Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: 2/15/2005
Publication Date: 3/4/2005
Citation: Carter, J.A., Xiao, R., Badger, T.M., Simmen, F.A. 2005. Dietary whey protein hydrolysate (wph) suppresses circulating insulin and c-peptide levels and inhibits colon tumorigenesis. The FASEB Journal. 19(4):A77.
Interpretive Summary: The ACNC has been studying the effects of certain dietary factors very early in life on prevention of diseases. We previously reported that dietary intake of whey protein hydrolysate (WPH), a milk protein source containing bio-active peptides and hormones, suppressed colon cancer incidence in rats. Insulin-related pathways are considered important in colon cancer. This study investigated the effects of a whey diet on insulin levels in male rats. Lifetime feeding of WPH suppressed insulin levels in rat serum and in parallel, reduced colon cancer occurrence. Results show that dietary consumption of WPH decreases insulin levels, which may contribute to observed reductions in colon tumor occurrence. Future studies will determine the impact of whey-induced insulin effects on other health-related issues, such as diabetes and heart health.
Technical Abstract: We previously reported that dietary intake of WPH, a milk protein source containing bio-active peptides and hormones, suppressed colon cancer incidence in rats. Insulin-related pathways are considered key in the etiology of colon cancer. This study investigated the effects of casein (control) and whey diets on serum insulin levels and azoxymethane (AOM)-induced aberrant crypt foci (ACF) in male rats. Pregnant (gestation day 4) Sprague-Dawley rat dams (Charles River Laboratories) were placed on AIN-93G diets formulated with casein or WPH as their sole protein source. Male progeny, weaned on postnatal day (PND) 21, were placed on the same diets as their dams and received AOM (15 mg/kg body weight) at PND 50. Animals from each diet group were sacrificed at 6, 12, 20, and 23 weeks and colons fixed for visualization of ACF. Sera from a random subset of each group were subjected to insulin and C-peptide quantification. Feeding of WPH suppressed insulin and C-peptide levels in rat serum and colon ACF occurrence. A significant overall diet (P = 0.031) and time (P = 0.044) effect was found for insulin. C-peptide exhibited a significant diet effect at 6 weeks (P = 0.020), 12 weeks (P < 0.001), 20 weeks (P < 0.001), and 23 weeks (P = 0.013), post-AOM. No correlation for insulin (or C-peptide) levels and ACF formation was apparent. Results show that dietary consumption of WPH decreases insulin and C-peptide sera levels, which may contribute to observed reductions in colon ACF occurrence.