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CARCINOGENS IN FOODS
by Ibrahim B.
Syed, Ph. D. Enjoin ye righteousness upon mankind. …… Surah, Baqara, 2: 44 Eat and drink of that which Allah hath provided, and do not act corruptly, making mischief in the earth. …………… Surah, Baqara, 2: 60 Those who believe and do good works: such are rightful owners of the Garden (Jannah). …… Surah Baqara, 2: 82 O mankind! Eat of that which is lawful and wholesome in the earth, and follow not the footsteps of the devil. Lo! he is an open enemy for you. ……..Surah, Baqara 2: 168 O ye who believe! Eat of the good things wherewith We have provided you... Surah, Baqara, 2: 172 The righteous man is he who wardeth off (evil). Surah, Baqara, 2: 189. The best provision is to ward off evil. .. Surah, Baqara, 2: 197 Allah loveth those who have a care for cleanness… Surah Baqara, 2: 222. ... So be mindful of your duty (to Allah) and do good works, and again: be mindful of your duty, and believe; and once again: be mindful of your duty, and do right. Allah loveth those who do good………Surah, Al-Ma'ida……5: 93 It is very well known that tobacco and tobacco products contain carcinogens (cancer causing substances) (1). However they are not used as edibles by humans. Caffeine is suspected to be a carcinogen (2). Scientific studies, particularly epidemiological studies have shown that food and life-styles are closely related to human cancer (3,4). A notable example is that the incidence of stomach and colon cancers among the descendents of Japanese immigrants dramatically changed from the pattern in Japan to that in the country of residence (5). This clearly shows the importance of food habits in inducing cancers of the digestive tract. Foods can act both as inhibitors and promoters of carcinogenesis. Various types of carcinogens in foods are known. There are naturally occurring carcinogens found in edible plants or spices, such as pyrrolidine alkaloids, flavonoids, and anthraquinones. Nitrosamines and nitrosamides are produced from food components and nitrite y nitrosation reaction either during cooking and food processing or in the stomach. Mycotoxins such as Aphlatoxins are produced by fungi contaminating in foods (peanuts). Heterocyclic amines and polycyclic aromatic hydrocarbons (PAH) are produced by the pyrolysis (breakdown by heat) of amino acids, proteins, and other food components. Food additives and contaminants could be carcinogenic. HETEROCYCLIC AMINES It was found that broiled dried fish had mutagenic activity. At present 7 out of 16 pyrolysis products have been demonstrated to be strongly carcinogenic. These seven carcinogenic chemicals are (6): 1. A alpha C = 2-Amino-9H pyrdo (2,3-b)-indole 2. Glu-P-1 = 2-Amino-6-methyl dipyrido-imidazole 3. Glu-P-2 = 2-Aminodipyrido-imidazole 4. IQ = 2-Amino-3-methylimidazo-quinoline 5. Me A alpha C = 2-Amino-3-methyl-9H-Pyrido-indole 6. Trp-P-1 = 3-Amino-1, 4-dimethyl-5H-pyrido-indole 7. Trp-P-2 = 3-Amino-1-methyl-5H-pyrido-indole When these chemicals were administered orally to rats or mice, they induced hepatocellular carcinomas in the livers and tumors in some other organs such as small intestine, colon, brain, skin, oral cavity, lung, clitoral gland, etc. One good news is that all these heterocyclic amines were quickly degraded and they also lost mutagenic activity on treatment with hypochlorite, which is usually present in chlorinated tap water. It is also found that fresh juices from vegetables and fruits, such as cabbage, broccoli, green pepper, egg plant, apple, burdock, stone-leek, ginger, mint leaf, and pineapple can inactivate the mutagenicities of tryptophan pyrolysis products. In extracts of leaves of cabbage a chemical was identified to be a peroxidase which inactivated Trp-P-1 and Trp-P-2. Table 1 shows the amounts of heterocyclic amines in cooked foods. POLYCYCLIC AROMATIC HYDROCARBONS (PAH): The presence of polycyclic aromatic hydrocarbons (PAH) as carcinogens in foods has been known since 1950s. At least 18 mutagenic and/or carcinogenic polycyclic aromatic hydrocarbons are known at present and these are shown in Table 2. These chemicals have also been found in uncooked vegetables, fruits, cereals, and vegetable oils. The amount of polycyclic hydrocarbons present in cooked foods depends on the time of cooking, the distance of materials from the heat source, whether the melted fat is allowed to drop into the heat source, etc., In vegetables, fruits, and cereals, the amounts of these chemicals depend on the degrees of industrial and traffic pollutants in the areas in which they are grown. The amounts of carcinogenic polycyclic aromatic hydrocarbons in foods vary from 0 to 400 micrograms/kilogram. 12 of the 18 polycyclic aromatic hydrocarbons that were detected in broiled meat or smoked fish are known to be carcinogens. These 12 are shown in Table 2, and are classified as Strong Carcinogens, Moderate Carcinogens, and Weak Carcinogens. STRONG CARCINOGENS: 1. Benz (a) anthracene 2. Benzo (a) pyrene 3. Benzo (b) fluoranthene 4. Benzo (j) fluoranthene 5. Dibenz (a, h) anthrene 6. 2-methylchrysene 7. 3-methylchrysene MODERATE CARCINOGENS 8. Benzo (e) pyrene 9. Chrysene 10. Indeno (1,2,3-cd) pyrene WEAK CARCINOGENS 11. Anthanthrene 12. Benzo (b) chrysene Available data are not sufficient to determine the carcinogenicities of benzo (g, h, i) perylene, coronene, perylene, and phenanthrene. There is no evidence to prove the carcinogenicity of fluoranthrene and pyrene per se in experimental animals. Table 1. Amounts of heterocyclic amines in cooked foods (ug/kg) (6)
Table 2. Amounts of Polycyclic Aromatic Hydrocarbons in Foods in ug/kg (6)
REFERENCES 1. I.B. Syed.: Smoking is Unlawful in Islam (1984): The Islamic Perspective, Vol. III, No.2. 2. I.B. Syed.: Extension of Halal Concepts to the personal habits of Muslims. (1986). The Islamic Perspective. Vol. V, No. 1 and 2, pp. 4-7. 3. R. Doll., R. Peto.: Quantitative estimates of avoidable risk of cancer in U.S. today (1981). J. Natl. Cancer Insti. 66: 1191-1308. 4. J. Higginson, C.S. Muir.: Guest editorial: Environmental carcinogenesis: Misconceptions and limitations to cancer control (1979) J. Natl. Cancer Inst. 63: 1291-98. 5. L.N. Kolonel, M.W. Hinds and H.J. Hankin.: Cancer patterns among migrant and native-born Japanese in Hawaii in relation to smoking, drinking, and dietary habits. In Genetic Environmental Factors in Experimental and Human Cancer (1980). Princess Takamatsu Symp., ed. H.V. Gelboin, B. MacMahon, T. Matsushima, et al, Tokyo: Japan Science Society 10: 327-340. 6. C. Furihata and T. Matsushima.: Mutagens and Carcinogens in Foods (1986). Ann. Rev. Nutr. 6: 67-94. |
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