Trace element inhibition of carcinogenesis and angiogenesis

Potassium inhibition of DMH-induced small intestinal tumors in rats

This is a preliminary report that shows that supplemental potassium partially prevents 1,2-dimethylhydrazine (DMH) induction of tumors of the small intestine in Sprague-Dawley rats. Male rats were injected weekly with 20 mg DMH/kg body wt for 20 weeks. Potassium chloride was provided in the drinking water one week before the first DMH treatment and was continued until sacrifice 14 weeks after the last DMH treatment. There were four groups of rats and they were identified as follows: DMH, DMH + K, K, and untreated control. Based on 24-hour food and water consumption data and food and water compositions, rats provided 0.5% potassium (from KCl in the drinking water) were ingesting 287.5 +/- 9.2 mg potassium per 24 hours (K/Na = 4.18) and the unsupplemented groups were ingesting 180.3 +/- 18.4 mg potassium per 24 hours (K/Na = 2.62). At sacrifice, the incidence of DMH-induced small intestinal tumors was significantly (p less than 0.05) reduced from 46% (6/13) in the DMH group to 6% (1/17) in the DMH + K group (p less than 0.05). The potassium supplement also significantly (p less than 0.05) reduced the cumulative small intestinal tumor incidence from 40% (8/20) in the DMH group to 5% (1/20) in the DMH + K group. The incidence of colon tumors and of zymbal gland tumors appeared to be reduced by the potassium supplement; however, these were not statistically significant observations (p greater than 0.05). Based on the complete blood count and other blood parameters measured, the level of potassium supplement used induced no apparent toxic effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary sodium and potassium intake and colorectal cancer risk

In a large, comprehensive, population-based case-control study of colorectal cancer (The Melbourne Colorectal Cancer Study), a high intake of sodium was shown to be a statistically significant risk factor for rectal cancer in males (RR = 1.72, p = 0.01) and was close to statistical significance in females (RR = 1.58, p = 0.06). This was independent of previously described dietary risk factors and also independent of the previously described beer risk. A high intake of potassium was protective for both males and females, but this effect disappeared after adjustment was made for the previously described dietary risk factors. A high ratio of dietary potassium to sodium was a statistically significant protective factor in females for both colon and rectal cancer, and the significance of this effect was reduced after adjustment was made for the previously described dietary risk factor (RR for colon cancer = 0.70, p = 0.08; RR for rectal cancer = 0.67, p = 0.08). So far, no biological explanations are available for these associations, and while they are of obvious etiologic interest, they should be interpreted with caution.