On Sat, 4 Sep 1999, Ilya wrote:

> I seem to remember seeing studies that show burned food being carcinogenic.

I believe the carcinogenic compounds generated in the burning of
meat are called heterocyclic amines.  Below is a reference on
this.  Perhaps the most interesting detail is the apparent
protective effect of fat.  It was the HCAa from *lean* protein
that caused trouble.

Todd Moody
[log in to unmask]

Nutr Cancer 1998;30(3):220-6

Feeding of a well-cooked beef diet containing a high heterocyclic
amine content enhances colon and stomach carcinogenesis in
1,2-dimethylhydrazine-treated rats.

Pence BC, Landers M, Dunn DM, Shen CL, Miller MF

Department of Pathology, Texas Tech University Health Sciences
Center, Lubbock 79430, USA. [log in to unmask]

Epidemiologic studies have linked the consumption of red meat and
the consumption of highly browned meats containing high levels of
heterocyclic aromatic amines (HCAs) to increased risk of
colorectal cancer or polyps. The present study determined the
effects of long-term feeding of beef-containing diets with low
and high levels of HCAs (in the context of a low or high beef
tallow diet) on a standard 1,2-dimethylhydrazine (DMH)-induced
colon tumorigenesis protocol. Very lean beef was cooked by a
variety of methods at different temperatures, and the levels of
the major HCAs (2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline,
2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline, and
2-amino-1-methyl-6-phenylimidazo[4,5-f]pyridine) were measured by
high-performance liquid chromatography. Diets incorporating beef
containing low or high levels of HCAs were fed for 12 weeks,
during which DMH was administered to induce colon tumors,
followed by various dietary regimens as promotional stimuli.
Feeding of a beef diet high in HCAs resulted in more DMH-induced
colon adenocarcinomas, but only in the context of a low-fat diet.
The high-HCA diets increased stomach tumors in all DMH-treated
rats. An apparent interaction of high HCA with a high fat level
reduced the colon tumor incidence and tumor numbers in those
diets containing both factors. These results support the
epidemiologic data linking well-cooked meat to increased risk for
colon and stomach cancer, but the role of dietary fat level
remains puzzling.

UI: 98294955