Glycemic impact

Nutritional Value of Potatoes Digestibility, Glycemic Index, and Glycemic Impact... 

In this chapter we review the relationship between potato consumption and blood glucose responses, and explore causes and variations in the glycemic impact of potatoes, and the opportunities that they provide for the potato industry. 

However, as people eat foods, not simply the carbohydrate in them, RGI is a more helpful way of communicating the glycemic impact of foods. 

Relevance to potatoes Gl gives an inflated idea of the glycemic impact of entire potatoes (Table 13.2) because it refers to the available carbohydrate alone, yet potatoes contain only about 20% available carbohydrate. Because it is an index, Gl does not directly indicate how glycemic impact is affected by the quantity of food consumed, unlike RGI. 

Relevance to potatoes Unlike Gl, RGI refers to the relative glycemic effect of the entire food, and depends on food quantity consumed (Table 13.2), so it allows a direct comparison ofthe relative glycemic impact of any amount of potato, such as a serving or lOOg, with a serving or any other amount of another food (Table 13.2). For potato RGI is much lower than Gl because fresh potatoes contain only about 20% available carbohydrate. 

Definition A single unit of RGI. One GGE unit is equivalent in glycemic effect to one gram of glucose. For example, one microwaved potato (Table 13.2) with a relative glycemic impact (RGI) of 15 GGE would... 

Relevance to potatoes Because it has weight units GGE can be used as if it were a food component, but representing glycemic impact. It allows the relative effect of a food to be shown concurrently with nutrient values for the food in food composition tables (e.g. Table 13.2), so has been termed a Virtual Food Component (Monro, 2004). 

Agronomic factors reportedly influence the rheology of potato starch (Beigthaller, 2004) but whether or not these effects have any relevance to glycemic impact has not been investigated. 

GI values. The relationship between maturity, starch structure, and glycemic impact requires further research. 

SDS formed by cool-treating cooked potato is largely reversed by heat treatment whereas RS is more stable. Where a role for SDS can be found in food products of low glycemic impact potato has the potential to make a valuable contribution. 

Monro, J. A., Shaw, M. (2008). Glycemic impact, glycemic glucose equivalents, glycemic index and glycemic load definitions, distinctions and implications. American Journal of Clinical Nutrition, 87, 237S-243S. 

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