Biofortification of Rice, An Impactful Strategy for Nutritional Security: Current Perspectives and Future Prospect

Abstract

Globally, especially in the developing world, an estimated 20,000 million people are affected by micronutrient deficiency, generally named “hidden hunger”. Crop biofortification is an impactful strategy in addressing nutritional security as well as providing a cost-saving, sustainable means by uplifting health and well-being to communities with deprived access to diversified foods and interventions regarding the micronutrient supply. Considering the global concerns about micronutrient deficiency, research organizations have initiated studies on ensuring the bioavailability of micronutrients in staple food crops. Mitigating hidden hunger with the biofortification of rice surely can be a beneficial strategy for people who consumes rice as a staple food. Significant enhancement in iron and zinc levels, as well as with other essential minerals and vitamins is achieved in rice biofortification by various approaches. Adoption of biofortified rice varieties in targeted countries would significantly increase daily micronutrient intake and help to holistically alleviate malnutrition in human populations. This review articulates the status and perspective of rice biofortification as well as summarizes dissemination and adoption along with trends in consumer acceptance. With a positive trend, attention should now need shift to an action-based agenda and robust policy directives for scaling up rice biofortification in improving nutritional security for humans.

1. Introduction

For thousands of years, rice has remained a significant part of the human diet. Rice was cultivated and consumed up to 10,000 years ago, according to historical evidence, and it is still the world’s most significant and accepted meal for humans, sustaining more people over a longer period than any other crop. Rice will continue to be a vital staple meal for billions of people in the future, making it one of the most crucial agricultural commodities in the world and is immensely linked with food security, economic growth, employment, culture, and regional peace of a nation. For half of the global population, represented by more than 3 billion people worldwide, rice has been an important crop for many countries. Rice not only meets the basic food demands but also contributes significantly to the economic growth of rice-growing countries through exports. Globally rice crop is estimated to cover 164.7 million acres [1]. Asia accounts for 90–92% of total rice acreage and is a major producer and consumer of rice [2]. To feed the world’s rising population, rice output has increased significantly, from 220 million tons in the pre-green revolution era to 729 million tons in 2017. Rice accounts for around 20% of per capita energy and 13% of the protein consumed by humans worldwide and contributes much more dietary energy and protein than 29.3 dietary energy and 29.1% dietary protein in many poor countries [3].

The health risks associated with micronutrient insufficiency in humans have become the main obstacle to meeting the Sustainable Development Goals (SDGs) set for 2035, which include reducing hunger and poverty, improving maternal health, and lowering child mortality. Micronutrients, though at trace levels are detrimental to the human body for general healthy growth and development. Micronutrient shortage has been associated with higher sickness and death rates, lower income, and detrimental impacts on infant and child growth, subsequent physical and mental development, and learning. The deficiency of iron and zinc is one of humanity’s most common scenarios, affecting 2 billion people globally and resulting in more than 0.8 million fatalities every year [4]. Micronutrient deficiencies are prominently detected in nearly two-thirds of all child mortality attributable to dietary inadequacies [5]. Hidden hunger can be decreased by adopting both direct (nutrition-specific) and indirect (nutrition-sensitive) techniques [6]. Direct treatments that target consumption habits include dietary diversification, vitamin supplementation, modifying food preferences, and fortification. Crop biofortification and addressing the underlying causes of malnutrition are examples of nutrition-sensitive therapy.

Biofortification is the process of increasing critical nutrient constituents and bioavailability in crops during the growth of plants by genetics and agronomic mechanisms [7]. In genetic biofortification, either traditional breeding or genetic engineering is applied [8]. Agronomic biofortification can be accomplished through the application of micronutrient fertilizers to the soil and/or foliar applications made directly to the crop’s leaves. Rice, wheat, corn, sorghum, millet sweet potatoes, and legumes are the primary targets of biofortification because they cover the majority of human diets worldwide, particularly for populations at risk of nutritional deficiencies having limited access to diversified diets, fortified foods, and marketed food supplements [9]. Although biofortification is universally accepted to be useful and is being implemented more effectively, the addition of only one nutrient per crop, either iron, zinc, or provitamin, remains a constraint. The breeding and the release process of the first wave of biofortified cultivars had taken 8–10 years. There are a few cases where the target crop species have enough genetic variation to add a second nutrient through traditional breeding methods, but this is expected to take several years.

There are numerous approaches to alleviating malnutrition induced by a lack of nutritional diversity. To assure micronutrient adequacy in populations, industrial fortification (e.g., iodine to salt, vitamins A and D to margarine, fluoride to toothpaste, and folic acid to flour) has been employed successfully. Supplementation is the distribution and ingestion of micronutrient-containing tablets, syrup, or capsules and has been used in both developed and developing countries. Even if micronutrients are offered free to customers, fortification, and supplementation both necessitate some level of manufacturing and/or delivery infrastructure, as well as the purchase of micronutrients. As a result, the human population who are marginalized and in need of micronutrients in their diets may be disadvantaged. Biofortification is an effective method for increasing micronutrient levels in widely consumed food crops such as rice. Furthermore, it is a practical and sustainable means of mitigating deficiencies related to micronutrients in people who primarily eat rice and have limited access to a range of foods or markets, and lack access to high-quality medical care [10]. Biofortification of staple crops, such as rice, is a promising technique for improving human health by boosting the nutrient density of meals. The readiness of consumers and farmers to adopt and use new biofortified crop varieties influences the technique’s viability. HarvestPlus is primarily focused on the release and distribution of biofortified varieties in Bangladesh, Indonesia, and India. In Asia, breeding programs at the International Rice Research Institute (IRRI), Bangladesh Rice Research Institute (BRRI), Indonesian Center for Rice Research (ICRR), and India’s National Agricultural Research System (NARS) have produced germplasm from early to late developmental stages, as well as elite lines and released a few varieties. Additionally, zinc-rich breeding pipelines aimed at Latin America were developed at the International Center for Tropical Agriculture (CIAT). HarvestPlus focuses on inbred varieties rather than hybrids because hybrids are not yet widely accepted outside of China. The crop’s availability and knowledge of its health advantages are two of the most critical factors for the acceptance and adoption of biofortified crops. Much of the research reviewed here reveal that biofortified crops were not readily available to the general people, and acceptance and adoption remained questionable. Many biofortified rice products have already completed the development phase, which should result in additional evidence of the substitution of current cultivars with biofortified types and the changes in consumer diets.

The purpose of this chapter is to understand the relevance of addressing micronutrient deficiencies as well as other types of nutritional inadequacies to minimize hidden hunger in all its manifestations, which remains one of the most difficult challenges in public health. The chapter also elucidates the likely causes and factors of hidden hunger, reviewing its global prevalence, and explores current strategies to mitigate it through rice biofortification. The authors hope that this chapter, along with our collective efforts, will provide a suitable platform for constructive dialog among scientists, researchers, entrepreneurs, policymakers, and growers to reduce the burgeoning issues of malnutrition with holistic information, approaches, and means as well as take a serious step in developing biofortified rice with their release and promotion for augmented adoption.

2. Malnutrition: the hidden hunger

Human health and well-being are dependent on proper nutrition. Every person on this planet has the right to safe, sufficient, and nutritious food, as well as the right to be free from all forms of food insecurity. However, one out of every three individuals worldwide suffers from some form of malnutrition, such as undernutrition, micronutrient deficiency, being overweight, or obesity, which leads to a variety of clinical illnesses. If current trends continue, the situation will deteriorate since malnutrition is projected to affect one out of every two people worldwide [11]. High levels of malnutrition are likely to persist unless humans have access to inexpensive healthcare facilities, safe drinking water and sanitization, affordable agricultural inputs, accessible technical help, education, employment, and social safety programs [11]. Combating hunger in all its manifestations is one of the most important concerns confronting many countries nowadays. The United Nations Decade of Action on Nutrition (2016–2025) reached its halfway point. However, the proportion of persons suffering from malnutrition has risen since 2015. One of the 17 SDGs is to eliminate hunger by 2030, and the UN Food Systems Summit and Nutrition for Growth Summit in 2021 emphasized a renewed emphasis on global nutritional research.

The term hidden hunger refers to the scenario of certain micronutrient deficiencies in the absence of diverse energy and nutrient rice diet. Hidden hunger is estimated to afflict over two billion people globally, particularly in low- and middle-income countries, where people rely on low-cost staples that are nutrition deficient, and their nutritious food options are limited due to lack of access and poverty. A long-term, cost-effective solution to eliminating hidden hunger is the need of the hour and must be able to reach the most isolated and neglected places. A system approach involving all aspects of the food value chain is essential to enable safe and sustainable food security that is resilient to external volatile market shocks. Even while the most severe occurrence of hidden hunger is experienced in developing countries, dietary deficiencies can affect anyone, at any age, and from any ethnic background around the world [12]. This remains one of the most significant impediments to socioeconomic advancement, leading to a vicious cycle of hunger, poverty, and underdevelopment. Although the impoverished world bears a greater proportion of the burden of hidden hunger, micronutrient inadequacy, particularly iodine and iron deficiency are highly ubiquitous around the world (Figure 1) [13]. Among micronutrient deficits, it is evident from Figure 1 that vitamin A deficiency is of the highest concern for children below 5 years of age globally (~33%), where the same as the continent-specific situation has been highest in Africa and lowest in Oceania. This is followed by iodine deficiency, which is ~29% globally and the same as the continent-specific situation been highest in Europe and lowest in Oceania. Vitamin A deficiency is highest in pregnant women in Asia, whereas iron deficiency in pregnant women is highest in Africa.

Figure 1.

Global population (in percentage) with major micronutrient deficiencies across continents. X-axis shows the global and continents, affected population in percentage in Y-axis as bars. Source: Ref. [13].

Micronutrient deficiency has long-term consequences for health, mental function, and efficiency, resulting in enormous social and public expenditures, lower working capacity due to high sickness and disability rates, and severe health risks. Low-income, resource-poor communities, socially excluded groups, and economically disenfranchised food-insecure households are usually among the most nutritionally challenged.

2.1 Goal of achieving zero hunger

One of the UN’s SDGs is to end hunger by attaining food security and improved nutrition, as well as supporting sustainable agriculture. In the context of this goal of zero hunger, several internationally agreed-upon targets have been defined, all of which must be met by 2030. Within this framework, performance objectives have been devised to allow different nations to monitor their progress, such as a decrease in the prevalence of stunting and malnutrition. Globally, little progress has been made to mitigate and minimize the proportion of children under the age of five suffering from severe malnutrition, which decreased from 23.1% in 2015 to 21.3% in 2019 [14]. Even while stunting has grown less widespread in recent years, 14 million children under the age of five were still affected in 2019, with Asia and Africa accounting for three-quarters of those affected. In terms of childhood obesity, 38 million children under the age of five were overweight in 2019 [15], and the figure is steadily rising in various nations. Asia was home to over half of all obese children under the age of five in 2019. Despite progress in combating malnutrition, the United Nations has expressed that the world is not on track to achieving hunger-free status by 2030.

2.2 Drive for diet diversification

Dietary diversity is an evaluation of an individual’s consumption of various foods from assorted food groups over a certain period. Analyzing dietary diversity patterns is an important tool in developing a strategic work plan to combat hidden hunger, since a diverse diet is less likely to be lacking in micronutrient supplies. Questionnaire-based approaches to assessing food diversity at the population level have been developed, which offers an advantage in determining nutrient consumption in a streamlined approach by acquiring data that does not rely on thorough, time-consuming food studies or highly competent enumerators.

2.3 Drive for nutrient supplementation

Nutrient supplementation can give a direct solution when nutritional deficiencies can be detected. Systematic reviews of the kinds of literature show that supplementation programs can increase micronutrient levels. Folate and iron supplements given to women of reproductive phases around the world have helped in improving anemia and pregnancy outcomes. Supplementation to cure hidden hunger at the community level is a difficult task and is dependent on public involvement since it is expensive and depends on the ability to reach those most vulnerable populations. Supplementation can help in the short term, but it will not solve the long-term problem of a nutrient-deficient diet.

2.4 Food fortification

The addition of nutrients to foods during the processing just before consumption is referred to as food fortification. One of the most successful fortification methods employed globally has been the fortification of iodine to edible salts. Iodine deficiency has substantial adverse health effects, which are associated with its crucial role in the synthesis of thyroid hormone causing stunted growth and limited cognitive development in humans. Many countries mandate iodine fortification of salts, with United Nations International Childers’s Emergency Fund (UNICEF) reporting 86% household approval worldwide [16]. The efficiency of a comprehensive fortification strategy depends on the successful supply and accessibility of fortified products, ensuring their availability in targeted locations. Furthermore, the fortifying system must be properly developed and monitored for quality management and safety, with at least regional-level supervision with adequate investment. As a result, food fortification favors metropolitan areas with better infrastructure for distributing fortified products than rural areas and higher socioeconomic status and health-related awareness.

2.5 Global perspective of hidden hunger

More than 2 billion people worldwide experience hidden hunger, out of 805 million people who do not have enough calories to eat [17]. Several variables contribute to this difficulty, as indicated briefly in Figure 2.

Figure 2.

A brief outline of the composition of the Global Hunger Index. Source: Ref. [13].

The South Asian subcontinent and a vast area of Africa, south of the Sahara, where hidden hunger is prevalent. Frequencies are quite low in Latin America and the Caribbean, where diets rely less on a single crop and are more influenced by significant usage of vitamin supplementation, education initiatives, and basic health care [18]. While malnutrition is more widespread in developing countries, iron, and iodine deficits are also common in developed countries. The worldwide malnutrition problem is becoming more complex. Developing countries are shifting away from traditional diets and inclining to processed meals, calorie-dense diets, and beverages that are low in micronutrients and contribute to obesity and chronic diseases associated with it. Micronutrient deficiencies are estimated to account for 1.1 million of the 3.1 million child deaths caused by malnutrition every year [19]. Vitamin A and zinc deficiency harmed children’s health and survival by weakening the immune system. Zinc deficiency both inhibits and causes stunted growth in youngsters. Iodine and iron deficiency inhibit youngsters from reaching their full physical and intellectual potential [20]. The eating habits of women before conception and throughout pregnancy have long-term effects on the growth and development of the fetus. Iodine deficiency causes brain damage in about 18 million infants each year. Severe anemia is the potential cause of the deaths of 50,000 women giving birth each year. Furthermore, iron deficiency causes low energy levels in 40% of women in underdeveloped nations [21]. Typically, efforts to reduce hidden hunger and improve nutrition performance target women, babies, and children. Interventions aimed at these individuals have a high rate of return because they improve later-life health, nutrition, and cognition [22]. The severity of most micronutrient deficits is difficult to communicate. There is a scarcity of data on the prevalence of certain micronutrient deficits. Scientists have not agreed on the usually recommended intakes for several of the 19 micronutrients that directly influence immune function, and physical and mental development [23]. Furthermore, it is unknown how different micronutrient intakes, and their benefits connect to one another. There are numerous significant micronutrients for which prevalence data are absent because appropriate biomarkers for nutritional insufficiency have yet to be discovered. If these data gaps persist, determining the full degree of hidden hunger will be challenging.

When all other measures fail to alleviate hidden hunger, biofortification is likely the only rationally viable choice. It provides a different and more cost-effective approach to increasing nutritional value and status in vulnerable populations. Once the biofortified variety is developed, the seed can be widely distributed and replicated by farmers as farm-saved seeds year after year, so boosting informal seed systems. Following the initial investment in breeding, ongoing costs are cheap, though help may be necessary to optimize fertilizer use to maximize the crop’s nutritional content potential. There is also an urgent and rigorous need to investigate the source of crop genotypes high in nutritional value, such as traditional landraces, and local variants, to generate biofortified products.

3. Rice with ethno-nutritional value

Neolithic people began domesticating numerous plants and animals around 12,000 years ago. This sparked the agricultural revolution, which resulted in the development of hundreds of animal breeds and crop landraces, as well as new animal and plant species [24, 25, 26]. Around 12,000 and 10,000 years ago in China (O. sativa ssp. japonica) and India (O. indica ssp. indica), respectively, rice is developed from the primordial Oryza rufipogon, through careful selection of domesticated rice (Oryza sativa L.) [27, 28]. Over millennia, local farmers have developed and cultivated hundreds of different rice landraces through painstaking selection and breeding trials. Crop genetic variety is the foundation for adaptability to environmental conditions, such as drought, seasonal flooding, salinity, and crop pest and disease resistance [29, 30]. Agricultural liberalization and industrialization processes, which homogenize the genetic basis, lessen the complexity of agroecosystems, and are associated with increased crop yields, have, nevertheless, depleted the rich reservoirs of natural crop diversity since the green revolution began in the late 1960s [30]. This has damaged farmers’ ability to control their food supply, resulting in local and national food insecurity [31]. For example, in India, which is a major rice-growing country, more than 90% of local rice landraces disappeared from agricultural areas between 1970 and 2000 [31]. The extinction of traditional rice genotypes threatens local culinary ethnicities as well as food security, which has disastrous consequences. Farmers who are willing to grow a few heirloom rice varieties despite high market prices are themselves uncommon species, as traditional cultural values associated with local landraces have mostly disappeared within sophisticated farming communities. Folk rice landraces are rapidly disappearing from farmer fields due to a lack of both cultural and economic motivation.

3.1 Indigenous knowledge systems and folk rice landraces

Aside from its agronomic benefits, Rice has a different cultural significance among major nations. Traditional farmers developed, nurtured, and maintained several folk rice varieties that were specifically tailored to the soil and climate of a specific region. Prior to the introduction of modern agriculture at the request of statutory authorities and the seed industry, most marginal farmers used to recollect their specific agronomic features and cultural purposes. Each landrace has its own unique climate, soil conditions, and adaptability. Local landraces are the ideal resource for developing superior cultivars since they contain a diverse set of genes for pest and disease resistance, as well as various nutritional attributes. Many farmer landraces can withstand situations such as severe rain, late rain, insufficient rain, prolonged flooding, and soil salinity that are sometimes missing in modern high-yielding cultivars [30]. Local acceptability is determined by aroma and amylose levels, which also influence how sticky cooked rice is. Several landraces are preferred for making beaten rice, puffed rice, rice pudding, and other delicacies. Esthetic preference is another aspect in the selection and breeding of distinct landraces with colors, such as red, black, purple, and gold for the awn and pericarp, as well as brown, purple, and black for the hull [30].

Many traditional rice varieties have different nutritional properties and medical purposes. In India, Laicha rice from Chhattisgarh and Nyavara rice from Kerala are two examples of medicinal rice used to treat peptic ulcers and chronic gastritis in India. Nyavara has traditionally been used to alleviate neurotic issues. Kabiraj-sal is recommended as a meal for recovering patients’ traditional medicine because it includes nutritional properties that improve overall wellness. Garib-sal is the only rice type known to contain silver in its grains, and it is utilized in traditional medicine to cure gastroenteric disorders [32]. The considerable amount of silver on the grains’ pericarp of Garib-sal, presumably promotes dangerous intestinal bacteria [32]. One of the South Indian versions, Mappillai samba, has antidiabetic and anticancer properties, as well as steroidal bioactive compounds and antioxidants [33]. Patients suffering from dysentery in Bihar and Jharkhand are given a paste made from the Karanga rice variety. In Assam, patients with jaundice are treated with starchy water from the Bora type of traditional rice [34].

Numerous laboratory studies have already shown that rice and its byproducts have anticancer characteristics and can be used to treat illnesses, such as diabetes, kidney problems, and excessive cholesterol. Although rice is commonly considered a starchy food, it also contains a significant amount of proteins, fatty acids, fiber, many minerals, and vitamins required for normal metabolic functioning [35]. Scientific evidence supports some of rice’s medical properties [36, 37]. Rice has antioxidant properties that can prevent cancer, and some traditional rice varieties with a low glycemic index can significantly check blood glucose levels and lower the risk of developing diabetes [38]. According to research, colored rice, such as traditional red and black rice, outperforms high-yielding types in terms of numerous nutritional and medicinal properties [39]. Rakktashali red rice was mentioned in ancient Ayurvedic writings as both food and medicine [40]. Ayurvedic practices typically employ Kerala’s well-known Nayavara rice as a body-enhancing material to combat pollutants and slow aging [41]. The pigmented black and red kinds are higher in minerals and polyphenols, which can fortify cells. Basmati rice, which is commonly used in weight-loss programs, has a low glycemic index [42]. Rice is a terrific diet for giving our bodies micronutrients, rejecting toxic metabolites, strengthening, rejuvenating, and revitalizing the body, managing blood pressure, and preventing skin disorders and premature aging due to its antioxidant characteristics [43]. Thousands of traditional rice landraces, which are only available to marginal farmers and conservationists, should be scientifically validated for their healing properties. To maintain these landraces, public awareness campaigns that compete with the existing market of high-yielding cultivars must be created.

4. Rice biofortification for nutritional security

Malnutrition affects over two billion people worldwide, while 815 million people are undernourished. Biofortification is a food-based technique for combating malnutrition by bringing nutrient-dense crops to the doorsteps of poor and needy populations [7]. Biofortification can increase the content of micronutrients in food crops. Biofortified crop types can be offered to populations that do not have access to or cannot afford diversified diets. Biofortification was listed as one of the most significant interventions to eliminate micronutrient deficiencies in low- and middle-income countries in both the 2008 Copenhagen Consensus and the 2013 Lancet series on maternal and child malnutrition. It is also one of the most cost-effective treatments for micronutrient deficiencies, with a 17-dollar return on investment (Copenhagen Consensus). The biofortification technique was initially implemented in the mid-1990s. Biofortification has now received a much bigger financial commitment thanks to the HarvestPlus initiative, which began in 2003 and has financed research projects and biofortification implementation programs all around the world. HarvestPlus is not the only organization that uses biofortification; it is also engaged in regional plant breeding efforts and government programs.

More than half of the world’s population derives their energy from rice, a popular staple grain, particularly in Asia that supplies up to 70% of its daily calories. Addressing hidden hunger by rice biofortification may be a sustainable alternative method for those who predominantly consume rice and have limited access to other nutrients. The biofortification procedure successfully raised the number of provitamins and essential minerals in rice grain. Milled rice loses several vital elements such as thiamin and vitamin B due to processing. Furthermore, the grinding and polishing processes destroy 67% of vitamin B3, 80% of vitamin B1, 90% of vitamin B6, 50% of the manganese and phosphorus, 60% of the iron, and all the dietary fiber and important fatty acids. While the consumers prefer white rice grains that are lighter, softer, more easily digestible, and have better eating and cooking qualities, the nutritional quality is compromised when rice is milled and polished due to the loss of the bran layer, the sub aleurone, the embryo, and a small portion of the endosperm [44, 45, 46, 47]. Even though education and awareness have improved brown rice consumption, the great majority of rice consumers still choose white polished rice. Researchers should consider developing nutritionally enhanced rice varieties via biofortification (endosperm specific) that can retain nutrients even after processing and polishing. The newly produced biofortified crop varieties, in addition to being an essential source of income for the poor, are also crucial in terms of nutritional security.

5. Biofortified rice: a food-based product to tackle malnutrition

The human body needs nutrition through micronutrients for proper growth and development and to maintain good health [48, 49]. However, shortages of these minerals, as well as the related health risks, are frequent among humans of all ages [50]. Micronutrient malnutrition affects an estimated one-third of the global population because of their significant reliance on cereal staples for daily energy demands and lack of varied diets for nutrient supplementation [51]. Rice biofortification is a novel, promising, cost-effective, and long-term strategy for providing micronutrients to people who do not have access to a varied diet or other micronutrient-based remedies. Unfortunately, our major food crops lack the micronutrients required for normal human development. Until now, our agricultural system has been designed primarily to improve grain yield and crop productivity, with little emphasis on improving human health. However, in the modern era, agriculture is transitioning away from high-yielding food crops and toward nutrient-rich food crops, notably cereals, to help combat “hidden hunger” or “micronutrient malnutrition”. This is particularly noticeable in emerging nations, where diets are dominated by micronutrients-deficient main food crops such as rice [52].

The development of nutritionally enhanced, high-yielding biofortified crops is one of the primary priorities of organizations such as the World Health Organization (WHO) and the Consultative Group on International Agricultural Research (CGIAR) [53]. Nutritional goals for biofortification include greater mineral content, better vitamin content, increased essential amino acid levels, improved fatty acid composition, and increased antioxidant levels in crops [54]. Crop plant biofortification can provide enough calories to meet energy needs while also delivering all the essential nutrients needed to maintain excellent human health. Furthermore, biofortified crops consumed by the world’s impoverished can significantly improve the well-being of the population of a specific geographic location [55]. Transgenic (Table 1), agronomic (Table 2), and breeding procedures (Table 3) are the three major the techniques for biofortification of essential micronutrients in agricultural plants. A few updates on previous attempts by researchers / scientific workers and the outcomes of these three approaches are depicted below.

Biofortified nutrients	Context of research	Publications
Beta-carotene Phytoene (precursor of beta-carotene)	Golden rice and its nutritional value; beta-carotene metabolism; genetic engineering provitamin	[56, 57, 58, 59]
Folate (vitamin B9)	Folate fortification and stability; metabolic engineering	[60, 61]
Iron	Nicotianamine aminotransferase genes; transgenic; multigene introduction; ferritin gene; endosperm biofortification	[62, 63, 64, 65, 66, 67, 68, 69, 70]
Phytic acid	Iron bioavailability and dietary reference values	[71]
Zinc	Over-expression of OsIRT1; involvement of genes for phytosiderophore synthesis	[72, 73]
High amino acid and protein content	Accumulation of glycinin with the glutelins; dihydrodipicolinate synthase gene; tryptophan accumulation; over-expression of aspartate aminotransferase genes	[63, 74, 75, 76, 77, 78]
Alpha-linolenic acid	Microsomal omega-3 fatty acid desaturase gene	[79]
Flavonoids and antioxidants	Flavonoids synthesis in the endosperm; transgenic	[80, 81]
Resistant starch	Amylose level control; antisense waxy gene; physicochemical properties	[82, 83, 84]
Human lactoferrin	Expression of human lactoferrin for the application in infant formula	[85]

Table 1.

Research publications on rice biofortification through the transgenic approach.

Biofortified nutrients	Context of research	Publications
Iron	Foliar application; iron fertilizers; grain accumulation; and grain nutritional quality	[86, 87, 88, 89]
Zinc	Foliar application at different growth stages; impact on seedling vigor; yield; with pesticides; zinc sulfate; and zinc oxide coatings	[86, 88, 90, 91, 92, 93, 94]
Se	Foliar application as fertilizers; sodium selenate; effects on human serum selenium levels; brown rice; selenate-enriched urea granules; antioxidant activity	[86, 95, 96, 97, 98]

Table 2.

Research publications on rice biofortification through the agronomic approach.

Variety name	Duration (Days)	Yield (t/ha)	Grain type	Institute, Country	Release Year	Biofortified nutrient
CR Dhan 310	125	4.5	Medium Slender	NRRI, Cuttack, India	2016	Protein (10.3%)
CR Dhan 311 (Mukul)	120–125	4.6	Long Bold	NRRI, Cuttack, India	2018	Protein (10.1%) and Zinc (20.1 ppm)
Bauna Kalanamak 101	135	3.5–4.0	Medium Slender	PRDF, Gorakhpur, India	2016	Zinc (18.9), Fe (4.6 ppm)
Bauna Kalanamak 102	135	4.5	Medium Slender	PRDF, Gorakhpur, India	2016	Zinc (20.75 ppm) and Fe (4.4 ppm)
Binadhan 20	125–130	4.5–7.0		Bangladesh Institute of Nuclear Agriculture (BINA), Bangladesh	2017	Zinc (26.5 ppm), Fe (20–31 ppm)
BRRI Dhan 100	148	7.7	Slender	Bangladesh Rice Research Institute (BRRI), Bangladesh	2020	Zinc (25.6 ppm)
BRRI Dhan 62	100–105	3.5–4.5	Slender	Bangladesh Rice Research Institute (BRRI), Bangladesh	2013	Zinc (19 ppm), Protein (9%)
BRRI Dhan 64	88–100	6.0	Medium Slender	Bangladesh Rice Research Institute (BRRI), Bangladesh	2014	Zinc (23.1 ppm), Fe (36.6 ppm)
BRRI Dhan 72	125–130	5.7	Long bold	Bangladesh Rice Research Institute (BRRI), Bangladesh	2015	Zinc (22.8 ppm), Protein (8.9%)
BRRI Dhan 84	140–145	6.0–6.5	Medium Slender	Bangladesh Rice Research Institute (BRRI)	2017	Zinc (27.6 ppm)
Chhattisgarh Zinc Rice 1	112	4.2	Long Slender	IGKV, Raipur, India	2016	Zinc (21.7 ppm)
Chhattisgarh Zinc Rice 2	120–125	4.5	Short Slender	IGKV, Raipur, India	2019	Zinc (>24 ppm)
CR Dhan 315	130	5.0	Medium Slender	NRRI, Cuttack, India	2020	Zinc (24.9 ppm)
CR Dhan 411	140	5.0–6.0	Medium Slender	NRRI, Cuttack, India	2021	Protein (10%)
DRR Dhan 45	130	5.0	Long Slender	IIRR, Hyderabad, India	2016	Zinc (22.6 ppm)
DRR Dhan 48	135–140	5.2	Medium Slender	IIRR, Hyderabad, India	2018	Zinc (24 ppm)
DRR Dhan 49	125–130	5.0–5.5	MS	DRR, Hyderabad, India	2018	Zinc (25.2 ppm
GNR 4	130–135	4.0–5.0	Long Slender	Navsari Agricultural University, Navsari, India	2016	Fe (50 ppm)
Kalanamak Kiran	135	5.0	Medium Slender	Participatory Rural Development Foundation (PRDF), Gorakhpur, India	2019	Protein (10.4%), Zinc, Fe
Ratnagiri 7	122–125	4.5	Short Bold	Agricultural Research Station, Shirgaon, Ratnagiri, India	2019	Zinc (24.25 ppm), Fe (7.9 ppm)
Swarna Shakti Dhan	115–120	4.5–5.0	SB	ICAR-RCER, Patna, India	2020	Zinc (23.5 ppm), Fe (15.1 ppm)
Swarna Sukha Dhan	110–115	3.5–4.0	MS	ICAR-RCER, Patna, India	2021	Zinc (23.1)
Zinco Rice MS	125–130	5.8	MS	IGKV, Raipur, India	2018	Zinc (27.4 ppm)

Table 3.

Details of rice biofortified varieties developed through the breeding approach in South Asia.

6. Dissemination and adoption trends of biofortified rice varieties

The widespread adoption of biofortified rice cultivars is reliant on the availability of appropriate varietal seeds, timely certification, and premium market pricing. As a result, efforts must be made to make these types of varietal seeds available on the market and to ensure premium pricing to entice producers with a value proposition. It is critical to recognize that biofortified crops require far more than a strong marketing push. Acceptability and augmented adoption of biofortified cultivars required significant policy-level interventions in the form of cost subsidies. HarvestPlus-led delivery efforts require around 9.7 million agricultural households to produce biofortified food in 2020, which will be consumed by 48.5 million people worldwide [99]. The global market for biofortification was estimated to be valued at approximately US $72 million in 2017 and is expected to grow to US $117 million over the next several years, rising at an 8.6% CAGR (Compound Annual Growth Rate). Rising consumer demand for high-nutritional-value foods, as well as advances in agricultural technology, are driving this increase.

The willingness of consumers and farmers to accept newly produced nutrient-rich seeds will be a critical success factor for biofortification [9]. Producers’ decisions about using biofortified crops will be impacted by yield, disease resistance, drought tolerance, and marketability. Consumer perceptions of biofortified varieties based on sensory features can considerably influence their uptake. A separate technique can be used to access the components that determine nutrient-rich varietal adoption (reflection of intention, initial decision, or action in testing an innovation) and acceptance (reflection of perception among the producers and consumers that innovation is fit for purpose) [100]. Preference testing and sensory studies reveal information on sensory features that influence consumer acceptability (Table 4).

Publication	Country	Conclusion
Study on gender-specific acceptability of Zinc fortified rice within China [101].	China	Biofortified rice is the least chosen. Acceptance can be improved when rice is cultivated locally, the government encourages it, and the rice kernels are large.
Study on sensory evaluation of rice in Nicaragua [102].	Nicaragua	The study population did not readily accept Azucena.
Study on sensory evaluation of biofortified rice in Panama [103].	Panama	Because of its potential, biofortified rice should be adopted by the agro-industry and other communities.
Study on sensory evaluation of high iron and zinc-rich rice in Cuba [104].	Cuba	Cuba should use biofortified rice since it can help avoid anemia and zinc deficiency.

Table 4.

Past studies on the sensory assessment of biofortified rice within low- and middle-income nations.

Cross-sectional questionnaire surveys reveal attitudes, impediments, and factors that aid or hinder consumers’ or producers’ adoption of biofortified cultivars. Effective experiments with frequent contrast intensities and less severe treatments are required to evaluate whether biofortified crops are acceptable and are adopted over a specific period. A comparative viewpoint for the acceptability of biofortified varieties against non-biofortified varieties should be mapped, indicating the need for a potential marketing and premium proposition when introducing these cultivars to the targeted territory [105].

Consumer acceptability of biofortified crops varies widely depending on crop type, locality, and consumer characteristics such as age, gender, socioeconomic level, and whether they prefer or dislike biofortified meals (Table 5).

Publication	Country	Conclusion
Study on consumer perceptions and impact of negative attributes for folate biofortified rice within China [106].	China	The initial acceptance rate would be cut in half if genetically engineered folate-fortified rice had a negative influence on taste, price, or the environment. Several aspects should be considered when developing biofortified crops.
Study on the potential market for genetically modified rice with health benefits within China [107].	China	There is considerable (segmented) commercial potential for second-generation genetically modified products, especially in the biofortified domain.

Table 5.

Past studies on consumers’ acceptance and adoption trends of biofortified rice in low- and middle-income.

Biofortified crops appear to be sensory acceptable to both rural and urban cultures when cooked using traditional methods or as an ingredient in nontraditional food items. The availability of biofortified varieties in the market and thorough knowledge about their health advantages are two of the most important variables influencing their acceptability and uptake. According to research, farmers and other stakeholders are prepared to pay a premium for seed production, and after-harvest consumption when they learn about the health benefits of nutrient-rich cultivars (Table 6) [112].

Publication	Country	Conclusion
Study of consumer’s willingness to pay in India in emerging markets for genetically modified foods [108].	India	Most respondents were willing to consume genetically modified foods, and they were willing to pay a considerable premium for golden rice with higher nutritional value.
Study on consumers’ willingness to pay for golden rice [109].	Philippines	Golden rice generated through genetic engineering has garnered positive feedback. The marginal impact of positive information versus no information WTP (on willingness to pay) is small for golden rice, whereas negative or two-sided information considerably lowers WTP.
Study on consumers’ willingness to pay for genetically modified rice with health benefits within China [110].	China	Nonstudents are less concerned about genetic engineering due to information about folate. Students show a fearful reaction, while in the nonstudent group, contradicting information leads to primacy bias. This demonstrates the need for segmented, targeted biofortification communication techniques.
Study on consumer preferences on folic acid supplementation and folate biofortification within China [111].	China	Positive responses to genetically engineered folate-rich rice support its potential as a supplemental micronutrient intervention.

Table 6.

Past studies on customer willingness to pay for biofortified rice in low- and middle-income nations.

To supplement the nutrient-rich varietal adoption, segmented, focused communication methods are required due to the diverse preferences of the respondents being investigated. Because many biofortified varieties have recently progressed from the research and development stage to the dissemination stage, more information on the benefits of biofortified varieties for replacing existing cultivars and bringing dietary changes to consumers should be forthcoming shortly [112].

To secure last-mile distribution, governments, multilateral organizations, farmers, universities, and the commercial sector must form strategic worldwide alliances. Public and private organizations, institutions, and other commercial entities gradually take the lead to assure increased biofortified seed production, enough on-ground delivery, capacity building, and technical assistance to a diverse range of stakeholders, including farmers.

One of the key obstacles to getting biofortified rice varieties broadly adopted and consumed in specific areas is the limitation on the effectiveness of their marketing and geographic spread [113]. There are also further hurdles to marketing nutrient-enriched rice varieties that may limit their widespread acceptance by farmers, other seed value chain actors, and, finally, consumers. Several of them are discussed below.

6.1 Challenges in the adoption of nutrient-enriched rice varieties

Most farmers are habituated to growing traditional/existing cultivars due to the assumption of low yields, high input costs, and potential crop loss of biofortified variety. The lack of awareness and empowerment with sufficient information on possible benefits and marketing of nutrient-enriched cultivars to farmers by regional organizations and extension functionaries creates a lengthier transition time for adoption. Most seed business participants, notably the R&D team, make less effort to generate varieties with a solid balance of top desirable features, such as yield, abiotic and biotic tolerance, and nutritional traits. Increased awareness, initiatives, and inclusive, coordinated promotional programs could help to accelerate the growth of nutrient-rich crops. A strengthened focus on R&D should be important for biofortified research. Local organizations struggle to secure enough breeder seeds to produce new varieties due to a lack of government incentives for producers and the inadequate capability of local seed firms. This is due to a lack of resources, capability, and incentives to meet market demand and make R&D investments. Most biofortified rice cultivars, unlike conventional crops, lack differentiating, targeted phenotypic features, such as the desired grain type as well as high yield. As a result, convincing farmers and value chain stakeholders of their greater features over traditional cultivars may be difficult.

Most of the rice growers are smallholders who are extremely price sensitive. Inaccurate pricing information and price changes may discourage farmers from cultivating biofortified cultivars over traditional ones. Nutrient enrichment can sometimes change the color of rice grains or crops. For example, for increased quantities of vitamin A, the ultimate product is orange rather than white rice. Customers may find it difficult to accept and become acclimated to its appearance because of this. Because it can be costly and time-consuming to devise and implement strategies to enhance the shelf life of nutrient-rich rice varieties, the limited shelf life of some biofortified grains may be a barrier to the development of processed products. Processed biofortified rice is being sought after and may fill a niche market. Consumer dynamics will be scaled with various sorts of biofortified rice-based products for consumers.

7. Biofortification in Rice, an impactful strategy for public health

Micronutrients are required for proper growth and development, as well as for optimum health [48, 49]. The primary cause of people’s high micronutrient deficits has been attributed to their poor bioavailability after dietary consumption, combined with limited soil micronutrient availability for crop production [114]. Micronutrient malnutrition affects an estimated one-third of the global population due to the dependency on cereal staples for daily nutritional needs along with the limitation to access to diverse nutritional foods and supplements [51]. Global recognition has been acknowledged as an important need for developing a malnutrition mitigation strategy for the SDGs [115]. Previously, numerous strategies were employed to reduce malnutrition, including food fortification, vitamin supplementation, and dietary variety. However, because of high adherence costs and a lack of accessibility and understanding among rural populations, the outcomes were mixed [116]. It has been shown that the biofortification of popular staple crops such as rice is an efficient and relatively low-cost means of alleviating malnutrition. By using this food-based strategy, a targeted population can regulate and avoid micronutrient deficiencies [117, 118, 119]. Shortages of iron, zinc, selenium, and iodine create substantial health concerns as well as significant financial losses [120, 121]. Crop production systems should incorporate nutrition-sensitive practices to generate micronutrient-enriched staple foods for the targeted populations [117, 122, 123].

Rice is the most important source of food in terms of energy for more than half of the world’s population [124]. It is a significant staple crop in over 40 nations globally, providing at least 20% of daily caloric intake to over 3.5 billion people [1]. However, because milled rice contains fewer nutrients, most marginal groups that rely largely on rice do not have access to a broad mineral supply. Rice biofortification is a long-term and cost-effective solution to the problem of micronutrient deficiency. Rice is a primary food crop for biofortification in many South Asian, Southeast Asian, and African countries [125].

Biofortification has the lowest per capita cost of any intervention, making it particularly accessible and affordable for rural areas [126]. It is critical to breed rice varieties that incorporate beneficial minerals and vitamins to generate a holistically single biofortified rice product. In the fight against hidden hunger, rice biofortification provides a sustainable alternative to chemical food additives, and it should be a top research priority for the most affected countries. Based on the HarvestPlus breeding programs, iron-biofortified rice, for example, is to reach a targeted iron content of roughly 30% over the estimated average requirement of 15 g/g (dry weight) in polished grain [127, 128]. Healthy rice has recently gained popularity and is in high demand in several parts of the world. As a result, to maximize the benefit of establishing nutritional security for public health, we must continue to produce nutritious rice at a rapid rate.

7.1 Policy recommendation

Despite some controversy, such as climate change and the COVID-19 epidemic, the recently concluded United Nations Food Systems Summit resulted in meaningful and revolutionary long-term efforts to achieve zero hunger. These action items were to be used as a measure of achievement to respect, preserve, and fulfill human rights with enough nourishment. Developing resilient food systems from a peace-building perspective can help to promote both long-term food and nutrition security and long-term peace, even if conflict resolution ultimately requires political solutions and societal transformation.

It is important to improve food system resilience to combat the consequences of conflict and environmental concerns while providing food security and nutrition. Moreover, rational decisions are to be made based on a thorough awareness of the situation, with inclusive support and locally driven efforts. Personnel involved in aid, development, and peacekeeping must regularly and methodically assess the current situation globally. Local, national, and international players should all be included in nutritional decision-making. Priority must be given to flexibility, competency, cross-sectoral and long-term planning, and financing. Donors, international entities, nongovernmental organizations, and local seed actors should strive to establish and maintain long-term cross-sectoral linkages. Priorities for funding must be set in a flexible and adaptable manner that considers local perceptions, aspirations, and concerns. Human rights and real community and civil society participation must serve as the foundation of multilateral food governance. The SDGs, the Paris Agreement on Climate Change, and human rights treaties must all be incorporated into food policy activities that prioritize vulnerable people. Governments must seize recent opportunities, such as the United Nations Climate Change Conference (COP 26) and the Tokyo Nutrition for Growth Summit in 2021, to reaffirm the commitment to ending hunger by investing in nutrition and resilience in volatile and conflict-effected environments.

8. Future prospect of biofortified rice

In the current context, biofortification intervention is a promising crop-based strategy for eliminating micronutrient insufficiency. The current biofortification methodology has a considerable research deficit, making general implementation challenging. The mechanisms of nutrient transfer from soil to seed are poorly understood in most food crops, including rice. As a result, a better understanding of the fundamental processes that limit the rate of micronutrient acquisition and translocation in the soil–plant system is required. Before making biofortified crops available to consumers, the safety risks, particularly for genetically modified kinds, must be thoroughly investigated. Another big knowledge gap is in the bioavailability of micronutrients in food grains and the pattern of mineral dispersion in plant systems. It is necessary to study the potential loss of micronutrients during processing as well as the deliberate removal of external tissues. Some of the most recent techniques, such as molecular cytogenetic gene transfer for higher iron and zinc content, uniform mineral distribution in grain to reduce micronutrient loss during postharvest processing, manipulation of phytic acid levels to increase bioavailability, and so on, can play an important role in enriching plant edible parts. We recently discovered that the judicious application of nano-based micronutrient fertilizers may enhance the biofortification process. As a result, it is vital to develop an integrated biofortification approach that can improve human health when eaten through the consumption of micronutrient-fortified food products.

However, there are always questions about the scientific validity of rice biofortification, its potential for adoption by farmers and consumers, its economic sustainability, and production stability before we can utilize it successfully to combat micronutrient deficiencies [129]. Although no significant initiatives to sell nutrient-rich rice have been identified, the purpose of developing biofortified rice is to use it more widely. The discovery of stable transgenic golden rice, a form of rice biofortified with beta-carotene, has resulted in extensive scientific research and development. However, there have been substantial delays in the marketing of golden rice [130]. Rice is the staple food for most of Asia. When considering the commercialization of biofortified rice, it must be kept in mind that the majority of rice is consumed in Asia, and many potential beneficiaries come from developing nations and low-income households. Regulations that prohibit the use of genetically modified rice alongside traditional rice may thus be a practical hurdle for such countries. An interdisciplinary research team comprised of crop science and human nutrition experts must collaborate to generate finished products with desirable nutritional attributes. Biofortified rice will also need to exhibit acceptable sensory and cooking characteristics to gain widespread adoption. Furthermore, it is critical to ensure that the biofortified rice varieties will yield at the required level and will be resistant to biotic and abiotic problems. The biofortification program for rice is being effectively implemented in several nations because of enhanced marketing, agricultural policy, nutrition education, and public awareness campaigns. As a result, additional deliberate efforts toward the development of biofortified crops along with suitable agronomic management practices must be adopted in the future to mitigate micronutrient deficiency in humans and provide food and nutritional security.

9. Summary

Malnutrition has a global impact on human learning ability, immune system function, and physical and mental development. Hidden hunger, often known as micronutrient deficiency, is a major global concern. The nonavailability of minerals and vitamins is expected to grow more in the future, and biofortification is on the path to the establishment as a feasible treatment. For greater human health, the interplay of iron, zinc, and vitamin must be synergistic and increase mineral bioavailability. This intrinsic “synergistic impact” stimulates plant breeders to combine these nutrients in the future to generate improved biofortified rice, which may be considered an advancement over other traditional approaches. Rice is being biofortified with additional vitamins and minerals to address hidden hunger. Biofortification of rice with folic acid (or folate), thiamin, riboflavin, niacin, pantothenic acid, pyridoxine, biotin, vitamin B12, ascorbic acid, vitamin D, and vitamin E is ongoing [131]. Rice biofortification should be a major focus of research and development efforts in affected countries. Researchers of biofortified rice, policymakers, stakeholders, and philanthropists should focus on policies that directly benefit rice consumers in affected countries, such as the public-private partnership model in agri-biotech research, “freedom to operate” biofortified rice varieties developed by private companies, area-specific production, better storage facilities, international rice distribution policies, and raising awareness. Furthermore, the COVID-19 pandemic, a current global health emergency, as well as several illnesses caused by micronutrient deficiency, have drawn attention to the utility of biofortified crops as a viable and cost-effective method of providing important micronutrients to billions of people worldwide. These biofortification strategies will assist those who are vulnerable in becoming more resilient to future shocks to food and income systems caused by unfavorable causes such as prospective pandemics and natural disasters. Governments should therefore encourage the widespread and augmented adoption of biofortified staple crops, particularly rice, by providing financial incentives. There has been great progress in this field, and with more planned studies and robust laws, rice biofortification may see considerable success in the coming years. As a result, biofortified rice has significant potential for addressing the issue of micronutrient insufficiency, with excellent prospects for its adoption and influence in assuring the nutritional security of the world’s population by reaching the unreached.

Acknowledgments

The authors acknowledge the efforts of Mr. Sarvesh Shukla (Agricultural Officer, IRRI-SARC) and Mr. Rabindra Moharana (Research Technician IRRI-SARC) in assisting during the preparation of the manuscript.