Vitamin D, Sunlight and Colon Cancer: The Implications for the Presence of the 1α-Hydroxylase in Normal and Malignant Colon Cancer Tissue

Abstract

Vitamin D deficiency has been implicated as a possible factor in the development of many cancers including cancer of the prostate, breast and colon 1, 2. Garland & Garland reported that mortality rates due to colorectal cancer in the United States are highest in areas with the least amount of solar radiation 3. Countries with the lowest prevalence of colon cancer are located within 20 degrees of the equator 4. Increasing latitude increases the risk of developing colon cancer with the exception of Japan where the diet is high in vitamin D from ingestion of fatty fish 5. A prospective cohort study of 1954 men determined that men who ingested more than 150 IU of vitamin D had a 50% lower incidence of colon cancer than those who consumed less than 150 IU of vitamin D 6. A twelve-year prospective study of over 89,000 female nurses found that the highest quintile of vitamin D intake was associated with a relative risk of 0.42 (95% CI 0.19 – 0.91) of developing colon cancer when compared to the lowest quintile of vitamin D intake 7. A 6 year prospective study of almost 48,000 men revealed that men in the highest quintile of vitamin D intake had half the incidence rate of colon cancer than men in the lowest quintile of vitamin D intake 8. A case-control study of 25,620 adults revealed that individuals with 25(OH)D levels greater than 20 ng/ml had one-third the risk of colon cancer compared to subjects who were vitamin D insufficient9.