Written by Marcia J. Egles, MD. Those with the highest levels of calcium and vitamin D each had a 36% reduced risk of colon cancer.
In recent years, nutritional research of vitamin D has reached beyond bone health to include potential benefits to the treatment of diabetes, cancer, heart and brain disease (1). The receptor to vitamin D has been identified within the cells of at least 37 different tissues of the body (2). Adequate levels of vitamin D and calcium may confer protection against many diseases including the risk of colon cancer and colorectal adenoma, as evidenced by an accumulating number of studies ( 3,4). Colorectal adenoma is a common benign tumor which is considered an early warning for colorectal cancer risk.
A study of colonoscopy patients in Tokyo, Japan (5), evaluated the influence of vitamin D levels on colorectal adenomas in relation to calcium intake and in relation to genetic variations of the vitamin D receptor. This study considered that the cancer fighting potential of vitamin D might be mediated not only by calcium metabolism but also through the vitamin D receptor. Genetic variations of this receptor might contribute to which subjects are more prone to develop colorectal cancer under conditions of insufficient vitamin D.
This case-control study (5) included 737 cases of colon adenomas found by colonoscopy exam in healthy Japanese men and women aged 40 to 79,during the years 2004-2005. Seven hundred and three persons had normal colonoscopies and served as controls. Subjects who used vitamin D or calcium supplements were not included in this study. Blood plasma 25-hydroxyvitamin D and vitamin D receptor genomic typing was measured in all participants. Life-style and food frequency questionnaires were also completed by the participants. Calcium intakes were estimated based on the responses from the questionnaires.
Some of the statistical results of this case-control study are as follows. Compared with the lowest quintile (lowest fifth) of vitamin D levels, the highest quintile of vitamin D levels was related to a significantly decreased odds ratios of adenomas ( odds ratio= 0.64, 95% confidence interval : 0.45-0.92). The average 25-hydroxyvitamin D level of the lowest quintile was 16 nanograms per milliliter. The average of the highest vitamin D levels was 32 ng/ml. All but the lowest quintile of calcium intake also presented reduced odds ratios for adenomas ( odds ratio for highest calcium = 0.64, 95% confidence interval :0.47,0.95). The dietary calcium intake of the lowest quintile was an average of 542 milligrams per day. The highest average of calcium intake was 590 mg/day. One genetic variant of the vitamin D receptor known as TaqI was noted to have a significant interaction with vitamin D levels but not with calcium intake levels.
In summary, the study found that both higher levels of vitamin D and higher dietary calcium intakes were associated with lower odds of colon adenoma. (Abstractors note- the low vitamin D levels and calcium intakes reported in this study might be indicative of vitamin D and calcium deficiencies in these populations.) An interaction between vitamin D levels and a genetic variant of the vitamin D receptor was observed and perhaps will be of importance to future studies.
Source: Yamaji, Taiki, et al. “Association between plasma 25-hydroxyvitamin D and colorectal adenoma according to dietary calcium intake and vitamin D receptor polymorphism.” American journal of epidemiology (2011): kwr295.
© The Author 2011. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health.
Posted February 20, 2012.
References:
- Dr. Edward Giovannucci, “The Nutrition Source: Ask the Expert” of Harvard School of Public Health.
- Norman, Anthony , “A vitamin D nutritional cornucopia: new insights concerning the serum 25-hydroxyvitamin D status of the US population,” editorial, American Journal of Clinical Nutrition, doi:10.3945/ajcn.2008.27049 Vol. 88, No. 6, 1455-1456, December 2008.
- Grant, WB. et al. “A critical review of studies on vitamin D in relation to colorectal cancer”, Nutr Cancer. 2004: 48(2): 115-123.
- Huncharek M. et al. “Colorectal cancer risk and dietary intake of calcium, vitamin D and dairy products: a meta-analysis of 26,335 cases from 60 observational studies. “ Nutr Cancer, 2009: 61 (1) : 47-69.
- Taiki Yamaji et al Association Between Plasma 25-Hydroxyvitamin D and Colorectal Adenoma According to Dietary Calcium Intake and Vitamin D Receptor Polymorphism American Journal of Epidemiology, advance access Dec.21, 2011.
