Modifications of the cholesterol and fatty acid content of egg : physiological and nutritional bases

Abstract

Despite their high nutritional value, eggs have a negative image associated with their high cholesterol content (250 mg/yolk), a primary risk factor in arteriosclerosis. Cholesterol is necessary for the development of the chick embryo, and it is therefore very difficult to reduce the quantity whether by genetic, nutritional or pharmacological means : the maximum observed reduction does not exceed 30 %, which is insufficient to make egg an "inoffensive" foodstuff in the eyes of doctors and consumers. However in contrast, the majority of egg lipids are composed of fatty acid esters which include the polyunsaturated fatty acids that have a vital structural and metabolic role in numerous physiological functions : the structure of cellular membranes (especially cerebral), in the coagulation and inflammation processes, in the prevention of arteriosclerosis. The organism cannot synthesise these fatty acids which must be obtained from diet. By altering the hens’diet it is easy to increase polyunsaturated fatty acid content, and even to modify, as necessary, the proportion of different fatty acids (n-6/n-3), in order to achieve the required nutritional value for various at-risk categories, such as neonates, the elderly or subjects with high cholesterol.