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Sir,

I read this article [1] with interest. Fat is described as the foremost dietary component contributing to the aetiology of prostate cancer. The role of essential fatty acids as a cause of prostate cancer has been described in some detail and some proposals made about the mechanism of carcinogenesis. However, the role of saturated fat and animal meat was not discussed. There has been some research to determine the role of saturated fat and the method of cooking in the aetiology of prostate cancer. Cooking animal fat and meat at high temperature produces polycyclic aromatic hydrocarbons (PAH), e.g. benzo[a]pyrene and heterocyclic amines (HCA), e.g. 2-amino-1-methyl-6-phenyl imidazopyridine, 2-amino-3-methyl imidazo quinoline, by pyrolysis of fat [2]. These hydrocarbons and heterocyclic amines are mutagenic in animal and human studies [3]. The PAH and HCA need to be biologically activated by the prostate before they form a DNA adduct. This involves N-hydroxylation by cytochrome p450 enzymes and these N-hydroxy derivatives are further o-esterified, catalysed by N-acetyl transferases (NATs)/sulpho-transferases to form reactive nitrenium ion derivatives. These covalently bind with DNA to form adducts. Studies have confirmed that the prostate necessarily expresses these key xenobiotic metabolising enzymes, i.e. cytochrome p450 1A2, 1A1 and 181 [4]. Wang et al.[5] identified the overexpression of NAT1 enzymes in human prostate tissue by PCR. Muir et al.[4] confirmed that these fat-derived PAH and HCA form DNA adducts in human prostate tissue by analysis after 32P-labelling. Further research is being undertaken to identify the correlation between diet, method of cooking and prevalence of DNA adducts induced by PAH and HCA among the general population and subjects with prostate cancer. Hence the role of fat in prostate cancer is more complex than suggested and simple addition or deletion of a particular type of fat/fatty acid may not alone be a sufficient preventive strategy. Lifestyle issues like mode of cooking need to be addressed when considering dietary manipulation.

  • 1
    Meyer J-P, Gillatt DA. Can diet affect prostate cancer? BJU Int 2002; 89: 2504
  • 2
    Knize MG, Salmon CP, Pais P, Felton JS. Food heating and the formation of heterocyclic aromatic amine and polycyclic aromatic hydrocarbon mutagens/carcinogens. Adv Exp Med Biol 1999; 459: 17993
  • 3
    El-Bayoumy K. Environmental carcinogens that may be involved in human breast cancer etiology. Chem Res Toxicol 1992; 5: 58590
  • 4
    Muir GH, Williams GH, Martin FL, Hewer A, Grover PL, Philips DH. Metabolic activation of carcinogens and expression of various cytochromes P450 in human prostate tissue. Carcinogenesis 2000; 21: 16839
  • 5
    Wang CV, Debiec-Rychter M, Schut HA, Morse P, Jones RF. N-acetyltransferase expression and DNA binding of N-hydroxyheterocyclic amines in human prostate epithelium. Carcinogenesis 1999; 20: 15915