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Nutrition and health

Processed supplementary foods for older infants and young children, with special reference to developing countries

Yngve Hofvander
International Child Health Unit, Department of Paediatrics, University of Uppsala, Uppsala, Sweden

Barbara A. Underwood
National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA

BACKGROUND

The "Guideline on Protein-Rich Mixtures for Use as Weaning Foods," PAG guideline no. 8, issued in 1971 by the Protein Advisory Group of the United Nations System (PAG guidelines referred to in this paper are on file at the World Health Organization and the Food and Agriculture Organization), has served as a basic reference on the subject. In recent years it has been supplemented by reports from the Codex Alimentarius Commission's Committee on Foods for Special Dietary Uses- whose documents provide guidelines for standards on the development and use of foods for infants and young children, including supplementary foods, in generic terms [1], but do not elaborate on the preparation and use of these foods specifically in developing countries.

The suggested new guidelines presented here build primarily on the technical information in the Codex committee's 1985 "Guidelines for Development of Supplementary Foods for Older Infants and Young Children'' [2], by providing practical suggestions to be considered when tailoring the development and use of supplementary foods to less than optimal conditions. These conditions usually require extra considerations to maximize the likelihood that the supplementary food will be affordable and that its preparation will lead to a nutritious, safe product. Even the most hygienic and nutritious supplementary foods can be rendered unsafe by exposure to contaminated environments or through handling by persons with poor personal sanitary practices.

PURPOSE, SCOPE, AND FOCUS

The purpose of these guidelines is to advise persons in developing countries on the preparation and feeding of low-cost, affordable processed foods that are suitable as supplements to breast milk or breast-milk substitutes when either becomes insufficient to satisfy the nutritional requirements of older infants and young children. (Throughout this article the term "breast milk" applies also to breast-milk substitutes if breast milk is not available.) Processed supplementary foods are intended primarily for use during normal infants' weaning period and also for the progressive adaptation of infants and young children to ordinary foods. They may be used as part of the total diet or as the only food under unusual circumstances, including emergency conditions.

The scope of these guidelines includes several considerations. Four to six months is the age range selected for introducing cereal-based supplementary foods. It is also recognized that (a) breast milk is adequate to meet the nutritional needs of younger infants under most circumstances, (b) younger infants require a milk product as the major food, and (c) formulated foods that contain a high proportion of milk generally are too expensive for most less privileged population groups [3-6].

The focus is the appropriate use of low-cost, affordable formulated supplementary foods. The emphasis, therefore, is on supplementary foods formulated from vegetable sources. When used as a complement to breast milk, they can provide the dietary increment in energy and nutrients that is needed to meet increasing physiological requirements to support normal growth and development.

An increased demand for low-cost supplementary foods in countries with developing economies is predictable. Current trends in such countries show a dramatic migration of low-income families to urban areas. This is associated with an increased economic necessity for the mothers to participate in work outside the home. Child-minders, often older siblings, are needed to provide food to infants and young children during periods when mothers are unavailable to breast-feed and/or provide supplementary foods. These circumstances necessitate that nutritionally adequate, hygienic foods be available that can be simply and safely prepared and fed, a role that low-cost formulated foods can serve.

Also, in some circumstances it is not possible to provide a nutritionally adequate diet for infants and young children from breast milk or affordable unprocessed local foods. Examples include when the mother dies, when lactation fails, when natural catastrophes decrease available food supplies, and when political upheavals dislocate families. In such emergencies, formulated supplementary foods may provide the only suitable temporary alternative for older infants and young children.

DEFINITIONS

Supplementary or complementary foods are formulated food mixtures meant to be used in addition to breast milk (or breast-milk substitutes) for infants from the age of 46 months until weaned, and thereafter in addition to local foods in order to provide diets that meet nutritional needs.

Processed foods are items that have been modified to achieve special characteristics, such as to improve digestibility, palatability, and ease of preparation.

Age ranges are defined as follows: younger infants, from birth to 4-6 months; older infants, from 4-6 months to 12 months; young children, 1 to 3 years.

PROPOSED MODEL FOR FEEDING OF SUPPLEMENTARY FOODS

Figure 1 shows a conceptual model for timing how foods should be used to complement breast milk so as to meet fully the energy and nutrient needs of infants and young children. Small amounts of the supplementary foods are required initially; their main purpose for older infants is to provide an additional safe source of energy that complements that of breast milk and fully supports growth and development. Beyond the age of 6 months, supplementary foods should gradually be increased in amount and variety to provide not only energy but other essential nutrients, including protein, vitamins, and minerals.

FIG. 1. Conceptual model for the introduction of supplementary foods into the diets of infants and young children (Source: Underwood and Hofvander (4])

The non-nutritional role of supplementary foods in traduced to older infants should also be recognized. These foods help to condition (educate or acculturate) infants and young children to a wider diet at weaning by providing experience with transitional liquid-to-solid variations in consistency, texture, and taste.

The nutrient composition of formulated supplements may have to be adapted to local circumstances since these foods are meant to provide such nutrients as are lacking in the basic staple food as defined by the Codex Alimentarius Commission [1, 2]. Local economic, cultural, and social acceptability factors also may influence the proposed composition of main ingredients. In addition, adjustments of a base formulation to reflect local conditions of use may require additions or deletions of certain vitamins and minerals to ensure that the daily total intake remains within safe limits.

Of greatest concern is assurance that the total diet provides the essential vitamins and minerals at a level that meets minimum nutritional needs, and that the intake of nutrients that are stored in the body, such as fat-soluble vitamins and minerals, does not consistently exceed maximum safe limits.

RAW MATERIAL USED IN SUPPLEMENTARY FOODS

In developing countries, for social and economic reasons, the raw materials used in supplementary foods should come from locally available ingredients wherever possible. The supplementary foods that are considered here are entirely or mainly based on raw material of vegetable origin. The basic ingredient is a cereal, to which are added pulses and/or oilseed flours. Animal products, such as fish or fish-protein concentrate and milk-powder products, could, or should, be added if feasible, acceptable, and economical. To increase the energy density, fat (and/or sugar) should be included among the ingredients or added to the food when it is eaten.

All milled cereals may be used to make supplementary foods. Certain cereals with a high fibre content such as millet, sorghum, and teff should be processed in such a way as to reduce the fibre content. The model composition proposed by the Codex committee suggests 5 g crude fibre per 100 g of product, but acknowledges that a higher fibre content may be acceptable after clinical testing [2]. It should be recognized that, in addition to carbohydrates, cereals contain a substantial amount of protein (8-12 per cent).

The combined use of cereals and pulses takes advantage of the fact that cereals (except rice) are relatively deficient in lysine while pulses have a high lysine content. A mutual amino acid complementation is thereby achieved by the combination, and the protein quality is improved. Tentatively, the ratio of cereal to pulses should be in the range of 3:1 or 4:1 in order to obtain the best mutual lysine complementation [6]. The quality may be improved further by adding small amounts of fish or milk products (or L-methionine). These additions, although desirable, may increase costs and may not be necessary if even small amounts of breast milk are given, or if the children are eating a reasonably mixed diet. The importance of these additions increases, however, if the supplementary foods are to be used for long periods as the only food.

The proportions in which the different raw materials are to be included should be governed by the desired final composition of the supplementary food as it relates to the total diet and by the intended use. Economic aspects should also be considered, particularly when it comes to the possible inclusion of animal food ingredients.

Although pulses provide a good source of protein (20-24 per cent), too high a proportion of pulses may be undesirable because of their content of anti-nutritional factors [1, 2], their need for long cooking times, and their tendency to produce flatulence. Examples of anti-nutritional factors are lectins (haemagglutines), trypsin, and chymotrypsin inhibitors. These factors can be destroyed by heating, pressure cooking, or prolonged cooking [2]. Fava beans should not be used when a deficiency of glucose-6-phosphate dehydrogenase (G6PD) is known to be prevalent because of the danger of favism in certain areas. Heating does not inactivate the toxic principles vicin and covicin in fava beans.

Oilseed flours (50 per cent protein), protein concentrates, and protein isolates (95 per cent protein) that are suitable for infants and young children include soya bean, groundnut, sesame, cottonseed, and sunflower seed. Appropriate conditions for the production of edible flours from soya beans, groundouts, cottonseed, and sesame are proposed in PAG guidelines nos. 5, 2, 4, and 1 4 respectively.

Dried, ground, edible fish species and edible fish-protein concentrates (with protein content of 70-80 per cent and a high lysine content) when produced under appropriate conditions (see PAG guideline no. 9) may be suitable to include as a protein source. Fish products, however, may introduce odours and flavours that are unacceptable in some cultures.

Refined or crude natural sugars are acceptable in moderation as raw ingredients to be added to increase the energy density and to improve palatability.

Fats also may be added (no more than 10 g per 100 g of product) to increase energy density and palatability. Vegetable oils and fats containing polyunsaturated fatty acids are preferred, but where advanced packaging technology is unavailable, these may reduce the shelf life because of oxidative changes (rancidity). Therefore, in many situations it is more advisable to add fat to the supplementary food at the time of feeding.

In selecting raw materials, attention should be paid to the colour, flavour, odour, texture, and consistency of the final product, realizing that these qualities must be acceptable to the mother before she will feed the product to her child. Traditional flavours added to supplementary foods may enhance acceptability. In addition, the raw ingredients in the formulated supplementary food should meet national and/or international standards with regard to wholesomeness and purity, content of toxic substances, and the inclusion of food additives [1].

NUTRITIONAL CONSIDERATIONS IN THE FORMULATION OF SUPPLEMENTARY FOODS

Energy Density

Because the energy content of the main components of supplementary foods (cereals, pulses, defatted oilseed flours) is relatively low, the energy density of the product will also be low, resulting in bulky voluminous food. Such food is unsuitable for older infants and young children, whose stomach capacity is limited. With no extra fat (or sugar) added, the vegetable-based supplementary food has only 350-400 kcal per 100 g dry weight. The energy density may be increased by adding fat (or sugar) to reduce bulkiness and by special processing of the main ingredients [2]. This processing may include toasting (roasting) of pulses and oilseeds, which improves flavour, taste, and digestibility (through dextrinization of starch) and reduces bulkiness.

Processing may also include sprouting and malting of cereals and pulses. This induces germination and predigestion of the starchy components, resulting in reduced bulk and increased nutrient density. Extrusion cooking and enzymatic predigestion are examples of more advanced processing technology to achieve basically the same results. For nutritional reasons, supplementary foods prepared from raw materials that have been specially processed as above do not require boiling during reconstitution with water. For hygienic reasons, however, boiling is usually required.

If processing alterations to reduce bulkiness are not feasible and packaging and storage conditions preclude pre-addition of fat, instructions should be given to add fats (and/or sugar) when preparing the supplementary food for consumption. This is particularly important if the supplement is to be used as the only food. If the protein content in the dry matter is 20 g per 100 9, about 20 g fat should be added (or an appropriate mixture of fat and sugar); about 10 g fat should be added if the protein content is 15 g per 100 g. This retains the protein calorie percentage at about 12-15, which is the range in mixed diets.

Although it would be desirable to incorporate adequate quantities of fat at the time of processing, this is technologically or economically seldom feasible because of stability and storage problems, as was noted earlier. In these cases, the instructions on the label should recommend adding specified quantities of fat at the time of preparation for feeding.

Protein

The Codex Alimentarius guidelines [2] are based on protein quality of at least 65, which corresponds to a protein-energy ratio (PER) of not less than 2.1. These values apply also to the products considered here.

PAG guideline no. 8 and the 1985 Codex Alimentarius Proposed model composition for supplementary foods [see 2, table 1 ] suggest that there should be 20 g protein per 100 g product and that 100 g product should provide about 400 kcal. Assuming that no extra fat (or sugar) is added when the food is prepared, the protein-energy percent age will be about or more than 20 kcal per cent, compared to about 12-15 kcal per cent in ordinary mixed foods. At this protein-energy level, (expensive) protein may be used physiologically for energy needs. If the protein content is lowered 15 g per 100 9, the corresponding ratio would provide about or more than 15 kcal per cent.

Recently an expert committee carefully considered energy and protein requirements, including the "safe level of protein intake" [7]. In the age range of 4-6 months to 3 years, the safe intake level of protein ranged between 14 and 15.5 g (protein quality equivalent to that in milk or eggs). Assuming a digestibility and quality in vegetable-based supplementary foods of about two-thirds that in milk or eggs (amino acid score of 65), the total daily safe level of protein intake would be 21 to 23 g. Therefore, to contribute two-thirds to three fourths of the recommended protein intake, the supplementary food should contribute 14-17 g protein.

It is therefore suggested that the protein content of 20 g per 100 g in the Codex proposed model composition for supplementary food should be lowered to 15 g (14-17 9) per 100 g and that the instructions for use should take the above considerations into account.

Fibre

Because dietary fibres are slowly absorbed and fermented by intestinal flora, thus causing a laxative effect, the crude fibre content of the supplementary food should not exceed 5 g per 100 g dry matter [2].

Vitamins and Minerals

Minimum Adequate Daily Intakes

The addition of extra vitamins should take the following into account:

- the vitamin and mineral content of the ingredients of the supplementary food itself,
- local nutrition and health problems, - the distribution of vitamins and minerals at MCH centres, and
- relevant national legislation.

Minimal safe daily intake levels from the total diet are shown in table 1. Only those vitamins and minerals listed by the Codex committee to be contained in supplementary foods are shown. These minimum levels of daily intake and the estimated energy requirement are based on infants 6 months and children 3 years of age [7, 8].

Maximum Safe Daily Intakes

Excessive intake of fat-soluble vitamins and some minerals over a long period of time may result in toxicities. The margin of safe intake varies considerably by nutrient. In this document we consider safe maximum levels only for vitamins A, D, and E and for the minerals calcium, phosphorus, iron, and iodine since these are the micronutrients in the Codex proposed model composition for supplementary foods.

Chronic toxicity is reported from daily ingestion of vitamin A in excess of 2,500 IU per kilogram of body weight (750 µg/kg) by infants 4-6 months old [9] (1 IU = 0.3µg retinol = 1 retinol equivalent [RE]). On the other hand, single doses of 100,000 IU given twice yearly to infants 6-12 months old and 200,000 IU given to children over 12 months old at similar intervals have been safely used in several large-scale vitamin A distribution programmes [10]. In view of the uses intended for the supplementary foods considered in these guidelines, maximum levels of vitamin A should not exceed 4,000-6,000 IU if the supplement is consumed daily as the sole food. Recognition of local circumstances, for example, an area where periodic high-dosage supplementation programmes are in operation, may be a reason to fortify the supplementary food at the minimum level.

TABLE 1. Safe minimum daily intake of some micronutrients for infants and young children from 4-6 months to about 3 years old, based on energy requirements

Figures are based on a daily average energy requirement of 800 kcal for an infant 46 months old and 1,350 kcal for a 3 year-old child [7, 9-11].

Hypercalcaemia in infants and young children is reported when total daily intake of vitamin D exceeds 2,000-4,000 IU for several months (1 IU = 0.025 m g vitamin D). Since the need for this vitamin is determined, in part, by exposure to sunlight and intensity of skin pigmentation, the safe level in the diet varies. These two factors also may affect whether it is appropriate to add vitamin D to formulated supplementary foods.

There are no reports of toxicities from ingestion of vitamin E in high levels, although excessive intake can interfere competitively with the absorption of other fat-soluble vitamins. It is unlikely that natural diets of infants or young children would contain vitamin E at toxic levels, and high-dose supplementation is also unlikely. Daily diets should aim at total intake of about 10-15 IU (1 IU = 1 mg a -tocopherol acetate).

Ingestion of calcium, phosphorus, iron, or iodine at toxic levels in the natural diets is unusual in the age groups for which supplementary foods are meant. In addition, the absorption efficiency of calcium is regulated by vitamin D. The greater concern with respect to safety is to maintain a habitual diet in which the ratio of dietary calcium to phosphorus is about 2 or less.

The limited availability of iron, especially in vegetable-based diets, makes toxicity of concern only when iron supplements exceed the range of 25-40 mg daily for older infants and young children. The desired range of daily iron intake is about 10-15 mg [11].

Total daily intake of iodine in excess of 600 m g can be injurious and is of concern only in areas where high doses of iodine are used in prophylactic programmes.

PROCESSING

The choice of processing method depends on many factors, among them the primary purpose of the product, the social and economic conditions of the area into which it is being marketed, the local dietary habits of infants and young children, the hygienic conditions in which it is being used, the technology available, and local cost-benefit considerations [1, 2].

PREPARATION FOR USE

Non-heat-processed mixtures of raw ingredients should be adequately boiled during preparation, while boiling (for nutritional reasons) may not be required for heat-processed or enzymatically pretreated mixtures. The option not to boil such processed mixtures after addition of water depends above all on the quality of the water available, sanitary conditions in the surroundings, and personal hygiene practices. Food that is safe as consumed is of primary importance in feeding infants and young children, especially those at risk for malnutrition. Therefore, if there is any doubt about food safety, even heat-processed products should be boiled before they are fed.

Guidelines concerning the addition of fat (or sugar) during preparation were discussed earlier. To summarize briefly, if (a) the product is the only food fed, (b) no fat was added in the processing, and (c) the protein content is 15 g per 100 9, about 10 g fat or 20 g sugar (or an appropriate combination) should be added per 100 g product. This contributes an extra 90 kcal if fat is added and 80 kcal if sugar is added.

HYGIENE AND PACKAGING

When tested by appropriate methods, the final processed product should be free from pathogenic micro-organisms (and/or substances originating from such) in amounts that may represent a hazard to health, and should not contain any poisonous or deleterious substances [1]. The product should be prepared, packed, and stored under sanitary conditions. It should be packed in containers that will safeguard hygienic and other qualities of the food.

LABELLING

The technical name of the product as proposed by the Codex committee should be "supplementary food for older infants and young children." In addition, any appropriate designation or brand name may be used in accordance with national preferences. At a minimum, the label should include the net content by weight, storage instructions, and instructions for preparation before feeding. Pictorial instruction should be considered where literacy levels are low. Other information on the label may be considered; however, it may not be possible (or indeed necessary)to declare, as suggested by the

Codex committee, the sources of protein, list of ingredients, nutrient value, and date marking. This information should be available, but not necessarily on the label. The label should state that the product is for use in feeding infants 4-6 months old and older.

It is expected that existing local and/or national legal restrictions or rules concerning the formulation, marketing, and sales of food products will be followed.

ACKNOWLEDGMENTS

This report was prepared at the request of Dr. Nevin Scrimshaw and with the support of the UNU Programme on Food, Nutrition, Biotechnology, and Poverty and the International Union of Nutrition Sciences.

The authors benefited from comments provided by the WHO Nutrition and MCH units; Professor M. K. Gabr, Cairo, President IUNS; Professor Joseph Hautvast, SecretaryGeneral IUNS; Professor J. Kusin, Amsterdam; and Professor Ricardo Bressani, Guatemala.

REFERENCES

1. Codex standards for foods for special dietary uses including foods for infants and children and related code of hygienic practice, Codex Alimentarius, vol. 9, 1st ed. (FAO/WHO, Rome, 1982) and Supplement 1 (Rome, 1984).

2. "Guidelines for Development of Supplementary Foods for Older Infants and Young Children," Report of the 14th session of the Codex Committee on Foods for Special Dietary Uses, appendix 12 (FAO, Rome, 1985).

3. A Ashworth, "Feeding of Infants and Young Children: An Annotated Bibliography," Trop. Dis. Bull. (Suppl.), 81: 1 -91 (1985).

4. B. A. Underwood and Y. Hofvander, "Appropriate Timing for Complementary Feeding of the Breast-fed Infant: A Review," Acta Paediatr. Scand. (Suppl.), 294: 1-32 (1982).

5. G. H. Beaton and H. Ghassemi, "Supplementary Feeding and Nutrition for the Child in Developing Countries,'' Am. J. Clin. Nutr. 35: 864-916 (1982).

6. M. Cameron and Y. Hofvander, Manual on Feeding Infants and Young Children, 3rd ed. (Oxford University Press, Oxford, England, 1983).

7. Energy and Protein Requirements, Report of a Joint FAO/WHO/UNU Expert Consultation, WHO Technical Report 724 (WHO, Geneva, 1985).

8. ESPGAN Committee on Nutrition, "Guidelines on Infant Nutrition: I. Recomendations for the Composition of an Adapted Formula," Acta Paediatr. Scand. (Suppl.) 262: 1-20 (1977).

9. J. C. Baurenfeind, The Safe Use of Vitamin A: A Report of the International Vitamin A Consultative Group (IVACG) (Nutrition Foundation, Washington, D.C., 1980).

10. K. P. West, Jr., and A. Sommer, Periodic, Large Oral Doses of Vitamin A for the Prevention of Vitamin A Deficiency and Xerophthalmia: A Summary of Experiences (Nutrition Foundation, Washington, D.C., 1984).

11. P. R. Dallman and M. A. Siimes, Iron Deficiency in Infancy and Childhood: A Report of the International Anemia Consultative Group (INACG) (Nutrition Foundation, Washington, D.C., 1979).

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