Description of the condition
Adequate vitamin and mineral nutrition is required for optimal growth and development of children and for the maintenance of adequate health and nutrition of adult populations. Vitamin and mineral deficiencies may result in conditions such as anaemia, blindness, birth defects, retarded growth, diminished mental development and other poor health outcomes (Howson 1998; Oakley 2004; Darnton-Hill 2005; A2Z Project 2008). Micronutrient deficiencies have also long been demonstrated to increase the risk of morbidity and, in some cases, mortality especially from infection (Bhaskaram 2002; Singhal 2002; Black 2003). They also significantly and negatively impact on socioeconomic development at the individual, community and national levels (Darnton-Hill 2005). Iron, vitamin A, iodine and zinc deficiencies constitute the world’s most common micronutrient deficiencies (WHO 2009b).
Approximately 1.6 billion people are anaemic worldwide (WHO/CDC 2008). Although anaemia can be caused by multiple factors, iron deficiency is estimated to account for up to 50% at least of the anaemia burden, making it the single most widespread nutritional deficiency in the world (Graham 2001; Rastogi 2002; Stoltzfus 2011). Other conditions such as parasitic infections, inherited haemoglobin disorders, or nutritional deficiencies such as of folate or vitamin B12 can also cause anaemia (WHO 2001). Thus, low haemoglobin concentrations are indicators of both poor nutrition and poor health (de Benoist 2008). Before birth and during the first years of life, iron deficiency affects growth, neurodevelopment and cognitive performance (Lozoff 2006; Carter 2010) and may increase susceptibility to infections (Scrimshaw 2010). In adults, iron deficiency and anaemia cause the loss of healthy and productive lives due to their effects on work and physical capacity (Haas 1996). Pregnant women with iron deficiency are at higher risk of suboptimal pregnancy outcomes, including complications at delivery, low birth weight infants and preterm births (Pena-Rosas 2009).
Vitamin A deficiency causes xerophthalmia, which leads to night blindness and weakens the immune system thereby increasing the risk of childhood morbidity and mortality (Sommer 1996). Vitamin A deficiency may increase the risk of morbidity and mortality during infancy, pregnancy and in the postpartum period (Sommer 1996; West 1999). It is estimated that vitamin A deficiency results in 18 million disability-adjusted life years (DALYs) lost, a measure of overall disease burden that is expressed as the number of years lost due to ill-health, disability or early death (WHO 2002). Vitamin A deficiency occurs mostly after prolonged deprivation of this vitamin (WHO/FAO 2004) and is a significant public health problem in many developing countries, most seriously affecting young children, women of reproductive age and pregnant women. According to recent estimates from the World Health Organization (WHO), 190 million preschool age children (under five years of age) and 19.1 million pregnant women have inadequate concentrations of retinol. Roughly 45% of all preschool age children and pregnant women with vitamin A deficiency live in the WHO regions of Africa and the South-East Asian regions of South and South East Asia while Sub-Saharan Africa accounts for another 25% to 35% of cases (WHO 2009a). Vitamin A deficiency alone is responsible for almost 6% of child deaths under the age of five years in Africa and 8% in South-East Asia (WHO 2009b).
Zinc deficiency is considered to be associated with morbidity and mortality in developing countries. Severe zinc deficiency in children may cause short stature, impaired immune function and other disorders, and is a significant cause of respiratory infections, malaria and diarrhoeal disease (WHO 2002). Adequate zinc nutrition is essential for human health because of zinc’s critical structural and functional roles in multiple enzyme systems that are involved in gene expression, cell division and growth, and immunologic and reproductive functions (Hess 2009). Although there is very limited national or first administrative level survey data on the prevalence of zinc deficiency, It has been estimated that zinc deficiency is responsible for approximately 4% of child mortality and DALYs (Black 2008).
Inadequate periconceptional folate status and folic acid intake are associated with congenital malformations including neural tube defects (IOM 2003). Folic acid is a synthetic form of folate used in supplements and fortified foods (like wheat and maize flour) to reduce the occurrence of neural tube defects (NTDs). These defects include spina bifida (or cleft spine), where there is an opening in one or more of the bones (vertebrae) of the spinal column and anencephaly where the head (cephalic) end of the neural tube fails to close. It has been demonstrated through controlled studies that the risk of neural tube defects can be substantially reduced (risk ratio (RR) 0.28, 95% confidence interval (CI) 0.15 to 0.52) with daily folic acid supplementation (alone or in combination with other vitamins and minerals) (MRC 1991; Czeizel 1992; De-Regil 2010). The effectiveness of mandatory folic acid fortification in flour programmes has also been documented by a decline in the prevalence of neural tube defects, in the United States, Canada, Costa Rica, Chile and South Africa (Berry 2010).
Other vitamins and minerals
In addition to iron, vitamin A, zinc and folate deficiencies, those of iodine, calcium, vitamin B12 and vitamin D impair health and development. For example, iodine deficiency is a major threat to the health and development of populations worldwide, particularly in preschool children and pregnant women, resulting in goitre, stillbirth and miscarriage, hypothyroidism and impaired growth (Andersson 2012). Vitamin D deficiency (VDD) may be a common health problem worldwide, both in children and adults (Bandeira 2006; Holick 2007). It has been estimated that about 40% to 100% of elderly men and women living in the United States and Europe are deficient in vitamin D (Holick 2007). Calcium and vitamin D deficiency are important causes of rickets and poor bone mineralization in children, while maternal B12 vitamin deficiency may also be associated with adverse pregnancy outcomes and developmental disabilities in infants.
Intervention strategies for micronutrient malnutrition
Current recommended intervention strategies for the prevention and treatment of micronutrient deficiencies include either one or a combination of supplementation, food-based approaches such as dietary diversification, mass food fortification or point-of-use food fortification; other public health control measures include deworming, health and nutrition education (Howson 1998; Zimmermann 2007; WHO 2011a). These strategies can be delivered through at least four platforms, the health systems, agriculture, market-based, and social protection programs (Olney 2012). Supplementation is still the most widely practiced intervention to control iron (Villar 1997; WHO 2001; WHO 2011b; WHO 2011c; WHO 2011d; WHO 2011e) and vitamin A deficiencies in high-risk populations (WHO/MI 1998; WHO 2011f).
Some adverse effects observed with high dose supplements as well as the active participation from users may affect compliance and the long-term sustainability of such programmes. Supplementation programmes can be cost effective (Baltussen 2004; Alderman 2007) but logistical and human resource constraints, such as bad road networks and generally fragile institutions, may hinder their effectiveness especially in developing countries where the intervention is needed most (Zimmermann 2007). In such cases, mass fortification of foods becomes an important option to combat vitamin and mineral deficiencies. There are fewer concerns related to mass food fortification and it can be a complementary intervention to supplementation for efforts to reduce vitamin and mineral deficiencies.
Meeting the recommended dietary intakes (WHO/FAO 2004) through the daily diet is desirable but not always possible for many populations. Poor dietary diversity and dependence on cereal-based diets, which are common in developing countries, are major contributing factors to the high prevalence of micronutrient deficiencies (Welch 1999). Cereals in addition to being poor sources of vitamins and minerals also contain high quantities of other dietary compounds that decrease the absorption of certain micronutrients, often called 'anti-nutrients' (Graham 2001). For instance, iron and zinc absorption is significantly inhibited by phytic acid, present in cereals and other grains; polyphenols, contained in red wine and chocolate; or calcium, abundant in dairy products (Gibson 1998; Hurrell 2010; Kim 2011). On this basis, dietary bioavailability of iron has been estimated to be in the range of 14% to 18% for mixed diets and 5% to 12% for vegetarian diets.
Cereals, however, are overwhelmingly the major source of food supplies for direct human consumption. Of the 2.4 billion tonnes of cereals currently produced, roughly 1.1 billion tonnes are destined for food use; around 800 million tonnes (35% of world consumption) are used as animal feed; and the remaining 500 million tonnes are diverted to industrial usage or seed, or are wasted. Despite the consumption falling per capita in China, rice is still the preferred or only available domestic staple in many countries in Asia, providing support for its production. While rice is produced in vast areas of the world, the physical requirements for growing this crop are limited to certain zones. Rice is the primary staple for more than half the world’s population, with Asia representing the largest producing and consuming region. In recent years, rice has also become an important staple throughout Africa (FAO 2012). At the global level, the growth of demand in rice has been tailing off, as evidenced in several large producing and consuming countries of South and East Asia; consumption has shifted to other foodstuffs in line with income growth. Given the importance of these regions in world rice consumption, these declines are reflected in the aggregate trends of the world. About 672 million tonnes of rice (paddy) were harvested in 2010. Rice is the principle staple in Asia, where production is rising in the South but falling in the East (FAO 2012).
Description of the intervention
Fortification is “the addition of one or more essential nutrients to a food, whether or not it is normally contained in the food, for the purpose of preventing or correcting a demonstrated deficiency of one or more nutrients in the general population or specific population groups" (Codex Alimentarius 1994). This process usually takes place during food processing by the food industry at a central level so that it massively reaches the intended population and does not require the active participation of end users. While there are some different definitions for enrichment, for the purposes of this review enrichment and fortification will be used interchangeably.
Results of a study in Vietnamese school children showed that iron fortified rice noodles are efficacious in reducing anaemia and improving haemoglobin and iron status indicators (Huong 2006). In places where rice is a the staple food, iron fortification has been shown to reduce the prevalence of iron-deficiency anaemia from 100% to 33% among preschool age children (Angeles-Agdeppa 2008), particularly when there is strong political support and intensive social marketing activities as well as efforts to keep the cost affordable (Angeles-Agdeppa 2011). Zinc fortification of cereals can boost total zinc consumed daily and absorbed zinc in infants, young children and adults (Brown 2007). Although less frequent, fortification of wheat and maize flours with vitamin A has the technological and biological potential to palliate this deficiency (Klemm 2010). Perhaps the most well known area of micronutrient fortification is that of folic acid, in both wheat and maize flours, and its effect on the prevention of birth defects (WHA 2010). Well conducted studies from several countries have documented decreases of 26% to 42% in the occurrence of neural tube defect (NTD) affected births after implementation of national regulations mandating wheat flour fortification with folic acid (WHO 2009b). Food fortification brings together the benefit of energy, fat and protein, and the complementary roles of vitamins and minerals to enhance the stability and bioavailability of vitamins and minerals used to fortify foods (Best 2011). In addition, this strategy has a dual advantage of reaching a wider and larger proportion of the population than supplementation without requiring radical changes in food consumption patterns (Howson 1998). Based on an analysis of the cost effectiveness of iron supplementation and fortification, it appears that fortification could be less expensive than supplementation irrespective of the geographic coverage of fortification (Baltussen 2004).
Food fortification practices vary nationally. The choice of nutrients (in this context also known as fortificants) varies according to their bioavailability. In the case of iron, for instance, many compounds such as ferrous sulphate, ferrous fumarate, ferric pyrophosphate and electrolytic iron powder can be used in food fortification (WHO/FAO 2006). However, many cereal foods are fortified with low-cost iron powders with absorption of iron lower than 2% (Hurrell 2010). For vitamin A fortification retinyl palmitate and acetate are frequently used while the synthetic form of folic acid is used to improve folate status.
A concern expressed by a few about food fortification is related to the possible toxicity of excessive vitamins and minerals among all groups, particularly those that are not at risk of deficiencies. This is especially so with iron excess (Gordeuk 1987), which may affect the risk of colonic adenomas and cancer (Knöbel 2006; Muthunayagam 2009) and a potentially more pathogenic gut microbiota that is associated with higher gut inflammation (Zimmermann 2010). Excess and chronic vitamin A intake during pregnancy has been shown to increase the risk of teratogenicity (Rothman 1995) and hip fracture (Penniston 2003). A hypothetical association between the prolonged consumption of folic acid enriched cereals and the increase in the incidence of colorectal cancer in the United States and Canada (Mason 2007) has been challenged with other studies where such an association has not been demonstrated (EFSA 2009). Another concern may relate to the possibility of over-consumption of rice given the potential benefits of additional vitamins and minerals. As a public health intervention, the use of a vehicle would imply not encouraging the population to consume greater amounts of the 'fortified' rice. Higher consumption of white rice is associated with a significantly increased risk of type 2 diabetes, especially in Asian (Chinese and Japanese) populations (Hu 2012).
Micronutrient deficiencies of public health significance are all widespread in most high rice consuming countries (Juliano 1993; Adamson 2004) and rice fortification has the potential to fill an obvious gap in current nutrition programmes and help aid vulnerable populations that are currently out of reach. A fundamental requirement in the adoption of food fortification as a public health intervention is the selection of the most appropriate and suitable food that will serve as a vehicle for the extra nutrients. It needs to be eaten in large amounts by the target population and be affordable and available all year round (Dexter 1998; WHO/FAO 2006). Although almost all foods can be fortified, cereals are widely grown, produced and consumed in developing countries (Welch 1999), making them important vehicles for fortification. Improving the micronutrient content of cereals or their subproducts could provide a sustainable solution to the worldwide problem of micronutrient deficiencies, particularly in populations where there is a marked social characterization of eating habits (Prattala 2012) and where the fortified foods will be reaching those in need of the vitamins and minerals. Poor children and their mothers systematically lag behind the better-off in terms of mortality, morbidity and undernutrition. Evaluations of the equity impact of health programmes and nutrition interventions are scarce. There are, however, some results suggesting that innovative approaches can effectively promote equity through, for example, employing appropriate delivery channels; removing financial barriers; and monitoring implementation, coverage and impact with an equity lens. Mandatory fortification of staple foods being consumed by the most vulnerable segments of the populations would potentially provide vitamins and minerals to those in a vulnerable situation (WHO 2010), although it is clear that tackling inequities requires the involvement of various programmes and stakeholders, both within and outside the health sector, that can help address social determinants (WHO 2010).
How the intervention might work
Rice is a globally produced, milled and traded staple food with an annual production and consumption worldwide of about 450 million metric tons. It is the dominant staple food crop of around three billion people worldwide, providing up to 50% to 60% of their daily energy and protein intake (IRRI 2010). Rice is cultivated in almost all parts of the world as it can grow in a wide range of soil and environmental conditions (Juliano 1993). It is estimated that 95% of the world's rice is produced in developing countries, of which 92% takes place in Asia (Juliano 1993). With its popularity, reach and quantum of consumption, rice far exceeds the requirements for adoption as a vehicle for food fortification for the purposes of a population-level intervention.
Globally, the main rice processing method is milling. The process is aimed at producing a maximum yield of unbroken milled rice compared to flour or meal in other cereals (Dexter 1998). The process involves cleaning the paddy or rough rice (unhulled rice grain) and de-hulling (removing hull, germ and bran layers) to produce brown rice (Dexter 1998). Brown rice consists of an average weight of 6% to 7% bran, 90% endosperm and 2% to 3% embryo (Saunders 1979). Further milling to remove the bran layer yields white rice. On average, paddy rice produces 25% hulls, 10% bran, and 65% white rice (Chen 1998). In some countries the milled white rice is coated with talc and glucose to improve its appearance (Dexter 1998). The various forms of rice are presented in Table 1. Milled white rice is low in vitamins and minerals as these vitamins (B vitamins) and minerals (iron) are found predominately in the germ and bran layers (Kik 1945; Dexter 1998). Parboiling is one of the ways by which nutrients in the rice grain can be partially preserved. The parboiling process of soaking the rough rice, applying heat, drying and milling results in the transfer of nutrients to the inner endosperm layer from the bran before milling (Dexter 1998). Parboiling is expensive and the end product, referred to as ‘golden colour rice’, may not be readily acceptable to consumers (Dexter 1998).
|Forms of rice||Description of rice|
|Rough rice (paddy rice)||Rice kernels still enclosed in an inedible, protective hull|
|Brown rice||Rice with only the hull removed. Bran layers and rice germ remain, giving the rice a brown colour|
|Parbolied rice||Rice pressurized to gelatinised the starch within the rice kernel, resulting in a firmer,more separate grain that is more stable and less susceptible to overcooking than regular-milled white rice|
|Regular-milled white rice (Milled rice)||Polished whole rice, or polished rice. hull, bran layer and germ have all been removed|
|Precooked rice||Regular milled white rice, parboiled milled white rice, and brown rice can be precooked and dehydrated before packaging. Examples of precooked rice are quick-cooking rice, instant rice, and boil-in-the-bag rice|
|Individually Quick Frozen (IQF) rice||Cooked grains are individually frozen before packaging|
|Crisped/Puffed/Expanded Rice||Kernels can be processed in a number of different ways and shapes to meet particular manufacturing need|
Previous attempts to fortify rice by simply adding a micronutrient powder to the rice that adheres to the grains by electrostatic forces (dusting) have proven unsuccessful (Leon Guerrero 2009) due to the typical washing and cooking methods employed in most developing countries, which results in the rinsing away of the enrichment. Three more sophisticated methods have been developed to overcome this problem (A2Z Project 2008). Coating involves spraying of the surface of ordinary rice grains in several layers with a vitamin and mineral mix to form a protective coating that will not easily rinse off the surface when washed (Kyritsia 2011). The grains (fortified premix) contain high concentrations of vitamin and mineral fortificants and must be blended with natural rice (that is commonly 1 part fortified premix to 199 parts untreated milled rice) to produce fortified rice. The extrusion technology is a totally different concept in rice fortification. In hot extrusion, a dough made of rice flour, vitamin and mineral mix and water is passed through a single or twin screw extruder and shaped into partially precooked grain-like structures resembling rice grains; that is then blended with natural polished rice at a ratio of about 1:200 to produce fortified rice. This process involves relatively high temperatures (70 to 110 °C) obtained by preconditioning or heat transfer through steam heated barrel jackets, or both. The cold extrusion follows a similar process at low temperature (below 70 °C) that does not primarily utilize any additional heat and produces uncooked, opaque fortified premix grains with a slightly softer consistency. This is then blended with natural polished rice at a ratio of about 1:200 to produce fortified rice.
Rice is a highly culturally sensitive commodity (Hariyadi 2011). Growing, selecting and cooking of rice grains are subject to regional, national and even local preferences. It is estimated that a large proportion of key vitamins and minerals are lost during milling (DSM/Buhler 2010). Additionally, rinsing and washing are common cooking methods which can potentially dissolve added or restored nutrients. There are many different ways of cooking rice. These are i) soaking, and boiling with excess water; ii) boiling in excess water; iii) boiling without excess water; iii) rinsing and boiling without excess water; and iv) frying and boiling without excess water. The use of these cooking preparations could have different retentions of micronutrients in fortified rice kernels as some vitamins are sensitive to heat and others are water-soluble (WHO/FAO 2006). Cultural preferences for specific types of rice characteristics may represent a barrier to mass fortification in some settings. A technical challenge is to produce fortified rice that resembles natural rice and resists normal meal preparation and cooking processes.
A study conducted as far back as 1948 in the Philippines demonstrated the effects of rice fortification in the prevention of beri-beri (Salcedo 1950). In Brazil, a bioavailability trial with vitamin A fortified rice showed an improvement in children's retinol levels (Flores 1994). Another study among young children from 6 to 24 months of age in Brazil found that rice fortified with micronized iron pyrophosphate was more effective than iron drops in decreasing anaemia from 100% to 62% and iron deficiency from 69% to 25% and improving iron status (Beinner 2010). In a study in India, fortified rice in school age children attending school showed a reduction of iron deficiency anaemia from 78% at baseline to 25% in the iron group (Moretti 2006). In another setting, the feeding of rice fortified with microencapsulated, micronized iron pyrophosphate to improve the iron status of women in Mexico showed significant increases in plasma ferritin concentrations and estimated body iron stores as well as a significant decrease in plasma transferrin receptor concentrations. Fortified rice reduced the prevalence of anaemia by 80% and iron deficiency by 29% in Mexican women working in a factory (Hotz 2008).
This proposed review will attempt to evaluate, based on existing research, the effectiveness of rice fortification as a public health intervention. The WHO/CDC logic model for micronutrient interventions in public health depicts the programme theory and plausible relationships between inputs and expected improvements in Millenium Development Goals (MDGs) and can be adapted to different contexts (WHO/CDC 2011). The effectiveness of rice fortification in public health depends on several factors related to policies and legislation regulations; production and supply of the fortified rice; the development of delivery systems for the fortified rice; the development and implementation of external and internal food quality control systems; and the development and implementation of strategies for information, education and communication for behaviour change among consumers. A generic logic model for micronutrient interventions that depicts these processes and outcomes is presented in Figure 1.
Why it is important to do this review
Vitamin and mineral deficiencies are important public health concerns worldwide. Among the options to address these deficiencies, mass fortification represents an appealing intervention as it takes advantage of the existing market and delivery systems, does not require the active participation of vulnerable populations to increase foods intake or diversify the diet, and has few safety concerns. Rice represents a suitable vehicle for fortification as it is considered a staple food in most of the world, especially in regions where micronutrient deficiencies are most evident.
Wheat and maize flour fortification with iron alone, or in combination with folic acid and other micronutrients, has been implemented in more than 50 countries (CDC 2008; WHO 2009b) and is showing promising results in reducing anaemia and neural tube defects. Based on this experience, an increasing number of countries across the world are rapidly adopting fortification of rice as a means to fight malnutrition. Mandatory fortification of rice has been adopted in some countries, such as the Philippines, Costa Rica, Papua and Nicaragua (GAIN 2010). Fortified rice is sold in China using a multi-micronutrient formula and in Japan enriched rice has been on the market since 1981. The United States has a mandatory food standard for 'enriched rice', prescribing levels of thiamin, niacin, riboflavin, folic acid and iron to be added to rice for enrichment. Although this requirement only applies in order for rice to be labelled as 'enriched; (FDA 2001), 70% of the rice eaten in that country is enriched or fortified (American Rice Inc. 2004; A2Z Project 2008). In India, Brazil and Colombia, fortified rice is currently being distributed through public safety net programs.
Despite this interest, to date there has been no systematic assessment of the benefits and harms of this intervention to inform policy making and assist countries in the design and implementation of appropriate food fortification programmes.