Endogenous formation of carcinogenic N-nitroso compounds (NOC) occurs in the human gut. Red meat is considered the most important dietary... » More

Endogenous formation of carcinogenic N-nitroso compounds (NOC) occurs in the human gut. Red meat is considered the

most important dietary component linked to NOC formation, although nitrate and vitamin C (VitC) also contribute. We

previously showed that high-protein weight-loss diets increased fecal NOC and this was enhanced by simultaneous

carbohydrate restriction. Although previous studies have focused on the effect of either 1 or 2 dietary components on

endogenous NOC formation, no study to date has investigated the combined contribution of various dietary components.

The current study therefore assessed the joint impact of several known dietary contributors to the endogenous formation

of NOC in obese men. It also aimed to identify further novel contributors and investigate their role in explaining shifts in

endogenous formation of NOC. Three dietary trials were conducted in obese men consuming body weight maintenance or

weight-loss diets, with NOC measured in fecal samples. Consumption of meat-based weight-loss diets increased (P <

0.001) fecal NOC. Red meat intake was positively correlated with the fecal log NOC concentration (r = 0.60; P < 0.001).

Dietary carbohydrate and sugar were negatively correlated with the fecal log NOC concentration (r = 20.66 for both; P <

0.001). Multiple regression analysis identified several dietary components that drive endogenous NOC formation, namely

red meat, nitrate, VitC, total energy, and nonstarch polysaccharides. We present a regression model that predicts

endogenous NOC formation in obese men based on their dietary intakes. This model could improve the estimation of

endogenous NOC formation, currently used in epidemiological studies into diet and cancer.

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