High-protein, Reduced-Carbohydrate Weight-loss Diets Promote Metabolite Profiles Likely To Be Detrimental To Colonic Health, American Journal of Clinical Nutrition, May 2011
There were three diets tested. Food was dispensed and consumption measured:
- 85g protein, 116g fat, 360g carb (Maintenance diet)
- 139g protein, 82g fat, 181g carb (High-protein Moderate-carb)
- 137g protein, 143g fat, 22g carb (High-protein Low-carb)
"After 4 wk, weight-loss diets that were high in protein but reduced in total carbohydrates and fiber resulted in a significant decrease in fecal cancer-protective metabolites and increased concentrations of hazardous metabolites. Long-term adherence to such diets may increase risk of colonic disease."Both of the high-protein reduced-carb diets increased hazardous compounds in the colon in just 4 weeks, compared to the lower-protein higher-carb diet.
From their literature review:
"When dietary protein is consumed in high amounts, more dietary protein may reach the colon and result in increased fermentation to products that include harmful nitrogenous metabolites. (This occurred in this study.)"
"Nitrosamine and heterocyclic amine concentrations in fecal samples are increased by high red-meat consumption, and these concentrations have been implicated in increased colon-cancer risk."
"Overall, high intakes of protein, in particular of red meat, may increase risk of developing colorectal cancer."