A study published in the American Journal of Clinical Nutrition in March, 2011 has raised concerns about the long term effect of high-protein, low-carbohydrate diets on bowel health. The study investigated the effect of a high-protein, low-carbohydrate (HP-LC) diet on levels of levels of protective compounds in the gut that are normally associated with a high fibre diet. The HP-LC diet reduced the levels of plant based substances thought to provide protection against colorectal cancer and whereas fecal concentrations of carcinogenic N-nitroso compounds were increased.
The authors point out that it would not be possible to quantify an increase in colorectal cancer reisk as this depends on many other factors such as the duration of the diet, and other diet and lifestlyle factors. These results suggest that including high fibre foods in the diet may counteract some of the disadvantagous effects of a HP-LC diet.
Am J Clin Nutr doi: 10.3945/ajcn.110.002188.