Low Glycemic Index Rice for Prediabetic and Diabetic Patients

Rise (rice) above for healthy food – Featuring red rice

April 26, 2023

One Pot Meal by Chef Dave

May 22, 2023

Published by Primera on May 3, 2023

By Dr Tang Pei Ling (Tunku Abdul Rahman University College)

Diabetes and effects on body

Diabetes is a serious non-communicable disorder characterized by the elevated blood sugar level in an individual. In 2014, about 422 million people in the world are diagnosed with diabetes, with a prevalence of 8.5% among the adult population. In the past 3 decades, the prevalence of diabetes has doubled globally. The rate of premature mortality (i.e., death before the age of 70) due to diabetes is substantially increased in countries of all income groups (low-, lower-middle-, higher-middle- and high-income). Among the types of diabetes, type II diabetes accounts for the highest rate. Among the risk factors, overweight and obesity are identified as the strongest factors of high type II diabetes prevalence. Besides, both risk factors have also been found to associate with the prevalence of prediabetes. Prediabetes is a condition at where the blood sugar level of an individual above the normal range but below the diabetes diagnostic range (impaired fasting glucose level at 6.1-6.9 mmol/L). Individual with prediabetes is at a higher risk of developing type II diabetes and bears the same risk of diabetes-related complications such as diabetic retinopathy, neuropathy, nephropathy, and cardiovascular diseases. Previous clinical study found that approximately 25% of prediabetic individuals progress to overt type II diabetes within 3-5 years, and as high as 70% of prediabetic individuals develop overt type II diabetes within their lifetime. Although both pre-diabetes and diabetes conditions could lead to poor life quality and high healthcare expenditure, the condition can be effectively controlled by adopting healthy diet and physically active lifestyle. The prediabetes condition may be reversible, and the diabetes condition can be under controlled with the implementation of lifestyle modification program.

Rice is the most widely consumed staple food of over the half of the world’s 7.7 billion people. It is largely grown in over 100 countries, with about 90% of the total rice is produced in Asian countries. Over half of the world’s rice production is from China and India. Furthermore, Asian also accounted for about 84% of global rice consumption, followed by Africa, South America and Middle East. Among the rice varieties, Japonica rice accounts for the highest share of the global rice trade, followed by Basmati rice. The milled white Japonica rice with low amylose content is welcomed by the majority of the population because of its soft texture and good taste. However, milled rice grain with low amylose content has high glycemic index (GI). GI is an indicator used to quantify the glycemic response of human body to carbohydrate upon digestion. Rice consumption is positively associated with the prevalence of type II diabetes. In China, the dose-response relation between rice intake and relative risk of type II diabetes was significantly rose beyond 1.00 under the current rice intake of 213 g for women and 256 g for men. China is an Asian country with the highest white rice consumption, and unfortunately with the highest incidence of type II diabetes and prediabetes. Therefore, more varieties of low GI (≤ 55) rice options are needed in the future food market to fulfil the needs of health-conscious consumers and mitigate the upsurge of prediabetes and type II diabetes prevalence. Low GI diet is claimed to be beneficial in preventing and managing prediabetes and type II diabetes.

Starch in rice

Starch is the main digestive carbohydrate in rice that provides calories upon ingestion. Amylose (the linear chain polysaccharide) and amylopectin (the highly branched polysaccharide) are the two main components of starch. The ratio of amylose-to-amylopectin and their molecular arrangement influence the crystallinity of starch granule, hence affecting the digestibility and GI of the rice. Resistant starch (RS) is the type of starch in which its granule is highly crystalline and resist to digestion. Rice grain that contains high fraction of linear chain amylose and long branched amylopectin contribute to high RS content due to the tightly packed molecular structure. Thus, RS content is negatively associated with GI of the rice. High crystalline nature of RS restricts the hydrolytic action of carbohydrate digestive enzymes. The rice containing high RS is digested slowly upon ingestion, hence resulted in slower release of glucose, and consequently lower insulin response in the individual. In addition, RS also increases the gelatinization temperature of the rice grain. Therefore, rice with high RS is usually harder in texture and requires longer cooking time than the one with low RS. Due to its resistance to hydrolysis, high-RS rice remains its low GI even after cooked. However, majority of rice varieties contain low RS. RS manipulation in rice to reduce GI can only be done through crossbreeding or genetically modification approaches, however trade-off with the yield and palatability. Consumers rejected the high-RS rice even knowing the health benefits because of the hard and coarse texture.

To address the needs of consumers to combat prediabetes and diabetes while fulfilling their satiety, the GI of soft low-amylose rice can also be lowered by modifying the post-harvest processing to preserve the dietary fibre and secondary metabolites, such as polyphenols, flavonoids, and anthocyanins in the whole rice grain. The secondary metabolites have long been proven to inhibit starch digestive enzymes, such as α-amylase and α-glucosidase and stimulate insulin secretion, subsequently reduce glucose uptake in the intestine. Furthermore, high dietary fibre intake also promotes the beneficial bacteria growth in the gut, hence modulating gut health. Immunity and general health of an individual begins from the gut health. Asides from offering additional health benefits, rice enriched with the bioactive colored polyphenol, flavonoid and anthocyanin pigments also effectively decelerate the glycemic response of body to starch digestion. Instead of scratching head for searching low GI crossbred white rice over the shelf, selecting rice by its color may be more decisive. Rice with intense color definitely contains higher bioactive secondary metabolites than the refined white rice.

Nonetheless, consumers should be reminded that diet size control and diversification are still necessary in the planning of well-balanced healthy diet to maintain general health of prediabetic and diabetic patients. Low GI rice will be the best staple option for prediabetic and diabetic rice-lovers to satisfy their satiety while countering postprandial blood sugar level.

References :

World Health Organization. 2016. Global report on diabetes. ISBN:9789241565257.
Hostalek, U. 2019. Global epidemiology of prediabetes – Present and future perspectives. Clinical Diabetes and Endocrinology 5:5. DOI: 10.1186/S40842-019-0080-0.
Bhandari,H. 2019. Global rice production, consumption, and trade: Trends and future directions. Proceedings of the Korean Society of Crop Science Conference 5-5.
Huang M, Hu L. 2021. Low glycemic index: The next target for rice production in China? Journal of Integrative Agriculture 20 (6), 1727-1729.
Kumar, A., Sahoo, U., Baisakha, B., Okpani, O.A., Ngangkham, U., Parameswaran, C., Basak, N., Kumar, G. & Sharma, S.G. 2018. Resistant starch could be decisive in determining the glycemic index of rice cultivars. Journal of Cereal Science 79, 348-353.
Jukanti, A.K., Pautong, P.A., Liu, Q. & Sreenivasulu, N. 2020. Low glycemic index rice – A desired trait in starchy staples. Trends in Food Science & Technology 106, 132-149.
Jabeen. I., Hafiz, M., Ratnam, W., Karupaiah, T., Dipti, S., Fujita, N., Umemoto, T., Li, Z. & Rahman, S. 2021. Differential expression of three key starch biosynthetic genes in developing grains of rice differing in glycemic index. Journal of Cereal Science 99, 103187.