Calcium May Cut Risk of Colon Cancer Tue Mar 19, 5:10 PM ET By Amanda GardnerHealthScoutNews Reporter TUESDAY, March 19 (HealthScoutNews) -- Increasing your calcium intake may reduce the risk of cancer in the distal -- or left side -- of the colon. "We found that a moderate intake of 700 milligrams to 800 milligrams of calcium per day may decrease the risk of left-sided colon cancer in both men and women," says Dr. Kana Wu, lead author of what she calls a preliminary study, and a research fellow at Harvard University's School of Public Health. Individuals who had the increased calcium in their diets showed a 40 percent to 50 percent lower risk of developing this type of colon cancer, compared with those who were taking less than 500 milligrams of calcium daily. Intakes higher than 700 or 800 milligrams, however, didn't show the same protective effect. In other words, there appeared to be a threshold or upper limit to the benefits. (Federal health officials recommend between 800 milligrams and 1,300 milligrams a day for adults, depending on your age and sex.) Wu stresses that the results of her research are preliminary. "This is the first prospective study that has looked at these associations in more detail and with a large number of cases," she says. "We certainly have to await results from other studies to confirm these results before any recommendations can be made." Other experts also caution that Wu's study is not the final word. "We've been toying with the thought of calcium being protective for many years, and certainly in animal models calcium does act as a protective factor. But the human studies have been equivocal, and I think pretty much continue to be so," says Dr. Robert Kurtz, chief of gastroenterology and nutrition service at Memorial Sloan-Kettering Cancer Center in New York City. The Harvard study looked at calcium intake from dairy sources and from calcium supplements in two large samples of people: about 47,000 male dentists, podiatrists, pharmacists, optometrists, osteopaths and veterinarians, and about 88,000 female registered nurses. The researchers believe that the calcium, and not some other component of dairy products, was responsible for the benefit because the protective effect was seen even among participants with low dietary calcium but higher calcium supplementation. One odd and unexplained finding was that the benefits of calcium appeared to be restricted to non-aspirin users, but this would have to be confirmed by other studies. "This was an unexpected finding and to the best of our knowledge has not been reported in another prospective study," Wu says. The researchers also found that the benefit from calcium could be enhanced by taking Vitamin D. "Vitamin D is important for absorption of calcium and these two nutrients are closely linked," Wu says. "If there is not enough vitamin D, the calcium cannot be absorbed properly. Other scientists have speculated that a protective effect from calcium might be due to the fact that it binds bile acids and fatty acids, which can cause the proliferation of cells. But much research remains to be done before calcium's cancer-fighting properties are proven. "This is one of the factors that probably does play a small role somewhere in the development of cancer or in the development of polyps from normal colonic tissue, and what it means for the average person is that calcium is good," Kurtz says. "Calcium is beneficial for bone strength, to prevent osteoporosis, and women who need to should take supplemental calcium irrespective of whether there is a preventive effect on colon cancer." But should calcium supplements replace other, proven methods of preventing or combating colon cancer, such as screenings? Definitely not, Kurtz says. "I hope that nobody would read this and say, 'Gosh, I'm taking 1,200 milligrams of calcium, therefore I don't need to be screened,' " he adds. "This is one piece of information that may, in fact, be useful in terms of our overall understanding of the development of colon cancer and colon polyps. "But until we know a great deal more, we still need to be screened. We know that by doing colonoscopies and finding polyps and removing them we prevent colon cancer. That data is in," he adds. The Harvard study appears in the March 20 issue of the Journal of the National Cancer Institute (news - web sites). What to Do: March is National Colorectal Cancer Awareness Month. For more information, check out the Cancer Research Foundation of America. For more information on how to prevent and treat colon cancer, visit the Colon Cancer Alliance, or the American Cancer Society.