Proposing nutrients and nutrient levels for rice fortification

Transcription

1 Ann. N.Y. Acad. Sci. ISSN ANNALS OF THE NEW YORK ACADEMY OF SCIENCES Issue: Technical Considerations for Rice Fortification in Public Health Proposing nutrients and nutrient levels for rice fortification Saskia de Pee 1,2 1 Nutrition Advisory Office, World Food Programme, Rome, Italy; and 2 Friedman School of Nutrition Science and Policy, Tufts University, Boston, Massachusetts Address for correspondence: Saskia de Pee, Office of the Nutrition Advisor, World Food Programme, Via Cesare Giulio Viola 68/70, Rome, Italy. Saskia.depee@wfp.org Micronutrient deficiencies are often linked to low dietary diversity. Rice fortification could substantially increase micronutrient intake in countries where rice is a staple food. The World Health Organization (WHO) interim consensus statement on maize and wheat flour fortification is based on the premise of the public health importance of specific micronutrient deficiencies and evidence of the benefits of increased micronutrient intake. Since this rationale for maize and wheat flour also applies to rice, it is recommended to fortify rice with iron, folic acid, vitamin B12, vitamin A, and zinc, as well as with thiamin, vitamin B6, and niacin, as polished rice has low levels of these micronutrients. To achieve intake that meets the estimated average requirement of adults, the following levels are recommended where rice consumption is g/cap/day (mg/100 g): iron, 7; folic acid, 0.13; vitamin B12, 0.001; vitamin A, 0.15; zinc, 6; thiamin, 0.5; niacin, 7; and vitamin B6, 0.6. These concentrations can be achieved at a 1:100 blending ratio of fortified:unfortified kernels. The costs of rice fortification are largely determined by the manufacturing of the fortified kernels rather than by the number of micronutrients that are added. These are general recommendations that can be adjusted locally, and monitoringand impact evaluation shouldaccompany the introduction of rice fortification. Keywords: rice fortification; micronutrient deficiencies; rice-consuming populations; staple food fortification Introduction Micronutrient malnutrition affects approximately two billion people worldwide, with the main cause being inadequate dietary micronutrient intake that is linked to low dietary diversity. Fortifying foods that are consumed by the majority of a population has proven to be a good strategy to reduce the risk of micronutrient deficiencies in middle- and highincome countries where consumption of processed foods is common. Food fortification is also increasingly used in developing countries and includes foods such as wheat and maize flour, cooking oil, salt, sugar, powdered milk, margarine, and specially formulated foods for specific target groups. Fortification of rice is not yet practiced at a large scale. Rice, maize, and wheat are the staple foods for two-thirds of the world s population, 1 and nearly half of the world s population consumes rice as a staple food. 2 Worldwide, annual rice consumption is more than 440 million metric tons (1000 kg). 3 Unprocessed paddy rice is a good source of thiamine (vitamin B1), niacin (vitamin B3), and vitamin B6. 4 However, due to dehulling, milling, washing, and cooking, polished rice is a poor source of micronutrients. 4 6 In 24 countries, rice provides at least one-third of the daily caloric intake (i.e., at least 70 kg/cap/year or 200 g/day). 7 In Southeast Asian countries, the average per capita rice consumption is 130 kg/year or 360 g/day, providing nearly two-thirds of caloric intake. 8 The high consumption of rice reflects a lack of dietary diversity, which, when combined with the poor micronutrient content of polished rice, is a risk factor for low micronutrient intake. Rice fortification has the potential to substantially increase micronutrient intake among populations that consume rice as a staple food. Fortification levels need to be such that they substantially contribute to micronutrient intake, are safe at higher levels of consumption in the population, and the fortified rice has to be palatable, have a long shelf-life, and be indistinguishable from unfortified rice. doi: /nyas Ann. N.Y. Acad. Sci (2014) C 2014 New York Academy of Sciences. 55

2 Nutrient levels for rice fortification de Pee These principles, which have been well described in the World Health Organization (WHO)/Food and Agriculture Organization (FAO) guidelines on food fortification with micronutrients, are similar to those of fortification of other foods. 5 Two studies that specifically assessed consumer acceptability of fortified rice found high levels of acceptance. 9,10 Furthermore, a recent review by Muthayya et al. summarized the evidence of biological effects of rice fortification, and this also appears to indicate that study participants did not have difficulties consuming fortified rice. 11 From a public health and nutrition point of view, the fortification of rice is similar to the fortification of wheat and maize flour, as these are also major staple foods for large numbers of people. From a technical and practical point of view, however, fortifying flour is very different from fortifying rice. Rice fortification occurs in two steps (except when dusting is used to fortify rice, but this is not an adequately robust technology). 6,7,11 First, fortified rice kernels are produced through extrusion and coating that resemble as closely as possible the rice kernels that they will be mixed with. Second, the fortified kernelsaremixedataricemillwithnormalriceat a ratio of, for example, 1:100, to create the fortified rice that will be consumed. Thefocusofthispaperistoproposenutrientcontent targets for rice fortification, considering (1) the micronutrient needs of populations for whom rice is a major staple food; (2) the micronutrient content of commonly consumed unfortified rice; (3) rice consumption levels; and (4) the technical feasibility of adding different micronutrients to fortified rice kernels. For a more detailed discussion of the latter, the reader is referred to Steiger et al. 12 Considering micronutrient needs of populations for whom rice is a major staple food The goal of a fortification program is to prevent deficiencies of micronutrients for which the daily dietary requirements are not routinely met. For fortification of staple foods and condiments, the likelihood of dietary deficiencies for different target groups in a population needs to be considered and, at the same time, excess intake among individuals with a high intake of the staple food or condiment needs to be avoided. In this regard, the comprehensive reviews that were done for The Second Technical Workshop on Wheat Flour Fortification: Practical Recommendations for National Application in 2008 in Stone Mountain, Georgia, which then led to the WHO interim consensus statement for wheat and maize flour fortification, 18 are a good starting point. There are a number of important points to note with regard to the papers prepared for that technical workshop and the interim consensus statement: (1) it focused on wheat flour fortification but then also extended its recommendations to maize flour; (2) the micronutrients considered for fortification were those that are of major public health importance (i.e., iron, folic acid, zinc, vitamin A, and vitamin B12); (3) the focus was on recommending fortification levels for developing countries and a wide range of wheat and maize flour consumption levels was considered; (4) technical aspects, such as the availability of compatible fortificant forms and the effects on sensory and shelf-life characteristics, were also considered; and (5) the recommendations are general recommendations that need to be adapted to local contexts on the basis of specific information on micronutrient intake and consumption levels of the food vehicle(s) among different groups of the population. Here, we will first assess from a public health and nutrition point of view whether the findings and recommendations from reviews on the nutrient content of fortified wheat and maize flour (Table 1) can also be applied to rice, considering population nutrient needs. We will then consider whether there are differences between wheat flour and rice in nutrient content and technological aspects that warrant modification of the recommendations made for flour, before applying them to rice. Which nutrients should be considered for food fortification in developing countries? A high prevalence of stunting among children under 5 years of age, and of anemia among those under 5 years old or among women of reproductive age, both indicate that micronutrient deficiencies are highly prevalent in that particular population. 19 Also, when people largely rely on an unfortified staple food for most of their caloric intake and, at the same time, consume a limited variety of other foods, for example, some vegetables and fruits and few animal sources and fortified foods, micronutrient deficiencies are very likely. 20,21 Solomons, in an 56 Ann. N.Y. Acad. Sci (2014) C 2014 New York Academy of Sciences.

3 de Pee Nutrient levels for rice fortification Table 1. Average levels of nutrients to consider adding to wheat or maize flour on the basis of extraction, fortificant compound, and estimated per capita flour availability 18 Level of nutrient to be added in parts per million (ppm) by estimated average per capita wheat flour availability (g/d) a Nutrient Flour extraction rate Compound <75 g/d b g/d g/d >300 g/d Iron Low NaFeEDTA Ferrous sulfate Ferrous fumarate Electrolytic iron NR c NR c High NaFeEDTA Folic acid Low or high Folic acid Vitamin B12 Low or high Cyanocobalamin Vitamin A Low or high Vitamin A Palmitate Zinc d Low Zinc oxide High Zinc oxide a These estimated levels consider only wheat flour as the main fortification vehicle in a public health program. If other mass-fortification programs with other food vehicles are implemented effectively, these would suggest that fortification levels may need to be adjusted downwards as needed. b Estimated per capita consumption of <75 g/d does not allow for the addition of sufficient levels of fortificant to cover micronutrient needs for women of childbearing age. Fortification of additional food vehicles and other interventions should be considered. c Not recommended (NR) because the very high levels of electrolytic iron needed could negatively affect sensory properties of fortified flour. d These amounts of zinc fortification assume 5 mg of zinc intake and no additional phytate intake from other dietary sources. article about the rationale for fortification in Asia, clearly shows that it is virtually impossible to complement diets in which refined rice, wheat, and/or maize provide approximately 70% of energy, with foods that collectively fulfill the remaining micronutrient gap while providing only 30% of the energy requirement, regardless of purchasing power. 20 The reviews conducted for the wheat fortification workshop assessed the evidence for dietary deficiencies of iron, vitamin A, folic acid, zinc, and vitamin B12 in developing countries, and for each nutrient it was concluded, from sources of information that ranged from nutritional status to dietary intake assessments, that deficiencies are widespread, affecting several population groups. The reviews also found that there are few population-based nutrient intake data available to (1) assess the prevalence and extent of low intake among different population groups and (3) determine the gap between actual and recommended intake. The first type of information is required to decide whether increasing intake through fortification is likely to benefit many people and the second type is required to decide on the nutrient level for fortification. Proxy indicators were therefore used to determine that fortification with specific nutrients is likely beneficial in a wide range of populations. These included anemia and iron deficiency for iron; 13 vitamin A deficiency and responses to supplementation or fortification with vitamin A; 14 the effect of fortification of flour with folic acid on the incidence of neural tube defects (NTDs) at birth in many countries; 15 a reduction of mortality and diarrhea and improvement of growth as a response to zinc supplementation (estimating that one-third of the world s population lives in a country with an elevated risk of zinc deficiency); 16 and the fact that vitamin B12 is only contained in animal source foods, of which consumption is low in many populations. 17 These rationales for the recommendation to fortify food with iron, vitamin A, folic acid, zinc, and vitamin B12 apply regardless of the vehicle(s) for fortification, but implementation is, of course, dependent on whether it is technically feasible to Ann. N.Y. Acad. Sci (2014) C 2014 New York Academy of Sciences. 57

4 Nutrient levels for rice fortification de Pee fortify a specific vehicle with these nutrients. For this reason, we should assess whether rice, like wheat and maize flour, could be a vehicle for delivering these nutrients and whether the same levels proposed for flour would be appropriate and feasible in rice. In addition to the nutrients recommended for flour fortification, it should also be considered whether it may be necessary to add additional micronutrients, particularly for populations that consume rice as their main staple food. Few data are available on intake of other micronutrients among populations consuming rice. The Food and Nutrition Technical Assistance (FANTA) project, funded by the United States Agency for International Development (USAID), conducted a detailed nutrient intake analysis on data collected by the International Food Policy Research Institute (IFPRI) in among nonpregnant lactating and nonlactating women in Bangladesh (total n = 111 and n = 299, respectively) who were enrolled in different programs. 22 For these women, grains and grain products (mainly rice and some wheat) provided 84.2% of their energy intake as well as a large share of their micronutrient intake, indicating very low dietary diversity. Intake of iron, vitamin A, folic acid, and vitamin B12, as well as of thiamin, riboflavin, niacin, vitamin B6, vitamin C, and calcium, were adequate for 0 36% of lactating women and for 2 53% of nonlactating women, except for vitamin B6, of which intake was adequate for 82% of this group. Zinc intake was adequate for 94% and 92% of women, respectively. Whether bioavailability of zinc was adequate was not assessed. For this population, fortifying with all nutrients assessed, except zinc, would be worthwhile, but not all may be feasible (see below). For zinc, possible bioavailability issues would have to be assessed as well as the prevalence of deficient zinc status among other groups of the population. Household economic survey data (Survei Sosial Ekonomi Nasional, SUSENAS) collected in 1993, 1996, 1999, and 2002 from Indonesia showed that cereals, particularly rice, provided 66 67% of household food intake (weight %) between 1993 and 1999 and 63% in 2002, while oil, fat, and sugar provided another 15% in Meat, fish, vegetables, fruits, legumes, tubers, and pulses together provided 20% of food intake by weight, which is unlikely to compensate for the relatively low micronutrient content of refined unfortified cereals, oil, and sugar. A prevalence of stunting of 36% 24 among children under 5 years old confirms that nutrient deficiencies are widespread in Indonesia. Especially affected are lower income groups, who consume a less diverse diet and have limited access to animal sources and fortified foods. 25 A food composition analysis of foods consumed by older infants (6 12 months) in Lombok, Indonesia, found that zinc, iron, and calcium content was highest in fortified complementary foods, lower in legumes (peanuts, mung beans, soybeans, and soybean products), and lowest in rice. 26 However, the legumes also had a high concentration of phytate, which limits mineral absorption. This illustrates the importance of fortification of complementary foods forthisagegroupandcanbeextendedtofortification of foods consumed by the general population for other age groups. Karen refugees on the Thai Burmese border rely on a diet largely consisting of polished rice and fermented fish paste, which is deficient in several micronutrients. In the late 1980s, thiamin deficiency was recognized to be a major cause of infant mortality in this population and supplementation of pregnant women with 100 mg thiamin/day was started. 27 A study conducted in 2004 of lactating mothers who received during pregnancy a food ration consisting of polished rice, mung beans, fermented fish, soybean oil, and dried chilies, as well as split mung beans, dried fish, and a supplement of iron, folic acid, and thiamine, found a high prevalence of iron and zinc deficiencies as well as anemia, but not thiamine deficiency. 28 Serum retinol, vitamin E, and copper levels were adequate and no other micronutrients were assessed. These findings suggest that the thiamine supplements were effective at preventing deficiency, but compliance with iron/folic acid supplements may have been lower, and the zinc from the food ration was not adequately absorbed. 28 After a fortified wheat soy blend was added to the food ration, replacing part of the mung beans and some of the rice, iron and zinc deficiencies were reduced and thiamine status improved further. 28 These studies among Karen refugees confirm deficiencies of thiamine, iron, and zinc in a diet that largely consists of polished rice. An analysis of household expenditure and food consumption data from Vietnam showed that per capita intake is below requirements for large proportions of the population: 87% for calcium, 58 Ann. N.Y. Acad. Sci (2014) C 2014 New York Academy of Sciences.

5 de Pee Nutrient levels for rice fortification 80% for iron, 88% for vitamin A, 31% for thiamin, 98% for riboflavin, 73% for niacin, and 83% for vitamin C. 29 A micronutrient survey conducted in 2010, however, concluded that the prevalence of anemia and iron deficiency in Vietnam has been markedly reduced over the last decade, but a large part of the population is still at risk for other deficiencies such as zinc, vitamin A, folate, and vitamin B12 especially the youngest children aged 6 17 months. Consequently specific interventions to improve food diversity and quality should be implemented, among them fortification of staple foods and condiments and improvement of complementary feeding. 30 And in a subsequent article, the authors note that among young children median intake of iron, vitamin A, zinc, thiamin, and riboflavin meets 16 48%, 14 49%, 36 46%, %, and 50 68% of the Vietnamese recommended dietary intake, respectively, depending on specific age group. 31 For nonpregnant women, these figures were as follows: 38%, 61%, 92%, 85%, and 60%, respectively (unpublished observations). When the authors then modeled the fortification of some of the main foods (rice, wheat, oil, sauces), they found that for womenaswellasforchildrenyoungerthan5years old, these items can make a substantial contribution to their micronutrient intake and bring them closer to meeting their requirements. 31 For rice and wheat flour, the authors modeled the following fortification levels: iron, 4 mg/100 g for both foods; zinc, 0.5 and 5 mg/100 g, respectively; and folic acid, 0.05 and 0.5 mg/100 g, respectively. The lower levels for rice take the higher consumption levels into account (>300 g/cap/day), whereas for flour the lowest level (<75 g/cap/day) is used. However, when both items would be fortified, the flour fortification level should take into account that rice is also fortified. 18 Preferred nutrients for fortifying rice On the basis of these findings from very diverse settings, the most comprehensive mixture of micronutrients for fortifying rice would depend on country needs and could, in principle, include the same nutrients as those recommended for wheat and maize flour (i.e., iron, zinc, folic acid, vitamin A, and vitamin B12), as well as thiamin, niacin, and vitamin B6. The reasons to also suggest thiamin, niacin, and vitamin B6 include the documented low intake in a range of populations discussed above, the fact that these vitamins are lost to a large extent when paddy rice is dehulled and milled into polished rice and that the content of these vitamins is higher in unfortified, wheat, and maize flours compared to white rice (Table 2). This effect of polishing is well known from the discovery of the cause of beriberi in the early 1900s by Eijkman, who found out that the disease was related to consumption of polished rice. Later, it was determined that the polished rice, in contrast to brown rice, contains much less thiamine and that thiamine deficiency is the cause of beriberi. 32 Beriberi is rare if the rice is parboiled or enriched. However, when polished rice is consumed and thiamine intake from other food sources is limited, thiamine deficiency can still occur. Beriberi also occurs among alcoholics. Data shown in Table 2 confirm that thiamine content of white rice is considerably lower than that of maize and wheat flours. Furthermore, it should be noted that most of the ongoing rice fortification programs fortify rice with iron, zinc, thiamin, niacin, and folic acid; some also add vitamin B12, and fortification with vitamins A and E and selenium has also been reported. 11 While the above referenced studies also documented low intakes of riboflavin, vitamin C, and calcium, adding these nutrients to rice is difficult. For example, riboflavin colors the kernel, which is not desirable for most rice fortification interventions. Vitamin C fortification is not recommended for staple food vehicles because of large losses that occur during cooking, and for calcium only relatively small amounts can be added compared to requirements. 12 Furthermore, Steiger et al. mention that it would also be technically possible to fortify rice with vitamins D and K, as well as with lysine. 12 Although experience fortifying rice with these nutrients is limited, it is worth considering where deficiencies are likely. Recommendations for the levels at which the specific nutrients can be added to rice are discussed below. For technical feasibility, the reader is referred to Steiger et al. 12 At what level should the proposed nutrients be added to rice? As mentioned above, the WHO/FAO recommends setting fortification levels on the basis of the following steps: measure daily intake of specific micronutrients among population groups at risk of deficiency; estimate bioavailability of the micronutrients from the local diet; compare intake Ann. N.Y. Acad. Sci (2014) C 2014 New York Academy of Sciences. 59

6 Nutrient levels for rice fortification de Pee Table 2. Content of selected nutrients of white rice, brown rice, parboiled white rice, white rice flour, whole-grain wheat flour, whole-grain white corn flour, and whole-grain yellow corn flour 46 White rice Brown rice White parboiled rice White rice flour Whole-grain wheat flour Wholegrain, white corn flour Wholegrain, yellow corn flour Water g Energy kcal Protein g Fat g Carbohydrates g Iron mg Vitamin A (RAE) g Zinc mg Folate (DFE) g Vitamin B12 g Thiamin mg Niacin mg Vitamin B6 mg Riboflavin mg Vitamin C mg Calcium mg Vitamin D g Vitamin K g na na Vitamin E mg na na Magnesium mg Phosphorus mg Potassium mg or estimation of absorbed amount of the nutrient, in the case of iron and zinc, to requirements; on the basis of this comparison, calculate the amount of the nutrient that is lacking in the diet; and then set the fortification level, considering total intake of the fortifiable food by the at-risk population group, for example, women of childbearing age. 5 Unfortunately, few countries have data available that allow them to follow this procedure. Below, for each nutrient recommended for wheat and maize flour fortification, we review how the levels were determined and whether they could also be applied to rice fortification. Iron According to Hurrell et al., fortification levels for iron in wheat flour, and extended to maize flour, were recommended on the basis of experimental evidence and pragmatism. 13 Experimental studies with different iron forms and different types and levels of consumption of food vehicles among different population groups formed the basis for the recommended levels of different iron fortificants in high- and low-extraction flour, by different flour consumption levels, that are expected to result in an improvement of iron status of the population, as summarized in the WHO interim consensus statement (Table 1). Bioavailability of iron is an important factor affecting its absorption and hence affect iron status. In cereal foods, phytate is the most important absorption inhibitor, binding nonheme iron, zinc, and calcium in an insoluble complex in the intestine, making it unavailable for absorption. 33,34 The molar ratio of phytate to iron should be 1inorderto allow iron to be absorbed. 35 This is equivalent to a minimum iron content of 8.4 mg/100 g for a food that has a phytate content of 0.1% (100 mg/100 g food). Naturally, almost all foods have a phytate content higher than 0.1%, 34,36 38 and their iron content is usually substantially lower than 8.4 mg/100 g. For rice, levels of phytate reported in the literature 60 Ann. N.Y. Acad. Sci (2014) C 2014 New York Academy of Sciences.

7 de Pee Nutrient levels for rice fortification range from 0.87 to 3.7 mg/g of dry matter, which equals % And even though polished rice has a relatively low phytate content, rice-based meals may have a higher phytate content, especially when they include lentils and/or legumes. Phytic acid content can be reduced by germination, fermentation, or soaking, which makes the phytate leak out of the food. For rice, soaking is sometimes practiced, but washing alone does not allow sufficient time to reduce phytate content. Other options include concurrent intake of vitamin C or ethylenediaminetetraacetic acid (EDTA), which can counteract the impact of phytate. EDTA is well known for its application as a source of bioavailable iron (iron EDTA) that is particularly recommended for fortifying high-extraction flour, which has a high phytate content. 18 Animal tissue also increases absorption of nonheme iron. White flour has an extraction rate of 72%, whereas whole-meal flour has an extraction rate of 100%. For the low- and high-extraction rates mentioned in the interim consensus statement, extraction rates of 75% and 90%, respectively, were assumed, corresponding with a phytate content around 0.12% and 0.3%, respectively, 39 which is comparable to what has been reported for rice When rice has been well polished, its phytate content is comparable to that of low-extraction wheat flour. For high-extraction flour, only iron EDTA is recommended as an iron fortificant. For low-extraction flour, iron EDTA, ferrous sulfate, ferrous fumarate, and electrolytic iron can be used, unless flour consumption is below 150 g/day, in which case electrolytic iron is not recommended because the high concentration required would affect taste. 18 For rice, few options exist for the iron fortificant. Moretti et al. explored the effect of adding different forms of iron to extruded rice, using different processing techniques, on color, texture, loss by rinsing, and sensory characteristics. 40 They found that only ferric pyrophosphate was acceptable because all other compounds (electrolytic iron, encapsulated ferrous sulfate in hydrogenated palm oil or in liposome, iron EDTA, and ferrous sulfate) colored the rice brown or gray. Among the different forms of ferric pyrophosphate used, reagent-grade ferric pyrophosphate, which is purer than food grade, caused the least coloration. Other compounds that are currently being investigated include ferrous orthophosphate and ferrous fumarate. When ferric pyrophosphate was applied at a higher concentration (1 g/100 g vs. 0.5 g/100 g), coloration slightly increased but did not do so for reagent-grade ferric pyrophosphate. 40 Taking bioavailability into account, Moretti et al. recommend using micronized ferric pyrophosphate (particle size of 0.5 m has relative bioavailability (RBV) of 95% compared to ferrous sulphate) or higher concentrations of 2.5 m or regular-sized ferric pyrophosphate (RBV of 70% and 45 58%, respectively). 40 Fortifying kernels with 0.5 g Fe/ 100 g and mixing them at a 1:100 ratio gives a concentration of 5 mg Fe/100 g rice. Adding 0.7 g Fe/100 g can also be done with a low possibility of being able to identify the fortified kernels (personal communication, DSM). In addition, whether one can distinguish the fortified kernels depends on the color of the unfortified rice. If a still higher concentration is desired, without increasing the iron concentration in the fortified kernels, the blending ratio can be increased, for example, to 1:50. Because iron deficiency and anemia are important reasons to implement rice fortification, there is limited data on the effectiveness of iron fortification of rice, the choice of iron compounds suitable for rice fortification is very limited, and bioavailability of ferric pyrophosphate (nonmicronized) is lower than that of ferrous sulphate, the recommended iron fortification level has been set at 7 mg/100 g for both the g/day and >300 g/day categories (Table 3). For the <75 g/day and g/day categories, the level is almost twice as high. It is important to note that these levels require blending at a higher ratio, such as 1.5:100 in order not to have a fortified kernel that can be distinguished from unfortified kernels. Also, organoleptic properties of this concentration need to be assessed. With regard to phytate affecting the absorption of fortification with iron, this effect is greatest when the phytate content of the rice is higher and when iron fortification is applied to all of the rice that is consumed, as opposed to, for example, consuming one special meal of iron-fortified rice per day or week. The latter was done to the extreme in Brazil, as reported in a recently published paper by Arcanjo et al. who provided one fortified rice meal per week containing 56.4 mg iron in 50 g of rice. 41 This is equivalent to 113 mg iron per 100 g and was achieved by blending fortified kernels with unfortified ones at a ratio of 6:100. This means that Ann. N.Y. Acad. Sci (2014) C 2014 New York Academy of Sciences. 61

8 Nutrient levels for rice fortification de Pee Table 3. Nutrient levels proposed for fortified rice at moment of consumption (mg/100 g) g Nutrient Compound a <75 g/d g/d g/d >300 g/d EAR b Iron c Micronized ferric pyrophosphate Folic acid d Folic acid Vitamin B12 d Cyanocobalamin Vitamin A d Vitamin A palmitate (f) (m) Zinc e Zinc oxide (f) 11.7 (m) Thiamin f Thiamin mononitrate (f) 1.0 (m) Niacin f Niacin amide (f) 12 (m) Vitamin B6 f Pyridoxine hydrochloride a Source: Steiger et al. 12 b It is important to note that these fortification levels aim at providing the EAR (estimated average requirement) by the particular food, which is in line with the WHO/FAO guidelines for micronutrient fortification. 5 When other mass fortification programs are implemented effectively as well, the suggested fortification levels may have to be adjusted downwards. c Concentration of 7 mg/100 g is proposed for both the g/d and >300 g/d categories because there are limited data about the effectiveness of iron fortification of rice, choice of iron compounds suitable for rice fortification is limited, and iron deficiency and anemia are important reasons to implement rice fortification. For the <75 g/d and g/d categories, the level is almost twice as high. It is important to note that these levels require blending at a higher ratio, such as 1.5:100 or 2:100 in order not to have a fortified kernel that can be distinguished from unfortified kernels. Also, organoleptic properties of this concentration need to be assessed. d Concentrations are the same as recommended for wheat and maize flour. 16 e Concentrations have been set between those recommended for high- and low-extraction flours and at a level that keeps the ratio with iron close to 1. f Concentrations have been set such that they provide the EAR, which is comparable to the levels proposed for folic acid and vitamin B12. g These are targets for consumption. Overages may be added for specifications for production, and ranges can be set for assessing compliance with specifications. the concentration of iron in fortified kernels was 1880 mg/100 g, which results in a colored kernel. At this concentration, the phytate:iron molar ratio, assuming a phytate content of 0.1%, is 0.07, which is much below 1 and iron absorption is therefore not reduced by the phytate content. However, as staple food fortification is rarely applied to a single meal per day or week, the results of this study are not applicable to typical staple food fortification. Vitamin A Klemm et al. reviewed the literature and experience with vitamin A fortification to propose a level of vitamin A fortification for wheat flour. 14 Widespread prevalence of vitamin A deficiency and demonstrated effectiveness of fortification of food items, such as sugar and monosodium glutamate, are reasons to recommend vitamin A fortification. The level should best be set on the basis of data on the distribution of vitamin A intake among different population groups, where the distribution is shifted such that <3% has an intake below the estimated average requirement (EAR). However, where availability of such data is limited, another approach that can be taken is to set the intake target from fortification at the amount required to close the gap between mean or median vitamin A intake and the recommended nutrient intake (RNI). This assumes that intake levels will then be more or less normally distributed around the RNI with a small proportion being below the EAR Ann. N.Y. Acad. Sci (2014) C 2014 New York Academy of Sciences.

9 de Pee Nutrient levels for rice fortification For vitamin A, the tolerable upper limit of intake (UL) is relatively close to the RNI, which often raises concerns when considering vitamin A fortification. It is important to note that the UL is the highest level of daily nutrient intake that is likely to pose no risk of adverse health effects to almost all individuals (97.5%) in the general population and applies to daily use for a prolonged period of time. It also applies to normal, healthy individuals with adequate stores and no deficits to be corrected; and acute toxicity occurs at much higher levels. 42 For vitamin A, the high-dose capsules that are provided every 4 6 months to young children contain a much higher dose than the UL, and this practice is considered safe. Also, the UL only applies to preformed vitamin A, because provitamin A carotenoids are only converted to retinol when the body requires it, and in developing countries, most dietary vitamin A intake is in the form of provitamin A from plant source foods. In practice, most vitamin A fortification programs have sought to deliver 30 60% of the RNI to specific population groups. 43 According to Klemm et al., provision of 15 50% of the RNI can be expected to meet both nutritional and safety goals, 14 and the levels put forward by them and included in the WHO interim statement provide approximately 25% of the RNI to adult women, preschool-aged, and school-aged children. The same vitamin A fortification level can be targeted for rice (Table 3). Zinc Brown et al. modeled required zinc content of fortified wheat flour using different assumptions for zinc and phytate content of the regular diet and of fortifiable wheat flour, in order to arrive at a total absorbed zinc content from the daily diet, including fortified wheat flour, that would meet the requirements of adult men. 16 The levels in the WHO interim statement were proposed on the basis of an assumed zinc intake of 5 mg from the existing diet and no phytate other than from wheat flour, and the maximum content was set at 10 mg/100 g flour because of possible effects on sensory characteristics. Brown et al. stated that zinc fortification is an appropriate strategy to increase intake and absorption of zinc, but that additional information is needed to confirm the efficacy of zinc fortification of cereal flour for improving zinc status and on the effectiveness of large-scale zinc fortification. 16 For rice fortification, considering that phytate content of wheat flour and rice are comparable (see section Iron above) and that native zinc content is not much lower in rice compared to wheat (Table 2), similar fortification levels could be applied (Table 3). A recent study reported improved zinc status among school children in Southern Thailand who consumed 50 g of rice per school day, fortified with zinc (18 mg/100 g), iron (20 mg/100 g), and vitamin A (2100 ug/100 g), estimated to bring total daily intake among 97.5% of the schoolchildren above the EAR for each of these nutrients. 44 Folic acid The main reason to fortify foods with folic acid is to prevent NTDs, which are an important cause of perinatal morality and infantile paralysis worldwide. 15 It has been estimated that approximately 200,000 of the 300,000 NTD-affected pregnancies worldwide annually are probably preventable with folic acid. 45 Areviewofdatafrom five countries that introduced folic acid fortification of at least wheat flour and wheat products, and of maize flour (in South Africa), or milk, corn flour, and rice (in Costa Rica), showed a decline of NTD rates ranging from 28% in the United States to 46% in Canada, and an increase of serum folate levels. 15 The recommended folic acid level for wheat and maize flour was set at a level that would contribute as much as possible to the RNI of 400 g/day of dietary folate equivalents (DFE, equivalent to 240 g folic acid) for anyone aged 14 years and older, and 600 and 500 g/day of DFE for pregnant and lactating women, respectively, while at the same time maintaining daily usual intake below the UL. 15 These levels, which would result in an intake slightly above the EAR, could also be applied to rice fortification (Table 3). Note that the DFE content of rice is slightly below that of wheat flour (Table 2). Vitamin B12 The high prevalence of depletion and deficiency of this vitamin among populations with limited consumption of animal-source foods, which is the only dietary source of this vitamin, was the main reason to recommend vitamin B12 fortification of wheat flour. 17 Furthermore, elderly people absorb the vitamin less efficiently and therefore rely on food fortification with this vitamin for a larger proportion of their requirement. The recommended fortification level is such that 2 g of vitamin B12 is provided Ann. N.Y. Acad. Sci (2014) C 2014 New York Academy of Sciences. 63

10 Nutrient levels for rice fortification de Pee per day, which is equivalent to the EAR and would therefore ensure that the majority of the population has an intake above that level. It should also be noted that there is no UL for vitamin B12. This recommendation can equally be applied to fortified rice, as plant-source foods do not contain vitamin B12 (Table 3). Thiamin, niacin, and vitamin B6 For thiamin and vitamin B6, both of which lack a UL, fortification is recommended to be such that it enables intake at the EAR level, which is similar to the recommendation for vitamin B12 fortification of flour (Table 3). In principle, niacin fortification should also ensure that intake at the EAR level is achieved (11 mg for women and 12 mg for men). However, in order to stay below the UL for niacin of 35 mg/day, it is particularly important that countries consider whether this recommendation for niacin needs to be adapted given the prevalence or likelihood of deficient intake and the consumption range of fortified rice. In addition, it would be worthwhile to consider niacin also for maize flour fortification, as its niacin content is about half that of wheat flour (Table 2). What should be the nutrient fortification level of fortified kernels and at what ratio should they be blended with normal rice? When the nutrients for rice fortification have been chosen and their desired levels have been set, decisions need to be made concerning nutrient concentration in the fortified kernels and the blending ratio for adding the fortified kernels to normal rice. It is important to note that, in the case of fortification of parboiled rice, some of the fortification levels can be adjusted downward because of the higher content of some of the micronutrients in parboiled compared to polished rice (Table 2). The price of fortified rice is largely determined by the production cost of the kernels, which depends on the capital investment for the machinery that is required and on the recurrent manufacturing costs, including the ingredients, and by the costs of transport and blending of fortified kernels with unfortified rice at the rice mill. 6,7 The vitamin/mineral mix is a minor cost component of fortified kernels and hence of the fortified rice. 6,7 Most of the costs are related to those of the equipment and its operation. Thus, in principle, the higher the micronutrient concentration in the fortified kernels and the lower the ratio at which fortified kernels are mixed with unfortified rice, the lower the cost. However, there are limits to the concentration of different nutrients that can be achieved in the fortified kernels without affecting their appearance in particular, and costs of achieving and controlling a specific blending ratio also need to be determined (a lower ratio maybemorecostlytocontrolandverify). The first constraint to maximizing the concentration of micronutrients in fortified kernels, without changing their appearance, is their iron content. As discussed above, the maximum iron concentration is approximately 7 mg/100 g of fortified rice when blended at a 1:100 ratio. This blending ratio appears to be a realistic one, allowing for an adequate micronutrient content at an affordable price (an increase of 1.5 3% of the retail cost compared to unfortified rice 11 ). Conclusion Table 3 summarizes the recommendation for rice fortification as presented in this paper. It is important to note that this is a general recommendation that can be adapted on the basis of national-level data on the nutrient intake and needs of vulnerable population groups. When more than one staple food is fortified, their combined intake, expressed as g/cap/day, should be used to set the concentrations that should then be the same for the different staple foods. While there are limited data available on efficacy and effectiveness of rice fortification, the rationale and technical feasibility are clear; thus, the next step should be to build experience with implementation at scale and to conduct thorough monitoring and evaluation of the impact. On the basis of that, nutrient level recommendations for rice fortification can then be updated in the future. And last but not least, it will be important to determine how the most vulnerable segments of the population could access fortified rice, considering possible channels through which fortified rice that has been blended at a limited number of rice mills can reach consumers, including in rural areas. Acknowledgments This manuscript was presented at the World Health Organization Consultation Technical Considerations for Rice Fortification in Public Health, convened in collaboration with the Global Alliance for 64 Ann. N.Y. Acad. Sci (2014) C 2014 New York Academy of Sciences.

11 de Pee Nutrient levels for rice fortification Improved Nutrition (GAIN) on October 9, and October 10, 2012, at the World Health Organization, Geneva, Switzerland. This article is being published individually, but will be consolidated with other manuscripts as a special issue of Annals of the New York Academy of Sciences, the coordinators of which were Dr. Luz Maria De-Regil, Dr. Arnaud Laillou, Dr. Regina Moench-Pfanner, and Dr. Juan Pablo Peña-Rosas. The special issue is the responsibility of the editorial staff of Annals of the New York Academy of Sciences, who delegated to the coordinators preliminary supervision of both technical conformity to the publishing requirements of Annals of the New York Academy of Sciences and general oversight of the scientific merit of each article. 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