Long term calcium supplement use equals long term protection The results of a study reported at the 96th Annual Meeting of the American Association for Cancer Research this month showed that long term use of calcium supplements offers long lasting protection against the formation of potentially precancerous colon polyps. The effect may be due to suppression of a precarcinogenic process that takes years to develop, according to John Baron, MD, of Dartmouth University, who presented the results.
The current study followed participants from the Calcium Polyp Prevention Study, which found a 19 percent reduction in polyp formation and a 28 percent reduction in the development of advanced adenomas among patients with a history of developing polyps who received a 1200 milligram daily calcium supplement for four years compared to those who received a placebo. In the Calcium Follow Up Study, Maria Grau MD of the Section of Biostatistics and Epidemiology at Dartmouth and colleagues tracked polyp formation and analyzed the effect of additional calcium supplements among 822 subjects from the original study.
They found that even after adjusting for the use of calcium supplements following the end of the original study, subjects who had received calcium during the trial experienced a 36 percent reduction in the development of new polyps in the five years that followed. For a type of polyp called nonneoplastic hyperplastic polyps, there was a 48 percent reduction. However, during the entire follow-up period, which was a great as ten years for some participants, the protective effect declined, although those who received supplements during the study still had a 19 percent lower risk of polyp development.
Dr Grau concluded, "This provides further evidence of the potential of calcium to be used as a chemopreventive agent against development of colorectal cancer."
Colorectal cancer Identifying and eradicating the causative factors responsible for the development of colorectal cancer is of the utmost importance to those individuals who are at high-risk for developing the disease and to those who have been diagnosed with colorectal cancer. These factors include diet, lifestyle, exercise, tobacco and alcohol use, parity, hormone use, energy intake, and nonsteroidal anti-inflammatory drug (NSAID) use.
Fiber, particularly bran and cellulose appear to be effective in reducing the risk of colorectal carcinogenesis (the generation of cancer from normal cells) (Greenwald et al. 1986). Fruit fiber consumption, as opposed to vegetable fiber, reduced the risk of colorectal adenomas (Platz et al. 1997).
There is a direct relationship suggested by epidemiological studies between total fat intake in the diet and increased risk of cancer in the colon and rectum. Animal fat, particularly dairy products, and red meat are associated with colon cancer risk, whereas there is no association with vegetable fats, and fish oils appear to have a protective effect (Schloss et al. 1997). Lower cholesterol levels have been shown in patients diagnosed with colorectal cancer (Forones et al. 1998). Conversely, elevated levels of serum triglycerides have been associated with a higher risk of adenomatous polyps (Bird et al. 1996b).
Low selenium levels exist in patients prone to colon adenomas. In fact, reduced selenium levels are associated with the diagnosis of large size adenomatous polyps (Fernandez-Banares et al. 2002). In a double-blinded, placebo-controlled trial, patients with colon adenomas presented with low serum levels of selenium and plasma glutathione peroxidase (pGPx) activity before treatment, but with interventional selenium supplementation, both parameters were normalized (Al-Taie et al. 2003). Fortunately, cancer cells are more sensitive to the effects of selenium than their noncancerous counterparts.
Calcium is an 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.
Se-methylselenocysteine (SeMC) is a naturally occurring seleno-amino acid that is synthesized by plants such as garlic and broccoli. Unlike selenomethionine, which is incorporated into proteins in place of methionine, SeMC is not incorporated into any proteins, thereby being fully available for the synthesis of selenium-containing enzymes such as glutathione peroxidase.