Nutrition BriefExcerpts from WHO/FAO publications.December 22, 2011

National Food Security Bill

The National Food Security Bill1, 2011, was cleared by the Union Cab- 1 http://eac.gov.in/reports/rep_

NFSB.pdfinet on Monday, December 19, 2011 and introduced in the Lok Sabha,the lower house, on Thursday, December 22, 2011 by the Union FoodMinister KV Thomas “to provide for food and nutritional securityby ensuring access to adequate quantity of quality food at affordableprices, for people to live a life with dignity.”

It seeks to cover upto 75 per cent of the rural population and50 per cent of urban households. It seeks to grant the right to 7

kilograms food grains per month per person, at Rs. 3 per kg forrice, Rs. 2 per kg for wheat and Rs. 1 per kg for coarse grains to thepriority beneficiaries.

Under the present Public Distribution System (PDS), the gov-ernment provides 35 kg of wheat and rice per month to 6.52 croreBelow Poverty Line (BPL) families at Rs. 4.15 and Rs. 5.65 per kg,respectively. About 11.5 crore APL (Above Poverty Line) families getsbetween 15 and 35 kg of wheat and rice per month at Rs. 6.10 and Rs.8.30/kg, respectively.

The Food Security Bill also promises hot, mid-day meals forchildren up to 14 years of age and Rs. 6,000 for all pregnant andlactating women as legal entitlements. The bill provides for cashreimbursement if the government fails to provide subsidized foodgrains because of natural calamities such as drought and floods.

Once the law is implemented, the food subsidy bill is expected torise by Rs. 27,663 crore to nearly Rs. 95,000 crore, while foodgrainsrequirement would go up to 61 million tonnes from 55 million tonnes,as per the Cabinet proposal.

Coarse cereals

In the 2010-2011 crop marketing year that ended in October, thegovernment procured 127,825 tonnes of coarse cereals, principallyjowar (sorghum), bajra (pearl millet), maize and ragi (finger millet).In 2009-10, it had procured 406,828 tonnes. The production of coarsecereals in India in the current financial year is expected to be 30.42

million tonnes2. This projected drop is attributed to poor rains in Gu- 2 Sanjeeb Mukherjee. After kharif,coarse cereals face trouble in rabiseason. New Delhi. Business StandardOnline December 12, 2011. http://www.business-standard.com/india/news/

after-kharif-coarse-cereals-face-trouble-in-rabi-season/

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jarat, Maharashtra, Madhya Pradesh and Karnataka, despite coarsegrains being arid land crops. 4.78 million hectares are under coarse

Nutrition Brief

Production Procurement

Wheat Rice Total Wheat Ratio of+ Rice production(%)

2000-01 69.68 84.98 154.66 41.91 27.102001-02 72.77 93.34 166.11 41.18 24.792002-03 65.76 71.82 137.58 32.22 23.422003-04 72.16 88.53 160.69 39.62 24.662004-05 68.64 83.13 151.77 39.47 26.012005-06 69.35 91.79 161.14 36.88 22.892006-07 75.81 93.36 169.17 36.24 21.422007-08 78.57 96.69 175.26 51.43 29.342008-09 80.68 99.18 179.86 59.07 32.842009-10 80.71 89.13 169.84 53.98 31.782010-11 82.00 95.41 177.41* 53.22** 30.002011-12

83.61 104.21 187.82* 56.35** 30.00(Phase 1)2013-14

85.61 106.41 192.02* 57.61** 30.00(Final)

* Projections as per Department of Agriculture & Cooperation,Govt. of India** Assuming an optimum procurement of 30% of total production

Table 1: Production and Pro-curement of Wheat and Rice (inmillion tonnes)

grains, 424,000 hectares less than last year. The Government of Indiaintends to procure and distribute coarse grains to priority categoryhouseholds, an initiative under the Food Bill strongly supported bycivil society organizations. Pearl millet is used in various industrialproducts. 100 g edible portion of pearl millet contains 11.6 g protein,67.5g carbohydrate, 9mg of iron and it has 132µg of carotene. Thoughit has phytic acid, polyphenol and amylase inhibitors, these can bereduced by soaking in water, germination, puffing and other cookingtechniques.

Sorghum

Food Energy Ca Fekcal mg mg

Pearl millet 361 42 8.0Sorghum 349 25 4.1Maize 342 10 2.3Finger millet 328 344 3.9

Table 2: Nutritive value ofcourse gain (100 gms of edibleportion)

“Traditional food preparation of sorghum is quite varied. Boilingsorghum is one of the simplest uses and small, corneous grains arenormally desired for this type of food product. The whole grainmay be ground into flour or decorticated before grinding to produceeither a fine particle product or flour, which is then used in varioustraditional foods. “Sorghum has unique properties that make it wellsuited for food uses. Some sorghum varieties are rich in antioxidantsand all sorghum varieties are gluten-free, an attractive alternativefor wheat allergy sufferers. “Because of its neutral taste, sorghum

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absorbs other flavors well. “Sorghum has a high yield potential andthe highest recorded yield for the crop is 20.1 tons per hectare (320

bushels/acre). However, yields in Africa and India remains verylow. As a continent, Africa is the largest producer of sorghum withapproximately 21.6 million metric tons (850.6 million bushels) pro-duced annually. Leading producers around the world during fiscalyear 2010 included Nigeria (11.5 million metric tons/452.7 millionbushels), The United States (9.7 million metric tons/381.9 millionbushels), India (6.98 million metric tons/274.8 million bushels) andMexico (6.25 million metric tons/246 million bushels). “Sorghum isone of the most drought tolerant cereal crops currently under culti-vation. It offers farmers the ability to reduce costs on irrigation andother on-farm expenses.”

Food items mg

Finger millet 344Agathi leaves 1130Curry leaves 830Drumstick leaves 440Ponnanganni 510(Alternanthera sessilis)Gingelly seed 1450(sesame oil)Buffao milk 210Cow milk 120Cheese 790

Table 3: Calcium rich foods(100g of edible portion)

Pearl millet

“Grown in Africa and the Indian subcontinent since prehistoric times,it is generally accepted that pearl millet originated in Africa and wassubsequently introduced into India. “Pearl millet is well adaptedto growing areas characterized by drought, low soil fertility, andhigh temperature. It performs well in soils with high salinity or lowpH. Because of its tolerance to difficult growing conditions, it canbe grown in areas where other cereal crops, such as maize or wheat,would not survive. “India is the largest producer of pearl millet. Itis locally known as bajra, and is primarily consumed in the states ofHaryana, Rajasthan, Gujarat and Madhya Pradesh. Bajra is a rain fedcrop.” “Pearl millet is a warm season crop, planted in early summerwhen soils have warmed up. Like any grain crop, pearl millet willyield best on fertile, well drained soils. However, it also performsrelatively well on sandy soils under acidic soil conditions, and whenavailable soil moisture and soil fertility are low.

“Pearl millet will respond to good soil fertility, but does not have ahigh nutrient demand. It can be considered similar to sorghum in itsfertility needs; rates recommended for sorghum by a soil test lab canbe applied to pearl millet. Millet may need somewhat less nitrogenthan sorghum, because current varieties yield less than sorghum.”

Finger millet

Finger millet is originally native to the Ethiopian Highlands and wasintroduced into India approximately 4,000 years ago.

Finger millet is often intercropped with legumes such as peanuts(Arachis hypogea), cowpeas (Vigna sinensis), and pigeon peas(Cajanus cajan), or other plants such as Niger seeds (Guizotiaabyssinica).

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Once harvested, the seeds keep extremely well and are seldomattacked by insects or moulds. The long storage capacity makesfinger millet an important crop in risk-avoidance strategies for poorerfarming communities.

Finger millet is especially valuable as it contains the amino acidmethionine, which is lacking in the diets of hundreds of millionsof the poor who live on starchy staples such as cassava, plantain,polished rice, or maize meal.

In India, finger millet (locally called ragi) is mostly grown andconsumed in Rajasthan, Karnataka, Andhra Pradesh, Tamil Nadu,Orissa, Maharashtra, Kumaon (Uttarakhand) and Goa. Ragi flouris made into flatbreads, including thick, leavened dosa and thinner,unleavened roti. Ragi grain is malted and the grains are ground. Thisground flour is consumed mixed with milk, boiled water or yogurt.

Ragi is considered to be of Indian origin. It has relatively highcalcium content, 344 mg/100gm. No other cereal has this muchcalcium. The iron content of ragi is 3.9mg/100gm, which is higherthan the other cereals except bajra. Ragi has been recommended as awholesome food for diabetic patients. Traditionally ragi is used as theweaning food in the form of porridge gruel etc. Now ragi vermicellian instant food is available in the market.

In Orissa the tribal and Western hilly regions ragi or Mandiaa isa staple food. The porridge and Pithas made up of ragi are morepopular among village folk.

In the Kumaon region of northern India, it is called Maddua andis traditionally fed to women after child birth. In southern parts ofIndia, pediatricians recommend finger-millet-based food for infantsof six months and above because of its high nutritional content,especially iron and calcium. Homemade ragi malt happens to be oneof the most popular infant food even to this day.

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Optimal nutrition

The inclusion of foods in the diet which have high micronutrientdensity- such as pulses or legumes, vegetables (including green leafyvegetables), and fruits- is the preferred way of ensuring optimalnutrition, including micronutrient adequacy, for most populationgroups. Most population groups who are deficient in micronutrientssubsist largely on refined cereal grain or tuber based diets, whichprovide energy and protein (with an improper amino acid balance)but insufficient levels of critical micronutrients. There is a need for abroadening of the food base and a diversification of diets. [Figures17.1-17.4 illustrate how addition of a variety of foods to four basicdiets (i.e. a white rice-based diet; a corn-tortilla-based diet; a refinedcouscous-based diet; and a potato-based diet) can increase the nu-trient density of a cereal or tuber-based diet.] Adding reasonableamounts of these foods will add micronutrient density to the staplediet and in doing so could reduce the prevalence of diseases resultingfrom a micronutrient deficiency across populations groups.3 3 World Health Organization (Con-

tribution by). Vitamin and MineralRequirements in Human Nutrition :Report of a Joint FAO/WHO ExpertConsultation (2nd Edition). Albany,NY, USA: World Health Organization,(date). p 320. http://site.ebrary.com/lib/britishcouncilonline/Doc?id=

10190690&ppg=339

The recent interest in the role of phytochemicals and antioxidantson health, and their presence in plant foods, lends further supportto the recommendation for increasing the consumption of vegetablesand fruit in the diet. The need for dietary diversification is supportedby the knowledge of the interrelationships of food components,which may enhance the nutritional value of foods and prevent unde-sirable imbalances which may limit the utilization of some nutrients.For example, fruits rich in ascorbic acid will enhance the absorptionof non-heme iron.

If energy intake is low (< 8.368 MJ/day), for example, in the caseof young children, sedentary women, or the elderly, the diet maynot provide sufficient amounts of vitamins and minerals to meetRNIs. This situation may be of special relevance to the elderly, whoare inactive, have decreased lean body mass, and typically decreasetheir energy intake. Young children, pregnant women, and lactatingwomen who have greater micronutrient needs relative to their energyneeds will also require an increased micronutrient density.

Vitamin A

Vitamin A The vitamin A content of most staple diets can be sig-nificantly improved with the addition of a relatively small portionof plant foods rich in carotenoids, the precursors of vitamin A. Forexample, a typical portion of cooked carrots (50 g) added to a dailydiet, or 21 g of carrots per 4.184 MJ, provides 500 mg retinol equiv-alents, which is the recommended nutrient density for this vitamin.

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The biological activity of provitamin A varies among different plantsources; fruits and vegetables such as carrots, mango, papaya, andmelon contain large amounts of nutritionally active carotenoids 4,5. 4 Parker RS. Absorption, metabolism,

and transport of carotenoids. FASEBJournal, 1996, 10:542-551.5 Jayarajan P, Reddy V, Mohanram M.Effect of dietary fat on absorption ofβ-carotene from green leafy vegetablesin children. Indian Journal of MedicalResearch, 1980, 71:53-56.

Green leafy vegetables such as ivy gourd have been successfully usedin Thailand as a source of vitamin A, and carotenoid-rich red palmoil serves as an easily available and excellent source of vitamin Ain other countries. Consequently, a regular portion of these foodsincluded in an individual’s diet may provide 100% or more of thedaily requirement for retinol equivalents [(Figures 17.1-17.4b)]. Vita-min A is also present in animal food sources in a highly bioavailableform. Therefore, it is important to consider the possibility of meetingvitamin A needs by including animal foods in the diet. For example,providing minor amounts of fish or chicken liver (20-25 g) in the dietprovides more than the recommended vitamin A nutrient density forvirtually all population groups.6 6 World Health Organization (Con-

tribution by). Vitamin and MineralRequirements in Human Nutrition:Report of a Joint FAO/WHO ExpertConsultation (2nd Edition). Albany,NY, USA: World Health Organization,2005. p 325.http://site.ebrary.com/lib/britishcouncilonline/Doc?id=

10190690&ppg=344

Role of vitamin A in human metabolic processes

Vitamin A (retinol) is an essential nutrient needed in small amountsby humans for the normal functioning of the visual system; growthand development; and maintenance of epithelial cellular integrity,immune function, and reproduction.

Definition of vitamin A deficiency

VAD is not easily defined. WHO defines it as tissue concentrations ofvitamin A low enough to have adverse health consequences even ifthere is no evidence of clinical xerophthalmia.

VAD can occur in individuals of any age. However, it is a dis-abling and potentially fatal public health problem for children under6 years of age.

There is no consistent, clear indication in humans of a sex differen-tial in vitamin A requirements during childhood. Growth rates, andpresumably the need for vitamin A, from birth to 10 years for boysare consistently higher than those for girls.

VAD is most common in populations consuming most of their vita-min A needs from provitamin carotenoid sources and where minimaldietary fat is available7. About 90% of ingested preformed vitamin 7 Mele L et al. Nutritional and house-

hold risk factors for xerophthalmia inAceh, Indonesia: a case-control study.American Journal of Clinical Nutrition,1991, 53:1460-1465.

A is absorbed, whereas the absorption efficiency of provitamin Acarotenoids varies widely, depending on the type of plant source andthe fat content of the accompanying meal

Where possible, an increased intake of dietary fat is likely toimprove the absorption of vitamin A in the body.

Food habits and taboos often restrict consumption of potentiallygood food sources of vitamin A (e.g. mangoes and green leafy vegeta-

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bles). Culture specific factors for feeding children, adolescents, andpregnant and lactating women are common.

Dietary sources

Preformed vitamin A is found almost exclusively in animal products,such as human milk, glandular meats, liver and fish liver oils (espe-cially), egg yolk, whole milk, and other dairy products. Preformedvitamin A is also used to fortify processed foods, which may includesugar, cereals, condiments, fats, and oils. Provitamin A carotenoidsare found in green leafy vegetables (e.g. spinach, amaranth, andyoung leaves from various sources), yellow vegetables (e.g. pump-kins, squash, and carrots), and yellow and orange non-citrus fruits(e.g. mangoes, apricots, and papayas). Red palm oil produced inseveral countries worldwide is especially rich in provitamin A

Foods containing provitamin A carotenoids tend to have lessbiologically available vitamin A but are more affordable than ani-mal products. It is mainly for this reason that carotenoids providemost of the vitamin A activity in the diets of economically deprivedpopulations.

Clinical indicators of vitamin A deficiency

Ocular signs of VAD are assessed by clinical examination and history,and are quite specific in preschool-age children. However, these arerare occurrences that require examination of large populations inorder to obtain incidence and prevalence data. Subclinical VAD beingthe more prevalent requires smaller sample sizes for valid prevalenceestimates

Subclinical indicators of vitamin A deficiency

Direct measurement of concentrations of vitamin A in the liver(where it is stored) or in the total body pool relative to known spe-cific vitamin A-related conditions (e.g. night-blindness) would bethe indicator of choice for determining requirements. This cannot bedone with the methodology currently available for population use.There are several more practical biochemical methods for estimatingsubclinical vitamin A status but all have limitations.

Although all biochemical indicators currently available have limita-tions, the preferred biochemical indicator for population assessmentis the distribution of serum levels of vitamin A (serum retinol).

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Vitamin C

Vitamin C An increased vitamin C intake can be achieved by includ-ing citrus fruit or other foods rich in ascorbic acid in the diet. Forexample, an orange or a small amount of other vitamin C-rich fruit(60 g of edible portion) provides the recommended ascorbic aciddensity [Figures 17.1-17.3c]. Adding an orange per day to a potato-based diet increases the level of vitamin C threefold [Figure 17.4c].Other good vitamin C food sources are guava, amla, kiwi, cranber-ries, strawberries, papaya, mango, melon, cantaloupe, spinach, Swisschard, tomato, asparagus, and Brussels sprouts. All these foods,when added to a diet or meal in regular portion sizes, will signifi-cantly improve the vitamin C density. Because ascorbic acid is heatlabile, minimal cooking (steaming or stirfrying) is recommended tomaximize the bioavailable nutrient. The significance of consumingvitamin C with meals is discussed relative to iron absorption below.8 8 World Health Organization (Con-

tribution by). Vitamin and MineralRequirements in Human Nutrition :Report of a Joint FAO/WHO ExpertConsultation (2nd Edition). Albany,NY, USA: World Health Organization,(date). p 325 http://site.ebrary.com/

lib/britishcouncilonline/Doc?id=

10190690&ppg=344

Folate

Folate is now considered significant not only for the prevention ofmacrocytic anaemia, but also for normal fetal development. Recently,this vitamin was implicated in the maintenance of cardiovascularhealth and cognitive function in the elderly. Staple diets consistinglargely of cereal grains and tubers are very low in folate but canbe improved by the addition of legumes or green leafy vegetables.For example, a regular portion of cooked lentils (95 g) added to arice-based diet can provide an amount of folate sufficient to meetthe desirable nutrient density for this vitamin [Figure 17.1d]. Otherlegumes such as beans and peas are also good sources of this vitamin,but larger portions are needed for folate sufficiency (100 g beans and170 g peas). Cluster bean and colacasia leaves are excellent folatesources used in the Indian diet. Another good source of folate ischicken liver; only one portion (20-25 g) is sufficient to meet the de-sirable nutrient density for folate and vitamin A simultaneously. Thebest sources of folate are organ meats, green leafy vegetables, andBrussels sprouts. However, 50% or more of food folate is destroyedduring cooking. Prolonged heating in large volumes of water shouldbe avoided, and it is advisable to consume the water used in thecooking of vegetables.

Iron and zinc

Minerals such as iron and zinc are found in low amounts in cerealand tuber based diets. The addition of legumes slightly improves

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the iron content of such diets. However, the bioavailability of thisnon-heme iron source is low. Therefore, it is not possible to meet therecommended levels of iron in the staple-based diets through a food-based approach unless some meat or fish is included. For example,adding a small portion (50 g) of flesh food will increase the total ironcontent of the diet as well as the amount of bioavailable iron. Forzinc, the presence of a small portion (50 g) of flesh food will securedietary sufficiency of most staple diets [Figures 17.1-17.4e].

The consumption of ascorbic acid along with food rich in ironwill enhance iron’s absorption.9 There is a critical balance between 9 World Health Organization (Con-

tribution by). Vitamin and MineralRequirements in Human Nutrition :Report of a Joint FAO/WHO ExpertConsultation (2nd Edition). Albany,NY, USA: World Health Organization,(date). p 327. http://site.ebrary.com/lib/britishcouncilonline/Doc?id=

10190690&ppg=346

enhancers and inhibitors of iron absorption. Nutritional status canbe improved significantly by educating households about foodpreparation practices that minimize the consumption of inhibitors ofiron absorption; for example, the fermentation of phytate-containinggrains before the baking of breads to enhance iron absorption.

Zinc

Role of zinc in human metabolic processes

Zinc is present in all body tissues and fluids. The total body zinccontent has been estimated to be 30mmol (2g).

Zinc is an essential component of a large number (>300) of en-zymes participating in the synthesis and degradation of carbohy-drates, lipids, proteins, and nucleic acids as well as in the metabolismof other micronutrients.

Zinc stabilizes the molecular structure of cellular componentsand membranes and in this way contributes to the maintenanceof cell and organ integrity. Furthermore, zinc has an essential rolein polynucleotide transcription and thus in the process of geneticexpression. Its involvement in such fundamental activities probablyaccounts for the essentialness of zinc for all life forms. Zinc plays acentral role in the immune system, affecting a number of aspects ofcellular and humoral immunity

The clinical features of severe zinc deficiency in humans aregrowth retardation, delayed sexual and bone maturation, skin le-sions, diarrhea, alopecia, impaired appetite, increased susceptibilityto infections mediated via defects in the immune system, and theappearance of behavioral changes.

Dietary sources and bioavailability of zinc

Lean red meat, whole-grain cereals, pulses, and legumes providethe highest concentrations of zinc: concentrations in such foodsare generally in the range of 25-50mg/kg (380-760mmol/kg) raw

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weight. Processed cereals with low extraction rates, polished rice, andchicken, pork or meat with high fat content have a moderate zinccontent, typically between 10 and 25mg/kg (150-380 mmol/kg). Fish,roots and tubers, green leafy vegetables, and fruits are only modestsources of zinc, having concentrations <10mg/kg (<150mmol/kg). Saturated fats and oils, sugar, and alcohol have very low zinc con-tents. The utilization of zinc depends on the overall composition ofthe diet.

Experimental studies have identified a number of dietary factorsas potential promoters or antagonists of zinc absorption. Solubleorganic substances of low relative molecular mass, such as aminoand hydroxy acids, facilitate zinc absorption. In contrast, organiccompounds forming stable and poorly soluble complexes with zinccan impair absorption. In addition, competitive interactions betweenzinc and other ions with similar physicochemical properties canaffect the uptake and intestinal absorption of zinc.

Isotope studies with human subjects have identified two factorsthat, together with the total zinc content of the diet, are major de-terminants of absorption and utilization of dietary zinc. The first isthe content of inositol hexaphosphate (phytate) in the diet and thesecond is the level and source of dietary protein. Phytates are presentin whole-grain cereals and legumes and in smaller amounts in othervegetables. They have a strong potential for binding divalent cationsand their depressive effect on zinc absorption has been demonstratedin humans

Zinc absorption from some legume-based diets (e.g. white beansand lupin protein) is comparable with that from animal protein-based diets despite a higher phytate content in the former

High dietary calcium potentiated the antagonistic effects of phy-tates on zinc absorption in experimental studies. The results fromhuman studies are less consistent and any effects seem to depend onthe source of calcium and the composition of the diet.

Thus, approximately twice as much zinc is absorbed from a non-vegetarian or high-meat diet than from a diet based on rice andwheat flour. Data are lacking on zinc absorption from typical diets ofdeveloping countries, which usually have high phytate contents.

The availability of zinc from the diet can be improved by reducingthe phytate content and including sources of animal protein. Lowerextraction rates of cereal grains will result in lower phytate contentbut at the same time the zinc content is reduced, so that the net effecton zinc supply is limited. The phytate content can be reduced byactivating the phytase present in most phytate-containing foods orthrough the addition of microbial or fungal phytases.

Phytases hydrolyse the phytate to lower inositol phosphates, re-

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sulting in improved zinc absorption. The activity of phytases intropical cereals such as maize and sorghum is lower than that inwheat and rye. Germination of cereals and legumes increases phytaseactivity and addition of some germinated flour to ungerminatedmaize or sorghum followed by soaking at ambient temperature for12-24 hours can reduce the phytate content substantially 10. Addi- 10 Gibson RS et al. Dietary interventions

to prevent zinc deficiency. AmericanJournal of Clinical Nutrition, 1998,68(Suppl.):S484-S487.

tional reduction can be achieved by the fermentation of porridge forweaning foods or dough for bread making. Commercially availablephytase preparations could also be used but may not be economicallyaccessible in many populations.

Populations at risk for zinc deficiency

The central role of zinc in cell division, protein synthesis, and growthis especially important for infants, children, adolescents, and preg-nant women; these groups suffer most from an inadequate zincintake. Zinc-responsive stunting has been identified in several stud-ies; for example, a more rapid body weight gain in malnourishedchildren from Bangladesh supplemented with zinc was reported.However, other studies have failed to show a growth promoting effectof zinc supplementation.

Zinc supplementation had a positive effect when stunting wasinitially present; a more pronounced effect on weight gain wasassociated with initial low plasma zinc concentrations.

Results from zinc supplementation studies suggest that a low zincstatus in children not only affects growth but is also associated withan increased risk of severe infectious diseases. Episodes of acutediarrhea were characterized by shorter duration and less severity inzinc-supplemented groups; reductions in incidence of diarrhea werealso reported. Other studies indicate that the incidence of acute lowerrespiratory tract infections and malaria may also be reduced by zincsupplementation.

Evidence used to estimate zinc requirements

The lack of specific and sensitive indexes for zinc status limits thepossibilities for evaluating zinc requirements from epidemiologicalobservations.

Experimental zinc repletion studies with low zinc intakes haveclearly shown that the body has a pronounced ability to adapt todifferent levels of zinc intakes by changing the endogenous intestinal,urinary and integumental zinc losses.

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Nominal category: High availability

Principal dietary characteristicsRefined diets low in cereal fibre, low in phytic acid content, and

with phytate-zinc molar ratio <5; adequate protein content princi-pally from non-vegetable sources, such as meats and fish. Includessemi-synthetic formula diets based on animal protein.

Nominal category: Moderate availability

Principal dietary characteristicsMixed diets containing animal or fish protein. Lacto-ovo, ovo-

vegetarian, or vegan diets not based primarily on unrefined cerealgrains or high-extraction-rate flours. Phytate-zinc molar ratio of totaldiet within the range 5-15, or not exceeding 10 if more than 50% ofthe energy intake is accounted for by unfermented, unrefined cerealgrains and flours and the diet is fortified with inorganic calcium salts(>1g Ca2+/day). Availability of zinc improves when the diet includesanimal protein or milks, or other protein sources or milks.

Nominal category: Low availability

Principal dietary characteristicsDiets high in unrefined, unfermented, and ungerminated cereal

grain11, especially when fortified with inorganic calcium salts and 11 Germination of cereal grains orfermentation (e.g. leavening) of manyflours can reduce antagonistic potencyof phytates; if done, the diet shouldthen be classified as having moderatezinc availability.

when intake of animal protein is negligible. Phytate-zinc molarratio of total diet exceeds 15

12,High-phytate, soya-protein products

12 Vegetable diets with phytate-zincratios exceeding 30 are not unknown;for such diets, an assumption of 10%availability of zinc or less may bejustified, especially if the intake ofprotein is low, that of inorganic calciumsalts is excessive (e.g. calcium saltsproviding >1.5 g Ca2+/day), or both.

constitute the primary protein source.Diets in which, singly or collectively, approximately 50% of the

energy intake is accounted for by the following high-phytate foods:high-extraction-rate (> 90%) wheat, rice, maize, grains and flours, oat-meal, and millet; chapatti flours and tanok; and sorghum, cowpeas,pigeon peas, grams, kidney beans, black-eyed beans, and groundnutflours. High intakes of inorganic calcium salts (>1g Ca2+/day), eitheras supplements or as adventitious contaminants (e.g. from calcare-ous geophagia), potentiate the inhibitory effects and low intakes ofanimal protein exacerbates these effects.

[a] At intakes adequate to meet the average normative require-ments for absorbed zinc, the three availability levels correspond to50%, 30% and 15% absorption. With higher zinc intakes, the frac-tional absorption is lower.

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Pregnant women

The total amount of zinc retained during pregnancy has been es-timated to be 1.5mmol (100mg). During the third trimester, thephysiological requirement of zinc is approximately twice as high asthat in women who are not pregnant.

Iron

Role of iron in human metabolic processes

Iron has several vital functions in the body. It serves as a carrier ofoxygen to the tissues from the lungs by red blood cell hemoglobin, asa transport medium for electrons within cells, and as an integratedpart of important enzyme systems in various tissues.

Requirements for growth

The newborn term infant has an iron content of about 250-300mg(75mg/kg body weight). During the first 2 months of life, hemoglobinconcentration falls because of the improved oxygen situation in thenewborn infant compared with the intrauterine fetus. This leads to aconsiderable redistribution of iron from catabolized erythrocytes toiron stores. This iron will cover the needs of the term infant duringthe first 4-6 months of life and is why iron requirements during thisperiod can be provided by human milk, which contains very littleiron.

In the weaning period, the iron requirements in relation to en-ergy intake are at the highest level of the lifespan except for the lasttrimester of pregnancy, when iron requirements to a large extent haveto be covered from the iron stores of the mother.

Iron requirements are also very high in adolescents, particularlyduring the period of rapid growth.

Menstrual iron losses

Menstrual blood losses are very constant from month to month for anindividual woman but vary markedly from one woman to another.

Iron absorption

With respect to the mechanism of absorption, there are two kinds ofdietary iron: heme iron and non-heme iron. In the human diet, theprimary sources of heme iron are the hemoglobin and myoglobinfrom consumption of meat, poultry, and fish whereas non-heme ironis obtained from cereals, pulses, legumes, fruits, and vegetables. The

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average absorption of heme iron from meat-containing meals is about25%. The absorption of heme iron can vary from about 40% duringiron deficiency to about 10% during iron repletion. Heme iron can bedegraded and converted to non-heme iron if foods are cooked at ahigh temperature for too long. Calcium is the only dietary factor thatnegatively influences the absorption of heme iron and does so to thesame extent that it influences non-heme iron.

Non-heme iron is the main form of dietary iron. The absorption ofnonheme iron is influenced by individual iron status and by severalfactors in the diet.

Iron compounds used for the fortification of foods will only be par-tially available for absorption. Once dissolved, however, the absorp-tion of iron from fortificants (and food contaminants) is influenced bythe same factors as the iron native to the food substance

Heme iron absorption

• Factors determining iron status of subject

1. Amount of dietary heme iron, especially from meat

2. Content of calcium in meal (e.g. from milk, cheese)

3. Food preparation (i.e. time, temperature)

Non-heme iron absorption

• Factors determining iron status of subject

1. Amount of potentially available non-heme iron (includes adjust-ment for fortification iron and contamination iron)

2. Balance between the following enhancing and inhibiting factors:

• Enhancing factors

1. Ascorbic acid (e.g. certain fruit juices, fruits, potatoes, andcertain vegetables)

2. Meat, fish and other seafood

3. Fermented vegetables (e.g. sauerkraut), fermented soy sauces,etc.

• Inhibiting factors

1. Phytate and other lower inositol phosphates (e.g. bran products,bread made from high-extraction flour, breakfast cereals, oats,rice - especially unpolished rice - pasta products, cocoa, nuts,soya beans, and peas)

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2. Iron-binding phenolic compounds (e.g. tea, coffee, cocoa, cer-tain spices, certain vegetables, and most red wines)

3. Calcium (e.g. from milk, cheese)

4. Soya

Inhibition of iron absorption

Phytates are found in all kinds of grains, seeds, nuts, vegetables,roots (e.g. potatoes), and fruits. Chemically, phytates are inositolhexaphosphate salts and are a storage form of phosphates and miner-als. Other phosphates have not been shown to inhibit non-heme ironabsorption.

Bran has a high content of phytate and strongly inhibits ironabsorption. Wholewheat flour, therefore, has a much higher phytatecontent than does white-wheat flour.

Fermentation for a couple of days (sourdough fermentation) can al-most completely degrade the phytate and increase the bioavailabilityof iron in bread made from wholewheat flour. Oats strongly inhibitiron absorption because of their high phytate content that resultsfrom native phytase in oats being destroyed by the normal heat pro-cess used to avoid rancidity. Sufficient amounts of ascorbic acid cancounteract this inhibition. In contrast, non-phytate-containing dietaryfiber components have almost no influence on iron absorption.

Almost all plants contain phenolic compounds as part of their de-fense system against insects and animals. Only some of the phenoliccompounds (mainly those containing galloyl groups) seem to be re-sponsible for the inhibition of iron absorption. Tea, coffee, and cocoaare common plant products that contain iron-binding polyphenols.Many vegetables, especially green leafy vegetables (e.g. spinach),and herbs and spices (e.g. oregano) contain appreciable amounts ofgalloyl groups, which strongly inhibit iron absorption as well. Con-sumption of betel leaves, common in areas of Asia, also has a markednegative effect on iron absorption. Calcium, consumed as a salt orin dairy products interferes significantly with the absorption of bothheme and non-heme iron. However, because calcium is an essentialnutrient, it cannot be considered to be an inhibitor of iron absorptionin the same way as phytates or phenolic compounds. In order tolessen this interference, practical solutions include increasing ironintake, increasing its bioavailability, or avoiding the intake of foodsrich in calcium and foods rich in iron at the same meal.

For unknown reasons, the addition of soya to a meal reduces thefraction of iron absorbed. This inhibition is not solely explained bythe high phytate content of soya. However, because of the high ironcontent of soya, the net effect on iron absorption with an addition

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of soya products to a meal is usually positive. In infant foods con-taining soya, the inhibiting effect can be overcome by the addition ofsufficient amounts of ascorbic acid. Conversely, some fermented soysauces have been found to enhance iron absorption.

Enhancement of iron absorption

Ascorbic acid is the most potent enhancer of non-heme iron absorp-tion. Synthetic vitamin C increases the absorption of iron to the sameextent as the native ascorbic acid in fruits, vegetables, and juices. Theeffect of ascorbic acid on iron absorption is so marked and essentialthat this effect could be considered as one of vitamin C’s physiologi-cal roles.

Each meal should preferably contain at least 25 mg of ascorbicacid and possibly more if the meal contains many inhibitors of ironabsorption.

Meat, fish, and seafood all promote the absorption of non-hemeiron. The mechanism for this effect has not been determined.

Meat thus promotes iron nutrition in two ways: it stimulates theabsorption of both heme and non-heme iron and it provides the wellabsorbed heme iron. Epidemiologically, the intake of meat has beenfound to be associated with a lower prevalence of iron deficiency.

Iron balance and regulation of iron absorption

The body has three unique mechanisms for maintaining iron balance.The first is the continuous reutilization of iron from catabolized

erythrocytes in the body. When an erythrocyte dies after about 120

days, it is usually degraded by the macrophages of the reticularendothelium. The iron is released and delivered to transferrin inthe plasma, which brings the iron back to red blood cell precursorsin the bone marrow or to other cells in different tissues. Uptakeand distribution of iron in the body is regulated by the synthesis oftransferrin receptors on the cell surface. This system for internal irontransport not only controls the rate of flow of iron to different tissuesaccording to their needs, but also effectively prevents the appearanceof free iron and the formation of free radicals in the circulation.

The second mechanism involves access to the specific storageprotein, ferritin. This protein stores iron in periods of relativelylow need and releases it to meet excessive iron demands. This ironreservoir is especially important in the third trimester of pregnancy.

The third mechanism involves the regulation of absorption of ironfrom the intestines; decreasing body iron stores trigger increasediron absorption and increasing iron stores trigger decreased ironabsorption. Iron absorption decreases until equilibrium is established

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between absorption and requirement.The three main factors that affect iron balance are absorption

(intake and bioavailability of iron), losses, and stored amount. Theinterrelationship among these factors has recently been describedin mathematical terms, making it possible to predict, for example,the amount of stored iron when iron losses and bioavailability ofdietary iron are known 13. In states of increased iron requirement 13 Hallberg L, Hulthén L, Garby L. Iron

stores in man in relation to diet andiron requirements. European Journal ofClinical Nutrition, 1998, 52:623-631.

or decreased bioavailability, the regulatory capacity to prevent irondeficiency is limited. However, the regulatory capacity seems to beextremely good in preventing iron overload in a state of increaseddietary iron intake or bioavailability.

Populations at risk for iron deficiency

Populations most at risk for iron deficiency are infants, children, ado-lescents, and women of childbearing age, especially pregnant women.The weaning period in infants is especially critical because of the veryhigh iron requirement needed in relation to energy requirement

Iron deficiency is defined as a hemoglobin concentration below theoptimum value in an individual, whereas iron deficiency anemia im-plies that the hemoglobin concentration is below the 95th percentileof the distribution of hemoglobin concentration in a population(disregarding effects of altitude, age and sex, etc. on hemoglobin con-centration). The confusion arises due to the very wide distribution ofthe hemoglobin concentration in healthy, fully iron-replete subjects(in women, 120-160 g/l; in men, 140-180 g/l)

Indicators of iron deficiency

The absence of iron stores (iron deficiency) can be diagnosed byshowing that there is no stainable iron in the reticuloendothelial cellsin bone marrow smears or, more easily, by a low concentration offerritin in serum (<15mg/l). Even if an absence of iron stores perse may not necessarily be associated with any immediate adverseeffects, it is a reliable and good indirect indicator of iron-deficienterythropoiesis and of an increased risk of a compromised supply ofiron to different tissues.

Causes of iron deficiency

Nutritional iron deficiency implies that the diet cannot supplyenough iron to cover the body’s physiological requirements for thismineral. Worldwide this is the most common cause of iron deficiency.In many tropical countries, infestations with hookworms lead tointestinal blood losses that in some individuals can be considerable.

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The average blood loss can be reliably estimated by egg counts instools. Usually the diet in these populations is also limited with re-spect to iron content and availability. The severity of the infestationsvaries markedly between subjects and regions.

Prevalence of iron deficiency

Iron deficiency is probably the most common nutritional deficiencydisorder in the world. A recent estimate based on WHO criteria in-dicated that around 600-700 million people worldwide have markediron deficiency anemia

Both better information about iron deficiency prevention andincreased consumption of fortified cereals by infants and childrenhave markedly improved the iron situation in these groups in mostdeveloped countries, such that, the highest prevalence of iron defi-ciency today is observed in menstruating and pregnant women, andadolescents of both sexes.

Iron supplementation and fortification

The prevention of iron deficiency has become more urgent in recentyears with the accumulation of evidence strongly suggesting a re-lationship between even mild iron deficiency and impaired braindevelopment, and especially so in view of the observation that func-tional defects affecting learning and behavior cannot be reversed bygiving iron at a later date. As mentioned, iron deficiency is commonboth in developed and in developing countries. Great efforts havebeen made by WHO to develop methods to combat iron deficiency.

Iron deficiency can generally be combated by one or more of thefollowing three strategies:

1. iron supplementation (i.e. giving iron tablets to certain targetgroups such as pregnant women and preschool children);

2. iron fortification of certain foods, such as flour; and

3. food and nutrition education on improving the amount of iron ab-sorbed from the diet by increasing the intake of iron and especiallyby improving the bioavailability of the dietary iron.

Dietary diversity

How to accomplish dietary diversity in practice It is essential to cre-ate strategies which promote and facilitate dietary diversification inorder to achieve complementarity of cereal or tuber-based diets withfoods rich in micronutrients in populations with limited financial

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resources or access to food. A recent FAO/International Life SciencesInstitute publication14 proposed strategies to promote dietary diversi- 14 Preventing micronutrient malnutri-

tion: a guide to food-based approaches.Washington, DC, International LifeSciences Institute Press, 1997.

fication as part of food-based approaches to preventing micronutrientmalnutrition. These strategies, which are listed below, have beenfurther adapted or modified by the present Expert Consultation:

1. Community or home vegetable and fruit gardens. Support forsmall-scale vegetable and fruit growing should lead to increasedproduction and consumption of micronutrient-rich foods (e.g.legumes, green leafy vegetables, and fruits) at the household level.The success of such projects depends on a good knowledge andunderstanding of local conditions as well as the involvement ofwomen and the community in general. These are key elements forsupporting, achieving, and sustaining beneficial nutritional changeat the household level. Land availability and water supply areoften constraints, and may require local government support be-fore they are overcome. The educational effort should be directedtowards securing appropriate within-family distribution, whichconsiders the needs of the most vulnerable members of the family,especially infants and young children.

2. Raising of fish, poultry, and small animals (rabbits, goats, andguinea pigs). Flesh foods are excellent sources of highly bioavail-able essential micronutrients such as vitamin A, iron, and zinc.Raising animals at the local level may permit communities to ac-cess foods which otherwise would not be available because of theirhigh costs. These types of projects also need some support fromlocal governments or nongovernmental organizations to overcomecost constraints of program implementation, including educationand training on how to raise animals.

3. Implementation of large-scale commercial vegetable and fruit pro-duction. The objective of such initiatives is to provide micronutrient-rich foods at reasonable prices through effective and competitivemarkets which lower consumer prices without reducing producerprices. This will serve predominantly the urban and non-food-producing rural areas.

4. Reduction of post-harvest losses of the nutritional value ofmicronutrient-rich foods, such as fruits and vegetables. Improve-ment of storage and food-preservation facilities significantlyreduces post-harvest losses. At the household level, the promotionof effective cooking methods and practical ways of preservingfoods (e.g. solar drying of seasonal micronutrient-rich foods suchas papaya, grapes, mangoes, peaches, tomatoes, and apricots) maypreserve significant amounts of micronutrients in foods, which in

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turn will lead to an increase of these nutrients in the diet. At thecommercial level, appropriate grading, packing, transport, andmarketing practices can reduce losses, stimulate economic growth,and optimize income generation.

5. Improvement of micronutrient levels in soils and plants, whichwill improve the composition of plant foods and enhance yields.Current agricultural practices can improve the micronutrient con-tent of foods by correcting soil quality and pH and by increasingsoil mineral content where it has been depleted by erosion andpoor soil conservation practices. Long-term food-based solutionsto micronutrient deficiencies will require improvement of agricul-tural practices, seed quality, and plant breeding (by means of aclassical selection process or genetic modification).

Practices which will enhance the success of food based approachesTo achieve dietary adequacy of vitamin A, vitamin C, folate, iron,and zinc by using food-based approaches, food preparation anddietary practices must be considered. For example, it is importantto recommend that vegetables rich in vitamin C, folate, and otherwater-soluble or heat-labile vitamins are minimally cooked in smallamounts of water. In the case of iron, it is essential to reduce theintake of inhibitors of iron absorption and to increase the intake ofenhancers of absorption in a given meal. Following this strategy, it isrecommended to increase the intake of germinated seeds; fermentedcereals; heat processed cereals; meats; and fruits and vegetables richin vitamin C. In addition, the consumption of tea, coffee, chocolate,or herbal infusions should be encouraged at times other than withmeals. Consumption of flesh foods improves zinc absorption whereasit is inhibited by consumption of diets high in phytate, such asdiets based on unrefined cereals. Zinc availability can be estimatedaccording to the phytate-zinc molar ratio of the meal.15 15 Milne DB et al. Ethanol metabolism

in postmenopausal women fed a dietmarginal in zinc. American Journal ofClinical Nutrition, 1987, 46:688-693.

This advice is particularly important for people who consumecereal based and tuber-based diets.16 These foods constitute the main

16 World Health Organization (Con-tribution by). Vitamin and MineralRequirements in Human Nutrition :Report of a Joint FAO/WHO ExpertConsultation (2nd Edition). Albany,NY, USA: World Health Organization,(date). p 328. http://site.ebrary.com/lib/britishcouncilonline/Doc?id=

10190690&ppg=347

staples for most populations of the world, populations which arealso most at risk for micronutrient deficiencies. Other alternatives-fortification and supplementation- have been proposed as stopgapmeasures when food-based approaches are not feasible or are still un-der development. There is a definite role for fortification in meetingiron, folate, iodine, and zinc needs. Fortification and supplementationshould be seen as complementary to food-based strategies and not asa replacement. Combined implementation of these strategies can leadto substantial improvements in normalizing the micronutrient statusof populations at risk. Food-based approaches usually take longerto implement than supplementation programs, but once established

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they are truly sustainable.

Fortification

Fortification is accepted as sustainable under most conditions and isoften cost effective on a large scale when successfully implemented.

There are at least three essential conditions which must be metin any fortification program 17,18: the fortificant should be effective, 17 Lotfi M et al. Micronutrient forti-

fication of foods. Current practices,research, and opportunities. Ottawa,The Micronutrient Initiative, andWageningen, International Develop-ment Research Center/InternationalAgricultural Center, 1996.18 Viteri FE. Prevention of iron de-ficiency. In: Howson CP, KennedyET, Horwitz A, eds. Prevention ofmicronutrient deficiencies. Tools forpolicymakers and public health workers.Washington, DC, National AcademyPress, 1998, 3:45-102.

bioavailable, acceptable, and affordable; the selected food vehicleshould be easily accessible and a specified amount of it shouldbe regularly consumed in the local diet; and detailed productioninstructions and monitoring procedures should be in place andenforced by law.

Iron fortification

Food fortification with iron is recommended when dietary iron isinsufficient or the dietary iron is of poor bioavailability, which is thereality for most people in the developing world and for vulnerablepopulation groups in the developed world. Moreover, the prevalenceof iron deficiency and anemia in vegetarians and in populations ofthe developing world which rely on cereal or tuber foods is signifi-cantly higher than in omnivorous populations.

Iron is present in foods in two forms, as heme iron, which isderived from flesh foods (meats and fish), and as non-heme iron,which is the inorganic form present in plant foods such as legumes,grains, nuts, and vegetables 19,20. Heme iron is the more readily 19 Hallberg L, Hulthén L, Gramatkovski

E. Iron absorption from the whole dietin men: how effective is the regulationof iron absorption? American Journal ofClinical Nutrition, 1997, 66:347-356.20 Allen LH, Ahluwalia N. Improvingiron status through diet. The applica-tion of knowledge concerning dietaryiron bioavailability in human popu-lations. Arlington, VA, John Snow,and Opportunities for MicronutrientInterventions Project, 1997.

absorbed (20-30%) and its bioavailability is relatively unaffected bydietary factors. Non-heme iron has a lower rate of absorption (2-10%),depending on the balance between iron absorption inhibitors (e.g.phytates, polyphenols, calcium, and phosphate) and iron absorptionenhancers (e.g. ascorbic and citric acids, cysteine-containing peptides,ethanol, and fermentation products) present in the diet 21. Because

21 Ibid.

staple foods around the world provide predominantly non-hemeiron sources of low bioavailability, the traditionally eaten staplefoods represent an excellent vehicle for iron fortification. Examplesof foods that have been fortified are wheat flour, corn (maize) flour,rice, salt, sugar, cookies, curry powder, fish sauce, and soy sauce22. 22 Ibid.

Nevertheless, the beneficial effects of consumption of iron absorptionenhancers have been extensively proven and should always be pro-moted (i.e. consumption of a vitamin C-rich food together with thenon-heme iron source).

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Supplementation

Supplementation refers to periodic administration of pharmacologicpreparations of nutrients as capsules or tablets, or by injection whensubstantial or immediate benefits are necessary for the group at risk.As established at the International Conference on Nutrition23, nu- 23 International Conference on Nutrition.

World Declaration and Plan of Actionfor Nutrition, 1992. Rome, Food andAgriculture Organization of the UnitedNations, 1992.

tritional supplementation should be restricted to vulnerable groupswhich cannot meet their nutrient needs through food (e.g. womenof childbearing age, infants and young children, elderly people, lowsocioeconomic groups, displaced people, refugees, and populationsexperiencing other emergency situations). For example, iron sup-plementation is recognized as the only effective option to control orprevent iron deficiency anemia in pregnant women. Supplementationwith folic acid must be considered for women of childbearing agewho have had a child with a neural tube defect to prevent recurrence.

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