Specific vitamins and minerals in the diet appear to prevent the development of colon cancer. However, too much iron may cause malignancies to grow. Emory University scientists recently announced these findings, based on biological markers that influence colon cancer risk, at the American Association for Cancer Research meeting in San Diego.
Earlier studies have suggested that calcium and vitamin D reduce colon cancer risk and the new Emory data may explain why. In a clinical study of 92 patients, the researchers found that diets supplemented with calcium and vitamin D increase the levels of a protein called Bax which "turns on" the programmed death of pre-cancerous cells in the colon, according to Emory researcher Veronika Fedirko.
"We were pleased that the effects of calcium and vitamin D were visible enough in this small study to be significant and reportable. We will have to fully evaluate each marker's strength as we accumulate more data," Fedirko stated.
In other related Emory research, a 200 patient case-control study found high levels of calcium and vitamin D together are associated with increased levels of E-cadherin, the main adhesion molecule of epithelial cells (cells that line internal and external body surfaces, including the inside of blood vessels and small cavities). Loss of E-cadherin mediated adhesion is known to contribute to the change from benign lesions to invasive, metastatic cancer, so an increase of the molecule could protect from colon cancer.
The studies, which used colorectal biopsy samples, are part of a larger effort to identify a host of measurements that together can estimate a person's risk of developing colon cancer. "We want to have the equivalent of measuring cholesterol or high blood pressure, but for colon cancer instead of heart disease," said Roberd Bostick, MD, MPH, professor of epidemiology at Emory's Rollins School of Public Health. "These measurements will describe the climate of risk in the colon rather than spotting individual tumors or cells that may become tumors."
Another Emory study shows that one mineral, iron, in excess might up the risk of colon cancer. High levels of dietary iron were linked to low levels of APC, a protein whose absence in colon cancer cells leads to their runaway growth. Although iron is a necessary nutrient, it is needed only in small amounts. Previous research has shown that when too much iron is absorbed, it is associated with an increased risk for heart disease as well as cancer.
Bostick and his research team are participating in a ten-year multi-center study of the effects of increased vitamin D and calcium and biomarker-guided treatment of colon cancer recurrence. The study involves close to 2,500 people throughout the U.S. who have regular colonoscopies.
Bostick is currently working on the development of non-invasive blood and urine tests for colon cancer risk ((http://whsc.emory.edu/_pubs/hsc/winter0...) .
Most cases of colon cancer begin as small, benign clumps of cells called adenomatous polyps that, over time, transform into colon cancers. About 112,000 people are diagnosed with colon cancer annually according to the American Cancer Society.
About the author
Sherry Baker is a widely published writer whose work has appeared in Newsweek, Health, the Atlanta Journal and Constitution, Yoga Journal, Optometry, Atlanta, Arthritis Today, Natural Healing Newsletter, OMNI, UCLA's "Healthy Years" newsletter, Mount Sinai School of Medicine's "Focus on Health Aging" newsletter, the Cleveland Clinic's "Men's Health Advisor" newsletter and many others.