Explain the Factors Affecting GI of Foods?

A variety of factors affect GI of foods. The factors which affect the rate of glucose absorption from starchy foods and therefore the GI value are:

Nature of starch: High levels of amylase decreases GI while low levels increase the GI.

• Nature of monosaccharide components: High levels of fructose and galactose decrease the GI whereas high levels of glucose increase the GI.
• Viscous Fibre: Presence of guar gum and P-glucan reduce the GI.
• Cooking/processing: Parboiling, cold extrusion decrease the GI while flaking, popping increase it.
• Particle size: Consumption of large particles of starchy foods reduces the GI. On the contrary, grinding of starchy foods results in an increase in the GI.
• Ripeness and food storage: Cooling of starchy food before consumption , decreases the GI. Similarly, unripe or under ripped fruits have a lower GI.
• a-amylase inhibitors: Presence of a-amylase inhibitors like lecithin, phytates lowers the GI.
• Nutrients-starch interactions: High levels of protein and fat decreases the GI. Fat and protein appear to modify the glycemic response to a carbohydrate food by slowing gastric emptying and increasing insulin secretion, respectively. However, neither protein nor fat in amounts found in most foods significantly b affect the GI. Protein levels of 30 g and fat levels of 50 g per 50 g of available carbohydrate may decrease the GI.