Does Beer Contain Compounds That Might Interfere with Cholesterol Metabolism?

Abstract

Elevated blood cholesterol is a problem for many people. Although a significant proportion of this cholesterol arises from metabolism within the body, approximately 50% comes from our diet. Certain plant sterols (phytosterols) are known to inhibit the absorption of this dietary cholesterol by the human body, and there are now several commercially available food products that contain these phytosterols. Barley malt, yeast and hops also contain phytosterols or similar materials that might potentially act as inhibitors of cholesterol uptake but this effect has not been studied. In this work we examine one aspect of the potential for competition between cholesterol and selected beer components when binding to a protein. The method used was ligand docking. This uses computer modeling to examine the binding energies expected when the ligand (e.g. cholesterol or analogue) binds to a protein. The two proteins examined were both natural cholesterol binding proteins. The cholesterol analogues, sitosterol (from barley) and ergosterol (from yeast), had similar binding energies to cholesterol and thus had potential for competition. Other molecules (iso-xanthohumol, 8-prenylnaringenin (8PN) and iso-humulone) had lower binding energies suggesting that they would not compete effectively. Standard beers normally contain very low levels of either sitosterol or ergosterol, although some wheat beers that contain high levels of yeast may contain elevated levels of ergosterol. We have also developed a beer that contains elevated levels of sitosterol by incorporating whole grain material. The level of β-sitosterol in these beers was still very low and even a whole grain beer would not contain sufficient of the cholesterol analogues to completely inhibit cholesterol uptake or transport.