ABSTRACT

Glucose is the most important energy source for the human body. The nutrient has a broad spectrum of physiological effects, and a precise regulation of glucose metabolism is required to maintain health and avoid diseases. The blood glucose concentration (glycemia) reects the combined effects of dietary carbohydrate uptake, delivery to the blood, production, cellular uptake, and utilization, and is tightly regulated by a homeostatic regulatory system (Jenkins et al. 2002; Ludwig 2002). Among those determinants for glucose metabolism, diet-induced glycemia results in the greatest daily variation (Giugliano et al. 2008). Therefore, it is not surprising that the glycemic index (GI) has been related to many disorders, such as diabetes and cardiovascular disease (CVD). The GI is a kinetic measure of glucose appearance in blood after consuming a carbohydrate-containing food. The dietary GI is a weighted sum of the GIs for all the foods in a diet. Interestingly, recent evidence shows that the dietary GI is related to an increased risk for several major age-related diseases,

including atherosclerosis and age-related macular degeneration (AMD) in nondiabetic populations (Balkau et al. 1998; Chiu et al. 2006a; 2007a; 2007b; 2009a; 2009b; Kaushik et al. 2008). In addition, accumulating evidence implies that glucose homeostasis and carbohydrate nutrition play an important role in human aging as well as in disease pathogenesis, and it is proposed that the pathophysiological effects of hyperglycemia that are operative in diabetes also affect nondiabetic people on aging (Brownlee 1995). However, the effects may vary due to subtle “pathophysiological” mechanistic differences as well as differences in composition, structure, homeostatic systems, microenvironment, and function between metabolically different tissues (Brownlee 1995; Chiu et al. 2005; 2006b; 2010).