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Food and nutrition bulletin
Published by the United Nations University, Tokyo, Japan.
Food and Nutrition Bulletin
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The Food and Nutrition Bulletin incorporates and continues the PAG Bulletin of the former Protein Calorie Advisory Group of the United Nations system and is published quarterly by the United Nations University in collaboration with the United Nations ACC Sub-committee on Nutrition. The views expressed are those of the authors and not necessarily those of the United Nations University or the ACC Sub-committee on Nutrition.
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Food and Nutrition Bulletin, vol. 11, no. 1
(c)The United Nations University, 1989
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A number of the industrialized countries have developed dietary guidelines for health, and several have produced excellent background documents giving the evidence for their recommendations. In this issue we are publishing a translation of the dietary goals for health in Latin America published in a current special issue of Archivos Latinoamericanos de la Nutrición, together with suggestions for developing national guidelines based on these goals. The issue will include fourteen chapters providing an analysis of the data on which nutritional goals and suggested dietary guidelines are based.
The nutritional goals proposed for the Latin American countries have universal application for rich and poor alike, but the diets to achieve these goals will differ greatly among and within these countries. The publication Healthy Nutrition, issued by the WHO Regional Office for Europe , which is reviewed in this issue, proposes similar dietary goals and presents the background for them.
Both the Latin American and European publications are based largely on prior WHO recommendations. They provide suggestions to governments for translating the nutritional goals into food goals and eventually into dietary guidelines relevant to their own dietary and cultural traditions, while taking into account economic and other constraints on the provision of food. Both stress that a coherent food policy, taking prevention into account, involves joint action by ministries of health, agriculture, food, education, industry, and economics if benefits to health are to be achieved with the use of local food production.
The United Nations University programme in Food and Nutrition has assigned a high priority to promoting the development in every country of dietary guidelines for health that are culturally acceptable and economically feasible. In the past year comprehensive reports have also been published by Australia  and the United States . These publications will be helpful to countries in other regions for developing dietary guidelines to meet the needs of their own populations
1. Healthy nutrition: preventing nutrition-related diseases in Europe. WHO regional publication, European series, no. 24. Copenhagen: WHO Regional Office, 1988.
2. Nestel PJ, ed. Diet, health and disease in Australia. Sydney: Harper & Row, 1987:155.
3. McGinnis JM, Nestle M. The Surgeon General's report on nutrition and health: policy implications and implementation strategy. Am J Clin Nutr 1989;49:23-28.
José María Bengoa, Benjamín Torún, Moisés Behar, and Nevin S. Scrimshaw
This is a translation from the Spanish of the first part of the report "Guías de alimentación: Bases para su desarrollo en America Latina" by the same authors, based on a workshop on that topic held in Caracas, Venezuela, 22-28 November 1987, sponsored jointly by the United Nations University and the Fundación Cavendes .
This first part of the report is concerned with quantitative nutritional goals that should be useful for nutritionists and health professionals in all countries. The second part, not presented here, gives suggestions for expressing these goals in terms of dietary guidelines adapted to the food availability and preferences of individual countries and populations in Latin America. The entire report, with sixteen background papers covering every major area of the nutritional goals and their rationale, is being published in Spanish as a special issue of Archivos Latinoamericanos de la Nutrición.
The terms "requirements," "needs," "recommendations," "goals," and "guidelines" are often used in different ways in relation to nutrition and consumption in different contexts. For the purposes of this report the following definitions are accepted.
Nutritional requirements: These are the quantities of energy and bioavailable nutrients in the foods that healthy individuals must eat to meet all of their physiological needs. By "bioavailable" is meant that they are digested, absorbed, and utilized by the organism. The nutritional requirements are individual physiological values that are expressed as averages for similar population groups-e.g. preschool children, adolescent males, pregnant women, and adult males with a determined physical activity.
Nutritional recommendations: These are the quantities of energy and nutrients that the foods consumed must contain to meet the requirements of almost all the individuals in a healthy population. They are based on requirement figures, corrected for bioavailability, to which the necessary quantity to cover the variability of the individual is added and, for some nutrients, an additional quantity is included as a margin of security.
Minimum and maximum limits exist for energy and nutrients outside of which the functioning of the organism and health are unfavourably affected.
Nutritional goals: These are the nutritional recommendations adjusted to a particular population for the purpose of promoting health, controlling deficiencies or excesses, and minimizing the risk of diseases related to nutrition. Furthermore, they take into consideration the sources of energy and nutrients, the proportions in which they are consumed, and the factors that affect their availability and consumption.
Nutritional guidelines: These are indications of practical ways to reach the nutritional goals of a given population. They are based on the habitual diet of the population and suggest necessary modifications. They take into consideration ecological, economic, social, and cultural characteristics of the population and its biological and physical environment.
Nutritional guidelines should be established for the total population of a country or region and also for special groups within that population with specific needs (e.g. young children) and for those at high risk for health problems related to nutrition (e.g. obesity).
To establish nutritional goals, the recommendations of energy and nutrients that have been proposed by other organizations and international groups of experts were used as a basis. Those proposals were interpreted in light of recent scientific information and on the basis of the specific characteristics of Latin American populations.
The nutritional goals for a population permit the recommendation of diets adequate in quality and quantity to meet the needs of the members of that population and to enable them to reach and maintain a good state of health. In this sense the goals should take on a preventive nature to avoid or reduce the incidence of diseases associated with poor nutritional practices. In order to establish these goals for Latin America, the following factors must be considered.
Prevailing nutritional and health conditions
In the majority of Latin American countries there are numerous children with malnutrition and retarded growth and development, and adults whose physical activity is limited by lack of enough calories. Both situations are due to insufficient and inadequate nutrition. This is aggravated by a high incidence of diarrhoea diseases and other infections. To these deficiencies are added nutritional anaemias and, in some populations, endemic goitre, vitamin-A deficiency, and other diseases of deprivation. Consequently, the diet must allow for the correction of these nutritional problems and compensate for the losses of and increased metabolic needs for various nutrients caused by infections.
In addition, in various sectors of the population an increase can be observed in the prevalence of diseases associated with nutritional excesses and the disproportional consumption of nutrients-such as obesity, diabetes, hypertension, and arteriosclerosis.
Heterogeneity of the population
In all Latin American countries there are urban concentrations and dispersed rural populations, with different habits and availability of foods according to their ecological circumstances. The diversity of socioeconomic and cultural conditions and levels of education also influences nutritional practices. Therefore, it is necessary to used different criteria and strategies to establish nutritional goals that will satisfy all or the great majority of the population. Nutrition and health education will play a fundamental role in those strategies.
Groups vulnerable or at risk
In all populations there are groups of individuals who are more vulnerable than others to nutritional diseases because of their age or physical state. In Latin America, furthermore, there are population groups that are at greater risk of having nutritional problems due to the socio-economic and cultural conditions in which they live. The problems are primarily those of deficiency in marginal urban areas and dispersed rural areas, while among urban groups of higher economic strata problems due to excess consumption predominate. These should all be taken into account in formulating the guidelines for attaining the nutritional goals.
Characteristics of diets
Large sectors of the rural Latin American population eat principally foods of vegetable origin. Diets based on these foods are very bulky and have a low concentration of various nutrients. Furthermore, the digestibility and/or bioavailability of some nutrients is less than in diets with a greater proportion of foods of animal origin such as are consumed by other population groups, which have advantages in nutrient content though they increase the risk of some chronic diseases.
Interactions between components of diet
A great number of interactions between components of diet have been described. Although many of them have been demonstrated only under experimental conditions, others can have practical importance in Latin American diets. Nutritional practices that lead to interactions with a beneficial effect, such as including foods with vitamin C and foods with iron in the same meal to increase the absorption of iron, should be promoted. On the other hand, combinations of foods with components that have undesirable interactions, such as tea along with sources of iron and zinc, should be avoided. This is expecially important when the diet contains small or marginal amounts of those minerals.
The nutritional goals should be expressed in adequate qualitative and quantitative terms. The qualitative aspects should consider the biological form of the nutrients, their natural sources, and the advantage of simultaneous or isolated consumption of two or more nutrients. The quantitative aspects include the quantities of nutrients and proportions of their sources to permit good nutrition.
It is advantageous to express quantities in a uniform way and to consider the family as a basic unit of consumption. This can be done if the following points are kept in mind: (a) each family member must be able to consume enough food to obtain all the nutrients needed, and (b) the diet must satisfy both the energy needs of the individuals and also their needs for other nutrients.
The first step, then, is to determine the quantities and concentration of energy that the diet needs to supply. The concentration of food energy should be high in the diets of young children, whose stomach capacity limits the amount of food they can eat. This is perhaps also true for the elderly, whose reduction in appetite can limit the amount of food they eat.
Once the quantity and concentration of energy in the diet are established, recommendations for the majority of nutrients can be expressed as functions of that energy-for example, quantities for each 1,000 kcal. This is consistent with the idea of establishing nutritional guidelines that use the family as the basic unit of consumption. On the principle that "the whole family eats from the same pot," it is most practical to recommend a balanced diet containing concentrations of nutrients that meet the requirements of each family member when they eat enough to meet their energy needs. Nursing children, obviously, need special nutrition.
It should be recognized that for almost all the nutrients there exist limits of adequacy and for some nutrients there can be risks from either low or high consumption. For these nutrients, the nutritional goals should express the minimum and maximum levels that are safe for the population. When the maximum limit is so high that it cannot be exceeded when consuming a common diet, it need not be mentioned. On the other hand, there are some nutrients that are not absolutely indispensable but that it is advisable to consume a certain amount of (for example, proteins of animal origin); in these cases, a minimum consumption is suggested.
The recommended allowances are expressed as daily intakes. However, this does not mean that the cited quantities should necessarily be consumed every day of the week but rather that they are quantities that should be consumed as a daily average, permitting some variability between one day and the next on the basis of body reserves and transitory metabolic adjustments. The magnitude of this variability and the period of time on which the average intake is based will depend on the nutrient in question.
Tables of food composition
For the correct interpretation of the goals and the implementation of guidelines, it is necessary to have tables of food composition that are complete and dependable. The tables presently available for Latin American countries need to be revised and updated, particularly with reference to dietary fibre and various micronutrients.
As a point of departure, the workshop accepted the recommendations made by a joint FAO/WHO/UNU expert consultation in 1985 . These establish that the energy needs of individuals are the amount of food energy required to compensate for energy expenditure when their size, body composition, and level of physical activity are compatible with a lasting state of good health and the maintenance of physical activity that is economically necessary and socially desirable. In children and pregnant or lactating women, the energy needs include, furthermore, those for the formation of tissues or the secretion of milk in a rhythm compatible with good health.
The FAO/WHO/UNU report also recommended that those energy needs should be calculated as multiples of basal metabolism, taking into consideration the age and sex of the individual. Within practical limits the requirements for food energy are expressed as energy units (calories or joules) per day or per unit of body weight per day, based on the basal metabolic rate, the level of physical activity, and the growth needs of the individual.
The energy requirement also depends on the activity that individuals need and that the environment and society impose. This obviously differs among different population groups of the same country. Therefore, it is not appropriate to designate persons of reference for all of Latin America or even for a whole country. Each population group has its own energy needs that depend on a series of factors that include the nature of its members' work, their volunteer and recreational social and community activities, their body mass, their physical state, the physical environment, etc. It is suggested that at the level of each country or population, the most characteristic types be established which will permit calculation in order to plan specific actions or programmes in that country or population.
Accommodation and adaptation
Humans have the capacity to modify their metabolic functions and their conduct in response to changes in energy consumption by way of adaptations and accommodations. We have differentiated between these two mechanisms according to the following considerations: When the modifications permit the individual to use the available dietary energy more effectively without suffering undesirable changes (for example, reducing the rate of basal metabolism or doing mechanical work with more efficient movements), we consider this to be adaptation. However, when these modifications permit individuals to survive but at the expense of changes that expose them to greater risks of disease and poor nutrition (for example, reducing their body reserves or rate of growth) or a decrease in the quality of their life (for example, limiting their physical capacity or reducing socially desirable activities), we classify this as accommodation or adjustment to the prevailing conditions.
Faced with a reduction of food energy, individuals first adapt by changing their pattern of physical activity and their energy use. When the reduction is of greater magnitude, they must accommodate by changes in weight and body composition and in activities of social importance. In children, the rate of growth is altered as well. When the changes persist for a sufficiently long time, they can have grave consequences for health and behaviour.
Energy consumption and energy use
The measurement of the energy consumption of a population should not be used as an indicator of its energy needs since different proportions of individuals consuming insufficient, sufficient, or excess dietary energy coexist in every country. Furthermore, it should be recognized that individuals and populations can accommodate themselves to dietary deficiencies by a decrease in their physical activity and, in case of children, by a reduction in their growth rate. However, both accommodations have important biological, economic, and social costs and do not represent desirable changes.
A chronic lack of sufficient dietary energy can also result in changes in the nature of a society. For lack of sufficient food energy an important proportion of the Latin American population has restrictions on its physical activity and/or its growth. In adults this affects the capacity to improve one's economic status, interact socially, and participate in the development of one's community. In some populations that are displaced or are at a low socio-economic level, the situation is growing even worse. In children there are important consequences for their physical and mental development.
On the other hand, an excess of food energy that results in excess weight produces adverse metabolic changes that can affect health, with a greater incidence of hypertension, diabetes, arteriosclerosis, and heart disease.
The nutritional goals should be directed at preventing all of these physiologically and socially undesirable consequences. Moreover, they are important for a realistic calculation of national requirements for food energy, based on the needs of different social and geographical sectors of the population and not on the needs of the most active or the most sedentary groups. An estimate based on the needs of the most active groups would result in an excessive figure for the agricultural and political planning of imports and would lead to recommendations that could produce obesity in many individuals. On the other hand, an estimate based on the needs of the most sedentary groups would result in insufficient production or importation of food and would cause many individuals to be malnourished.
There exists a limit in the recommendation to reduce food energy to avoid obesity. A certain level of occupational or discretional exercise is necessary to develop and maintain the physical capacity of the individual and to reduce the risk of cardiovascular diseases. Therefore, it is better to increase physical activity than to reduce the minimum energy supply of the diet.
A child should consume the amount of food necessary to attain his/her genetic potential for growth. The body size he or she reaches in adult life is not of primary importance, but the retardation in growth due to nutritional and environmental circumstances is associated with higher rates of morbidity and mortality, learning deficiencies, and a more limited physical capacity in adult life.
In some populations a loss of body weight can be observed during certain periods or seasons of the year. This weight loss demands additional consumption in a subsequent season or period of time, and influences the quantity of food consumed in a country during different times of the year. Similarly, during periods of acute infections energy intake is reduced, and during the period of recuperation additional dietary energy is needed for accelerated compensatory recovery and growth.
Digestibility of the diet
The digestibility of dietary energy sources diminishes in diets with a high fibre content. In accordance with the recommendations of the FAO/WHO/UNU consultation , it is suggested that the energy requirements be multiplied by 1.05 to calculate the energy that diets high in fibre supply in rural populations, and by 1.025 to calculate the energy supplied by urban diets with a moderate amount of fibre.
Energy density and food volume
The energy density of the diet is a conditioning factor important in the total dietary energy intake. If the concetration of energy is low, a young child will not be able to eat enough food to satisfy his/her energy needs. Because of this it is recommended that liquid foods for infants and preschool children should be prepared with an energy density of 0.4 kcal per millilitre. Solid foods for these children should have an energy density on the order of 2 kcal per gram. For older children and adults, an energy density on the order of 1.4-2.5 kcal per gram-combining the densities of liquid and solid foods-will permit the diet to meet the energy needs, without being so high as to cause obesity.
The workshop discussion referred to the minimum criterion of 1.27 x BMR (basal metabolic rate) suggested by the FAO as a minimum energy supply. This only permits survival without physical activity beyond eating and attending to personal functions and is not compatible with long-term health. The group estimated that for adults an energy consumption of 1.4 x BMR represents the appropriate minimum for even sedentary survival.
For individuals who engage in discretional activities, socially desirable and necessary for promoting health, and in occupational activities that require light, moderate, or intense physical strength, these values increase to 1.55, 1.80, and 2.1 x BMR respectively. The average food energy requirements for individuals according to sex and age group are summarized in table 1. For those older than 14 years, the requirements depend on the intensity of habitual activity. For children less than 14 years old, a moderate level of activity that is considered the desirable minimum for physiological and social development is assumed.
In order to satisfy the needs of all the individuals in a population, the diet should provide a quantity of protein above the average individual requirement as a safety margin. The proposal of the FAO/WHO/ UNU consultation  to add 25% of the average requirement of individuals of determined sex and age is considered adequate. In addition, adjustments related to the digestibility of the diet's protein must be made.
It is advisable to take into account populations that live under poor hygienic conditions and have changes of intestinal mucus that diminish the digestibility of proteins. To do so would justify an increase on the order of 10% in the recommended proteins for these populations.
During an episode of diarrhoea or other acute infectious disease, a net loss of protein occurs. The loss of appetite associated with infectious disease aggravates the situation further. It is therefore necessary to increase protein intake during the period of convalescence, when appetite has recovered. Further-more, rapid catch-up growth can be observed in children during this period, which also requires more protein. It is suggested, therefore, that estimated protein needs can be as much as 40% higher in preschool children and 20% higher in school-age children. These considerations can have special relevance when infectious diseases are endemic in populations.
TABLE 1. Calculated energy requirements for Latin America
|0.3 - 3||_a||100||_a|
Calculated on basis of ref. 2.
a. Depends on age.
Essential amino acids
The content of essential amino acids in diet should be consistent with the patterns suggested by the FAO/WHO/UNU consultation (table 2), in accordance with the amino acid requirements of preschool children. Recent studies support the use of this pattern for all age groups.
TABLE 2. Reference amino acid patterns- suitable for all age groups except infants (milligrams per gram of protein)
Source Ref. 2
Foods of animal origin, such as meat, eggs, fish, and milk, help to provide a desirable content of protein and essential amino acids in the diet because they have a high concentration of easily digested proteins and an excellent pattern of amino acids. However. these foods are not indispensable, and, when their availability is limited, two or more sources of vegetable proteins with complementary amino acid patterns can be used, with or without some animal protein. One of the sources. at least, should have a relatively high concentration of protein. A classic example of this system is the use of grain and legumes in proportions that reciprocally complement the limiting amino acids of each component. The system can be improved significantly by the use of genetically improved grains (e.g. corn high in lysine), grains cultivated with agronomic techniques that increase their protein concentration (e.g. rice), or small proportions of animal protein. The consumption of 10% - 20% of proteins of animal origin, in addition to supplying essential amino acids, increases the supply and bioavailability of essential minerals in the diet.
Recommended protein quantity
On the basis of the former considerations, the daily recommended intake of protein would be 1 g per kilogram of body weight per day for an adult male who consumes one of the mixed diets common in Latin America with proteins with a "true" digestibility of 80%-85% and with a quality of 90% in relation to the pattern of reference for essential amino acids. Table 3 shows the values of reference protein (milk, egg) and of the protein of a mixed diet suggested above.
Maximum quantity of proteins and protein-energy relationships
From a practical point of view it is not necessary to fix a maximum limit for protein consumption, given the quantity that usual diets supply. However, it is recommended that proteins of animal origin should be limited to 30%-50% of the total proteins consumed, except for children under one year old. The reason for limiting the consumption of meats and other sources of animal protein is their saturated fatty acid content, as discussed in the section on fats below.
TABLE 3. Daily protein allowance (grams per kilogram of body weight, except as otherwise indicated).
Milk or eggs
|first 6 months||
|after 6 months||
Source Ref. 2.
a In years, except as otherwise indicated.
b. Extra allowance, in grams per day.
The concentration of proteins in relation to the total volume or mass of the diet should be taken into account, since a low concentration can prevent the fulfilling of protein needs, particularly in young children and the elderly.
As to the percentage of energy derived from proteins in relation to the total energy in the diet (PE%), healthy children and adults who eat enough to satisfy their energy needs can meet their protein needs if the diet provides between 8% and 10% of the energy in the form of good quality protein. For populations with limited animal protein in their diets and who do not live in a hygienic environment, between 10% and 12% is more appropriate, a figure very consistent for diverse populations of the world. By consuming a diet that satisfies the total food energy needs, that proportion of protein energy permits the recommendations of table 3 to be reached, even taking into account the 20%-40% additional protein suggested for children with a high incidence of infection. For the elderly whose energy consumption is reduced because of inactivity or weakness, it is recommended that the proportion of energy derived from proteins be increased to 12%-14%.
Use of local foods
Taking into account the previous considerations and the characteristics of common foods that are available in the majority of low-income homes in Latin America, it is feasible to establish dietary guidelines for diets with good quality protein without having to imitate the diets of countries or population groups with higher socio-economic status.
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