Cancer is a multi-factoral disease resulting from the perturbation of the normal regulatory processes of a cell. Cancer cells are generated from healthy cells by an accumulation of genetic alterations. These alterations can take the form of mutations, losses, amplifications or re-arrangements in so called oncogenes or tumor suppresser genes. The many potential mutations giving rise to cancer are initiated by carcinogenic substances and by certain environmental conditions . Carcinogenic substances can be loosely classified as "endogenous", which may be naturally occurring, iatrogenic, environmental contaminants or life style-related or endogenous, for example reactive oxygen species which can be produced in vivo. The human diet consists of an array of microbial, animal and plant derived material and a link between diet and health has been recognized for many centuries. The specific relationship between diet and cancer however is ill defined and uncertain and the evidence is contradictory. Dietary constituents are believed to play both a protective and causative role in the aetiology of the disease and the link between dietary factors and carcinogenesis has been relentlessly investigated by way of animal experiments. Numerous, albeit rather general epidemiological studies have also supported the notion that dietary status can influence carcinogenesis.
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[...] It is hence extremely difficult to assign a preventative or causative role to any one dietary constituent. It is extremely difficult also to distinguish causal relationships from indirect associations and there is the added complication of possible synergistic relationships between dietary components. Both epidemiological and experimental studies have their drawbacks. Human epidemiological studies are notoriously difficult to plan and interpret and laboratory studies on animals often involve the induction of tumors by various carcinogens, also the anti-carcinogen in question is administered in high doses therefore the relevance to human exposure scenarios is questionable. [...]
[...] Doll and Peto have suggested that variations in dietary status may account for as much as 90 percent of the variation in rates of colorectal cancer among different populations. Numerous studies, for example Burkitt have reported a lower incidence of colon cancer in certain regions of Africa, where the typical diet contains a high level of fiber. What is the proposed mechanism of action of fiber as an anti-carcinogenic agent? The substance is known to shorten the intestinal transit time of food, thus potentially limiting the length of time that carcinogenic substances are held in the gut. [...]
[...] Dietary anticarcinogens/antimutagens. Laboratory studies have identified an array of anti-mutagens and anti- carcinogens (Table1.), many of which are plant derived, Anti- carcinogens/ mutagens may act via various mechanisms; by blocking the activation of the carcinogen, for example by blocking the induction of various metabolic enzymes, or by enhancing DNA repair mechanisms. Alternatively, they may “suppress” the effects of a carcinogen. Anti- mutagens can be chemicals that interfere with DNA repair or metabolism of mutagens and mutagen scavengers, such as vitamins C and E. [...]
[...] The dietary status of an organism may influence sensitivity to this carcinogen. Protein deficient diets reduce the toxicity of nitrosamines, but can give rise to an increased susceptibility to nitrosamine-induced kidney tumors as their metabolism is reduced and the kidney is exposed to a higher concentration of the carcinogen Red meat and colon cancer. Epidemiological studies have consistently identified an association between the intake of meat, particularly well-cooked red meat and cancer of the colon and rectum This association has lead to significant alarm among the general public over the last few years. [...]
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