Calcium phosphate: an alternative calcium compound for dietary prevention of colon cancer? A study on intestinal and faecal parameters in healthy volunteers.

In an effort to reduce the risk of colorectal cancer development, oral calcium carbonate supplementation has been used in previous studies for the precipitation of cytotoxic bile acids and fatty acids. In human intervention trials its effect on mucosal hyperproliferation in the colorectum has not always been satisfactory. Because the complexation of calcium and bile acids requires the formation of calcium phosphate, we performed an intervention study in 14 healthy volunteers, giving them 1,500 mg calcium as Ca3(PO4)2 for 1 week. The effects of tricalcium phosphate on luminal and faecal parameters of cytolytic activity were evaluated before, during, and after calcium phosphate supplementation. The cytolytic activity of faecal water and intestinal alkaline phosphatase activity in faecal water were not affected by supplemental calcium phosphate. In duodenal bile, the proportion of cholic acid tended to increase, whereas that of chenodeoxycholic acid tended to decrease during calcium phosphate supplementation. Neither concentrations of total and individual faecal bile acids, nor that of faecal fat were affected during calcium phosphate supplementation. It is suggested that, although phosphate is involved in bile acid precipitation, phosphate competes for calcium in the binding of fatty acids. This might possibly explain the unchanged cytolytic potency of faecal water, and therefore does not make tricalcium phosphate a suitable calcium compound for dietary intervention.

Epithelial cell proliferation in the sigmoid colon of patients with adenomatous polyps increases during oral calcium supplementation.

To study the effect of oral supplemental calcium on colonic epithelial proliferation, 17 adenomatous polyp patients received 1.5 g Ca2+ as calcium carbonate daily during 12 weeks, while on a calcium constant diet, based on the patients' habitual diet. Seven subsequently continued calcium supplementation for 9 months without dietary restrictions. Epithelial proliferation rate in colonic biopsies, expressed as labelling index (%), was determined with 5-bromodeoxyuridine and immunohistochemistry. Biopsies were taken from the midsigmoid at time of polyp excision and at the end of the intervention period. Median labelling index increased from 6.1% before to 8.7% after 12 weeks calcium (n = 17, P < 0.02). This was due to increased labelling in the basal third of the crypts (11.9 vs 16%), whereas labelling in mid and luminal compartments was not affected. Labelling index remained increased after 1 year calcium supplementation at 8.8%. Crypt length was not affected by calcium. These results are in contrast to those of others, who have shown a decrease of rectal epithelial proliferation during similar doses of calcium. Therefore, the effect of nutritional intervention on colonic epithelial proliferation should be studied in biopsies taken not only from the rectum, but also from more proximal parts of the colon. Caution with respect to large scale intervention studies with calcium in high risk groups is mandatory.

Tube feeding of cancer patients treated with chemotherapy.

As many chemotherapeutic agents affect the alimentary tract the use of hyperalimentation with tube feeding during and after chemotherapy has been limited. However, patients do tolerate tube feeding well despite chemotherapy. The feeding has to be administered as continuous drip infusion and in case of bone marrow depression sterile feeding is necessary. Enteral nutrition is more physiologic, safer, easier and less expensive than parenteral nutrition. With enteral hyperalimentation the nutritional needs can be fulfilled to a large extent. Much research will be necessary to investigate the effect of enteral (hyper)alimentation on tumor metabolism and clinical effect of chemotherapy.

Effect of chemotherapy on taste sensation in patients with disseminated malignant melanoma.

The effect of combination chemotherapy (bleomycin, actinomycin D, vindesine and DTIC) on taste sensation in patients with malignant melanoma was evaluated. Five concentrations of 4 basic tastes (sweet, bitter, sour and salt) were tested. Lowest concentrations of all tastes were subjectively rated more intense after chemotherapy than before. This change was significant for sweet, sour and salt. The highest concentration of sweet was rated significantly less intense following chemotherapy. The discrimination between highest and lowest concentration was diminished for sweet, sour and bitter and marginally for salt. The changes in taste sensation following chemotherapy could attribute to anorexia in cancer patients treated with cytostatic agents.