Diet and fecal steroid profile in a South Asian population with a low colon-cancer rate
Article Abstract:
South Asian immigrants living in England and Wales have a lower mortality rate from colon cancer but a higher rate of death from coronary artery disease than the native British population. This is surprising because international statistics link rates of colon cancer and heart disease with each other and also with a high-fat diet. The South Asians surveyed in London had a diet similar in total fat to the British but substantially higher in fiber and beta-carotene, the form of vitamin A found in plant foods. Stool samples were analyzed from 61 Asian and 36 British volunteers to evaluate the metabolism inside the colon. Previous studies have implicated fecal bile acids (also called fecal steroids) in colon cancer development. Secondary bile acids appear to promote cancer growth more than their precursors, the primary bile acids. It is hypothesized that the high-fiber South Asian diet produces fewer secondary bile acids, thereby reducing exposure of the colon to these possible carcinogens. Another explanation of the low colon cancer rate could be that fiber and beta-carotene have a protective effect on the colon independent of bile acid metabolism. The Asian subjects had lower total fecal bile acids and secondary bile acids, and more primary bile acids than the British subjects. No difference was found between vegetarian and nonvegetarian Asians.
Publication Name: American Journal of Clinical Nutrition
Subject: Health
ISSN: 0002-9165
Year: 1989
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Low vs high dietary fiber and serum, biliary, and fecal lipids in middle-aged men
Article Abstract:
Dietary fiber encompasses a group of substances which are resistant to breakdown, or digestion, in the intestines. It has been suggested that low-fiber diets are related to the high incidence of elevated blood cholesterol, coronary heart disease, obesity, and gall stones in industrialized societies. Fiber is classified as either soluble or insoluble. It is thought that soluble types (such as oat bran) increase the excretion of cholesterol and the bile acids, while insoluble fiber (such as wheat bran) may decrease cholesterol synthesis in the body. In this study, 34 men aged 47 to 55 years followed a low-fiber diet for eight weeks and a high-fiber diet for eight weeks. Their compliance with these diets, and the effects on cholesterol metabolism, were studied. Fiber intake more than doubled on the high-fiber diet (from 11.6 to 26.2 grams per day), causing slight but significant decreases in protein and total calories consumed. Also on the high-fiber diet, the serum concentrations of total cholesterol and its subclasses, HDL (high-density lipoprotein) and LDL (low-density lipoprotein) cholesterol, decreased by 5, 7 and 8 percent, respectively, and this was probably due to an increased excretion of cholesterol-derived bile acids. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: American Journal of Clinical Nutrition
Subject: Health
ISSN: 0002-9165
Year: 1990
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