Red meat is associated with increased risk of colorectal cancer and increases the endogenous formation of N-nitrosocompounds.
Dr Sheila Bingham and colleagues from England investigated the genotoxic effects of N-nitrosocompounds arising from red meat consumption.
The research team assessed 21 volunteers who consumed high red meat of 420g per day, vegetarian, and high-fiber diets for 15 days.
The team conducted a randomized crossover design while living in a volunteer suite.
Food was carefully controlled and all specimens were collected.
The results were based on measurements by apparent total N-nitrosocompounds in feces.
|There was an increase in N-nitrosocompounds with red meat vs the vegetarian diet|
The team found a consistent and significant increase in endogenous formation of N-nitrosocompounds with the red meat diet compared with the vegetarian diet.
In colonic exfoliated cells, the percentage staining positive for the N-nitrosocompounds-specific DNA adduct, O6-carboxymethyl guanine was higher on the red meat diet.
In 13 volunteers, the team noted that levels were intermediate on the high-fiber, high red meat diet.
Fecal N-nitrosocompounds were positively correlated with the percentage of cells staining positive for O6-carboxymethyl guanine.
The researchers reported that O6 carboxymethyl guanine was also shown in intact small intestine from rats.
The team noted that the animals in that study were treated with the N-nitrosopeptide N-acetyl-N'-prolyl-N'-nitrosoglycine.
O6 carboxymethyl guanine had also been observed HT-29 cells, or human colon adenocarcinoma cells, treated with diazoacetate.
Dr Bingham's team concludes, “This study has shown that fecal N-nitrosocompounds arising from red meat include direct acting diazopeptides or N-nitrosopeptides able to form alkylating DNA adducts in the colon.”
“As these O6-carboxymethyl guanine adducts are not repaired, and if other related adducts are formed and not repaired, this may explain the association of red meat with colorectal cancer.”