Title

Response to dietary cholesterol and carotenoids provided by eggs, in an elderly population

Date of Completion

January 2006

Keywords

Chemistry, Biochemistry|Health Sciences, Nutrition|Biology, Physiology

Degree

Ph.D.

Abstract

The risk of cardiovascular disease has been associated with elevated plasma cholesterol while being a significant cause of death in older adults. Eggs are a natural source of carotenoids and protein and can provide quality nutrition for the elderly, however there is concern regarding the cholesterol content in eggs. The objective of this dissertation was to investigate the modulation of plasma lipoproteins and carotenoids by egg consumption in an elderly population. Utilizing a randomized, crossover design, 29 postmenopausal women and 13 men over the age of sixty, were assigned to consume either 3 eggs (640 mg/d additional dietary cholesterol, and 600 μg lutein and zeaxanthin) or an equivalent amount of fat-free, cholesterol free egg substitute (0 mg/d dietary cholesterol and 0 μg of lutein and zeaxanthin) for two 30 day periods. Subjects were classified as hyporesponders (fluctuations in total cholesterol (TC) < 14 mg/dL) (HYPO) or hyperresponders (fluctuations in TC > 16 mg/dL) (HYPER) to dietary cholesterol. The primary analysis evaluated changes in plasma lipids due to the intervention. Significant increases in TC, LDL cholesterol (LDL-C), and HDL cholesterol (HDL-C) were noted for both genders following egg supplementation. However, there were no changes in the LDL-C/HDL-C ratio, a significant marker of coronary heart disease risk. In addition, LDL size was increased and lecithin cholesterol acyl transferase activity was higher for HYPER. Women did have a significantly lower LDL-C/HDL-C ratio due to their elevated baseline values of HDL-C when compared to men. Secondary analysis studied alterations in lipoprotein subclasses indicated that HYPER significantly increased the large LDL and HDL particles in response to egg consumption. Both classifications increased HDL size at the end of egg period. Carotenoids also increased significantly as a result of egg intake with HYPER showing significantly higher plasma levels when compared to HYPO. The antioxidant properties of the carotenoids contained in eggs and the formation of less atherogenic lipoproteins allow a postulate that eggs may be beneficial to the elderly. ^