Life Extension Update
|June 21, 2004|
|Life Extension Update Exclusive |
Calcium supplements associated with lower risk of advanced colon polyps
Nine hundred thirty participants in the Calcium Polyp Prevention Study were assigned 1200 milligrams calcium carbonate per day or a placebo, and were scheduled for colonoscopies one year and four years after their initial examination. Participants had a history of having at least one colon polyp surgically removed within three months of the study’s onset. Nine hundred thirteen participants completed at least one of the follow-up colonoscopies within four years. Of these, 30.6 percent had at least one hyperplastic polyp, which have no potential for malignancy, and 41.8 had at least one tubular polyp, which have a low malignancy potential. Advanced adenomas occurred in 12.3 percent of the subjects, and large adenomas in 6 percent.
Calcium supplementation was associated with a decrease in all types of polyps, however its protective effect was the greatest for advanced polyps. The protective effect of calcium appeared to be the strongest in individuals consuming a high fiber and low fat diet, but this finding was not determined to be statistically significant.
In an editorial in the same issue of the JNCI, Arthur Schatzkin, MD, DrPH and Ulrike Peters, PhD of the National Cancer Institute announced, "studies are now in place with the potential to provide a compelling--almost proven--case that a nutritional factor (calcium) can alter the occurrence of malignant disease (colorectal cancer). That would be a tremendous advance."
Accumulating evidence shows that calcium supplementation regulates the growth pattern of colonic epithelium in the individual at high risk for colon cancer (Wargovich et al. 1992). An inverse association between dietary calcium intake and colorectal cancer risk was found in a study of 61,463 women (an average 11.3 years of follow-up). Women with the highest calcium intake (median 914 mg/day) had a reduced risk of colorectal cancer compared with women with the lowest intake (median 486 mg/day). Furthermore, the inverse association was found to be strongest in relation to distal cancers and among older women (Terry et al. 2002).
Calcium supplementation reduces colonic cell proliferation, in part, by decreasing the level of diacylglycerol (DAG). A high luminal level of DAG, a key factor in cell growth control, enhances colonic cell proliferation. Bacterial DAG production is increased by bile acids and phospholipids, both of which may be precipitated by calcium. Calcium was shown to alter fecal lipid composition and to reduce cell proliferation. Oral elemental calcium therapy, 2.4 or 3.6 g/day, for three months markedly reduced fecal DAG concentration and output without enhancing DAG production (Steinbach et al. 1994).
Twenty-two individuals with a history of resected adenocarcinoma of the colon, but free of cancer, were supplemented with 2000 or 3000 mg of calcium for 16 weeks. Calcium supplementation significantly decreased the primary bile acids concentration resulting in a healthier bile acid profile suggesting a protective effect of calcium on colon cancer (Lupton et al. 1996).
In high-risk individuals, the use of multivitamins has been shown to reduce the risk of adenoma formation (Whelan 1999). A reduced risk of colon cancer is associated with the use of vitamin C (Howe et al. 1992). Vitamins C, E, and A showed protection against the risk of developing colorectal cancer (Newberne et al. 1999). Low levels of selenium correlated with the presence of adenomas (benign tumors), whereas increased levels were associated with reduced risk of adenomas (Russo et al. 1997).
Calcium is a major essential mineral that is often inadequately supplied, inefficiently absorbed, or excreted faster than it is being assimilated. The citrate salt of calcium has been documented to be well absorbed and utilized by the body. Calcium is important in maintaining bone mineral density and in blocking the absorption into the bloodstream of free radical generating iron.
Vitamin D3 is included to enhance calcium absorption and utilization.
This unique formulation allows PectaSol® to be easily absorbed into the bloodstream, where it can bind to the galectin molecules on the surface of cells. It is postulated that it is this adherence of the modified citrus pectin to the dividing cells that prevents them from sticking to each other, which may interfere with their growth cycle and block their ability to adhere to new sites in the body.
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