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Health News Archive 61 - Colon Health (con't)
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• Calcium May Help Prevent Colorectal Cancer
• High-Glycemic Diet Raises Colorectal Cancer Risk
• Higher Selenium Levels Linked to Lower Colorectal Cancer Risk
• Soybeans May Help Block Colon Cancer
• Reduction of Side Affects of Anticancer Drugs (6-mercaptopurine) by AHCC

Calcium Reduces Long Term Colon Polyp Cancer Risk

Taking calcium supplements protects against the development of colon polyps, which can become cancerous, and this benefit appears to persist for up to 5 years after people stop taking the supplements, according to a new study.
"There is ample epidemiological and experimental data suggesting the a high intake of calcium may decrease the risk of colorectal cancer," Dr. John A. Baron from Dartmouth Medical School in Lebanon, New Hampshire, said during a briefing at the May 2005 meeting of the American Association for Cancer Research.

In 1999, data from the Calcium Polyp Prevention Study involving 930 adults, who were randomly assigned to take an inactive placebo or 1200 milligrams calcium daily for 4 years, showed a 20 percent reduction in the risk of all colorectal cancers with calcium supplementation.

At the meeting, Baron reported data on 822 of the original participants who were followed for at least 5 years after the end of the treatment phase of the study. During that period, there was a 41 percent reduction in the risk of polyps and a 35 percent reduction in risk of all colon cancers. "These were more pronounced reductions than were seen during the treatment phase," Baron said. This reduction in risk did not persist beyond 5 years after the calcium supplements were stopped.

These data, Baron said, indicate that "calcium is effective in reducing the risk of colorectal adenomas and, after the end of the supplementation, there is no rebound in risk at all. In fact there appears to be a delayed, more pronounced suppression of colorectal neoplasia during the 5 years after treatment."
 

Calcium May Help Prevent Colorectal Cancer

Calcium, whether taken as a supplement or in your diet, can help prevent colon cancer.

In a study involving more than 45,000 American women followed for about 8.5 years, researchers show that calcium can cut women's risk of colorectal cancer. The best results came from combining a calcium-rich diet with supplements. The results appear in the January 2005 issue of Cancer, Epidemiology, Biomarkers & Prevention.

At the start of the study, the women who were free of colorectal cancer were about 62 years old. They filled out a 62-item food survey, describing their diets for the previous year. The women also reported calcium intake from multivitamins and cancer-specific supplements.

During the study, 482 women developed colon or rectal cancer. Colon cancer is the third most common cancer found in men and women in the U.S. Nearly 105,000 people will be diagnosed with colon cancer this year in America, predicts the American Cancer Society. Routine screening is the best way to find colorectal cancer early so treatment can result in cure of the disease.

Some studies have suggested that vitamins might lower the risk of getting colorectal cancer, while others suggest that getting calcium in your diet helps reduce your risk of the disease.

The researchers didn't only want to see if calcium affected colon cancer. They also were curious about whether the source of calcium made a difference. Were calcium-rich foods or supplements more helpful? To find out, the women were grouped by their calcium intake from food and supplements.

Calcium's Effects
Calcium intake slashed colorectal cancer risk, whether the women got their calcium from foods or pills.

Women who ate the most calcium-rich foods (greater than 830 mg/day) were 26% less likely to have colorectal cancer, compared to women whose diets contained the least amount of calcium (less than 412 mg calcium per day). The best results were seen in women who got the most calcium from food and also took the highest level of supplements (consuming more than 412 mg/day from diet plus 800 mg/day from supplements). Their colorectal cancer risk was 46% lower than those who skimped on calcium from either source (those receiving less than 412 mg/day from diet and less than 800 mg/day from supplements).

Women who ate a lot of calcium-rich foods but didn't get as much calcium from supplements had intermediate results. Their risk of colorectal cancer was reduced by only 18%.

Regardless of the source, calcium was the key. The researchers aren't sure how it lowered colorectal cancer risk, but they ruled out other influences. For instance, vitamin D -- which often accompanies dairy products -- didn't explain the results.

Some studies have shown that calcium also cuts men's colorectal cancer risk, says Dr. Flood in a news release. However, he also says other research suggests that fat in dairy products could increase prostate cancer risk.

Sources:
Flood, A. Cancer Epidemiology, Biomarkers & Prevention, January 2005; vol 14: pp 126-132.

American Cancer Society: "Overview -- Colon and Rectal Cancer: How Many People Get Colorectal Cancer?" News release, University of Minnesota.

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High-Glycemic Diet Raises Colorectal Cancer Risk

Increased insulin levels resulting from a diet of high-glycemic foods markedly increased the risk of colorectal cancer in a large sample of American women, according to researchers at the University of California, Los Angeles.

Well-established research shows that daily consumption of more than five servings of fruits and vegetables high in soluble fiber affords significant protection against chronic diseases such as diabetes and heart disease, as well as cancers of the colon, breast, and prostate. The "fiber hypothesis" suggests that a diet rich in fiber favorably alters gastrointestinal absorption and digestion, by reducing direct carcinogen exposure, preserving antioxidant activity, decreasing tumor-promoting secondary bile acids, and increasing tumor inhibition via short-chain fatty acid synthesis.

The glycemic index measures the rate of carbohydrate absorption by the gastrointestinal tract. High glycemic foods stimulate a rapid, heightened release of insulin, which has been suggested as a major risk factor for diabetes and cancer. Simple sugars such as pasta and white bread are absorbed rapidly and rank high on the glycemic index, whereas complex carbohydrates such as fruits, vegetables, and whole grains are absorbed slowly and rank low on the index.

The UCLA researchers sought to determine how increased insulin levels caused by a high-glycemic diet affected the risk of contracting colorectal cancer. They prospectively followed nearly 40,000 women for eight years, recording detailed dietary information and noting the incidence of colorectal cancer. The study demonstrated a significantly increased risk of developing colorectal cancer in those who followed a high-glycemic diet. The researchers attributed this enhanced risk to total and non-fiber carbohydrates in the diet.

Blunting the pancreatic secretion of insulin with a diet of low-glycemic foods that are rich in soluble fiber-such as fruits, vegetables, nuts, legumes, and seeds may pre-empt the development of cancer and metabolic diseases.

Reference
Higginbotham S, Zhang ZF, Lee IM, et al. Dietary glycemic load and risk of colorectal cancer in the women's Health Study. J Natl Cancer Inst. 2004 Feb 4; 96(3):229-33.

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Higher Selenium Levels Linked to Lower Colorectal Cancer Risk

The Journal of the National Cancer Institute published an analysis of data derived from three randomized trials, which revealed that an elevation of blood selenium confers protection against the recurrence of colorectal adenomas, which are precursors of colorectal cancer. The findings were reported in the November 17 2004 issue of the journal.

The current study analyzed three trials that examined the ability of nutritional therapies to prevent colorectal adenoma recurrence: the Wheat Bran Fiber Trail, the Polyp Prevention Trial and the Polyp Prevention Study. Serum selenium levels were ascertained from blood samples provided by 1,763 participants upon enrollment. The reoccurrence of adenomas were ascertained by colonoscopies conducted during the studies' follow up periods.

In all trials, participants whose selenium levels were the highest experienced the lowest risk of developing a new colorectal adenoma. It was discovered that subjects whose blood selenium was in the top one-fourth of participants had a 34 percent lower risk of a new adenoma than those whose selenium was in the lowest quarter.

In an accompanying editorial (96, 22:1645-7, 2004) entitled, “Can selenium prevent colorectal cancer? A signpost from epidemiology,” Scott M Lippman, MD and and Imad Shureiqi of the University of Texas M.D. Anderson Cancer Center, and Anna J Duffield-Lillico of Memorial Sloan-Kettering Cancer Center observe that oxidative metabolism of arachidonic and linoleic acids contribute to the formation of colon tumors. Selenium and selenium-containing compounds, are well known for their antioxidant activity. There is also evidence that the inhibition of cell growth observed in selenium-treated cultured cells is accomplished in part by a reduction in mechanisms dependent upon cyclooxygenase 2 (COX-2).

Dr Lippman and colleagues predict that the findings of this analysis should intensity the interest in clinical trials of selenium and/or other compounds in the prevention of colorectal adenomas.

SOURCE: Jacobs ET, Jiang R, Alberts DS, Greenberg ER, Gunter EW, Karagas MR, Lanza E, Ratnasinghe L, Reid ME, Schatzkin A, Smith-Warner SA, Wallace K, Martinez ME. Selenium and colorectal adenoma: results of a pooled analysis. J Natl Cancer Inst. 2004 Nov 17;96(22):1669-75.

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Soybeans May Help Block Colon Cancer

A substance found in soybeans may reduce the risk of colon cancer, the world's third most common form of cancer.

Georgia Tech researcher Dr. Al Merrill, along with colleagues from Emory University and the Karmanos Cancer Institute, found that soy glucosylceramide, or soy GlcCer, was effective in reducing the formation and growth of tumor cells in the gastrointestinal tract in mice.

The results are published in the May 2004 issue of the Journal of Nutrition.

Soy GlcCer is just one of the many types of sphingolipids found in plants and animals. Merrill and colleagues have already shown that milk sphingolipids can suppress tumor formation. But this is the first study to deal with colon cancer, he said.

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Reduction of Side Affects of Anticancer Drugs (6-mercaptopurine) by AHCC

Active Hexose Correlated Compound (AHCC), mycelia extracts of cultured basidiomycetes, was examined in animal models to relieve side effects, such as anemia, alopecia and liver injury induced by anticancer drugs.

1. Male ddY mice were treated with fluorouracil (5-FU, 50 mg/kg) or cyclophosphamide (CY, 100 mg/kg) or both daily for 14 days by l.p. and AHCC was given in a 5% diet for the same period. Treatment with 5-FU or/and CY resulted in body weight loss, decrease in the numbers of peripheral cells in blood and polychromatic erythrocytes in bone marrow and were significantly restored by coadministration with AHCC.

2. Male and female SD rats received cytosine arabinoside (Ara-C, Lp., 50 mg/kg. daily) for 7 days. AHCC was given for the same period by either p.o. (500 mg/kg). Lp. (500 mg/kg) or local swabbing 10% AHCC-solution). The rats treated with Ara-C showed severe alopecia (50-100% hair loss). However, coadministration of Ara-C with AHCC protected from alopecia, especially when AHCC was given p.o. in which only slight alopecia (0-50% hair loss) was observed.

3. Male ddY mice were treated with mercaptopurine (6-MP, 30 mg/kg) and metholrexate (MTX. 2.5 mg/kg) by p.o. for 4 weeks. AHCC was given at a dose of 1 g/kg simultaneously. Treatment with 6-MP and MTX resulted in the decreases of body weight gain, serum albumin and triglyceride levels, liver drug-metabolism enzyme activities and the increases of liver weights. sGPT and sGOT levels obviously. The liver injury was significantly improved by the coadministratlon with AHCC.

The results show that AHCC relieved the side effects induced by anticancer drugs in animals.

Reference:

Sun. B., Mukoda, T., Kosuna, K., and Okada, F. Proceedings of the American Association for Cancer Research. Volume 40 March 1999

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