Including sorghum in diets can contribute to keeping the glycemic index (GI) constant. This was a research finding from a study developed at the Federal University of Viçosa (UFV) in partnership with Embrapa Maize and Sorghum. The results were published in the paper “Consumption of a drink containing extruded sorghum reduces glycemic response of the subsequent meal” in the European Journal of Nutrition."Glycemic control is essential to prevent the manifestation of diabetes in predisposed individuals and the development of other complications associated with the illness”, clarifies the nutritionist Pamella Cristine Anunciação, who studied the subject during her PhD course. The work assessed the effect of the consumption of a drink containing extruded sorghum on the postprandial glycemia of a second meal in individuals who have suitable weight for their height (eutrophical subjects) and who have normal glucose and insulin rates (normoglycemic subjects). The results have shown that the inclusion of sorghum in diets can make glycemia more constant, which reveals the cereal's potential to be used in the nutricional treatment of patients with diabetes or pre-diabetes. The study was conducted at UFV's Laboratory of Vitamin Analysis, in Minas Gerais, and coordinated by professor Helena Maria Pinheiro-Sant'Ana. The entire work was performed in partnership with the researchers Valéria Vieira Queiroz and Cícero Bezerra de Menezes, from Embrapa Maize and Sorghum, and Carlos Wanderlei Piler de Carvalho, a researcher from Embrapa Food Technology. The paper is also signed by the nutritionists Leandro de Morais Cardoso, from the Governador Valadares campus of the Federal University of Juiz de Fora (UFJF), and Rita de Cássia Gonçalves Alfenas, from UFV. According to Pamella Anunciação, some animal studies already pointed that the chronic consumption of phenolic compound extracts from sorghum improved glucose metabolism. “Considering all of that, the aim of this research was to assess the effect of extruded sorghum consumption, and the profile of bioactive compounds, on postprandial glycemia of a subsequent meal in normal-weight and normoglycaemic subjects," she said, explaining that the sorghum was offered as a drink to be more easily consumed. According to the researcher Valéria Queiroz, the drink that presented best results was developed from grains of the SC319 sorghum genotype, which Embrapa Maize and Sorghum selected out of 100 genotypes due to its higher content of phenolic compounds (especially tannins and 3-deoxyanthocyanidins), dietary fiber, and resistant starch. For Pamella, such compounds work by reducing glycemic response. “The dietary fibers reach the intestines unbroken and consequently slow gastric emptying, reducing digestion rates and the absorption of carbohydrates”, she details. She stresses that sorghum phenolic compounds may contribute to glycemic control because they modulate the absorption of carbohydrates. “Sorghum tannins can reduce the activity of the α-amylase enzyme, which digests starch. Thus, the rate of digestion and absorption of such carbohydrate, which is the main constituent of the sorghum drinks, may have been reduced, resulting in a lower glycemic response. Moreover, the tannins can interact with the starch to form resistant starch, which is not digested. Consequently, there is a reduction in the postprandial glycemic response”, she explains. All of this is possible because whole sorghum is rich in fibers, and the “variety” used also contained high content of resistant starch, a compound that is slowly digested by the organism. “This slows down glucose absorption, thus preventing peaks in glycemia”, explains Pamella Anunciação. Moreover, research has already proven that the consumption of low GI and fiber-rich meals not only reduces glycemia, but also improves glucose and insulin after the subsequent meal. Pamella Anunciação explains that the glycemic index is a parameter used to classify foods containing carbohydrates according to the glycemic response that they promote as opposed to the response observed after the consumption of a reference food (glucose). The foods that are quickly digested and cause a higher increase in the glycemic response present a high GI, while those that are associated with a lower glycemic response reveal lower GI figures. “In that case, sorghum can contribute, as whole sorghum-based products have lower GI and anti-diabetes potential due to the synergic action of its nutrients (e.g. calcium, magnesium, zinc and resistant starch) and bioactive compounds, especially phenolic compounds and dietary fibers. This effect can vary, depending on the profile of sorghum grain nutrients, preparation and processing conditions”, Pamella Anunciação asserts. Results Beverages containing sorghum, especially the one that contained the SC319 genotype, resulted in lower postprandial glycemia in the two hours after the consumption of a glucose solution (the subsequent meal), reducing peaks in glycemia. “Therefore, the tannins, the 3-deoxyanthocyanidins, the fibers and the resistant starch, which are the compounds present in higher concentrations in this SC319 genotype, favored this lower glycemic response”, stated Pamella Anunciação, explaining that the drinks were consumed 30 minutes before assessing the response to the glucose solution to ensure that the response observed reflected the sorghum-stimulated production and release of insulin. Pamella Anunciação considers that keeping glycemia close to normal levels is the main goal of nutricional interventions in patients with diabetes or pre-diabetes. “The peaks of high glycemia can contribute to the development of complications associated with diabetes, especially cardiovascular diseases. In this context, the addition of whole sorghum to diets is a viable alternative to control glycemia in such patients. Therefore, the observed effect of sorghum on glycemic response is clinically relevant, especially for people who have type-2 diabetes. In these patients, insulin synthesis is reduced and it takes some stimuli to increase the release of such hormone. The consumption of sorghum can thus lead to better glycemic response in such patients”, the nutritionist concludes. However, she stresses that despite such results, more research is necessary. “In this study, the synergistic effect of sorghum's bioactive compounds contributed to a lower glycemic response. But evaluating which of sorghum's bioactive compounds are more effective in glycemic control is still necessary, and we also suggest studies to assess postprandial insulin response”, she notes. Sorghum as food The researcher and nutritionist Valéria Vieira Queiroz, from Embrapa Maize and Sorghum, remarks that research with sorghum for human food in Brazil started about a decade ago, when there was a glimpse of the cereal's vast, unexplored potential. “Sorghum does not contain gluten and thus it is totally safe for the development of products for celiac or gluten-intolerant individuals. It has soft flavor and lower production cost compared to other cereals, which are relevant factors for the food industry. In addition to such advantages, sorghum offers a variety of bioactive compounds with high antioxidant capacity, with potential for use in products with a functional, that is, health-promoting appeal”, the researcher claims. Embrapa Maize and Sorghum have been working in this line of research through three main projects, funded by Embrapa, with support from the Minas Gerais State Foundation of Research Support (Fapemig) and the National Council for Scientific and Technological Development (CNPq), which are developed in partnership with Embrapa Food Agrindustry and the Federal Universities of Viçosa (UFV), of Minas Gerais (UFMG), of São João Del Rei (UFSJ/SL), of São Paulo (Unifesp), as well as the University of Brasilia (UnB) and the State University of Campinas (Unicamp). According to Vieira Queiroz, the main goals of the projects are: evaluating a diversity of sorghum genotypes (varieties) and identifying those that are sources of nutrients and bioactive compounds; developing, through genetic improvement, sorghum cultivars that are suitable as food; assessing the stability of the compounds in different environments, storage and processing; assessing the effect of such compounds based on parameters related to human health, with in vitro and in vivo tests in guinea pigs and human beings; developing and assessing new gluten-free sorghum-based processes and products in sensorial and nutritional terms; promoting and disseminating the potential of sorghum as human food. Valéria reports that, at the first stage of the project, over 100 different sorghum genotypes were assessed with regard to nutrient contents (proteins, fiber, lipids, carbohydrates, minerals, vitamins) and bioactive compounds (total phenols, anthocyanins, carotenoids, tannins, resistant starch) and antioxidantt activity. Sources of such compounds were identified and the promising genotypes were multiplied and submitted to the partner universities for the assessment of their functional effects.. “After the study results, Embrapa Maize and Sorghum's sorghum breeders started working with such superior genotypes aiming at the development of cultivars for food, that is, they are more nutritional and with higher biocompound content that can contribute to promoting health. To carry on with the study, we are currently assessing about 300 other materials”, Valéria Vieira asserts. Studies with rats, conducted in partnership with UFV and Unicamp, have also been demonstrating the positive effects of sorghum consumption in parameters related to nutrition and health. The projects also included the development of several gluten-free sorghum products, such as cereal bars, bread, pasta, cakes, biscuits, sweets, savoury snacks, beverages, enteral nutrition formula, and extruded products (morning cereals and soluble flour). “All of the products have been sensorially tested and accepted, some of which with high scores of acceptance, which is evidence of the cereal's great potential, especially in gluten-free food production, in view of the scarcity of products with good sensorial and nutricional quality in such market. The results from the studies have shown that all products prepared with whole sorghum presented significantly higher content of nutrients and bioactive compounds compared with the traditional versions prepared with gluten-free flours/starches then available in the market (rice flour, potato and cassava starches, maize starch). “Thus, whole sorghum has risen as a highly safe and viable alternative to supply the growing demand of the food industry for gluten-free products that are healthy, nutritional and flavorful, so that it can especially contribute to the improvement of the quality of life of individuals with some degree of gluten intolerance”, Valéria underscores. “Today we can already count on more than five different brands of gluten-free sorghum based grains, flours and products in the Brazilian market, with a real trend of growth in upcoming years, which could have an impact in reducing the costs of such products, particularly contributing to food and nutritional security, especially for target celiac audiences with low income”, concludes Valéria Vieira. Translation: Mariana Medeiros