Diet, Nutrition, and Cancer (1982) / Chapter Skim
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5 Lipids (Fats and Cholesterol)
5 Lipids (Fats and Cholesterol)
Pages 73-105
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From page 73... ...
These investigators found significant associations with total fat, with animal fat, and with both saturated and unsaturated fats. The findings of three case-control studies support a role for dietary fat in the risk for breast cancer.
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From page 74... ...
(The men were participants in a prospective cohort study of Japanese men in Hawaii.) These investigators reported a direct association between consumption of high fat diets by the husbands and breast cancer in their wives, who were assumed to have adhered to similar eating patterns.
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From page 75... ...
also reported little difference in fat intake between the population of Utah (with a low risk for colon cancer) and that of the United States as a whole.
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From page 76... ...
(1978) observed a direct association between risk of colon cancer and frequent consumption of foods high in saturated fat.
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From page 77... ...
Cholesterol High-fat diets have been associated with atherosclerosis -- a condition that has also been associated with elevated serum cholesterol levels. Therefore, there has been interest in studying the relationship of serum cholesterol levels as well as cholesterol intake to the incidence of cancer.
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From page 78... ...
examined total serum cholesterol levels in 186 controls and 122 subjects with malignant tumors. Their data also generally showed lower cholesterol levels in the cancer patients.
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From page 79... ...
When cancer deaths were evaluated by site, there was a significant inverse association between serum cholesterol and deaths from sarcoma, leukemia, and Hodgkin's disease in the nearly 2,000 men studied for 17 years, but not for deaths from lung cancer, colorectal cancer, cancer of the oral cavity, pancreatic cancer, or all other cancers combined. There was, however, a suggestion of a direct association for breast cancer in women.
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From page 80... ...
Furthermore, only women, not men, had significantly lower serum cholesterol levels with advancing disease. The lack of an association in early disease supports the concept that low serum cholesterol levels observed in colon cancer patients may be the result of a metabolic change accompanying tumor growth and may not necessarily precede tumor formation.
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From page 81... ...
Pioneering efforts by Hill and his colleagues (1971) pointed to an association between rates of mortality from colon cancer and fecal excretion of bile acids as well as the fecal degradation of cholesterol and its metabolizes.
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From page 82... ...
. Bacterial conversion of primary to secondary bile acids occurred more extensively in rats fed the high fat diet than in those fed the low fat diet.
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From page 83... ...
Evidence that increased quantities of bile acids in the colonic lumen were associated with an increase in azoxymethane (AOM) -induced colon tumorigenesis in rats was provided by Chomchai et al.
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From page 84... ...
The quality or type of lipid was also shown to be an important factor in the induction of breast cancer by DMBA (Carroll and Khor, 1971~. The incidence of tumors at this site was uniformly high with all dietary fats tested at a level of 20% in the diet, but the number of tumors per group and per tumor-bearing rat was proportionally greater in the rats fed unsaturated fats.
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From page 85... ...
The enhancement of DMBA-induced mammary tumorigenesis in rodents by high fat diets (especially those containing polyunsaturated fats) has been observed by a number of investigators (Carroll and Khor, 1971; Hopkins and West, 1976; Ip, 1980; King et al., 1979~.
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From page 86... ...
Pure linoleic acid in the diet at 0.1% was as effective as 15% corn oil in enhancing the growth of a transplantable mammary adenocarcinoma (Hillyard and Abraham, 1979~. In studies of cell cultures with and without added polyunsaturated fat, Kidwell _ al.
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From page 87... ...
Hyperplastic nodules formed from AAF more frequently and the latent period was shorter in rats fed a low fat diet (2% linoleic acid) than in rats fed diets with high saturated fat (18% coconut oil and 2% linoleic acid)
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From page 88... ...
These investigators also observed that rats fed the 20% saturated fat diet had a greater incidence and multiplicity of tumors than those fed the 5% saturated fat diet. However, they pointed out that rats fed the low fat diet consumed fewer calories, gained much less weight, and thus received less of the carcinogen than did rats fed the high fat diets.
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From page 89... ...
Sprague-Dawley rats were fed isocaloric cholesterol-containing diets supplemented with either 20Z coconut oil to promote hypercholesterolemia and vascular lipidosis or 20% safflower oil to maintain lower serum cholesterol levels and, presumably, to shunt cholesterol through the gut. Rats fed the 20% polyunsaturated fat diet experienced less vascular lipidosis but developed more bowel tumors than did rats fed the saturated fat diet.
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From page 90... ...
The relationship between dietary cholesterol and cancer in humans is not yet clear. Many studies of serum cholesterol levels and cancer mortality have indicated that there is an inverse association with colon cancer in males, but the evidence is inconsistent and is not sufficient to establish a causal relationship.
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From page 91... ...
Mammary tumorigenesis is enhanced by obesity and is inhibited by restriction of total food intake. Diets containing 20% polyunsaturated fat enhance tumorigenesis more effectively than saturated fat, provided that it serves as an adequate source of essential fatty acids.
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From page 92... ...
When total fat intake is low, polyununsaturated fats appear to be more effective than saturated fat in enhancing tumorigenesis; however, the effect of polyunsaturated fats becomes less prominent as total dietary fat is increased to 20% of the diet. Dietary fat appears to affect tumor promotion rather than tumor initiation, although an effect on initiation cannot be excluded.
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From page 93... ...
Both epidemiological studies and experiments in animals provide convincing evidence that increasing the intake of total fat increases the incidence of cancer at certain sites, particularly the breast and colon, and, conversely, that the risk is lower with lower intakes of fat. Data from studies in animals suggest that when total fat intake is low, polyunsaturated fats are more effective than saturated fats in enhancing tumorigenesis, whereas the data on humans do not permit a clear distinction to be made between the effects of different components of fat In general, however, the evidence from epidemiological and laboratory studies is consistent.
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From page 94... ...
1974. Letter to the Editor: Colon cancer and bloodcholesterol.
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From page 95... ...
1979. Dietary polyunsaturated fat versus saturated fat in relation to mammary carcinogenesis.
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From page 96... ...
1981. Serum cholesterol and risk of death from cancer and other causes in three Chicago epidemiological studies.
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From page 97... ...
1981. An apparent inverse relationship between serum cholesterol and cancer mortality in Puerto Rico.
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From page 98... ...
1979. Effect of dietary polyunsaturated fatty acids on growth of mammary adenocarcinomas in mice and rats.
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From page 99... ...
1978. Unsaturated fatty acid requirements for growth and survival of a rat mammary tumor cell line.
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From page 100... ...
1981. Dietary factors and breast cancer risk.
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From page 101... ...
1979. Fecal bile acids in two Japanese populations with different colon cancer risks.
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From page 102... ...
1971. Incidence of cancer in men on a diet high in polyunsaturated fat.
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From page 103... ...
1977a. Effect of type and amount of dietary fat and 1,2-dimethylhydrazine on biliary bile acids, fecal bile acids, and neutral sterols in rats.
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From page 104... ...
1981. Ultrastructural modifications of intestinal and colonic mucosa induced by free or bound bile acids.
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From page 105... ...
1972. Ten-year mortality and morbidity related to serum cholesterol.
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