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Interpretation of data on human food availability and nutrient consumption

Nevin S. Scrimshaw
Senior Adviser, World Hunger Programme

Richard Lockwood
Consultant, World Hunger Programme

Introduction

The determination of sound agricultural policy for a country requires knowledge of food production requirements, both qualitative and quantitative, to meet national needs. No agricultural programme can succeed in eliminating hunger, however, unless overall government policy serves to close the gap between human need and effective demand and to achieve an appropriate balance between national consumption needs and exports. The first task of agriculture should be to supply a sufficient quantity and quality of food to meet energy and protein needs of the local population. Once this is done, the requirements for micronutrients, vitamins, and minerals are relatively easily met.

A major problem lies in determining national needs for food energy and protein from available data. The usual means of estimating calorie and protein needs is a comparison of per capita food supplies or food consumption with estimated per capita requirements for energy and safe allowances for protein. Unfortunately, this is not a sufficient basis for identifying the relative adequacy or inadequacy of food supplies because it tells nothing about the food actually received by the lowest socio-economic group, and because FAO/WHO estimates of protein and energy needs cannot be applied uncritically to such populations.

These issues are addressed by the World Hunger Programme (WHP) of the United Nations University (UNU) as indicated in the Annex.

Significance of Calorie Intake Data

The large per capita variation in available calories and protein among regions is illustrated in Table 1. In most developing countries, and for a sizeable proportion of their populations, food balance data show caloric intakes

Prepared as a United Nations University background paper for the Working Group Meetings on Food and Agriculture for the Inter" national Colloquium on Science, Technology, and SocietY-Needs, Challenges, and Limitations; Vienna, Austria, 13 - 17 August 1979, to be less than estimates of average requirements. On a continent basis, Reutlinger and Selowsky ' report a deficit of 8.3 per cent for Africa, 5.5 per cent for the Middle East, and 10.4 per cent for Asia compared with a surplus of 3.4 per cent for Latin America. This becomes a deficit when Argentina and Uruguay are excluded. Such figures not only obscure great variation among countries, but completely fail to reflect the consequences of maldistribution of food supplies within countries. Dietary surveys of low-income groups show that for poorer sectors of the population, the deficit may be as much as 20 - 30 per cent.

For example, Figure 1 shows that although average energy intakes for Brazil are slightly above average FAO/WHO requirements, clearly large sections of the population receive inadequate calorie intakes while more affluent sectors "consume" much more than they need. Overheating and obesity would account for only a small part of this; much of it is simply wasted. Levels of 2,000 calories and below of the figure shown represent a physiological adaptation, while those above about 3,000 calories represent wastage and must be subtracted from the estimated per capita average food consumption. The policy implication to be derived by planners from Figure 1 is the advantage to all segments of society of a more equitable pattern of consumption. The poorer classes would be able to consume more in order to become healthier and more productive, and the more affluent would be less wasteful and less likely to become obese.

TABLE 1. Per Capita Food Supply 1972 - 1974

Source: FAO Fourth World Food Survey, 1977.

Significance of Protein Intake Data

Whereas a physiological adaptation is possible to a low energy intake, there is no comparable regulatory mechanism to compensate for lack of protein. There is an increased retention of absorbed protein at deficiency levels of intake, but this is effective only when individuals are depleted and not when they return to normal protein status. An added factor is that not only quantity but quality of protein must be considered.

FIG. 1. Effect of Income on Energy Intake in Brazil (Mean Requirement = 2,450 kcal/day)

FIG. 2. Effect of Income on Protein Intake in Brazil

If only average per capita protein consumption data are analyzed, it would appear from Figure 2, showing average protein intakes for Brazil, that protein needs have been met. However, examination of protein intake by income groups clearly shows the protein deficiency in the diets of low-income groups.

At deficit levels of protein intake, the difference is actually greater than shown because of a poorer quality of protein that is less efficiently utilized. Therefore, protein intake should be expressed as the percentage of available proteins compared to the recommended allowance.

Protein-Calorie Ratio

For planning and policy purposes, it is desirable to know the per cent of total calories derived from protein. This dietary protein-calorie ratio illustrates the variation in protein-energy ratio by socio-economic groups when the average protein "requirement," based on 1973 FAO/WHO standards,² is consumed. The assumption is made that no relationship exists between protein and energy needs in energy requirements the same individual. Beaton and Swiss³ conclude from the data they assembled that the correlation between protein and energy requirements could be zero, and does not exceed 0.2 per cent.

FIG. 3. Protein Calories as Percentage of Total Calories for Adults

The upper line of Figure 34 represents the situation exhibited for the mean plus two standard deviations in protein requirement, taking into account normal variation in energy intakes. Using a protein/calorie ratio, based conceptually on protein needs sufficient to cover 97.5 per cent of a population (the mean plus two standard deviations), and energy needs adequate for only 2.5 per cent (the mean minus two standard deviations) ensures that, statistically, the protein needs of 97.5 per cent of a normal population will be met when energy needs are met.

Based on the 1973 FAO/WHO allowances for proteins and the mean minus two standard deviations of energy requirements, nearly 7 per cent of protein calories as egg or milk would be needed for adults. In low-income countries, among lower socio-economic classes where plants are the predominant protein source, the protein/energy ratio might reach as much as 13 - 14 per cent to assure a coverage of over 97.5 per cent of the population if the poorer quality of protein is taken into account, and allows for the higher probability of infection and malabsorption in this segment of the population.

Figure 4 shows that average food intake for the Brazilian population would provide 8 per cent of protein calories if they were fully utilized. However, to provide 8 per cent of available protein calories would require 9 - 10 per cent of protein calories even for the quality of the diets of the most affluent 30 per cent of the population; 11 - 12 per cent for those in the middle range of income distribution; and 13 - 14 per cent for that of the poorest 30 per cent of the population. Therefore, a sloping line becomes a more appropriate basis for estimating the relative significance of the per cent of protein calories for the various socio-economic groups.

Agricultural planners interested in having a positive effect on consumption and nutritional status of high-risk populations, where protein-calorie malnutrition is most likely, must take into account not only total food availability (caloric intake), but also the protein concentration in the diet and the biological value or quality of the dietary protein. In planning a nutrition intervention, bulky foods of low caloric density, rather than food availability per se, may be the limiting factor in feeding young children. Supplements with higher caloric density may be the important issue, but the protein-calorie ratio should always be considered.

Agricultural planners interested in having a positive effect on consumption and nutritional status of high-risk populations, where protein-calorie malnutrition is most likely, must take into account not only total food availability (caloric intake), but also the protein concentration in the diet and the biological value or quality of the dietary protein. In planning a nutrition intervention, bulky foods of low caloric density, rather than food availability per se, may be the limiting factor in feeding young children. Supplements with higher caloric density may be the important issue, but the protein-calorie ratio should always be considered.

FIG. 4. Brazilian Per Capita Protein Consumption by Income Group Related to Protein Needs and Utilization

Nutritional Requirements

Two facts require emphasis. First, we do not know the nutritional requirements for various populations in developing countries under different tropical environments, and information on the capacity of local diets to meet nutritional needs is even more limited. Second, meeting a requirement applicable to healthy individuals in a temperate climate does not assure adequate nutrition for populations of the developing world, because of such added factors as parasitic infection, malabsorption, and fever associated with infectious diseases.

The FAO/WHO Expert Committee on Energy and Protein Requirements: adopted a reference man and a reference woman with a way of life corresponding to a selected daily cycle of activities. The estimates are based on activity levels observed in individuals performing various tasks under conditions in which food intake is not a limiting factor They do not take into account the fact that individuals react physiologically to limited caloric intakes by reducing activity.

Not only is there no true adaptation to an inadequate protein intake, but also stress factors affecting underprivileged populations may increase the protein needs of populations forced to adapt to low caloric intakes.⁵ The increase in the per cent of protein nitrogen retained by deficient individuals compared with well-nourished ones does not prevent the adverse consequences of the deficiency.

There is some recent experimental evidence that, even for well nourished individuals, the current FAO/WHO protein allowances are too low for long-term adequacy.^6-8 There is even more reason to believe that under conditions of frequent, acute or chronic infections, protein requirements for prompt recovery are increased.⁹ If protein intake is not adequate for recovery from such infections, individuals become progressively depleted and may develop clinical signs of nutritional deficiency. Protein deficiency has particularly serious consequences for young children whose growth and development may be permanently retarded, and for pregnant and lactating women whose children may be affected by a maternal deficiency.

Protein-Energy Interrelationships

It is important that agricultural planners understand the interrelationships of protein and calories so that planning programmes effectively meet the needs of vulnerable groups. It has been shown that a reduction in energy intake below requirements results in a loss of body protein in the adult and reardation of growth in the young.¹⁰ Second, when energy intakes are deficient beyond the point of physiological adaptation, some dietary protein is used to provide energy. When intakes of both protein and energy are inadequate, a planner must find a practical way to provide more of both.

Per Capita Availability Data (Food Balance Sheets)

As indicated earlier, the major additional problem is that food balance sheet data give no indication of the severe maldistribution of food among socio-economic groups that characterizes most developing countries.

Differences between supply and utilization are presumed to represent total availability of food stocks. Per capita availability is calculated by dividing total availability by total population. The tendency is to understate the supply side and overstate the utilization side, with the consequence that food availabilities can be under-reported by as much as 15 per cent.' I A further problem in using food balance sheet data is that food habits are not necessarily homogeneous throughout a country. The differences between Muslims and Hindus in India, and Chinese and Malaysians in Malaysia are examples.

Chen' 2 demonstrated the problems of drawing conclusions regarding food and nutrient availability from production and import data in Bangladesh. The reliability of production-import statistics can be of such uneven quality that to rely on only one set of data or one approach can be misleading. The agricultural planner needs three sets of data along with an understanding of their validity: (a} food and nutrient availability, (b) food and nutrient consumption, and (c) food and nutrient requirements, needs, or allowances. Per capita availability is dependent on total availability and population size. Variations in population estimates naturally result in differences in per capita availability.

Errors in calculating total food availability generally result from mistaken estimates of domestic production rather than from underestimates of imports. Third World data collection is all too often unreliable. Reports of yields and acreage planted are often derived from no more than guesses by local extension agents. Basically a subjective method, estimates of local levels of production are then aggregated by country, state or province, and region. Backyard crops, especially roots and tubers, are commonly not included. Storage losses, amount of feed grains used for livestock, and seed distributed are also rough approximations, generally projected at 15 - 20 per cent of available supply.

Food Consumption Data (Dietary Surveys)

The use of per capita food consumption data has many of the same inherent problems associated with use of food availability data. When countries undertake national nutrition surveys or national household budgetary surveys, the 24-hour recall method is generally employed, although 3- to 7 day diet records combined with some actual weighing of food as it is prepared is also used.

Optimal length of observation for dietary surveys is hard to determine; seasonal variations occur between harvesting and planting (surplus and scarcity), market days, and festival seasons, any of which may inflate or deflate consumption levels. Years of bumper crops or droughts can bias intake data. The main problem is that household consumption data must be disaggregated by region, income group, sex, and age to allow for recognition of possible nutrient deficiencies in vulnerable groups. Thus, for planning purposes, per capita food consumption data are of little more value than data on average food availability.

Summary

The determination of sound food and nutrition policy requires an understanding of the severe limitations of per capita data, whether based on national food balances or family dietary surveys. Per capita calorie data hide serious inequities in distribution with income group and food waste at higher income levels. Per capita protein data not only conceal severe quantitative variation with income, but also these are exacerbated by the poorer quality of protein at lower income levels.

The protein-energy levels suggested for healthy, well nourished individuals in favorable environmental circumstances may not be appropriate under the stress conditions prevailing for some developing country population groups, and additional research is required on this. A percentage of protein calories of 9 - 10 per cent is presumed adequate for most individuals consuming a good mixed diet that includes animal protein. After adjusting for protein quality, this becomes 11 - 12 per cent for predominantly cereal diets, and 13 - 14 per cent for some diets based primarily on cassava, assuming calorie intakes are adequate.

Annex: Contribution of the United Nations University World Hunger Programme

Conceptual Basis of the United Nations University World Hunger Programme

It is often assumed that the primary means of preventing hunger and malnutrition is to grow more food, but the issue is much more complex. In general, food to meet human needs is obtained in only two ways: by purchase and by procurement (home production, hunting and gathering). Even for food distributed without charge for relief purposes, someone must pay. The amount of money available and utilized for food purchases determines the effective demand for food. Effective demand for food and consumption of food are obviously closely linked. For the populations of developing countries, a gap often occurs, however, between consumption of food and nutritional needs. Simply producing more food will not meet human needs unless it leads to increased consumption. At a country level, it can lead mainly to more exports or to surpluses that people cannot afford to buy even at prices ruinous to farmers. I n the latter case, the ultimate result is decreased production.

The specific human needs that exist for the nutrients and dietary energy supplied by food are conditioned by the effect on the human host of various environmental factors. These include the interaction of physical, biological, and social influences in the environment with individual genetic characteristics, and with a variety of physiological and pathological states. Nutritional needs have been all too little studied for populations living under conditions prevailing in developing countries and consuming local diets.

The gap between effective demand for food and human needs can be approached in disparate ways: For example, in theory, people can buy more food if prices are lowered by price controls, subsidies, decreased production costs, or lower distribution costs. The same result might be achieved by increased purchasing power through better employment and income generation, higher minimum wages, reduced taxes, food subsidies, and the like. Each measure has its disadvantages as well as advantages. For some families, increased home production, or hunting, fishing, and gathering can close the gap.

Some nutritional deficiencies can be overcome, at least in part, for given populations through fortification of a staple food to improve its nutritional value. Examples are the ionization of salt to control endemic goiter, vitamin A fortification of sugar or another appropriate food vehicle for prevention of eye disease, and iron fortification of food to prevent anemia. For the poorest and the most vulnerable individuals, free or greatly subsidized distribution of food may be introduced as a temporary measure while designing specific programmes to improve the economic situation. Without sacrificing yield objectives, plant breeders can assist by adding limited specific nutritional goals to their programmes. Measures that will control infectious diseases can help by decreasing human nutrient need. Because much malnutrition is due to poor food choices and dietary habits, nutrition education has a role.

Despite the complexity of the problems, and even where structural, political, or economic changes are obviously needed, there are feasible measures to improve significantly the nutritional and health status of the underprivileged even before other changes take place.

World Hunger Programme Priorities

The principal sub-programmes of the United Nations University World Hunger Programme are as follows.

WHP Sub-programme 1: Food and Nutrition Policy and Programme Planning. The issue of unequal distribution of food among and within populations, and policies to deal with it, are major concerns of this sub-programme.

WHP Sub-programme 2: Post-Harvest Conservation of Food. The waste of food already produced leads to lower availability than official figures indicate and requires both quantitative evaluation of the losses and effective means of reducing them.

WHP Sub-programme 3: Human Nutritional Needs and their Fulfillment through Local Diets. More accurate knowledge of human nutritional requirements, especially for dietary energy and proteins, is essential to reliable policy formulation.

Activities of the World Hunger Programme

Fellowship training

Fellows in the UNU/WHP are selected by personal visits of staff to developing country institutions on the basis of institutional needs and opportunities in the WHP sub-programme areas. Prospective Fellows have relevant basic disciplinary competence and are selected for multidisciplinary applied training to deal with their country's problems. Nearly 100 individuals from more than 30 developing countries have completed training or are in the process of advanced study at one of the ten institutions currently associated with the UNU/WHP Training Programme. Most receive Fellows on an individual tutorial basis, although in some cases opportunity to participate in formal course work or in degree programmes is provided.

Three training cycles have been completed by the Nutrition Center of the Philippines, and another is in progress. These provide opportunities for the Fellows to participate in the development of food and nutrition programmes for implementation at national and community levels, and to obtain several weeks of practical field experience in rural areas. During the last week, the Center arranges for a study mission of senior health programme administrators from the countries of the participating Fellows to inform these administrators about the content and objectives of the training.

Institutional collaboration

The institutions working in the programmers activities for research and training are:

- Institute of Nutrition of Central America and Panama, Guatemala City, Guatemala
- Central Food Technological Research Institute, Mysore, India
- Nutrition Center of the Philippines, Manila, Philippines
- Institute of Nutrition and Food Technology, Santiago, Chile
- Tropical Products Institute, London, UK
- Venezuelan Institute for Scientific Research, Caracas, Venezuela
- MIT-Harvard International Food and Nutrition Policy and Planning Program, Cambridge, Massachusetts, USA
- Centre for Research in Nutrition, Laval University, Quebec, Canada
- National Food Research Institute, Tokyo, Japan
- Institute for Animal Nutrition Research (ILOB) Wageningen, Netherlands

University Fellows in research and training at the Institute of Nutrition of Central America and Panama (INCAP) in Guatemala are involved in activities relevant to the three sub-programmes. This gives them a better understanding of the multifaceted nature of world hunger problems, the multisectoral approaches to their solution, and the multidisciplinary research needed. Applied research projects undertaken by the Fellows include:

- the effect of energy intake on protein requirements of Central American pre-school age children in determining the most favorable energy-protein ratio in local diets;
- biochemical and physiological studies to determine the consequences of new national salt iodization programmer;
- the nutritional value and physical characteristics of Nigerian diets, and development of inexpensive, practical approaches to modify them to increase their nutritional content;
- ways of meeting iron needs through diet enrichment, and the implications of iron deficiency, with special reference to its effects on immune response;
- research on population factors and characteristics as determinants of infant mortality rates, and the effects of improved nutrition and other means to modify them;
- contribution of plant breeding to select better varieties of legumes, with higher nutritional value, and physical and chemical characteristics more suitable for processing with simple technology.

The Central Food Technological Research Institute (CFTRI) in India offers facilities for study and investigation of problems of post-harvest conservation and preservation and processing of foods, directed particularly to the typical needs of developing countries. The applied research initiated by the Fellows as part of their training includes the following:

- development and testing of inexpensive packaging made from indigenous material to prevent losses of grains, fruits, and vegetables during handling, storage, and transportation;
- development of simple methods of preservation of ruits for off-season use, with particular reference to preservation of fruits and vegetables in the form of concentrates;
- utilization of oilseed meals for the development of nutritious food for child-feeding programmer;
- development of appropriate models for efficient management of research and development institutions in the area of food science and technology in the developing countries;
- primary processing of cereal grains;
-development of a training programme in food science and technology in the Sudan.

The Tropical Products Institute (TPI) in London provides training in post-harvest food conservation to supplement that at CFTRI in Mysore, India. It is one of the leading centres for the study of post-harvest problems, including the various scientific, technological, and economic issues arising in post-harvest handling, processing, preservation and storage, quality control, marketing, and utilization of foods as renewable natural resources. The Institute is particularly well placed to offer Fellows from Africa experience in practical research in selected areas of food conservation.

The International Food and Nutrition Policy and Planning Program (IFNP) of the MIT-Harvard consortium offers Fellows multidisciplinary training that includes nutrition and food science, as well as the social, economic political, administrative, and public health considerations necessary in the improvement of nutritional status in the developing countries. Formal training is followed by field experience in the Philippines, Guatemala, or India.

The Centre for Research in Nutrition (CRN) of Laval University in Canada provides Fellows with training and applied research experience, designed specifically for Fellows from French-speaking Africa in post-harvest food conservation and food and nutrition policy considerations in planning. It is also giving assistance to the development of the Institute of Food Technology in Senegal. The association developed with the Department of Nutrition and Food Science at the University of Ghana is intended to strengthen their applied research activities and to help them to develop appropriate training programmer.

The National Food Research Institute (NFRI) of Japan will receive advanced study Fellows for training in post-harvest food conservation. It will provide training for Asian and other scientists that would help reduce the loss of nearly one-third of the rice harvested during milling and processing.

The Institute for Animal Nutrition Research (ILOB) in Wageningen, Netherlands, is providing facilities for research and training in the use of microbial and biomass products (MBP) for animal feeding as part of a joint project of the UNU Programmes on World Hunger and the Use and Management of Natural Resources on the microbial production of biomass from organic residues at the village level.

Applied research projects

Research project grants are awarded by the World Hunger Programme to support the training of Fellows and to help strengthen applied research competence and research networks in developing countries. The research projects will yield new knowledge for application in solving food and nutrition problems. To help fill a clear gap in existing knowledge of human nutritional needs, the programme is concentrating on the problem of protein and energy requirements under conditions prevailing in developing countries.

Five interlinked projects being undertaken at the Institute of Nutrition and Food Technology (INTA) in Chile deal with human nutritional requirements and the capacity of local diets to satisfy them, and with food and nutrition objectives in national development planning. The projects are:

a. iron deficiency anaemia in infancy and its prevention;
b. evaluation of a Chilean mixed diet to meet protein and energy requirements of adults in low-income groups under customary living conditions;
c. the role of education motivation in stimulating breast-feeding in marginal urban communities;
d. evaluation of environmental sanitation as a tool for nutrition improvement;
e. the purchasing power of low-income urban families and its effects on food consumption as the basis for developing economic indices to predict the groups susceptible to high nutritional deficiency.

The results of these investigations can be used in planning suitable programmes for nutrition improvement throughout Latin America and in many other countries.

University association with the Venezuelan Institute for Scientific Research extends the Institute's effective programme of applied research on the problem of human iron deficiency to other Latin American countries. It will contribute to its prevention through the identification of suitable foods and procedures for iron fortification in these countries, and in other parts of the world. The Institute co-ordinates its research with its counterparts in Guatemala and Chile.

WHP Advisory Committee Recommendations

The Advisory Committees of the WHP have urged that governments incorporate the following purposes into their agricultural and national policies:

a. to increase productivity, procurement, or food purchasing power of the family;
b. to decrease post-harvest losses of all kinds;
c. to take nutritional factors into consideration in agricultural research and planning;
d. to improve environmental sanitation and other measures to lessen infection and nutritional stress;
e. to decrease food costs by more efficient distribution systems.

Agencies of the United Nations, including the United Nations University, should:

a. estimate nutritional needs by review of data disaggregated according to income groups;
b. develop more effective technologies to reduce storage losses and to transfer the knowledge where it is needed;
c. provide for adequate protein-calorie ratios in planning agricultural production and practical diets;
d. examine the effect of price policies on food consumption and human nutrition;
e. take nutritional impact into account in evaluating social and economic development projects.

References

1. S. Reutlinger and M. Selowsky, Malnutrition and Poverty: Magnitude and Policy Options, World Bank Staff Occasional Papers, No. 23 (Johns Hopkins University Press, Baltimore and London, 1976).

2. FAO/WHO, Energy and Protein Requirements. Report of a Joint FAO/WHO Ad Hoc Expert Committee, WHO Tech. Rep. Ser., No. 522, (WHO, Geneva, 1973).

3. G.H. Beaton and L.D. Swiss, "Evaluation of the Nutritional Quality of Food Supplies: Prediction of 'Desirable'or'Safe' Protein: Calorie Ratios,"Am.J.,Clin. Nutr., 27: 485 - 504 (1974).

4. N.S, Scrimshaw, "W.O. Atwater Memorial Lecture-Through a Glass Darkly: Discerning the Practical Implications of Human Dietary Protein-Energy Interrelationships," Nutr. Rev., 35 (12): 321 - 337, (1977).

5. N.S. Scrimshaw, "Shattuck Lecture-Strengths and Weaknesses of the Committee Approach: An Analysis of Past and Present Recommended Dietary Allowances for Protein in Health and Disease," New Engl J. Mere., 294: 136 - 142,198 - 203 (15 and 22 Jan. 1976).

6. C. Garza, N.S. Scrimshaw, and V.R, Young, "Human Protein Requirements: The Effect of Variations in Energy Intake within the Maintenance Range," Am. J. Nutr., 29: 280 - 287 (1976).

7. C. Garza, N.S. Scrimshaw, and V.R. Young, "Human Protein Requirements: A Long-Term Metabolic Nitrogen Balance Study in Young Men to Evaluate the 1973 FAO/WHO Safe Level of Egg Protein intake," J. Nutr. 107(2): 335 - 352 (1977).

8. C. Garza, N.S. Scrimshaw, and V.R. Young, "Human Protein Requirements: Interrelationships between Energy Intake and Nitrogen Balance in Young Men Consuming the 1973 FAO/WHO Safe Levei of Egg Protein, with Added Non-Essential Amino Acids," J. Nutr., 108 (1): 90 - 96 (1978).

9. N.S. Scrimshaw, "Effect of Infection on Nutrient Requirements," Am. J. Clin. Nutr., 30 (9): 1536 - 1544 (1977).

10. H.N. Munro, "Carbohydrate and Fat as Factors in Protein Utilization and Metabolism," Physiol. Rev., 31: 449(1951)

11. T. Jogaratman and T.T. Poleman, "Food in the Economy of Ceylon," Cornell Internat Agric. Dev. Bull., 11 (Oct. 1969)

12. L. Chen, An Analysis of Per Capita Foodgrain Availability, Consumption and Requirements in Bangladesh: A Systematic Approach to Food Planning ( Ford Foundation, Dacca, Bangladesh, 1974).

13. E. Linussion, D. Sanjor, and E. Erickson, "Validating the 24-Hour Recall Method as a Dietary Survey Tool," Archiv. Latinoamer. Nutr., XXIV (3): 277 - 294 (1974).

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