Review SectionCarcinogenic Heterocyclic Amines in Model Systems and Cooked Foods: A Review on Formation, Occurrence and Intake
Section snippets
History and Introduction
Epidemiological studies have shown diet to be an important factor in the global variation in human cancer rates (Doll and Peto, 1981). By gaining an understanding of the specific factors in cancer causation we may be able to explain this variation and propose strategies for cancer prevention. The presence of carcinogenic substances in foods was first reported by a Swedish scientist, Professor Widmark, at Lund University who, in 1939, found that organic solvent extracts of grilled horse meat
Formation of IQ compounds
The Maillard reaction has been suggested to play an important role in the formation of HAs. In 1983, Jägerstad et al. suggested that creatine, free amino acids and hexoses, present in raw meat, were precursors of the IQ compounds, and outlined a pathway for their formation (Jägerstad et al., 1983a). It was postulated that creatine formed the amino-imidazo part of the molecule by cyclization and water elimination. The remaining parts of the IQ compounds were assumed to arise from Strecker
Formation of PhIP
It has been convincingly demonstrated that phenylalanine and creatine are precursors of PhIP by dry heating 13C-labelled phenylalanine and creatine (Felton and Knize, 1991). PhIP may also be produced from creatine heated together with leucine, isoleucine and tyrosine (Johansson et al., 1995a; Övervik et al., 1989). Glucose was found to have a considerable influence on the formation of PhIP produced from phenylalanine and creatine in a liquid model system (Skog and Jägerstad, 1991). Furthermore,
New HAs and unidentified mutagenic compounds
Two new HAs, TMIP (2-amino-1,5,6-trimethyl-imidazopyridine) and DMIP (2-amino-1,6-dimethyl-imidazopyridine), have been found in fried meat products (Becher et al., 1988, Becher et al., 1989; Felton et al., 1984). In addition, two mutagenic compounds, with molecular weights (MW) of 202 and 216, have been isolated from fried minced beef and pork, and from a fried meat emulsion (Becher et al., 1988; Felton et al., 1986; Gry et al., 1986). A methylimidazo-furopyridine containing oxygen (MW 202) has
Factors affecting the yield of HAs in model systems
The identification of several HAs from modelling experiments (see Table 1) shows that model systems are good tools for studying the influence of different physical parameters and various precursors on the formation of HAs.
Factors affecting the yield of HAs in cooked foods
The most important variables affecting the formation of HAs are cooking temperature, cooking time, cooking method and type of food, that is, content of precursors and inhibitors. The influence of these factors on the formation of HAs has been the subject of several studies.
Levels of HAs in cooked foods
The first quantitative data on HAs in various meat and fish products, based on HPLC or GC–MS analysis, was published in the late 1980s. Earlier literature data on HA levels in foods consist mainly of amounts estimated from the mutagenic activity according to the Ames/Salmonella assay. The complex food matrix, the low amounts of HAs present, and the need for several isolation steps makes accurate quantification difficult, but recently several new methods for the extraction, purification and
Estimates of dietary intake of HAs
Accurate assessments of the consumption of HAs are essential for the evaluation of human cancer risks. Cooked meat and fish are important sources of exposure to HAs, as are pan residues in countries where they are used to make gravy. Other parameters influencing the dietary intake of HAs are type of food, cooking method, portion size and intake frequency. Table 3 summarizes estimates of the daily intake of HAs reported in the literature during the past 5–6 years. (Only studies based on chemical
Concluding remarks
The human cancer risk associated with HAs depends on the level of dietary exposure in the population, the biologically effective doses arising from those exposures within relevant target tissues, and the relationship between these effective doses and predicted increased cancer risk. As recently pointed out by Felton et al. (1997), risk assessment for a human population consuming these compounds requires the integration of knowledge of dosimetry, metabolism, carcinogenic potency and
Acknowledgements
This study was financially supported by the Swedish Cancer Society (1824-B96-15XBB) and also had the financially support of the Commission of the European Communities, Agriculture and Fisheries (FAIR) specific programme, CT96-1080, “Optimisation of the Maillard reaction. A way to improve quality and safety of thermally processed foods”.
References (160)
- et al.
Effects of plant-derived flavonoids and polyphenolic acids on the activity of mutagens from cooked food
Mutation Research
(1986) - et al.
Counteraction of the genotoxicity of some cooked-food mutagens by biogenic amines
Food and Chemical Toxicology
(1987) - et al.
Mutagenicity of basic fractions derived from lamb and beef cooked by common household methods
Food and Chemical Toxicology
(1990) - et al.
Transfer of the food mutagen PhIP to foetuses and newborn mice following maternal exposure
Food and Chemical Toxicology
(1994) - et al.
Investigation of contributor of radicals to the mechanism of the early stage of the Maillard reaction
Food Chemistry
(1996) - et al.
Effects of synthetic antioxidants (BHA, BHT and PG) on the mutagenicity of IQ-like compounds
Food Chemistry
(1992) Genotoxic potential of β-carbolines: a review
Mutation Research
(1995)- et al.
Comparative carcinogenicity of the food pyrolysis product, 2-amino-5-phenylpyridine, and the known human carcinogen, 4-aminobiphenyl, in the neonatal B6C3F1 mouse
Cancer Letters
(1988) - et al.
Modifying actions of solvent extract from fruit and vegetable residues on 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) induced mutagenesis in Salmonella typhimurium TA98
Mutation Research
(1995) - et al.
Food-borne heterocyclic amines. Chemistry, formation, occurrence and biological activities. A literature review
Toxicology
(1993)