cancer risk in the Health Professionals Follow-Up Study of 51,529 male subjects and multiple sources of vitamin D (including sun exposure, dietary and supplemental vitamin D, skin pigmentation, adiposity (“Higher body mass index or obesity has usually been associated with substantially lower blood concentrations of 25(OH)D, probably as a result of decreased bioavailability of 25(OH)D because of its deposition in body fat compartments”1), geographic residence (lower sun exposure in northern latitudes), and leisure-time physical activity. The researchers updated nondietary vitamin D exposures every 2 years and dietary information every 4 years from 1986 to 2000.

They found that the absolute annual rate of total cancer was 758 per 100,000 men in the lowest decile (lowest 10%) of predicted vitamin D (estimated from analysis of the above factors) and 674 per 100,000 men in the highest decile. Cancer mortality was 326 per 100,000 in the lowest decile compared to 277 per 100,000 in the highest decile. Digestive-system cancer mortality was reduced from 128 to 78 per 100,000 in the lowest compared to the highest decile. An increment of 25 nmol/L of vitamin D was associated with a 17% reduction in total cancer incidence and a 29% reduction in total cancer mortality, as well as a 45% reduction in digestive-system cancer mortality.

The authors conclude that “Low levels of vitamin D may be associated with increased cancer incidence and mortality in men, particularly for digestive-system cancers. The vitamin D supplementation necessary to achieve a 25(OH)D increment of 25 nmol/L may be at least 1500 IU/day.” [Emphasis added]

In the editorial accompanying the above paper,2 the authors state that “… the present recommended allowance for vitamin D—400 IU—for individuals aged 50–70 years is inadequate even to maintain skeletal health and is probably too low for meaningful anticancer effects. A dose of 400 IU of vitamin D3 will raise serum levels of 25(OH)D3 only modestly, by about 7 nmol/L or less than 3 ng/mL. The use of this low dose, in conjunction with the relatively short duration of the trial, may explain the recent failure of vitamin D to reduce the incidence of colorectal cancer in the Women’s Health Initiative.”

References

  1. Giovannucci et al. Prospective study of predictors of vitamin D status and cancer incidence and mortality in men. J Natl Cancer Inst 98(7):451-9 (2006).
  2. Schwartz and Blot. Vitamin D status and cancer incidence and mortality: something new under the sun. J Natl Cancer Inst 98(7):428-9 (2006).

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