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A high-protein diet can reduce body weight and increase insulin sensitivity, but whether the type of dietary protein affects these outcomes is unknown. We hypothesized that feeding insulin-resistant rats a high-protein diet (32%) containing whey protein concentrate (WPC) would reduce body weight and tissue lipid levels and increase insulin sensitivity more than a diet containing red meat (RM). Rats were fed a high-fat diet (300 g fat/kg diet) for 9 wk, then switched to a diet containing either 80 or 320 g protein/kg diet, provided by either WPC or RM, for 6 wk (n = 8). The rats were then killed after overnight food deprivation. High dietary protein reduced energy intake (P < 0.001) and visceral (P < 0.001), subcutaneous (P < 0.001), and carcass fat (P < 0.05). Increasing the dietary density of WPC, but not of RM, reduced body weight gain by 4% (P < 0.001). Dietary WPC also reduced plasma insulin concentration by 40% (P < 0.05) and increased insulin sensitivity, compared to RM (P < 0.05). These findings support the conclusions that a high-protein diet reduces energy intake and adiposity and that whey protein is more effective than red meat in reducing body weight gain and increasing insulin sensitivity. J. Nutr. 134: 1454-1458, 2004. KEY WORDS: * whey protein * red meat * protein density * weight gain * insulin sensitivity

There is a need for better understanding of the roles of dietary fats and fibers in colon cancer risk. We examined the effect of different dietary fiber and fat sources on an azoxymethane (AOM)-induced colon cancer in rats. In a 2 x 3 factorial design, rats were fed a semipurified diet containing soy-derived fiber (Fibrim), [alpha]- cellulose (Solkafloc) or resistant starch (RS; Hi-maize) at 10 g dietary fiber/100 g diet, combined with fish oil (FO) or sunflower seed oil (SSO) at 10 g/100 g diet, and lard added to all diets at 10 g/100 g, to provide a total of 20 g mixed fat/100 g diet. Sprague-Dawley rats (28 d of age) consumed diets for 4 wk and then two doses of AOM (15 mg/kg body) were administered 1 wk apart by subcutaneous injection. Rats were killed after 13 wk of consuming experimental diets. Colons were fixed in formalin and aberrant crypt foci (ACF) were quantified after staining. ACF counts were higher (+66%, P < 0.01) in rats fed SSO and RS, than in those fed [alpha]-cellulose and FO. Rats fed FO had 19% fewer ACF than those fed SSO (P < 0.05). [alpha]-Cellulose was associated with the highest cecal butyrate concentration (P < 0.001), the highest [beta]-glucuronidase specific activity (P < 0.001) and the lowest cecal water cytotoxicity (P < 0.001) relative to soy fiber- and RS-fed rats. There were inverse correlations between the number of ACF and cecal butyrate concentration (r = -0.33, P < 0.05) and between cecal water cytotoxicity and [beta]-glucuronidase activity (r = -0.70, P < 0.001). The greatest protection was associated with a-cellulose as the fiber source and FO as the fat source as measured by colon ACF numbers in rats. KEY WORDS: * fiber * polyunsaturated fatty acids * aberrant crypt foci * cecal water cytotoxicity * rats

Abstract Wholegrain and wholemeal cereal foods are important components of a healthy diet, making a major contribution, via their dietary fibre and associated phytochemicals, to disease prevention. Outer layers of [...]

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. KEY WORDS: * rats * chickpeas * casein * wheat * colon tumors

This study investigated the effect of feeding peas (Pisum sativum) and chickpeas (Cicer arietinum) processed by boiling or extrusion on growth performance, plasma cholesterol concentrations and organ weights of rats. Casein was used as the protein source in the control diets. Complementarity of wheat and legumes on protein quality was also evaluated. Boiled or extruded legumes significantly increased body weight gain (BWG) of rats but not protein efficiency ratio (PER) when compared with raw legumes. Rats fed processed chickpeas and those fed casein had similar BWG, and both groups had greater BWG than rats fed peas. Extruded wheat combined with peas or chickpeas increased sulfur amino acid (SAA) levels in the diets and significantly improved BWG and PER of rats compared with those fed sucrose as an energy source. There was a linear correlation between the SAA to dietary protein ratio and BWG of rats (r = 0.902, P < 0.014), indicating that SAA are the limiting amino acids in legumes. Plasma cholesterol concentrations were lower in rats fed legumes than in those fed casein. Cholesterol-lowering ability was affected by processing method, with extrusion being most effective for peas; boiling and extrusion were equally effective for chickpeas. Raw legume feeding resulted in greater pancreatic and small intestine weight relative to body weight. Chickpea fed rats had lower spleen, thymus and liver relative weights and higher cecum and colon relative weights than rats fed casein. There were no differences in growth, PER, organ relative weight or plasma cholesterol concentration between rats fed extruded legumes and those fed boiled legumes, suggesting that extrusion improves nutritional value of these legumes to the same extent as the traditional boiling method. INDEXING KEY WORDS: * legumes * processing methods * body weights * cholesterol * rats

The impact of different dietary protein sources (whey, casein, soybean, red meat) on the incidence, burden and mass index of intestinal tumors induced by dimethylhydrazine in male Sprague-Dawley rats was assessed. A purified diet (based on AIN-76A) with a fat concentration of 20 g/100 g and other proteins substituted for casein (20 g/100 g) was used. Whey and casein diets were more protective against the development of intestinal tumors than were the red meat or soybean diets, as evidenced by a reduced incidence of rats affected (P = 0.15), fewer tumors per treatment group (burden, P < 0.005), and a reduced pooled area of tumors (tumor mass index) that formed (P = 0.39). Intracellular concentration of glutathione, an antioxidant and anticarcinogenic tripeptide, measured in liver, was greatest in whey protein- and casein-fed rats and lowest in soybean-fed animals (P < 0.001). For other tissues (spleen, colon, tumor) the differences were not significant, although the whey-fed animals had the highest concentrations of glutathione (P = 0.8). Whey is a source of precursors (cysteine-rich proteins) for glutathione synthesis and may be important in providing protection to the host by stimulating glutathione synthesis. A positive correlation was observed between mean fecal fat concentrations for rats in each treatment group and large intestinal tumor burden ([r.sup.2] = 0.898, P = 0.05). Fecal fat could be involved in aiding initiation and/or promotion of carcinogenesis. Whatever the mechanism(s), dairy proteins, and whey proteins in particular, offer considerable protection to the host against dimethylhydrazine-induced tumors relative to the other protein sources examined. INDEXING KEY WORDS: glutathione; fecal fat; rats; intestinal cancers; dietary proteins

A study was conducted to determine the bioavailabilities of selenium (Se) from Se-enriched whole milk in artificially reared neonatal pigs. Results indicated that Se in milk from cows fed selenised yeast is highly bioavailable and may offer a way of delivering supplemental Se to humans too.

Research has provided ample evidence on the use of selenium supplements in significantly inhibiting some forms of cancer. It has been found that TaturaBio Se appears to be an excellent source of selenium supplementation for humans.

Processed wheat aleurone flour (WAF) is a source of insoluble fermentable dietary fiber that comes from the outer layers of the wheat kernel. A study was designed to evaluate WAF, wheat bran (WB) and [Alpha]-cellulose as the source of dietary fiber (5 g/100 g of diet) in a semipurified high fat (20 g/100 g of as 1:1 lard/sunflower seed oil) diet fed to male Sprague-Dawley rats in which intestinal tumors were induced using azoxymethane (AOM). WAF at 33 g/100 g of diet (WAF33) and WB at 16 g/100 g of diet (WB16) increased the weight of feces and produced significantly higher concentrations in the cecum of the short-chain fatty acid butyrate (P [is less than] 0.001) than did no fiber (NF) and WAF added at only 10 g/100 g (1.5 g of dietary fiber) (WAF10). Cecal and fecal pH were both significantly lower in the WAF33 and WB16 treatments relative to control and no fiber treatments (P [is less than] 0.001). The intestinal tumors in the rats were assessed at 6 mo after the study began, and the WAF33- or WB16-fed rats showed a trend (P = 0.06) with 43% fewer colon adenomas relative to control. There was a significant inverse relationship between [Beta]-glucuronidase activity and colon adenomas in the rat colon ([r.sup.2] = 0.37, P = 0.001). WAF fiber influenced some metabolic markers of fermentation in the colon in a manner similar to that of WB, which, independent of the bulking effect, was associated with a trend to reduced colon adenomas. Significantly increased cecal [Beta]-glucuronidase activity and/or butyrate concentrations may have protective influences in this context by mechanisms not yet fully elucidated. J. Nutr. 131: 127-131, 2001. KEY WORDS: * azoxymethane * colon tumors * wheat aleurone flour * [Beta]-glucuronidase * rats