This studt was published in Nutrition and Metabolism 2006 Jan 6;3:6
Study title and authors:
Plasma LDL and HDL characteristics and carotenoid content are positively influenced by egg consumption in an elderly population.
Greene CM, Waters D, Clark RM, Contois JH, Fernandez ML.
Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA. christine.greene@uconn.ed
This study can be accessed at: http://www.ncbi.nlm.nih.gov/pubmed/16398934
The reseachers of the study note that the habitual consumption of eggs has been shown to provide many nutritional benefits such as higher daily intakes of vitamins C, E and B12, in addition to folate. Deficiencies in these vitamins have been associated with increased risk of cancer, cardiovascular disease and Alzheimer's disease. Therefore, the addition of eggs to the diet could actually prevent disease development, particularly in an older age demographic who are at elevated risks for the onset of chronic diseases. Additionally, current research has shown that eggs supply a significant amount of the carotenoids lutein and zeaxanthin, which have been linked to the prevention of age-related macular degeneration, the most common cause of blindness in those over the age of 60. On average, each egg yolk contains 292 μg of lutein and 213 μg of zeaxanthin, along with 0.7 mg vitamin E, 0.5 mcg vitamin B12, and 23.5 mcg folate, all in a highly bioavailable food matrix.
The study investigated the effects of egg consumption on cholesterol subclasses and levels of carotenoids. The study included 42 men and women, aged 50 to 80, who were assigned to either:
(i) Three eggs per day (640 mg cholesterol per day) (egg diet).
(ii) An equal volume of cholesterol-free egg substitute (0 mg cholesterol per day) (egg free diet).
The participants were further classified by the change in their cholesterol levels after egg consumption:
(iii) Those who had an increase in cholesterol levels of over 2.2 mg/dL (.056 mmol/L) for each additional 100 mg of dietary cholesterol were classified as hyper-responders.
(iv) Those who had an increase in cholesterol levels below 2.2 mg/dL (.056 mmol/L) for each additional 100 mg of dietary cholesterol were classified as hypo-responders.
The study found:
(a) Hyper-responders had higher levels of both low density lipoprotein (LDL) cholesterol and high density lipoprotein (HDL) cholesterol after the egg diet.
(b) After the egg diet, hyper-responders had larger less atherogenic LDL cholesterol particle size and larger healthier HDL cholesterol particle size, with no significant difference in the total number of LDL or HDL particles.
(c) Levels of LDL cholesterol and HDL cholesterol did not differ between the egg diet and egg free diet for the hypo-responders.
(d) Both hyper-responders and hypo-responders had an increase in lutein levels and zeaxanthin levels after the egg diet.
(e) Hyper-responders had higher levels of both lutein and zeaxanthin than hypo-responders after the egg diet.
The data from the study shows the significant increase in the larger LDL and HDL particles for hyper-responders, suggests egg consumption gives a protective effect from cardiovascular diseases. In addition, the increase in lutein and zeaxanthin levels following egg consumption may provide a valuable source of carotenoids in the diet.
The researchers conclude: "This study suggests that egg consumption may be permitted, and perhaps promoted".
