Danger from Well-Done Meats Underestimated

Technology developed in Norway shows that the health risks from well-done meats have been severely underestimated. Innovative research carried out using special mice shows that the danger of developing intestinal tumors from crusty meat (the surface formed during cooking at high temperatures) increased from 31 to 80 percent.

Mice are truly the "test rats" of medicine and are used to assess whether or not substances in food harm humans. To get correct results, humans and mice must metabolize substances in the same way. But humans and mice have differences in certain enzymes called sulfotransferases (SULT). In humans, the enzymes are found in several places, but are only found in the livers of ordinary laboratory mice. SULT-enzymes can make some substances in food less harmful, but they can also change harmless substances into carcinogens. As a result of these differences, the health risks can also be different between the two species.

Researchers at the Norwegian Institute of Public Health have adopted a mouse type in which human enzymes have been inserted to examine whether people may be more sensitive to certain carcinogenic substances from heat-treated foods. Researchers used laboratory mice with the same amount of SULT-enzymes in the intestines as humans in their experiments.

When food is cooked at high heats — such as during grilling or frying — the heat can form carcinogenic substances called food mutagens. In the study, the mice received the food mutagen often found in highest quantities in the crust of meat and fish. The researchers wanted to study tumor development in the intestines of the "human-like" mice, and compare this with tumor development in normal mice given the same food mutagen.

The results found that the incidence of intestinal tumors increased from 31 to 80 per cent in "human-like" mice after consuming substances from the meat crust, showing that normal laboratory mice are not a good model for assessing the health risk to humans following ingestion of food mutagens from well-done meat and fish.