β-carotene and oxidative desaturation of fatty acids: a plausible explanation of the conflicting responses of coronary heart disease to β-carotene?

Abstract

Studies of the desaturation of saturated fatty acids in animals may help explain conflicting reports of the response of coronary heart disease (CHD) to β-carotene in humans. A negative relationship exists between desaturation and adipose β-carotene in cattle when they consume different quantities of β-carotene. Opposing this finding, however, is a positive relationship between desaturation and adipose β-carotene when cattle are fed the same quantity of β-carotene. The reason for this apparent contradiction appears to be due to differences in consumption, or variability in the metabolism of β-carotene. Animals that efficiently metabolize β-carotene to vitamin A have low desaturation but high antioxidant potential. These results in animals show some similarity between the consumption of the antioxidant β-carotene and the risk of coronary heart disease where the oxidation of low-density lipoproteins (LDL) is believed to play a role in the development of atherosclerotic plaque. Genetic differences in carotenoid metabolism in humans, similar to those in animals, would assist in explaining differences in lipoprotein oxidation in humans and variation in the risk of coronary heart disease.