Phytochemicals and cardiovascular disease. A statement for healthcare professionals from the American Heart Association.

Abstract

Epidemiological studies have often shown relationships between vegetable/fruit intake and coronary heart disease that are not clearly attributable to major macronutrients or known vitamins and minerals. This suggests that other components of plants may be important in lowering risk of cardiovascular disease. Although the literature contains studies of a myriad of possible plant components, many of these studies are small or poorly controlled. Further, the supposition itself has led to claims of “miracle” ingredients with supposed mitigating effects on cardiovascular as well as other chronic diseases. A substantial body of evidence has accumulated in three areas: plant sterols, flavonoids, and plant sulfur compounds. This review summarizes the state of knowledge in these three areas and explores possibilities for future work. The plant kingdom contains a number of sterols that differ from cholesterol by having ethyl or methyl groups or unsaturation in the side chain. The predominant ones—sitosterol, stigmasterol, and campesterol—can be present in Western diets in amounts almost equal to dietary cholesterol.1 The most prominent is β-sitosterol, which differs from cholesterol in that it has an ethyl group at carbon 24 of the side chain. In the early 1950s it was noted that the addition of sitosterol to the diet of cholesterol-fed chickens or rabbits lowered cholesterol levels in both species and inhibited atherogenesis in the latter.2 Sitosterol or mixtures of soy sterols were studied extensively as cholesterol-lowering agents between 1950 and 1960.3 The preparations achieved cholesterol lowering of approximately 10%.4 The mode of action appears to involve inhibition of cholesterol absorption, although the plant sterols themselves are absorbed very poorly.5 The mechanism of inhibition of cholesterol absorption is believed to be through crystallization and co-precipitation. Ingestion of …