Glycaemic and insulinaemic responses to natural foods, frozen foods and their laboratory equivalents.

ABSTRACT

Glycaemic response to a food is determined by a large number of factors, of which composition is only one. The present study was designed to study the effect of composition and overnight refrigeration on the glycaemic response. The study involved determination of the glycaemic and insulinaemic response of healthy human volunteers to rice or potato, and to meals equivalent to these foods in terms of carbohydrate, protein, fat and fibre content; but made up of cornflour, casein, corn oil and cellulose. Further, each of these meals was served either freshly cooked, or after overnight storage in a refrigerator and rewarming. The natural foods led to a higher postprandial glycaemia than their respective equivalents, and the freshly cooked foods led to a higher glycaemic response than the refrigerated and rewarmed forms of the corresponding foods. No such consistent differences were observed in case of the insulinaemic responses. The difference in the glycaemic response to foods and their laboratory equivalents may be due to the unique physical arrangement of nutrients within the food or due to specific chemical differences in terms of macro-or micro-nutrients, non-nutrients or anti-nutrients. The difference in the glycaemic response to freshly cooked and refrigerated foods may be due to the formation of resistant starch during cold storage.