A diet containing chickpeas and wheat offers less protection against colon tumors than a casein and wheat diet in dimethylhydrazine-treated rats.
We examined the influence of extruded chickpeas and wheat relative to casein and wheat in a dimethylhydrazine (DMH)-induced colon tumor study in male Sprague-Dawley rats. The three diets, based on a modified AIN76 rodent diet with fat present at 10 g/100 g dry matter (DM), were as follows: casein with wheat starch (Cas/S) as control, casein with wheat (Cas/W) and chickpeas with wheat (CP/W). All diets were fed from 5 wk of age throughout the 28-wk study. At 28 wk, there was a significantly lower incidence of large intestinal tumors in rats fed Cas/W relative to those fed CP/W ( 11 vs. 56%, chi-square test, P = 0.018). The colonic tumor burden (tumors/tumor-bearing animal) was not different in Cas/W-fed and CP/W-fed rats (1 vs. 1.7), but the tumor mass index was significantly lower in the former group (0.22 vs. 1.21, P = 0.026). Rats fed the CP/W diet had significantly lower plasma cholesterol concentration (P < 0.01) than rats fed the other two diets. The cecal contents of rats fed the CP/W diet had significantly greater relative weights (46%, P < 0.05) than those of the Cas/W-fed rats; this was associated with higher concentrations of all short-chain fatty acids. Fecal analyses showed significantly (P < 0.05) higher concentrations of total fat (54%), total steroids (83%) and secondary bile acids (179%) in the CP/W-fed rats relative those fed Cas/W. There were higher concentrations of nitrogen in the feces of CP/W rats relative to the Cas/W-fed rats (84%, P < 0.05), associated with greater fecal weights (67%, P < 0.05). Although wheat and its fibers have been shown to be protective against DMH-induced cancers in rats, this was not the case in this study in which chickpeas (45 g/100 g diet) provided the protein and were an important source of soluble fiber. Elevated fat, secondary bile acid concentrations and/or nitrogenous compounds could be responsible for the increased colon tumorigenesis seen and may reflect a legume effect.
McIntosh
G H
GH
CSIRO Division of Human Nutrition, Adelaide, South Australia 5000.
Wang
Y H
YH
Royle
P J
PJ
D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002273:Carcinogens / Q000633:toxicity; D002364:Caseins / Q000008:administration & dosage*; D002784:Cholesterol / Q000097:blood; D015331:Cohort Studies; D003110:Colonic Neoplasms / Q000097:blood / Q000139:chemically induced / Q000517:prevention & control* / Q000652:urine; D004127:Dimethylhydrazines / Q000633:toxicity; D007887:Fabaceae; D005232:Fatty Acids, Volatile / Q000032:analysis; D005243:Feces / Q000737:chemistry; D008297:Male; D009584:Nitrogen / Q000378:metabolism / Q000652:urine; D010946:Plants, Medicinal; D051381:Rats; D017207:Rats, Sprague-Dawley; D014908:Triticum
D002273:Carcinogens; D002364:Caseins; D004127:Dimethylhydrazines; D005232:Fatty Acids, Volatile; D002784:Cholesterol; D009584:Nitrogen