Low Plasma Levels of Vitamin D May Increase the Risk of Cancer in Men
Updated March, 2012

“Prospective study of predictors of vitamin D status and cancer incidence and mortality in men,” Giovannucci E, Liu Y, et al, J Natl Cancer Inst, 2006; 98(7): 451-9.

Summary: In a study involving an examination of data from 47,800 men involved in the Health Professionals Follow-Up Study, low vitamin D status was found to be associated with an increased incidence of cancer and an increase in death from cancer, particularly for digestive system cancers.

Between 1986 and January 31, 2000, 4,286 incident cancers were documented (excluding organ-confined prostate cancer and nonmelanoma skin cancer), and 2,025 deaths from cancer were documented. Vitamin D exposure was considered based on multiple determinants, including dietary and supplementary vitamin D, skin pigmentation, adiposity, geographic residence, and leisure-time physical activity to estimate sunlight exposure. Using multiple linear regression modeling, the researchers quantified the relation of these six determinants to plasma 25(OH)D levels using a small sub-group of men (1,095) whose levels of plasma 25(OH)D had been measured. These results were then used to compute a predicted 25(OH)D level for all the men in the cohort (47,800). Multivariable Cox proportional hazards modeling was then used to analyze this variable in relation to cancer risk.

Results: The subjects in the lowest tenth of predicted 25(OH)D level (lowest exposure to vitamin D) had an absolute annual rate of total cancer of 758 per 100,000 men, and a total cancer mortality rate of 128 per 100,000 as compared to subjects in the highest decile or predicted 25(OH)D level who had an absolute annual rate of total cancer of 674 per 100,000 men and a total cancer mortality rate of 78 per 100,000. It was determined that an increase in predicted 25(OH)D level by an increment of 25 nmol/L was associated with a reduction in total cancer incidence by 17% (multivariable relative risk [RR] = 0.83], a reduction in total cancer mortality by 29% (RR=0.71), and a reduction in digestive-system cancer mortality by 45% (RR=0.55). The current RDA for vitamin D is 400 IU (equivalent to 10 micrograms/da! y), which would only raise 25(OH)D levels by 7 nm/L. In order to achieve a 25(OH)D increment of 25 nmol/L, supplementing with 1500 IU/day vitamin D may be necessary. The results of this study suggest that low levels of vitamin D (through sun exposure, diet, supplements, etc.) and low plasma 25(OH)D levels may increase the risk of cancer. Current recommendations for the daily allowance of vitamin D may need to be reconsidered.

This study, from 2006, suggested a vitamin D dose of 1,500 IU per day.

We know much more about vitamin D dosing in 2012. For instance, the vitamin D researchers at www.vitaminDcouncil.org find that many adults need 6,000 IU per day to arrive at blood levels above a desirable 40 ng/mL. However, more ideal blood levels are between 50 and 60 ng/mL.

I, personally, am taking 11,000 IU of Vitamin D3 per day because my blood tests show that this dose makes my blood Vitamin D register 59 ng/mL, an optimal blood level for reduction in the risk of cancers.

I suggest that people base their vitamin D dosage on blood tests to be sure of what dose is optimal for you, as we are all individual, rather than just taking high doses.

Ideally, you would take a specific dose of vitamin D3 for two months to allow your blood level to stabilize.

Then you would get an "OH-vitamin D" blood test. You can do this with your doctor or use the service of the Vitamin D Council, where you can get the blood test for $65.

Michael Mooney
www.michaelmooney.net