Genotoxicity of heat-processed foods

Gene-environment interactions include exposure to genotoxic compounds from our diet and it is no doubt, that humans are regularly exposed to e.g. food toxicants, not least from cooked foods. This paper reviews briefly four classes of cooked food toxicants, e.g. acrylamide, heterocyclic amines, nitrosamines and polyaromatic hydrocarbons. Many of these compounds have been recognised for decades also as environmental pollutants. In addition cigarette smokers and some occupational workers are exposed to them. Their occurrence, formation, metabolic activation, genotoxicity and human cancer risk are briefly presented along with figures on estimated exposure. Several lines of evidence indicate that cooking conditions and dietary habits can contribute to human cancer risk through the ingestion of genotoxic compounds from heat-processed foods. Such compounds cause different types of DNA damage: nucleotide alterations and gross chromosomal aberrations. Most genotoxic compounds begin their action at the DNA level by forming carcinogen-DNA adducts, which result from the covalent binding of a carcinogen or part of a carcinogen to a nucleotide. The genotoxic and carcinogenic potential of these cooked food toxicants have been evaluated regularly by the International Agency for Research on Cancer (IARC), which has come to the conclusion that several of these food-borne toxicants present in cooked foods are possibly (2A) or probably (213) carcinogenic to humans, based on both high-dose, long-term animal studies and in vitro and in vivo genotoxicity tests. Yet, there is insufficient scientific evidence that these genotoxic compounds really cause human cancer, and no limits have been set for their presence in cooked foods. However, the competent authorities in most Western countries recommend minimising their occurrence, therefore this aspect is also included in this review. (c) 2005 Elsevier B.V. All rights reserved

Colour photographs for estimation of heterocyclic amine intake from fried pork chops of different RN genotypes indicate large variations

A questionnaire complemented with colour photographs was used to obtain information on dietary practices and preferences regarding home-prepared pork chops in a small (n = 151) sample of Swedish consumers. The results from the questionnaire were combined with analytical results from meat of different RN genotypes, and showed that fried chops from a pig that was carrying the RN- allele (high glycogen content) had a darker crust and contained lower levels of mutagenic heterocyclic amines (HCAs) than chops from a non-carrier (low glycogen content). In this study population, the intake of fried pork chops only contributed slightly to the total HCA exposure; the total monthly intake of mutagenic HCAs was on average 256 ng, ranging from 0 to 1982 ng/month. However, using lower frying temperatures and meat from pigs carrying the RN- allele can further reduce the intake. From the photographs, most of the respondents chose fried chops from the non-carrier, which would result in an average contribution to the monthly HCA intake of 359 +/- 402 ng (mean SD) compared to 35 +/- 60 ng/month for consumers who preferred the RN(-)Irn(+), chops. More than 20 times the amount of mutagenic HCAs was formed when frying chops of the non-carrier of the RN- allele at an initial pan temperature of 200 degreesC instead of 160 degreesC; 4.13 compared to 0.18 ng/g cooked meat. (C) 2004 Elsevier Ltd. All rights reserved

Natural variations of precursors in pig meat affect the yield of heterocyclic amines - Effects of RN genotype, feeding regime, and sex

Pig meat shows natural variations in the concentrations of precursors of heterocyclic amines (HCAs), which may affect formation of HCAs in cooked pig meat. To study this, 26 pigs with an inherent genetic variation (carriers and noncarriers of the RN- allele) were subjected to different feeding regimes (conventional feed compared with feed composed according to organic standards). In addition, the effect of sex (castrated males or females) was considered when assessing chemical and technological meat quality parameters. Concentrations of precursors of HCAs, i.e., creatine, residual glycogen, dipeptides, and free amino acids, were analyzed in the raw meat, and the levels of some HCAs (4,8-DiMelQx, MelQx, PhIP, harman, and norharman) were then determined in fried meat patties prepared from these pigs. The FIN genotype most affected technological meat quality parameters and the level of precursors of HCAs, especially the level of residual glycogen, where carriers of the RN- allele showed levels four times as high as those of noncarriers (75.3 +/- 2.6 compared with 17.2 +/- 2.4,mumol/g meat, least-squares means +/- SE). The increased level of residual glycogen resulted in about 50% lower amounts of total mutagenic HCAs in cooked meat compared with cooked meat from normal pigs. Fried meat from carriers of the RN- allele obtained darker crust color than meat from noncarriers. Feeding regime and sex did not significantly affect the chemical composition of the meat or the formation of HCAs