In what is being seen as a significant breakthrough, a recent study has identified rice varieties that hold great promise in managing blood glucose levels, particularly in individuals with diabetes.
Conducted by a team of researchers from Kerala, the study not only sheds light on the micronutrient content of rice but also highlights its potential impact on human health, specifically in diabetes management.
Combating micronutrient deficiencies
This comes at a time when the Indian government is actively addressing malnutrition through rice fortification, while also grappling with a rise in obesity and diabetes cases associated with rice consumption.
The findings of this study from the University of Calicut hold great potential for biofortification efforts and could pave the way for healthier rice options.
Rice, a staple food for billions of people worldwide, plays a crucial role in combating micronutrient deficiencies.
The study — published in the peer-reviewed journal Food Bioscience by Prof Jos T Puthur and researcher Veena Mathew from the Department of Botany, University of Calicut, along with researchers from Poland — sheds light on the micronutrient content of rice samples and its potential impact on human nutrition.
Speaking to South First, Prof Jos, Professor and Head of Department of Botany, University of Calicut, says, “Several rice varieties of landraces — the traditional rice varieties — that we used for our research are highly nutritious. Unfortunately, most of these varieties are not available in the market. It would definitely benefit health-wise if farmers adapt to growing such varieties and government pays attention to this.”
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What did this study on rice aim to find?
Prof Jos explains that, globally, when it comes to finding the nutritional quality of rice, there is a lot of effort being put into research and understanding how to increase the zinc content in the rice varieties.
“So, as a pilot study, we decided to look into the traditional varieties of rice for the study to find the nutritious quality in it,” he says.
The researchers wanted to compare two different types of rice: Landrace and hybrid varieties.
Landrace are rice plants that have been grown for many generations in a specific region and they have a wide range of genetic diversity. Hybrid rice varieties, on the other hand, are created by crossbreeding different types of rice to produce specific traits.
The study aimed at understanding the differences in the composition and nutritional value of these two types of rice. This is important because it helps us find rice varieties that are both nutritious and can contribute to food security.
The researchers in the published paper stated that the results of their study will help people make better choices in breeding rice and developing new varieties to make sure there is enough food in the future.
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Method used for the study on rice
For the study, Kerala Agricultural University and Kerala Department of Agricultural Development and Farmers Welfare collaborated and compared different varieties of rice.
They selected 30 rice varieties, including 15 landrace and 15 hybrid varieties, for their analysis. Some of the popular ones among the landrace type were Adukkan, Kuruva, Palthondi Matta, Rakthashali, Paalthondivella, Urunikayama rice varieties, while the hybrid ones included Vytila 6, Ponmani, Manuvarna, among others.
The researchers then analysed the mineral composition of the rice grains using a method called inductively coupled plasma mass spectrometry (ICP-MS), which is a technique that helps scientists understand the composition of materials.
ICP-MS is highly sensitive and can reportedly detect elements at very low concentrations, even in complex matrices. They also estimated the levels of nutraceutical factors such as amylose, phenolic compounds, flavonoids, and anthocyanins.
The study found significant variations in the elemental composition of the two rice types, particularly in calcium, rubidium, and selenium. It was discovered that the pigmented rice varieties, which had colours like red, contained higher levels of antioxidants such as phenolic compounds, flavonoids, and anthocyanins, which are beneficial for health.
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What vitamins and nutrients are there in rice?
According to the study, deficiencies in zinc and iron can lead to severe micronutrient malnutrition. The researchers compared the zinc content of the samples with indigenous aromatic rice varieties in West Bengal and the Gangetic plains of India.
While the zinc content of the studied rice samples was lower than those varieties, it was similar to the concentrations observed in landrace types from Arunachal Pradesh.
Notably, brown rice with a zinc content of 35 mg/kg or more is considered suitable for biofortification, and several landrace and hybrid varieties studied exceeded this limit, making them ideal candidates for future biofortification programmes.
On the other hand, the iron levels in the samples were lower than those reported in other parts of India, such as West Bengal. According to researchers, this emphasises the need to understand the hindering factors affecting iron accumulation in rice varieties and find ways to improve iron uptake.
The study also examined the presence of other essential trace elements, such as manganese (Mn), boron (B), molybdenum (Mo), nickel (Ni), and selenium (Se).
While manganese deficiency in humans is rare, it is essential for the activity of certain enzymes. The manganese content in the studied rice samples was similar to that found in rice samples from the Gangetic plains. Furthermore, the landrace types were rich in selenium compared to the hybrid varieties, suggesting their potential use in selenium biofortification programmes.
Emerging essential trace elements, including rubidium (Rb), strontium (Sr), and vanadium (V), were also analysed in the study.
Contrary to previous beliefs, vanadium was found to be an essential trace element for both plants and humans, contributing to human health through its pharmacological and antimicrobial activities. The rice samples contained vanadium — within the safe range — making a positive contribution to human nutrition.
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The study also highlighted the importance of chromium (Cr) as an essential trace element for humans. Adequate levels of chromium are essential for carbohydrate and lipid metabolism and insulin action.
Fortunately, the rice varieties studied had sufficient amounts of chromium required for a healthy diet. Additionally, high rubidium content in landrace varieties compared to hybrid varieties can serve as an indicator to distinguish between the two, aiding in genetic characterisation.
The macronutrient analysis revealed the nutritional efficiency of the rice samples. Potassium (K), magnesium (Mg), and calcium (Ca) were found to be essential for various enzymatic activities and maintaining osmotic potential, supporting photosynthesis, respiration, nucleotide synthesis, and healthy bone development.
Furthermore, the study addressed concerns regarding toxic metals in rice, such as arsenic (As), cadmium (Cd), lead (Pb), and lithium (Li). The concentrations of these toxic metals in the studied rice samples were within permissible limits, making them safe for consumption.
Importantly, the study indicated that the investigated landrace and hybrid varieties are suitable for human consumption, reducing the risk of health disorders associated with toxic metal exposure.
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Traditional rice and link to diabetes
While several studies have shown that there has been an increase in diabetes and obesity in the rice-eating population, this study also delved into the amylose content of rice, highlighting its impact on physicochemical properties and health benefits.
“The reason why diabetics are asked to avoid rice in their diet is due to the fact that polished white rice tends to have more starch, leading to a shooting up of glucose levels. However, we found that rice varieties with high amylose content were found to have a lower glycemic index, potentially aiding in controlling blood glucose levels and reducing the risk of developing health disorders, particularly diabetes,” Prof Jos explains.
This characteristic is vital in managing blood sugar levels and reducing the risk of health complications associated with diabetes.
However, Prof Jos clarifies to South First that this should not be considered as a “cure” to diabetes but instead these kind of rice varieties could benefit a patient with diabetes to manage blood glucose levels.
Moreover, the researchers examined coloured rice grains containing phenolic compounds, flavonoids, and anthocyanins. These compounds have shown anti-hyperglycemic effects and the ability to inhibit carbolytic enzymes, which can be beneficial for individuals with diabetes or those at risk of developing the condition.
The tested rice varieties demonstrated the presence of these compounds, further adding to their potential health benefits.
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Implications of the study
The identified rice varieties offer a glimmer of hope for individuals with diabetes, as they provide a dietary option that aligns with their nutritional needs.
While the primary focus of the study was on blood glucose management in diabetes, it is important to note that the identified rice varieties offer broader health benefits.
By including these varieties in the diet, individuals can avail themselves of the nutritional advantages, including improved insulin sensitivity, better lipid metabolism, and reduced risk of associated health disorders, adds Prof Jos.
The study also showed the importance of landrace varieties as a source of nutraceutical factors for rice improvement and breeding. By leveraging the unique traits present in landrace types, researchers can develop new rice varieties that are not only nutritionally rich but also better suited for addressing specific dietary needs.
“This knowledge opens up opportunities to guide conventional plant breeding practices or apply advanced molecular techniques to enhance the nutritional value of rice and ensure ongoing food security,” Prof Jos explains.
He says, “By focusing on the nutraceutical factors found in landraces, we can develop rice varieties that contribute to better health outcomes, particularly for individuals with conditions such as diabetes.”
The implications of this study extend beyond rice cultivation and consumption.
With a better understanding of the nutritional characteristics and benefits offered by landraces, researchers can explore similar approaches in other crop species, further enhancing the overall nutritional value and health benefits of diverse food crops.
