Rice is the principal staple and energy source for nearly half of the world’s population and therefore has significant nutrition and health implications. There is increasing concern about the rising prevalence of insulin resistance (Diabetes Mellitus) as a result of the consumption of large amounts of rice. Therefore, devising ways and means of reducing the glycemic index of rice is imperative.

The concept of Glycemic Index (GI) was first proposed by Jenkins. The GI is a value assigned to foods based on how slowly or how quickly these foods cause an increase in blood sugar levels.

The important factors affecting the glycemic index of rice are Resistant Starch, Amylose, and Amylopectin in rice. Resistant starch (RS) is a part of food starch that is not digested to glucose in the gastrointestinal tract and thus reaches the colon where it is fermented by microbiota to release short-chain fatty acids like butyrate.

There are mainly five important types of RS (RS1, RS2, RS3, RS4, and RS5), out of which RS3 and RS5 are mostly found in rice. RS3 undergoes retrogradation, whereas RS5 forms an immiscible structure, both of which result in slower digestion. Amylose is a long linear carbohydrate made up of glucose molecules linked by α 1-4 glycosidic linkage, whereas amylopectin is a highly branched carbohydrate made up of glucose molecules linked by both α 1-4 glycosidic linkage and α 1-6 glycosidic linkage.

Usually, rice varieties high in resistant starch and amylose content are preferable as they reduce the glycemic index.

There are several breeding strategies to develop low glycemic index rice cultivars, like marker-assisted backcrossing, mutation breeding, and genome editing. CRISPR-Cas 9 technology is very much preferred because of its precision, specificity, speed, efficiency, and cost.

The development of low glycemic index (GI) rice cultivars is a promising area of research that aims to improve the nutritional profile of rice, making it more suitable for individuals with diabetes or those seeking healthier carbohydrate sources.

REFERENCES

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