Magnesium and calcium both needed for colorectal cancer protection
In a presentation at the American Association for Cancer Research's Seventh Annual International Conference on Frontiers in Cancer Prevention Research, held November 16-18, 2008 in National Harbor, Maryland, Qi Dai, MD, PhD reported that it may be necessary to have a greater intake of magnesium in order for calcium to protect against colorectal cancer.
While increased magnesium intake has been associated with a reduction in the risk of colorectal cancer, Americans have a similar intake of the mineral as East Asians yet have a much higher incidence of the disease. However, the risk of colorectal cancer increases when East Asians immigrate to the United States.
Calcium has also been shown to help inhibit colorectal cancer, although high levels of the mineral may reduce the absorption of magnesium. Referring to the fact that Americans have a higher intake of calcium than East Asians as well as a greater incidence of colorectal cancer, Dr Dai remarked, "If calcium levels were involved alone, you'd expect the opposite direction. There may be something about these two factors combined – the ratio of one to the other – that might be at play."
Dr Dai, who is an assistant professor of medicine at Vanderbilt University in Nashville, along with John Baron, also of Vanderbilt, utilized data from the Calcium Polyp Prevention Study, a double-blinded, placebo-controlled study of the use of calcium supplements to help prevent colorectal polyp recurrence. (Colorectal polyps are a precursor of colorectal cancer.) In the trial, 930 participants were supplemented with 1000 milligrams calcium for four years. Colonoscopies were performed at the beginning of the study, at one year, and at the trial's conclusion to evaluate the presence of polyps.
By analyzing data from dietary questionnaires completed at the beginning and end of the trial, Dr Dai found that calcium supplements reduced the risk of polyp recurrence only if the ratio of calcium to magnesium was low and remained low over the course the study. "The risk of colorectal cancer adenoma recurrence was reduced by 32 percent among those with baseline calcium to magnesium ratio below the median in comparison to no reduction for those above the median," Dr Dai stated. When the calcium to magnesium ratio at four years was analyzed, the results were similar.
Among subjects who received calcium during the trial and whose calcium to magnesium ratio was low, increased magnesium was found to be associated with a greater reduction in the risk of polyp recurrence. Participants whose magnesium intake was in the highest third of this group had a 42 percent lower risk of polyp recurrence, and those whose intake fell among the middle third experienced a 34 percent lower risk than those whose intake was among the lowest third. No associations were found among those who received placebos.
The findings imply that it may be better to optimize one's intake of both minerals rather than supplementing with either mineral alone to help prevent colorectal cancer. "These findings, if confirmed, may provide a new avenue for the personalized prevention of colorectal cancer," Dr Dai concludes.
Related Health Concern: Colorectal cancer
Seemingly unrelated diseases have a common link. People who have multiple degenerative disorders often exhibit excess levels of pro-inflammatory markers in their blood. Here is a partial list of common medical conditions that are associated with chronic inflammation:
Interventions that can prevent the development of colorectal cancer include screening for adenomas, removal of polyps by endoscopic polypectomy, excision of the large bowel (in familial adenomatous polyposis) (Munkholm P 2003; Watson P et al 1998), and regular NSAID use (Reeves MJ et al 1996; Giardiello FM et al 1993), in addition to the following dietary interventions:
Fiber from bran and cellulose is effective in reducing the risk of colorectal cancer development (Gonzalez CA 2006b); Greenwald P et al 1986). In those with low intake of dietary fiber, doubling of total fiber intake could reduce the risk of colorectal cancer by 40 percent (Bingham S 2006). Fruit fiber consumption, as opposed to vegetable fiber, reduces the risk of colorectal adenomas (Platz EA et al 1997). High-fiber foods include legumes, beans, seeds, nuts, wild rice, and oatmeal.
Calcium reduces the growth rate of rectal and colon epithelial cells both directly and by binding bile acids and fatty acids in the stool, resulting in compounds that are less likely to adversely affect the colon (Rozen P et al 1989). Calcium's beneficial effects may occur only in individuals who have a low level of fat intake (Cats A et al 1995). Oral calcium supplementation reduces benign tumor (adenoma) formation by 19 percent (Baron JA et al 1999) and slightly reduces cell proliferation in the rectum (Cats A et al 1995). Foods such as broccoli, kale, Chinese cabbage, milk, cheese, and yogurt are good sources of calcium.
Curcumin is currently being investigated in human clinical trials for the prevention and treatment of colorectal cancer (Jiao Y et al. 2006a). Curcumin may be effective in preventing the development of colon cancer related to Apc mutations (Corpet DE et al 2003; Pierre F 2003; Reddy BS et al 1994, 2002). The suggested daily dose is 1.6 grams (Perkins S et al 2002). Curcumin is extracted from turmeric root and is used as a spice in cooking.
Multivitamin use reduces the risk of benign tumor (adenoma) formation in high-risk individuals (Whelan RL et al 1999). Vitamins C, E, and A reduce the risk of developing colorectal cancer (Howe GR et al 1992; Newberne PM et al 1990).