Glycemic carbohydrates

Monro, J. A., Mishra, S., Venn, B. J. (2008). Relative glycemic responses to foods modelled using in vitro digestive analysis of glycemic carbohydrate and a dose-sensitive baseline for glucose disposal (In preparation). 

A For Creatine supplementation to result in an increase in strength and protein synthesis, the cellular concentration level must reach 20 MMOL/KG DM. During a 5 day loading periods with a high glycemic carbohydrate such as Dextrose and Creatine, the level reaches MMOL/KG DM. When Creatine levels increase in muscle cells, the active Creatine transporters are down-regulated, so less Creatine is transported. This could be avoided if the Creatine is fortified with the Creatine substrate 3-guanidinopropionate. Second, Creatine cannot be diffused across the muscle cell... 

In the case of complex carbohydrates the glycemic index is a measure of how quickly the carbohydrate is broken down. An example is to compare potato starch and polydextrose. Both are polymers of dextrose but potato starch in the form of mashed potato is rapidly broken down and causes a surge in blood sugar, i.e. it has a high glycemic index. In contrast, polydextrose, which has the dextrose units linked 1 - 6, a link that is rare in nature, is only 25% metabolised and has a very low glycemic index. 

Reducing diets seem to come and go. At the time of writing the popularity of the Atkins diet seems to be decreasing. The Atkins diet is a low carbohydrate diet that is not conducive to the sales of baked products however, the Atkins diet seems to be being superseded by diets based on the principle of a low glycemic index. This is unlikely to increase the sale of baked goods but is less antipathetic to them. A new diet based on bread has appeared and so the wheel may go full circle. 

Eshuis, et al. Effect of method of administration of psyllium on glycemic response and carbohydrate digestibil- PO067 ity. J Amer Coll Nutr 1991 10(4) ... 

Dietary fiber Can slow absorption of refined carbohydrates and lower glycemic index of foods, resulting in reduced effects of diabetes due to lower availability of glucose Preuss (2009)... 

Glycemic index (GI) is a measure of the effect of the consumption of a carbohydrate food on blood glucose levels. The glycemic index, introduced by Jenkins et al. (1981), provides a ranking of carbohydrates on a scale from 0 to 100 according to the postprandial (after meal) impact on blood sugar levels. It is defined as the incremental area under the blood glucose response curve associated with a 50 g carbohydrate portion of atest food expressed as a percent of the response to the amount of carbohydrate from a standard food taken by the same subject. 

For many years, and still, controlling available carbohydrate intake has been a cornerstone of diabetes management. However, in many foods available carbohydrate, measured as carbohydrate available in food analysis, is not quite the same as carbohydrate that is available in the gut in food as normally consumed. Glycemic response depends not only on the amount of potentially available carbohydrate consumed, but also on how rapidly it is digested, absorbed, and disposed of in the body, and that depends on a myriad of factors including food structure and the influence of other food components that vary in importance from food to food. 

The glycemic index was, therefore, introduced as an adjunct to available carbohydrate values in diabetes management, to indicate the glycemic potency of available carbohydrate in foods relative to glucose (Jenkins et al., 1981). In recent years GI has developed its own momentum, helped by vigorous promotion, and despite continued discussion about the value it adds to... 

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. 

Relevance to potatoes Available carbohydrate is often not a good indicator of glycemic response because its value does not include a component for the rate of digestion of carbohydrate, or account for a range of other factors that may alter absorption rate. 

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