The glycemic index (GI) is an indicator that reflects the level of blood sugar response after a carbohydrate meal. GI reflects the relative change in postprandial blood glucose compared to a reference (glucose or white bread) and can be used as a basis for categorizing the glycemic raising capacity of available carbohydrates. Slowly digesting food carbohydrates are low GI foods (GI ≤ 55), while foods with moderate digestibility are medium GI foods (55 < GI < 70), and high GI foods contain fast digesting food carbohydrates (GI ≥ 70 ). A high GI diet has been linked to numerous metabolic diseases and health conditions such as diabetes, obesity, and more. Therefore, low GI foods have come into the public eye, and more and more people pay attention to the intake of low GI foods in order to have a healthier dietary structure.

A Brief Introduction to Dietary Fiber.

The American Association of Cereal Chemists (AACC) defines fiber as "an edible part of a plant or analogous carbohydrate" that is indigestible and not absorbable in the human small intestine but fully or partially fermented in the large intestine. Dietary fiber has the functional properties of lowering postprandial blood sugar levels, in addition to lowering blood lipids, lowering cholesterol, and regulating intestinal health. Soluble dietary fiber (SDF) includes inulin, fructooligosaccharides, gums and pectins. The functional properties of SDF to reduce postprandial blood sugar are related to its viscosity, while insoluble dietary fiber (IDF) uses more structural properties to reduce food postprandial blood sugar levels. The results of the study showed that dietary fiber, especially SDF, has the ability to reduce the digestibility of starch in food.

Mechanisms by which dietary fiber lowers postprandial blood glucose.

There are two mechanisms for dietary fiber to reduce postprandial blood sugar. One is to form a physical barrier due to properties such as viscosity, structure, and group to hinder the production or diffusion of glucose. The other is to regulate blood sugar by affecting the secretion of hormones in the body. Dietary fiber with high viscosity can change the state of food, wrap carbohydrates or digestive enzymes, thereby hindering the hydrolysis of carbohydrates by digestive enzymes, and can affect blood sugar production by hindering the diffusion of free glucose. The network structure and voids of dietary fiber are good physical barriers, which can hinder the diffusion of digestive enzymes and reducing sugars, thereby reducing the production of glucose. In addition, the hydroxyl group contained in dietary fiber has good water absorption capacity, which can increase satiety, thereby reducing food intake, and preventing blood sugar elevation or obesity caused by overeating.

Dietary fiber can also regulate blood sugar levels by causing the secretion of hormones such as insulin and glucagon in the body. According to the difference in solubility, dietary fiber is divided into insoluble fiber and soluble fiber. Common SDFs include oat beta-glucan, inulin, and resistant dextrin. Oat β-glucan is a non-starch polysaccharide and the main soluble fiber component in oats. It has been proven to effectively reduce postprandial blood sugar and is beneficial to human health. Inulin, commonly used in the food industry, is mainly derived from chicory and consists of oligosaccharides and polysaccharides. Inulin resists hydrolysis by digestive enzymes in the human small intestine and reaches the large intestine almost intact, where it is fermented by the gut microbiota to produce short-chain fatty acids that benefit gut health. Resistant dextrins are glucose polymers (rich in α-1,4 and α-1,6 linkages) derived from wheat or corn that are not fully hydrolyzed and absorbed in the small intestine, but are fermented in the colon. High doses of resistant dextrin (10 g/day) can have beneficial effects on blood sugar levels, weight control, etc. in humans.

Insoluble dietary fiber, especially dietary fiber in whole grains, has a good effect on the prevention of type 2 diabetes. Large-scale prospective follow-up studies from many European countries have shown that dietary fiber intake from grains increased by 10g per day, The incidence of type 2 diabetes can be reduced by 25%, and the dietary fiber intake from vegetables and fruits has no such obvious effect. Insoluble dietary fiber can promote intestinal peristalsis and help maintain stool regularity. Eating more whole grains can help lose weight, and obesity is closely related to the occurrence of diabetes. These are the reasons why insoluble dietary fiber can help prevent diabetes.

Might as well start adding dietary fiber to your meals today!