Normal laboratory mice are not a good model for assessing the health risk to humans from well-done meat and fish, says a new study.
The study suggested that researchers might be underestimating the health risk to humans from heat-treated foods while testing on mice.
Mice are often used to test whether substances in food are harmful to humans. his requires that mice and humans metabolise substances in the same way.
But humans have certain enzymes in more parts of the body than mice.
Researchers at the Norwegian Institute of Public Health have adopted a mouse type where human enzymes have been inserted to examine whether people may be more sensitive to certain carcinogenic substances from heat-treated foods.
The results showed that the incidence of intestinal tumours increased from 31 per cent to 80 per cent in "human-like" mice who consumed substances from meat crust (i.e. the surface formed during heat-treatment).
Heat processing of food can lead to the formation of carcinogenic substances.
The formation of carcinogenic substances - so-called food mutagens - usually occurs at high temperatures when frying or grilling.
There are enzymes called sulfotransferases (SULT) in several places in the human body, but these are only found in the livers of normal laboratory mice.
SULT-enzymes can make some substances in food less harmful, but they can also transform harmless substances into carcinogenic substances.
Using results from laboratory mice to predict health risk to humans consuming food mutagens can therefore be underestimated, the study concluded.