The persistence of global hunger and malnutrition highlight the continuing problems of food insecurity (defined as a situation in which all houses

Transcription

1 4 Food Security 81 Introduction The persistence of global hunger and malnutrition highlight the continuing problems of food insecurity (defined as a situation in which all houses do not have both physical and economic access to adequate food for all members, and where households are not likely to gain such access (World Bank 2004)) and the need for invigorated attention to the development of improved food policies. Increasingly, Bank task managers need to support the design of food policy sector work, develop survey instruments that address all three aspects of food systems supply, distribution, and consumption and work with intersectoral teams to create and sustain viable food policy for individual countries. Food data Food supply, production, and consumption data are used to measure the variations in consumption of total food, food by type and specific food commodities by price, source, season, consumer characteristics and geographical regions. These data provide the basis for measuring and interpreting the relationship between the variations in patterns of food consumed and nutrients supplied. They also help to analyze food consumption, food intake, and nutritional intake by various demographic, socioeconomic, cultural, environmental and institutional factors and conditions. The best source for global food data is the Food and Agriculture Organization of the United Nations (FAO). 1 Analyzing food data The concept of food security is frequently applied at three levels of aggregation: National, regional, and household or individual. Within food security are three core determinants which can function at each of the 1. Request publications from the Publishing Management Service, FAO Information Division, Viale delle Terme di Caracalla, Rome, Italy. Fax: or

2 82 three levels and help to determine the food secure or insecure status of a country, region, community or household: food availability, food access, and food utilization. All three determinants or pillars are requisite to achieving food security. Adequate food availability is defined as sufficient food for all people through production or purchase. It is assured through policies and programs that remove impediments to an increased supply of food and requires investments in agriculture and distribution systems. Policies affecting foreign trade and food aid, agricultural input/output pricing, and resource (land, water) access impact on food availability. Food collection, storage, and distribution systems should be evaluated and may need to be improved. Updated food processing technologies and systems may also contribute to increased food availability. Strengthened rural institutions such as agriculture extension services will support and enhance policy reforms. To increase food supply, resources must go to rural development schemes that support increased food productivity, as well as to investments in agricultural research and technology (Lindert, 1996). Food access depends on adequate purchasing power and market function. In the face of inadequate access to food, efforts need to focus on reducing poverty, increasing household income, and improving market infrastructure. Poor food utilization can result from inadequate intrahousehold allocation of food and other resources and increased nutritional needs due to growth, disease, or poor nutrient absorption. Adequate food in the household will not ensure good nutrition outcomes if feeding behaviors, resources such as mothers time, or poor health status negatively impact food availability. It is important to invest in complementary resources such as nutrition education, health care, safe water provision, and sanitation to strengthen food utilization.

3 83 Food consumption data/survey methods Food consumption data are of three types: 1) household food expenditure (monetary value of food consumed); 2) quantities (in weight) of foods consumed or acquired; and 3) nutritive values (kcal, protein, fat) of food consumed or acquired. Economists generally collect data about food in household expenditure surveys that detail the household acquisition of food and non-food items. Often, however, income and expenditure surveys ask only about aggregate food expenditures rather than about specific commodities, quantities, and prices. Food consumption data thus reflect food acquired by or available to the household during a reference period; wastage or losses in the household are often not taken into account (FAO, 1993b). Nutritionists, on the other hand, collect food consumption data from specialized dietary surveys in which they gather information on the actual food intake of individual members of the household. Information on food wasted and food consumed away from the house is also collected; nutritive values are calculated by applying the appropriate food composition factors to the quantity data (FAO, 1993b). Table 4-1 summarizes the characteristics and uses of three common types of food surveys. Food balance sheets have been compiled by FAO since 1949 and are the most frequent source of international data for comparative purposes. FAO bases the food balance sheets on national data for agricultural and industrial production and trade. However, they do not take into account distribution of food intake across the population. The household income and expenditure survey is the most common type of survey undertaken as it provides data used for multiple purposes including estimates of consumer price indexes.

4 84 Table 4-1: Food Surveys Method Characteristics Food availability Derived from statistics on national and international agricultural and Food Balance Sheet industrial production and trade Provides information on the supply or availability of foods at the national level Describes the current and evolving structure of the national diet in terms of major food groups Does not reveal differentials by region or SES, nor information on consumption patterns Good for trend analysis but not for analysis of specific foods in any given year Useful for projections Overestimates actual food available at country and household levels Food access Focus is on household acquisition of food/non food items Food Expenditure Collected by interview or record keeping Survey (generally Collects information on subsistence production; good surveys impute income part of an income and consumption from subsistence production; impute value of percentage and expenditure consumed survey) Small numbers of specific foods can be added to questionnaire (e.g., questions about salt consumption in preparation for national iodization) Supplemental information on meals consumed away/outside should also be collected Express amounts per adult equivalent (e.g., calories) Identifies food acquired or available, but not necessarily consumed (wastage, losses); generally overestimates food available for consumption, underestimates alcohol consumption Collects quantity and price of foods if specifically requested Does not collect information on intrahousehold distribution of food Tabulation of nutrition values beyond calories done very rarely (often groups of foods not sufficiently disaggregated to estimate specific nutrients) Unreliable with greater than 2 week recall (except imputed value of home production) Food utilization Usually measured at the kitchen or individual level by weighing the food Special Dietary items consumed or recalled using 24-hour recall or food frequency methods Survey Food consumed away from home is captured by record keeping or interviewing Nutritive values are obtained by applying preexisting food composition values to the quantity data (local foods may not be listed) Can capture intrahousehold variation in food consumption if all members intake recorded More costly, complicated; need highly trained enumerators Underestimates dietary intake when food/beverages consumed outside the home are not captured Day-to-day variation in food intake is not reflected (can be compensated by multiple day records) Demands high degree of cooperation by respondents, and is usually characterized by small sample size Requires careful probing to elicit information about bad foods (e.g., alcohol; scavenged foods) and about items that may not be considered food (drinks, condiments) Requires estimation of breastmilk intake for young children Food composition tables may lack data on local foods

5 Uses Calculate the expected food deficit (or surplus), the necessary food import requirements and food aid requirements at the national level only Used for trend analysis of economic and demographic factor impacts on food availability Source Ministries of Agriculture FAO National statistical yearbooks Bureau of Statistics 85 Used to investigate consumer economic behavior, National survey office and to construct standard of living indices or Ministry of Planning, set poverty lines Economics, or Finance Used to examine impact of economic policy changes on household food security and consumption To identify candidate foods for fortification Measure food ingested by households and individual household members, and the corresponding nutritional values Used to identify patterns of nutritional deficiency, at-risk populations, possibly identify some determinants of undernutrition Usually nutrition division of Ministry of Health or Agriculture, but possibly national survey office Useful for suggesting themes for nutrition education formative research NGOs

6 86 Food availability The information on food availability comes from national, regional (incountry), and subregional (in-country) food balance sheets. These balance sheets are disaggregated by commodity. Food balance sheets provide no information on consumption patterns; ns; the data relate only to the supply or availability of foods at the national level (Becker and Helsing, 1991). They provide an account of the annual production of food, changes in stocks, imports and exports, and agricultural and industrial uses within a country. The remaining food available for human consumption is expressed in kilograms per year or grams per day. Per caput energy, protein, and fat availability is also usually calculated. Data reliability is a chronic problem, with broad assumptions built into the food balance sheets. In general, data on primary production are presented, but some export/import foods are composite in nature and cannot be converted to primary commodity equivalents. Estimates of food lost to feed, seed, and waste are also prone to error and may change over time. Data presentation is another issue of concern in food balance sheets. Grouping of commodities sometimes splits foods, with whole milk entered under milk and butterfat found under fats and oils. Conversion of food to nutrient data are rough averages as are data on micronutrients. Micronutrient fortification of foods is not recorded. Uses of food balance sheets While food balance sheets do not provide information on consumption patterns, they do describe the current structure of a national diet in terms of the major food commodities. It is possible to track the influence of macroeconomic, agricultural, and demographic factors over time using national food balance data. Relationships between food and nutrient availability and national trends in chronic disease mortality have been used to look at the role of diet in disease development, while compari-

7 87 sons of national food balance sheets indicate the progress of one country in relation to another (Becker and Helsing, 1991). Food access Household budget or income and expenditure surveys are generally conducted on a periodic basis to formulate and revise the average foodbasket used to construct consumer price indexes. In addition, they provide information on household level access to food and allow for the identification and characterization of food insecure households beyond the estimates that are generated from food availability calculations. The World Bank uses income and expenditure surveys, including Living Standard Measurement Surveys (LSMS), to define poverty and track changes in it over time. Depending upon the types of household data collected in a food expenditure survey, they may also characterize food and nutrient patterns by subgroups of households (e.g., disaggregated by social, economic, geographic and demographic factors). It is important to make sure that data on specific commodities, quantities, unit prices, and dining out are gathered. Capturing subgroup trends in household food access assists with policy decision-making about food taxes, subsidies, fortification, and supplementation. Data are generally derived from food purchased by the household and not consumption by an individual. Data are usually collected by a survey questionnaire (completed either by an interviewer or member of the household) covering food purchases in the previous 2 weeks, previous month, and previous year. Useful data to collect include: household composition (number, age, gender of members, location of the household, urban/rural/regional, occupational category of household head) total household expenditure (proxy for income) by expenditure deciles, area, region

8 88 total calories/protein intake by expenditure deciles, area, region consumption of major food products (quantity and expenditures by expenditure group, area, region) recommended minimum levels for calorie/protein intake implicit/in-kind food acquisition (from own production) Presentation of household budget survey data Household budget/food expenditure data are often presented as: median values, averages per household, per caput average percent contribution of each food group to total food expenditure and to total caloric consumption (reflects food expenditure pattern) percent contribution of each food group to total calories (reflects dietary pattern) percentage expenditure on food (of total expenditure) corresponding to income classes (reflects level of welfare of household) subsistence ratio Many household budget surveys collect information only on expenditures, not amounts of food purchased. Depending on market data available, household expenditures are converted into quantity of food for consumption at the household level based on the actual prices of food at the time of acquisition. Alternatively, food prices are calculated from expenditure and food quantity data. These data may be used to estimate amounts of food consumed, composition of the diet, and nutrient availabilities, both at the household and individual level.

9 89 Once data are converted from expenditures to amounts of foods purchased, it is possible to calculate from food composition tables the average daily availabilities of important foods, food groups, and nutrients from the purchased food supply for different household types. The percentage of calories or protein from different foods or food groups can also be tabulated. If food prices from different regions or market sources are available, a measure of the nutritional efficiency of different food sources can be estimated. In a review of food policy studies (Andrews, 1989), household income and expenditure surveys frequently did not include the full set of data needed for food policy analysis. Among the commonly missing data were: food prices, food consumed from home production and changes in food stocks, and individual intakes. Experience varies widely over time and by region. In Eastern Europe, community price surveys are a more reliable source of information than data collected at the household level (H. Gordon, 1999 personal communication). Adult equivalencies Food or nutrient availabilities are often reported in terms of adult equivalencies or household consumption units to facilitate comparison with recommended intakes. Adult equivalencies or household consumption units is a system of weighting household members according to ratios based on calorie requirements for different age and sex categories. Table 4-2 illustrates one weighting scale for adult equivalencies, with a sample calculation given in Box 4-1.

10 90 Table 4-2: Adult Equivalencies or Household Consumption Units Age (years) Females Males < a a 1.0 > a. Assumes heavy agricultural labor. Use 0.8 if doing moderate work. (FAO, 1990) Box 4-1: Sample Calculation for Household Consumption Unit Tabulation Household Composition Consumption Unit Woman aged 30 years 0.9 Man aged 49 years 1.0 Girl aged 15 years 0.9 Boy aged 10 years 0.7 Household consumption units 3.5 (FAO, 1990) Use of household expenditure survey data in World Bank documents Poverty and social assessments are two of the key types of World Bank analytical work underpinning the development of country assistance strategies. Household income and expenditure survey data are regularly incorporated in these assessments, as Table 4-3 illustrates.

11 91 Table 4-3: Food and Nutrition Data in Action Togo Poverty Assessment 1996 Tanzania Poverty Assessment 1995 Ivory Coast Poverty Assessment 1996 Niger Poverty Assessment 1996 Tables: Food consumption and poverty Percentage underweight children Annual average food balance Food crop price variations Target yield increases for major crop Constructed poverty lines via cost of basic needs method Ranking households using estimates of adult equivalents and consumption per adult equivalent Constructed estimates of nutritional vulnerability based on whether or not a household s consumption basket provided adequate calories Tables: Percentage of nutrient needs met, by poverty level Food as a share of monetary expenditures by poverty level Monetary food expenditure shares by income level Estimated consumption per capita of major food types (including home production and purchases) Nutrition status of children Trends in expenditure structure of households over time (Extracted from World Bank Internal Documents) Food utilization Data on household-level food purchases can mask food insecurity of individual members due to uneven or inadequate intrahousehold allocation of food or increased nutrient needs due to growth and development or disease burden demands. To assess individual food consumption,

12 92 data are collected through quantitative daily consumption methods (for example, 24-hour recall surveys), dietary history from over a longer period of time, and food frequency questionnaires (Gibson, 1990). Dietary survey data allow the calculation of both the mean and the distribution of a population s intake as well as the intakes of different groups within a population. The survey sample should be representative of the study population if the purpose of the survey is to characterize average intake for a population group. All days of the week should also be included proportionately in order to account for intra-week variation in consumption patterns (Gibson, 1990). Dietary intake assessment techniques The two main categories of assessment include recall and record methods. Recall methods (e.g., 24-hour recall and food frequency questionnaires) require subjects to recall food and beverages consumed over a period of time (usually 24 hours). Record methods (food records) have subjects maintain records of all items ingested; there are variations in the precision of estimated portions based on whether records are kept by menu, household measures, or weighing. 24-hour recall ecall. The purpose is to provide information on respondents exact food intake during the previous day. Interviewers record a list of all the foods and beverages consumed, cooking methods used, and portion size. Nutrient intake can be calculated using food composition tables. Memory errors, biased reporting (e.g., underestimation of foods with high fat or sugar content), and errors in estimation of portion size are limitations of this method. Some surveys will do repeated 24-hour recalls during over a week and during different agriculture seasons to capture day-to-day or day of the week variations, and broader seasonal diversity of the diet, particularly at the individual level. Food frequency questionnaires (FFQ). This method is designed to collect qualitative or semi-quantitative information about usual food consumption patterns. The frequency with which certain food items or

13 93 food groups are consumed during a specific time period (usually one week or one month) is assessed. The questionnaire has two sections: a list of foods and a set of frequency categories. The food list can be specific to a nutrient or food group, or be more extensive in order to estimate total food intake. FFQ data are used to rank individuals in categories of high, medium, and low intake or risk. They can also identify dietary intake patterns associated with consumption of specific nutrients this is useful for determining whether fortification with micronutrients is necessary and/or feasible. FFQs are commonly used for assessing dietary vitamin A availability. Because it is concentrated in a limited number of foods, the FFQ assessment technique is well suited to this micronutrient. Limitations of FFQ include the inability to determine (quantitatively) individual intake of foods or nutrients, the fact that only partial food intake is assessed (foods are selected for their link to a particular survey objective), and the lack of precise information regarding nutrient bioavailability. Food recor ecords ds. These provide a quantitative assessment of food intake over several days (3 7 is usual). All food and beverages consumed are recorded on a form intended to capture information on time, place, detailed description of each food item, and weight or portion size. Drawbacks to this methodology include: The need for respondents to be numerate and literate, high time requirements for the task, and the likelihood that eating behavior will change on the recorded days. Table 4-4 summarizes the range of dietary assessment methods and the types of information they can best provide. Analysis of dietary survey data Analysis of dietary intake data requires knowledge of available local food sources, the nutrient content of these foods, frequency of consumption and portion size, and the preparation and storage techniques for these foods. The basic protocol for a dietary intake assessment includes:

14 94 measurement of food ingested, calculation of the nutrient content of food ingested based on food composition tables, assessment of absorbed intakes, using estimates of the bioavailability of nutrients in foods ingested, and evaluation of the nutrient intakes in relation to recommended daily intakes or other standards (Gibson, 1990). Table 4-4: Summary of Dietary Intake Assessment Methods Information Desired Precise nutrient intake over finite time period Preferred Assessment Technique Chemical analysis of duplicate meals or calculated intake from weighed records Estimate of usual nutrient intake 24-hour recall with large number of in free-living subjects group subjects and adequate representation average of days of week Proportion of the population Replicate observations of 24-hour recall at risk or diet history Individual intake for correlation Multiple replicate observations on each individual Group or individual pattern of food use, proportion of population with particular pattern Food frequency questionnaire Average use of a particular food Food frequency questionnaire or a 24- or food group hour recall with large number of subjects and adequate representation of days of the week (Adapted from Gibson, 1990)

15 95 Food composition tables In order to convert quantities of food measured to nutrient composition values, food composition tables have been constructed for different regions and locales around the world. Currently more than 160 food composition tables are available in print, varying widely in content, length, and accuracy. 2 The only truly precise way to determine the nutrient profile of a food is to analyze a sample directly. This is costly, however, in terms of money, time, and effort; instead, representative values from food composition tables are used. These figures attempt to account for variation in factors such as different soils, climates, seed variety, and the stage of maturity at harvesting. 3 Precision problems in food-to-nutrient conversions While the representative figures for raw foods found in food composition tables are generally consistent with the results from direct analysis, fat and water content may be variable and should ideally be determined locally. The composition of milk may also be problematic in its regional variability. Make every effort to use locally derived food composition tables when possible (assuming an acceptable degree of confidence in the nutrient information). In addition to significant nutrient content variability between even closely related cultivars, growing conditions, the 2. Under the guidance of the United Nations University Food and Nutrition Program, the International Network of Food Data Systems Project (INFOODS) has established a global network of regional data centers for the collection, compilation, and reporting of food component data. Information about INFOODS, including directories of food composition tables, is accessible on the Internet at: < 3. There is currently no analytic method that can adequately account for the variations in biological activity of a nutrient consumed because of the highly specific nature of various determining factors. These include the total profile of components in the food itself, the profile of the foods with which it is consumed, and the physical condition of the person consuming the food.

16 96 maturity of animals at slaughter, and what portions are considered edible or not (e.g., apple peels, cheese rinds, animal fat) differ by location. Processing and preparation techniques are culture- and locationspecific as well, necessitating the use of local food composition table data when feasible. Take into account the fact that food composition table figures do not reflect bioavailability of specific nutrients, or the effects of food preparation such as water loss or iron gain from cooking vessels. In addition, many nutrients and food components zinc, iodine, fiber, caffeine, phytates are missing from food composition tables, curtailing their usefulness. Table D-1, Annex D contains examples of food composition tables. Changes in food nutrient content Food processing, including preparation and cooking, alters the nutrient content of raw foods. Food processing methods encompass the milling of cereals causing substantial nutrient loss such as decreased protein, iron, thiamin, niacin, and calcium content, and parboiling refined cereals such as rice and bulgur wheat prior to milling which preserves nutrients. Malting or germination increases riboflavin, niacin, and iron content and sprouting increases vitamin C and riboflavin content as well as destroys natural toxins and improves digestibility. Fermenting and souring increases riboflavin and niacin contents and increases iron absorption. Drying generally preserves nutrients if dried away from direct sunlight, canning increases water absorption due to cooking which may decrease nutrient concentration, and fortification of commercially processed foods adds vitamins and minerals (Cameron and Hofvander, 1983). Table D-2, Annex D contains comparative energy and selected nutrient values of several foods in raw and processed forms. In most cases, the absorption of water and the addition of fat during the cooking process accounts for altered nutrient density. Food preparation and cooking accounts for changes in nutrient content which varies from culture to culture and between individual households.

17 97 For rice, tubers, starchy fruits and roots, vegetables, and legumes, food preparation involves trimming, washing, and/or soaking which can cause some nutrient loss. Cooking also causes losses depending on the amount of fat or water used, type of utensils, the presence of acids or alkalis, cooking temperature and length of time being cooked. For example, the longer the cooking time (and generally the higher the cooking temperatures), the greater the destruction of vitamin C, vitamin A, folic acid, and thiamin. Storage procedures also affect the nutrient content of food. Up to 30 percent of stored crops may be lost due to insect or rodent infestation. In addition to quantity, quality may also deteriorate as proteins, fats, thiamin, and vitamin C break down over time. Yield estimates Nutrient content is generally reported either in terms of the as purchased weight of food or the as consumed weight of food (i.e., per 100 grams of edible portion with estimated waste reported as a percentage of the food as purchased). For example, 33 percent of bananas purchased in the market are inedible waste. These data are useful when developing recipes for complementary or supplementary foods the most economical sources of various nutrients can be determined using market prices and food composition tables (refer to Table D-1, Annex D for estimated waste per 100 grams edible portion of selected foods). It is also important to consider whether the yield estimates for prepared foods from raw ingredients have considered gains or losses of water and fat during preparation. Measurement of foods Measurement issues are a significant concern for the design and analysis of household food intake surveys as well as food supplementation programs. Frequently, food consumed is measured in household utensils

18 98 necessitating appropriate conversions of household or volume measures to weights before food composition tables can be used. Tables D-3 and D-4 in Annex D give standard measures with some equivalent weights for volumes. Table D-5 in Annex D provides the conversion factors for calculating approximate weights from known volumes of several raw staple foods. In addition to the nutrient density changes discussed earlier, cooking has variable effects on the weights and volumes of foods due to the absorption or loss of water. Table D-6, Annex D provides approximate weight and volume changes for select foods during cooking (for example, the volume of raw rice increases threefold when cooked). While these values are useful as general guidelines, the local standards for amount of water used and the length of time foods are cooked should be assessed for greatest accuracy. Food equivalents and substitutes Calculating yields of milled cereals and dealing with the need to design supplementary food rations on the basis of available local foods are additional issues of concern. The FAO manual, Food and nutrition in the management of group feeding programs (1993a), pulls together practical information to guide such decisions about food-based interventions in projects. Tables D-7 and D-8, Annex D present extraction rates 4 and equivalent amounts of flour and whole grains for wheat, maize, sorghum and rice, as well as a number of suggested equivalent foods for delivery of similar amounts of energy and protein. 4. When estimating amounts of whole grain cereals needed for delivery of supplementary food, allowance for losses during milling is necessary. The extraction rate varying by individual mill is the percentage of the whole grain used to make the milled product. For example, with an extraction rate of 80 percent for wheat flour, 100 kg of whole grain wheat will yield 80 kg of wheat flour (FAO, 1993a).

19 99 To convert quantities of milled wheat flour to bread, apply a conversion factor of 1.3 (100 kg of flour yields approximately 130 kg of bread). Nutrient requirements and recommendations Food intake data, collected by one of the methodologies discussed earlier, are usually evaluated (following conversion to nutrient composition) by comparing them with recommended intakes of energy and other nutrients. This can be done on a population level (for example, looking at the average protein intake per caput per day) or on an individual level. In both cases, the conclusion is approximate: Dietary intake data indicate only the probability that a person or population is adequately fed (Wheeler and Haraldsdottir, 1991). Definitions Two terms, confusingly close in wording, are critical to understanding the analytical process. Nutrient requirements are the levels of particular nutrients in the lowest amount necessary to maintain a person in good health. They vary between individuals, although the requirements of a group of similar people (age, sex, body size and physical activity level) will fall within a certain range. Recommended intakes 5 are the levels of nutrients thought to be high enough to meet the needs of nearly all the people within a similar group (as characterized above) and prevent illness. WHO and FAO set this recommendation by taking the mean minimum requirement for a nutrient plus two standard deviations. Recommended intakes were originally used for population-level planning of food supplies, hence the need to set nutrient levels high enough to meet the needs of most members of a population. A third term, dietary guidelines, is the practical linkage for the general public between recommended nutrient intakes and the translation of these recommendations to food-based guidelines. 5. Synonyms used in the literature include recommended daily allowances (RDAs) and recommended daily intakes.

20 100 Setting nutrient requirement and recommended intake levels There is no single system for establishing minimum requirement levels for nutrients, and methods differ depending upon the nutrient. In addition, the goal of the requirement may differ, varying from the amount needed to prevent clinical symptoms of a deficiency, to the amount of a nutrient needed to maintain body stores at a particular level, to the amount needed to replace expected body losses of the nutrient. Recommended intake levels are based on the estimates of minimum requirements for a nutrient plus a standard additional amount. This addition is usually either two standard deviations or a fixed percentage increment of the mean requirement for the group. Sometimes it is an arbitrarily determined typical intake based on dietary surveys (for example, in the United Kingdom, protein recommendations were set at 10 percent of total dietary energy on the basis of typical food intake data). Evaluating dietary intake While useful as planning tools, there are potential hazards to applying recommended nutrient intakes (or RDAs) to dietary intake data. Interpreting nutrient intake levels (based on conversion of dietary intake data to nutrient intake information) above recommended levels is straightforward, but intakes below recommended levels pose problems of interpretation particularly for individuals, because recommended levels of nutrient intakes exceed actual requirements in nearly all cases. Food survey data and dietary adequacy As discussed in Table 4-1, food balance sheet data are not useful for describing dietary intake adequacy of a population. These surveys collect information on the total amounts of food available for consumption by a population, but cannot provide the data to evaluate dietary intake by households or individuals. Household budget surveys provide some insight into the dietary adequacy of the household as a whole. Food consumption data for the household are evaluated in relation to dietary

21 101 standards or nutritional requirements, yielding conclusions about the group s intake being below, distributed around, or above the standard or requirement. Dietary intake surveys allow the more precise application of standards or requirements to individual intake data. Energy requirements The energy requirement for an individual is that amount of dietary energy (supplied by food) needed to maintain health, growth, and an appropriate level of physical activity (Torun, et al., 1996). Appropriate physical activity refers to survival or occupational as well as discretionary activities. For children, this would include the energy needed to explore the environment and interact with other children and adults. Estimates of energy requirements are ideally based on energy expendi- ture data, although it is possible to generate rough estimates on the basis of energy intake data from dietary surveys. For children, there is an additional allowance for growth. Because requirements are usually derived from data originating in healthy populations, they may need to be adjusted for groups in which malnutrition, disease, and other disabling conditions are prevalent. 6 Factors that influence energy requirements include: basal metabolic rate (constituting between 60 and 70 percent of total energy expenditure), physical activity, body size and composition, 6. Recommendations from the May 2003 WHO Report of a technical consultation on nutrient requirements for people living with HIV/AIDS ( hivaids_nut_require.pdf) suggests the following increased energy amounts: For adults and adolescents, during the asymptomatic phase, energy requirements increase by 10 percent over the intake levels recommended for health non-hivinfected individuals of the same age, sex, and physical activity. During the symptomatic phase, energy requirements increase by 20 to 30 percent. For children, increase energy requirements by 10 percent during the asymptomatic phase over the intake levels recommended for health non-hiv-infected children of the same age, sex, and physical activity; by 20 to 30 percent during the symptomatic phase with no weight loss, and by 50 to 100 percent during the symptomatic phase with weight loss.

22 102 age, climate and ecological factors, and disease conditions. In children, adolescents, and pregnant/lactating women, growth or fetal development is an additional factor. In malnourished children and adults, catch-up growth adds to energy requirements although further research is needed to determine the magnitude of the increment. Calculating energy requirements: BMR factorial approach Estimating population-based adult energy requirements uses a simple equation: Energy requir equirements ements = BMR (basal metabolic rate) x PAL (physical activity level) The basal metabolic rate (BMR) represents the minimal rate of energy expenditure compatible with life, and in most cases will be calculated using published data. To calculate BMR directly, individual oxygen consumption is measured and then converted to units of heat or energy output. Intra-individual BMR variability has been shown to be minor, while inter-individual BMR can vary widely. Refer to Table D-9, Annex D, for published examples of adult BMRs. Physical activity level (PAL) factors have been calculated for varying levels of occupational and non-occupational activity (see Annex D, Table D-10). Based on revised studies undertaken for the 1994 meeting of the International Dietary Energy Consultative Group (IDECG), Shetty et al. (1996) suggest that a PAL of is an average for what is termed a sedentary lifestyle typical of developed countries. This average falls in the middle of the earlier 1985 FAO/WHO/UNU Expert Consultation estimates of PAL factors for light and moderate activity, leading to the 1994 recommendation to continue using the PAL s in Table D-11, Annex D. Estimated mean per capita energy requirements Estimates of mean per capita energy requirements (EMPCER) are by necessity dependent upon the underlying assumptions that feed into the

23 103 calculations. These assumptions range from the demographic distribution of a population to the estimated basal metabolic rates, physical activity level, energy requirements for growth, pregnancy, and lactation, climate, and degree of malnutrition. Scientifically justifiable EMPCER figures range from 1,900 to 2,500 kcal. The Committee on International Nutrition of the Institute of Medicine, National Academy of Sciences arrived at a single EMPCER 2,100 kcal for use in food emergency situations; Table D-12, Annex D presents EMPCER disaggregated by age group and sex. Adjustments to EMPCER 2,100 kcal is based on an assumption of light activity. In the case of moderate activity, increase EMPCER by 100 kcal/day and for heavy activity, increase it by 400 kcal/day. In cold environments, add 100 kcal/day at 15 C, 200 kcal/day at 10 C, and 300 kcal/day at 5. For populations with a body size similar to industrialized countries, add 100 kcal/day. And while 2,100 kcal/day should be adequate to cover the catch-up growth needs for malnourished children, it is insufficient to permit adult body weight recuperation. See Allen and Howson, 1995 for detailed information on adult weight gain energy needs. Infant energy requirements The IDECG concluded that the 1985 recommendations for infant energy requirements are too high, ranging from 9-39 percent higher than IDECG s estimates, possibly leading to overfeeding of infants. The IDECG estimates 7 are found in Table D-13, Annex D. 7. IDECG recommends further expansion of the global database on total energy expenditure of healthy infants across the full age range of infancy (particularly the second 6 months), in order to confirm the accuracy of the lower energy requirement estimates.

24 104 Table 4-5: PAL Cut-Offs for Energy Requirement Estimates Age PAL 1 5 years (boys and girls) years (boys) years (girls) (IDECG, 1994 in Shetty et al, 1996) Children and adolescents energy requirements While acknowledging that there is considerable variation between physical activity levels of children and adolescents in different societies and settings, IDECG recommends the following PAL factor cut-offs (Table 4-5) for estimating energy requirements: As with adults, it is recommended that estimates differentiate between three levels of habitual physical activity. Table D-14 in Annex D provides estimates of total daily energy expenditure using PALs found in Table D-15, Annex D. Additional research is needed to further clarify energy (and other nutrients) requirements for stunted and wasted children (Torun et al., 1996). Pregnant and lactating women The optimal additional energy increment needed to support pregnancy (obtained either through additional food or reduced activity) has been estimated as 96, 265, and 430 kcal/day for each of the three trimesters (Prentice et al., 1996) or 255 kcal/day over the entire pregnancy. Basic energy requirements are calculated as for non-pregnant/non-lactating women using the BMR x PAL equation cited above. Two sets of incremental figures are suggested for energy requirements during the first six months of lactation. Full costs indicate the total amount

25 105 of energy required for milk production assuming no contribution of maternal fat stores, whereas the second set of figures assumes an approximate 500 gm weight loss/month for the first 6 months. Table D-16 in Annex D provides detailed estimates based on breastfeeding status (full or partial) and time post-partum. Global average figures follow in Table 4-6: Table 4-6: Calorie Costs of Breastfeeding Cost in Calories to Support Lactation Age Full cost Allowing for fat loss 0 6 months 635 kcal/day 480 kcal/day 6+ months (fully breastfed) a 525 kcal/day 6+ months (partially breastfed) b 285 kcal/day a. Babies receive only limited complementary feeds after 3 4 months, and breastmilk is intended to provide the primary source of nourishment for 6 months or more. b. Babies are fed breastmilk exclusively or almost exclusively until 3 4 months of age; weaning foods are then introduced progressively as part of an active weaning process. (Adapted from Prentice, et al., 1996) Protein requirements in adults The requirement for protein in non-growing adults is the minimum amount needed to meet the body s metabolic demands for nitrogen. While appearing to be straightforward, estimating protein requirements is complicated by several factors: high-energy intake improves nitrogen balance (and therefore underestimates requirements), protein utilization is not 100 percent (even with proteins such as egg or beef), and protein quality affects overall requirements. Protein quality Proteins are made up of combinations of amino acids. Nine amino acids are termed essential because they are not synthesized by the body or are synthesized at levels insufficient for human metabolic needs. Proteins are

26 106 evaluated in terms of their ability to provide these essential amino acids in the correct quantity and ratio to support growth and maintain and repair tissue (e.g., growth in childhood and adolescence, during pregnancy, and following injury, infection, surgery or prolonged malnutrition). Complete proteins are those which meet these criteria. Egg, milk, meat, fish, and poultry proteins are examples of complete proteins. Incomplete proteins are found in vegetables and grains. They are missing one or more essential amino acids, and must be combined, either with small amounts of complete protein foods or with other complementary incomplete proteins to provide the necessary mix of amino acids. Alternative methods for measuring food insecurity Both household expenditure and dietary intake surveys present problems with the accuracy and interpretation of consumption data. Maxwell (1996) suggests that neither provides a full picture of food security because of their mutual failure to measure vulnerability (such as intrahousehold distribution inequities) or sustainability. Seeking a solution to these and other problems of current methodologies, (for example, a lack of valid and reliable data for income, expenditures, and production, and high data collection costs of 24-hour recalls), Maxwell has developed a quantitative indicator of individual (short-term) coping strategies used in the face of insufficient food in the household (see Table D-17, Annex D). The data used to develop the index were collected through indepth interviews to identify the coping strategies, followed by focus group discussions for purposes of ranking the strategies according to perceived severity Among the advantages of the index is its ability to capture intentional responses to perceived food insufficiency, including information about food preparation and distribution rather than relying on production and expenditure information alone. Applying this method does not require highly trained enumerators or complex statistical analysis. It is compatible with rapid rural appraisal, anthropometric surveys, and possibly other rapid data collection methods.