P W Larking1. 1. Decision Support Group, Dunedin Hospital, First Floor, Private Bag, Dunedin, New Zealand. PeterLa@healthotago.co.nz
Abstract
BACKGROUND: It is proposed that the mechanism responsible for the low plasma cholesterol-cancer associations reported in the literature is related to blood and tissue levels of cholesterol precursors and products, reflecting rates of cholesterol synthesis rather than the plasma cholesterol level itself. METHODS: Data have been collated from Japanese and Northern European studies on plasma levels of a cholesterol precursor, lathosterol, and one product, cholestanol, each a marker of cholesterol metabolism. Situations in which the rate of cholesterol synthesis is altered have also been examined for their relationship to cancer incidence. RESULTS: The data though minimal suggest that lathosterol and cholestanol may be higher in the blood of the Japanese compared with the Northern Europeans, despite lower plasma cholesterol levels in the Japanese. In accord with the hypothesis the Japanese have a low incidence of many cancers. Cholesterol synthesis is lowered when dietary cholesterol and fat intake are increased and incidence of cancer is increased in these states. Conversely cholesterol synthesis is raised in vegetarianism, the Mediterranean diet, pregnancy, and lactation, and incidence of some cancers is lowered. CONCLUSIONS: At least some of the variation in cancer incidence with plasma cholesterol levels and also with dietary saturated fat and cholesterol, as well as vegetarianism, the Mediterranean diet, pregnancy, and lactation, can be accounted for by their effects on the rate of cholesterol synthesis and the level of cholesterol precursors and/or products so generated. Copyright 1999 American Health Foundation and Academic Press.
BACKGROUND: It is proposed that the mechanism responsible for the low plasma cholesterol-cancer associations reported in the literature is related to blood and tissue levels of cholesterol precursors and products, reflecting rates of cholesterol synthesis rather than the plasma cholesterol level itself. METHODS: Data have been collated from Japanese and Northern European studies on plasma levels of a cholesterol precursor, lathosterol, and one product, cholestanol, each a marker of cholesterol metabolism. Situations in which the rate of cholesterol synthesis is altered have also been examined for their relationship to cancer incidence. RESULTS: The data though minimal suggest that lathosterol and cholestanol may be higher in the blood of the Japanese compared with the Northern Europeans, despite lower plasma cholesterol levels in the Japanese. In accord with the hypothesis the Japanese have a low incidence of many cancers. Cholesterol synthesis is lowered when dietary cholesterol and fat intake are increased and incidence of cancer is increased in these states. Conversely cholesterol synthesis is raised in vegetarianism, the Mediterranean diet, pregnancy, and lactation, and incidence of some cancers is lowered. CONCLUSIONS: At least some of the variation in cancer incidence with plasma cholesterol levels and also with dietary saturated fat and cholesterol, as well as vegetarianism, the Mediterranean diet, pregnancy, and lactation, can be accounted for by their effects on the rate of cholesterol synthesis and the level of cholesterol precursors and/or products so generated. Copyright 1999 American Health Foundation and Academic Press.