Glycemic

BIOQUÍMICA

ARTÍCULO: Glycemic index, glycemic load and insulinemic index of Chinese starchy foods.


NUTRICIÓN

Glycemic index, glycemic load and insulinemic index of Chinese starchy foods.

Lin MH, Wu MC, Lu S, Lin J.
Department of Food Science, National Pingtung University of Science and Technology, 1, Shuefu Road, Neipu, Pingtung 91201, Taiwan, China.
World J Gastroenterol. 2010Oct 21;16(39):4973-9.

INTRODUCTION
Insulin resistance increases the risk of type 2 diabetes[1-3]. One characteristic that can be associated with insulin resistance is hyperinsulinemia that may result in deterioration of b-cell function, which is involved in the pathogenic process of diabetes[4]. In the context of current dietary strategies to prevent hyperinsulinemia and insulin resistance, itis imperative to consider diets/foods in terms of their ability to reduce the degree of postprandial glycemia and insulinemia[5]. These issues have important public health implications. Any diet to counteract diabetes should be evaluated for its effects on glucose response and insulin secretion. To do this, it is urgent and necessary to continuously determine the glycemic index (GI) andinsulinemic index (II) values of foods in different countries, especially the GI of agricultural foods.
    GI was introduced to describe the extent to which different foods elicit varying degrees of postprandial blood glucose. It is defined as the incremental area under the 2 h blood glucose response curve (IAUC) after consuming a test food compared to the corresponding area after acarbohydrate-equivalent amount of a reference food (either glucose or white bread)[6,7]. Expanding this theory to the postprandial insulin levels evoked by foods, the II of foods can also be determined from the corresponding incremental blood insulin areas[8]. Because insulin is the hormone that maintains blood glucose homeostasis, a food or diet high in II could induce a higher degree of postprandial insulinconcentration and thus result in higher insulin demand in the long term[9,10]. Therefore, it is compulsory to grade foods based on their GI, along with the II, to prevent both postprandial glycemia and insulinemia in humans. Glycemic load (GL), on the other hand, is a concept that summarizes both GI and the carbohydrate content and is considered to represent the overall glycemic effects of a food[11].Recent studies have shown that increased dietary GL resulted in predictable increases in glycemia and insulinemia in humans[12,13]. Therefore, it is important to evaluate the concept of GI value of foods together with their concurrent II and GL values.
    Tubers and cereals have been considered as the main carbohydrate sources in Chinese diets since the early 1960s. They are not only rich in starch,but also contain vitamins, minerals, phytoestrogens, and trace elements. In the agricultural epoch of Taiwan, where rice and grains are considered rare and expensive, people often consume tubers, such as taro and yam, as a main meal or as a rice substitute to help them harness energy for endurance farm work. In the book, “Ben Chou Gun Mu”[14], a very famous Chinese ancient medical book, they wereeven described as having medical purposes. With rapid development of the economy, however, eating habits and lifestyle in Taiwan are changing. There is some concern that people think it is detrimental to consume tubers and some cereal products because they are high in starch and regular eating may cause hyperpostprandial glucose responses. Some people even avoid grains or tubers in their diets,particularly diabetic patients. Therefore, it is necessary to evaluate these foods according to their glycemic and insulinemic responses, since they are involved in diet management that helps maintain normoglycemia (possibly also maintaining insulin demand). The five most available starchy foods that are controversial regarding their glycemic effects on humans were chosen for this study. The...