Diet, Nutrition, and Cancer Directions for Research (1983) / Chapter Skim
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6. Macroconstituents
6. Macroconstituents
Pages 25-35
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From page 25... ...
Where such a distinction was possible, however, total fat and saturated fat were implicated most frequently (National Research Council, 1982, Chapter 5~. The committee also noted that the epidemiological data are not entirely consistent, even though they point in the same direction.
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From page 26... ...
At low intakes of total fat, polyunsaturated fat appears to be more effective than saturated fat in enhancing tumorigenesis; however, the effect of polyunsaturated fat becomes less prominent as total dietary fat is increased to 20% of the diet, suggesting that total fat intake is the more significant factor. In general, the epidemiological data and the laboratory evidence are consistent (National Research Council, 1982~.
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From page 27... ...
Thus, it is not clear whether low blood cholesterol is a consequence or possible cause of cancer (National Research Council, 1982~. If causal, the responsible mechanism could be the excretion of high levels of cholesterol breakdown products in the intestine of persons with low blood cholesterol.
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From page 28... ...
Chemically induced carcinogenesis is generally enhanced as protein intake is increased up to 2 or 3 times the normal requirement; however, higher levels of protein begin to inhibit carcinogenesis. A review of the preliminary data on possible mechanisms of action suggested that protein may affect both the initiation and the subsequent growth and development of tumors (National Research Council, 1982)
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From page 29... ...
However, in the only case-control study and the only correlation study in which the total fiber consumption was quantified rather than estimated from the fiber-rich foods in the diet, no association was found between total fiber intake and the risk of colon cancer. Thus, the committee concluded that the epidemiological evidence suggesting an inverse relationship between total fiber intake and the occurrence of colon cancer is not compelling (National Research Council, 1982~.
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From page 30... ...
It concluded that the epidemiological evidence supporting total caloric intake as a risk factor for cancer is slight and largely indirect, because much of it is based on associations between body weight or obesity and cancer rather than on direct measurements of caloric intake. Studies that have evaluated both the caloric content of the diet and the intake of fat suggest that dietary fat is the more relevant variable (National Research Council, 1982, Chapter 4~.
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From page 31... ...
However, because the intake of all nutrients was simultaneously depressed in these studies, the observed reduction in tumor incidence or delayed onset of tumors might have been due to the reduction of other nutrients such as fat. It is also difficult to interpret experiments in which caloric intake has been modified by varying dietary fat or fiber, both of which may by themselves exert effects on tumorigenesis (National Research Council, 1982~.
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From page 32... ...
Specific Recommendations Fat: Epidemiological Studies . o More discriminating data are needed on the effect of the level and type of fat intake by humans.
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From page 33... ...
o The mechanism underlying the reported association between low blood cholesterol and neoplasia should be determined. For example, it would be helpful to know whether hypocholesterolemic individuals are at high risk only if they consume a high fat diet and whether lowering fat intake in such individuals will reduce their risk.
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From page 34... ...
However, the effect of replacing dietary fat with protein or carbohydrate in isocaloric diet s has not been examined . Although thi s may be difficult to accomplish, it is important to attempt to study the individual effects of protein, carbohydrate, and fat in animals fed ad libitum.
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From page 35... ...
Alcohol: Laboratory Studies · Studies should be conducted to determine the influence of nonalcoholic components of alcoholic beverages on experimentally induced carcinogenesis. · The association between carcinogenesis and nutrient deficiencies imposed by excessive alcohol intake should be evaluated.
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