Biomedical subjects
D Kritchevsky
Publications and source records attributed to D Kritchevsky.
American Cancer Society guidelines on diet, nutrition, and cancer. The Work Study Group on Diet, Nutrition, and Cancer.
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The role of dietary fiber in health and disease.
Dietary fiber has been, for several years, the glamour ingredient in popular nutrition. Based on epidemiological evidence, lack of fiber in the diet has been impugned as a major risk factor for development of colon cancer, heart disease, diabetes and a variety of lesser ills. Animal experiments suggest that some components of the complex mixture of substances called fiber will reduce cholesterol levels to a modest extent and will inhibit atherosclerosis induced by diet. In man the data center on the effects of fiber on plasma cholesterol levels and some fibers such as pectin or guar exert significant hypocholesterolemic effects whereas others, such as bran, do not. The situation is similar with regard to colon cancer. Some types of fiber, bran and cellulose for instance, inhibit experimentally induced colon cancer. There are a number of ways of establishing experimental colon cancer; feeding the carcinogenic agent, injecting it, or instilling it intrarectally. There also exists a variety of carcinogenic agents. The effect of fiber is the sum of the type of fiber and carcinogen used and the mode of establishing the cancer. Different combinations give different results in animal studies. In man the data bearing on this subject are wholly epidemiological. A few case-control studies have provided suggestions that low fiber diets may predispose to colon cancer but these studies point to a dietary life-style in which many components other than fiber vary. The most notable success in wedding practice to hypothesis has been in the area of diabetes. Here it has been shown clearly that increasing dietary fiber results in reductions in lipemia, glycemia and insulin requirement. What remains? More work in the cancer and heart disease fields but mainly a greater effort to identify the specific structure of those fibers which exert a beneficial effect. This will have the two-fold benefit of identification of specifically useful structural types of fiber and of possibly providing clues to mechanism of action or of carcinogenicity. Most experts agree that a modest increase in intake of fiber will have a generally beneficial effect but they can only support these statements with epidemiological proof. Future research must include studies designed to confirm the epidemiological findings and to identify the specific components responsible for them.
Newer hypolipidemic agents.
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Conjugated linoleic acid suppresses the growth of human breast adenocarcinoma cells in SCID mice.
Conjugated linoleic acid (CLA), which is mainly derived from dairy products, has been shown both in vitro and in animal models to have strong anti-tumor activity. Particular effects were observed on the growth and metastatic spread of transplantable mammary tumors. In this study, we examined the effect of dietary CLA on the growth of human breast adenocarcinoma cells in severe combined immunodeficient (SCID) mice. Mice were fed 1% CLA for two weeks prior to subcutaneous inoculation of 10(7) MDA-MB468 cells and throughout the study. Dietary CLA inhibited local tumor growth by 73% and 30% at 9 and 14 weeks post-inoculation, respectively. Moreover, CLA completely abrogated the spread of breast cancer cells to lungs, peripheral blood, and bone marrow. These results indicate the ability of dietary CLA to block both the local growth and systemic spread of human breast cancer via mechanisms independent of the host immune system.
Opposite effects of linoleic acid and conjugated linoleic acid on human prostatic cancer in SCID mice.
The relationship between dietary fat intake (level and type) and cancer development is a matter of concern in Western society. The purpose of this study was to determine the effect of three different diets on the local growth and metastatic properties of DU-145 human prostatic carcinoma cells in severe combined immunodeficient (SCID) mice. Animals were fed a standard diet or diets supplemented with 1% LA or 1% CLA for 2 weeks prior to subcutaneous (s.c.) inoculation of DU-145 cells and throughout the study (total of 14 weeks). Mice receiving LA-supplemented diet displayed significantly higher body weight, lower food intake and increased local tumor load as compared to the other two groups of mice. Mice fed the CLA-supplemented diet displayed not only smaller local tumors than the regular diet-fed group, but also a drastic reduction in lung metastases. These results support the view that dietary polyunsaturated fatty acids may influence the prognosis of prostatic cancer patients, thus opening the possibility of new therapeutic options.