Nutritional and Health Aspects of Sweeteners - Sweeteners: Nutritional Aspects, Applications, and Production Technology - page 330

and is a unitless index value unresponsive to food intake. Glycemic load (GL) is the theoretical
cumulative exposure to glycemia over a period of time and is derived from GI as GI × carbohy-
drate intake. Contracted to a single intake of food, GL approximates RGI but cannot be accurately
expressed in terms of glucose equivalents, because GI is measured by using equal carbohydrate
intakes with usually unequal responses. RGI, on the other hand, is based on relative food and refer-
ence quantities required to give equal glycemic responses; hence, it is accurately expressed as GGE.
The properties of GGE allow it to be used as a virtual food component in food labeling and in food-
composition databases linked to nutrition management systems to represent the glycemic impact of
foods alongside nutrient intakes. GGE can also indicate carbohydrate quality when used to compare
foods in equal carbohydrate food groupings (Monro and Shaw 2008).
Mitchell (2008) showed how the glycemic concept is being used by the food manufacturing
industry, how it is perceived and understood by consumers, and how different countries rate its
importance in terms of regulatory provision and consequent labeling implications. The use of GI
is the most prominent form of labeling in the marketplace to date, and the use of GI symbol pro-
grams and other labeling initiatives is considered. The Australian market has been exposed to the
GI phenomenon the longest, and consumer awareness in this market is very high. However, on a
global scale, the picture is very different, and consumer awareness varies considerably. A broader
view of how the global consumer uses nutritional labels is given. She reviewed how consumers are
willing to adopt foods that offer health beneits in general and, more speciically, from the glycemic
concept. She also summarized aspects to be addressed for consumers to beneit from the glycemic
concept in action in the longer term.
In Table 11.1, the glycemic and insulinemic responses to bulk sweeteners and alternatives
are presented for monosaccharides, disaccharides, hydrogenated monosaccharides, hydrogenated
disaccharides, and other alternatives. GL should be limited to 120 g/day according to Foster-Powell
et al. (2002).
Intense sweeteners are consumed in such small quantities that they have no glycemic response
of their own (Livesey 2006). Aspartame and sucralose are intense sweeteners with no acute glyce-
mic response (Rodin 1990; Abdallah et al. 1997; Mezitis et al. 1996). However, if aspartame and
sucralose are compared with maltodextrins, maltose, glucose, and sucrose under controlled condi-
tions then marked reductions in the acute glycemic response would be expected for comparable
sweetness (Livesey 2006). The use of intense sweeteners in place of glycemic carbohydrates wher-
ever bulk is necessary for technological or organoleptic reasons requires the glycemic response to
bulking agents to be considered too. The glycemic (and insulinemic) response to maltodextrin, bulk
sweeteners, and bulking agents varies considerably, as shown in Table 11.1.
Fructose alone is low glycemic due to both slow absorption and the need for conversion to glu-
cose in the liver prior to appearance in the blood as glucose. In addition, the carbohydrate may be
partly stored as glycogen rather than released into the circulation. Furthermore, the energy from
fructose is conveyed in the circulation for oxidation partly as lactate more than is the case for glu-
cose. A similar situation occurs for sorbitol and xylitol, although slower absorption likely gives rise
to less lactate; in addition, a high proportion escapes absorption. With isomalt and lactitol, an even
greater proportion escapes absorption, which gives these polyols the lowest glycemic response of
all so far mentioned. Another polyol, erythritol, is almost unique; most is absorbed and is low gly-
cemic, because it is poorly metabolized in the tissues and escapes into the urine. Mannitol behaves
similarly, although it is largely (75%) unabsorbed (Livesey 2006).
Trehalose, a rearrangement of sucrose, has a glycemic response comparable to sucrose (Table
11.1) in terms of its GL, although it peaks less sharply.
Isomaltulose, also derived by the rearrangement of sucrose, has a lower glycemic response
to trehalose, although most of the isomaltulose is absorbed. Other low-glycemic carbohydrates
include tagatose, fructans (fructooligosaccharides and inulin), polydextrose (PDX), and resistant