Introduction
Nutrition is a fundamental domain of global health; it is fundamental to the health of individuals, the stability of populations, and the academic discipline that is global health.
Nutrition is also a domain of global health where military forces are likely to be called upon to assist. Undernourishment is chronic in many less-developed regions across the globe, and many more people are acutely vulnerable to undernourishment with even the slightest perturbation in their local economy or community. War and conflict often serve as major disruptors that push vulnerable populations into acute states of undernourishment, and already-undernourished individuals into the most desperate of circumstances. This chapter will begin with an overview of the fundamentals of nutrition as should be understood from the perspective of a global health practitioner, and then transition to a discussion of the relationship between nutrition and security.
The Global Burden of Malnutrition
It is important to comprehend the scope and depth of the problem of malnutrition if one aspires to assist in combating the problem. There are currently 795 million people in the world who are undernourished. Although hunger and food insecurity can be found even in the wealthiest countries, the overwhelming majority of clinically undernourished people reside in developing countries. Of all people who live in developing countries, 12.9% are undernourished. The following figure ( Fig. 5.1a ) from the World Food Program illustrates the prevalence of undernourishment in various parts of the world.
Undernourishment represents such an enormous burden to global health and development that it is the subject of the second Sustainable Development Goal: “End hunger, achieve food security and improved nutrition and promote sustainable agriculture.” In the era of the Millennium Development Goals (MDGs), undernourishment was represented by goal number 1c: “Halve, between 1990 and 2015, the proportion of people who suffer from hunger.”
Despite the profound challenges and diverse obstacles to addressing undernourishment, significant progress was made in most regions of the world during the period of the MDGs. Fig. 5.1b shows that all regions have made positive progress toward addressing undernourishment, with Western Asia being an unfortunate but lone exception. Fig. 5.2 shows the general decline in overall undernourishment worldwide from 1990 through 2016. It is important to consider, however, that despite progress in the right direction, 795 million people suffering chronic undernourishment is a tragic burden on an enormous scale.
Basic Terminology in Global Nutrition
It is important to have a precise understanding of the basic terms used in this subfield. Nutrition challenges are large, complex, and require multidisciplinary teams working together toward common goals. A common lexicon understood by all is therefore of significant import. This section will precisely define the most common terms used within this subfield and highlight the relationships between these terms that give them meaning to global health planners and practitioners.
Proper nourishment for all is the goal, and improperly nourished individuals are said to be “malnourished.” Malnourished is a term that includes both “undernourished” and “overnourished” ( Fig. 5.3 ). The phenomenon of overnourishment is creating a rapidly increasing health burden, particularly in middle-income countries, as it leads to costly secondary conditions such as obesity, heart disease, diabetes, and stroke, among others. Those conditions of overnourishment (sometimes referred to as “noncommunicable diseases”) are not the focus of this chapter. This chapter will focus on the challenge of undernourishment because it is believed that although the two subfields have some overlap, they generally require different approaches and strategies to work toward solutions. The problems of undernourishment are also thought to be more closely linked to security and instability.
“Undernourishment” is further divided into two major categories: macronutrient deficiency (sometimes called “PEM” for “protein-energy malnutrition”) and micronutrient deficiency (sometimes referred to as vitamin-mineral deficiency). The “macronutrients” are carbohydrates, proteins, and fats—the large molecules that provide energy, measured in kilocalories. An acute shortage of macronutrients leads to wasting (extreme thinness), whereas chronic deficiency leads to stunting (poor growth) among many other problems discussed later in this chapter. “Micronutrients” are vitamins, minerals, and other small molecules that serve as catalysts in various chemical processes in the human body; they are an essential component of healthy growth and development and result in a wide manifestation of unique symptoms as will be discussed later in this chapter. The most common micronutrient deficiencies in stable populations are iron, vitamin A, zinc, and iodine deficiency. In unstable populations, attention needs to additionally be paid to thiamine, niacin, vitamin C, and riboflavin deficiencies.
The category macronutrient deficiency (PEM) subdivides into two categories based on time/duration of deficiency: acute (“wasting”) and chronic (“stunting”). Acute or “short-term” deficiency in macronutrients results, predictably, in “thinness” which, when excessive, is referred to as wasting. Someone who is “wasted” will be thin and will have low “weight-for-height” and probably also low “weight-for-age” measurements, but will typically have a normal “height-for-age.” In other words, the short duration of the macronutrient deficiency precludes any measurable effect on the child’s linear growth measurement. A patient is said to be wasted when their weight-for-height measurement is greater than two standard deviations (SDs) below the mean. High numbers of cases of wasting are typically seen in populations experiencing conflict, natural disaster, or displacement for any reason.
“Chronic” macronutrient deficiency is a long-term phenomenon that is most common in least developed countries but also prominent in poorer, usually rural areas of middle-income countries. Children who suffer chronic macronutrient deficiency will become “stunted” as measured by a low height-for-age. Stunting is defined as greater than two SDs below the mean for height for that patient’s age. Patients certainly can be stunted and wasted (suffering from both chronic and acute macronutrient deficiency), in which case they would be both short-for-age and very thin. Children can also be stunted without being wasted, which is the case when they have previously suffered long periods of chronic macronutrient deficiency (and are now stunted) but are not acutely experiencing undernourishment (so they are no longer wasted).
Macronutrient deficiency also has three recognized subtypes: marasmus, kwashiorkor, and marasmic-kwashiorkor. Marasmus refers to a deficiency of energy, usually measured in kilocalories ( Box 5.1 ). Marasmus implies that a person is suffering from deficiency of all the macronutrients—proteins, fats, and carbohydrates. Patients with marasmus are thin, with skinny arms and legs. They often have soft, sparse hair; extra skin around the buttocks (referred to as the “baggy pants” effect); and a look that is described as “old man facies.” These patients can be either apathetic or alert and are often hungry.
Energy in food is most often measured in “kilocalories.” In the United States, a kilocalorie is often referred to simply as a “calorie,” but that is not technically correct. Sometimes kilocalorie is written as “Calorie” (with a capital C) to signify that it represents 1000 calories, or 1 kilocalorie. In general, a calorie is such a small unit of energy that it has no practical value in nutrition, thus energy in food is measured in kilocalories.
Kwashiorkor refers to a deficiency of protein specifically. Patients with kwashiorkor have often been eating a diet that is exclusively carbohydrate in composition, such as rice or potatoes, without meat or other protein source. In contrast to the patient with marasmus, patients with kwashiorkor often have a poor appetite. Most significantly, they often have edema (in the abdomen, as well as the hands, feet, and elsewhere) that disguises their otherwise thin stature.
The combination of lack of appetite and edematous appearance can cause these patients to be overlooked when one is screening for malnutrition. In addition to disguising their thinness, the edema also increases these patients’ weight measurements, and therefore they are easy to overlook. Physical examination to include assessment for edema (particularly of the abdomen, hands, and feet) is therefore an essential component of screening for malnutrition. Patients with kwashiorkor are also often irritable; sometimes have what is described as “moon facies”; and often present with pale, sparse, sometimes reddish hair and sometimes an enlarged liver.
Perhaps the most distinctive features of kwashiorkor (other than edema) are the “flag sign” and the “flaky-paint” rash. The flag sign refers to a distinct band of pale or blonde hair in an otherwise dark-haired individual. This stripe of blond hair represents a period of time when the patient suffered from severe protein deficiency (kwashiorkor). All-blonde hair in a patient of a genetic makeup that would not be expected to have blonde hair is a sign that is concerning for kwashiorkor. Patients with kwashiorkor often have a rash that looks like the skin has peeled or flaked off as would old paint from a wall. The rash, when present, is therefore referred to as the flaky-paint rash.
Marasmus and kwashiorkor have traditionally been thought of as separate entities, the former being a global deficiency in all macronutrients (fats, protein, and carbohydrates) and latter a severe deficiency specific to protein. There was clinical value in recognizing these as separate conditions because they call for different treatment plans, and because it is important to not overlook patients with kwashiorkor who, because of the edema, might not appear malnourished to the untrained eye. As the subfield advanced its understanding of undernourishment, however, it was recognized that a significant number of severely malnourished children actually suffer from both marasmus and kwashiorkor and therefore require specific attention and treatment for both clinical syndromes. These patients are said to have “marasmic-kwashiorkor.” Patients suffering from marasmic-kwashiorkor are in a particularly dangerous physical state and need urgent skilled, comprehensive care (see section Treatment of Severe Acute Malnutrition).
Assessing Malnutrition
Four basic measurements used to rapidly assess for malnutrition are height, length, weight, and middle-upper arm circumference (MUAC). The related terms height and length actually have an important clinical distinction when assessing for malnutrition: height is measured with the patient standing, and length is measured with the patient lying down. Although the distinction might sound trivial, the difference in measurement technique is clinically significant when assessing toddlers and young children. In general, children under the age of 2 years should have their length measured (lying down); children over 3 years of age should have their height measured; and between 2 and 3 years of age children can be measured by either method, but the clinician must ensure that their chosen method is the same as that used to generate the reference table or growth chart of normal values. Plotting a 2.5-year-old child’s length, for example, on a chart where the standard values are height measurements will decrease the sensitivity of the assessment.
In contrast to height and length, weight measurements are intuitive and can be assessed with a variety of scale types. Once height (or length) and weight are known, standard World Health Organization (WHO) growth charts can be used to plot weight-for-age, height-for-age, and even weight-for-height. A particularly low weight-for-length implies acute macronutrient deficiency. A very low height-for-age suggests likely chronic macronutrient deficiency. A patient with low weight-for-age can be suffering from either (or both) acute or chronic macronutrient deficiency.
Measuring and plotting weight-for-height, height-for-age, and weight-for-age is not particularly difficult, but it does require an amount of time and effort, which can be particularly burdensome when there is a need to assess a large population in a short period of time with very limited staff. MUAC is therefore an alternative measurement that was developed for these more time-limited situations. MUAC is a simple measurement that involves the use of a flexible tape to measure the circumference of the midportion of the upper arm. MUAC measurements are so simple that one does not even need to consider a young child’s age when taking the measurement because it is theorized that the mid-upper arm circumference is stable enough from 6 months through 5 years of age—particularly when one is assessing for severe acute malnutrition in a distressed population. MUAC measurements are therefore argued to have reasonable sensitivity and specificity for use in time-pressed situations. International organizations have established cutoff values for severe, moderate, and mild malnutrition, and children are sometimes simply classified according to this one metric.
Worth noting, however, is that international organizations have not always agreed on what MUAC measurement constitutes severe, acute, or mild malnutrition. For example, Médecins Sans Frontières (MSF) defines severe acute malnutrition as any child with a MUAC of less than 125 mm, but the United Nations Children’s Fund (United Nations International Children’s Emergency Fund [UNICEF]) uses 115 mm as its cutoff. UNICEF actually increased its cutoff from 110 to 115 after it determined that 115 mm correlates approximately with SDs below the mean on weight-for-height measurements. Despite these disagreements over cutoff values, however, the use of MUAC to assess malnutrition has advantages that include ease of use, speed of assessment, and minimal training requirements, and only a minimal amount of equipment (just the tape) is needed.
There are several disadvantages to using MUAC measurements, however. It has been shown, for example, that the norms for MUAC actually do differ somewhat between 6 months and 5 years of age, despite prior claims to the contrary. MUAC has been shown to have more measurement error than height and weight measurements—and this error applies to both individual and interuser variability in measurements. In addition, in general, MUAC has been shown to be less specific than height-for-weight measurements when assessing for wasting.
Perhaps as a result of these recognized limitations, a practical compromise has been reached when it comes to MUAC measurements: their use should be limited to situations when rapid screening is needed to quickly determine admission to treatment facilities, but they should not be used for prevalence studies, and they are not to be interpreted as a predictor of mortality. Even better, MSF has adopted a two-step protocol: they use a fairly high cutoff value (125 mm instead of 115 mm) to assess for severe malnutrition (thus ensuring adequate sensitivity of their screening process), and then all patients with less than 125 mm MUAC measurement receive follow-up testing via the more conventional methods of weight-for-height and weight-for-age (ensuring adequate specificity).
Height, length, weight, and MUAC are all categorized as anthropometric measurements—measurement of the human individual. “Assessment” and screening for malnutrition, however, requires assessment beyond pure measurements. There are physical findings related to kwashiorkor, for example, that must be recognized when present. Edema, particularly of the hands, feet, and abdomen; flaky-paint rash; and flag sign in the hair are all signs of kwashiorkor for which anthropometric screening tests do not have adequate sensitivity and must be recognized on an individual basis by clinical assessment. Beyond kwashiorkor, there are several important micronutrient deficiencies (vitamin A, thiamine, iodine, and iron) that each cause a spectrum of signs and symptoms that must be assessed. These signs and symptoms of micronutrient deficiency are discussed in the section on micronutrient deficiencies later.
The treatment of severe acute malnutrition differs from that of moderate acute malnutrition; it is important, therefore, to first properly assess and triage the patient into the appropriate category. The three criteria of symmetrical edema, weight-for-height measurement, and height-for-age measurement will allow one to do this ( Table 5.1 ).
a For further information about anthropometric indicators, see reference 1.
b The diagnoses are not mutually exclusive.
c This includes kwashiorkor and marasmic-kwashiorkor in older classifications. However, to avoid confusion with the clinical syndrome of kwashiorkor, which includes other features, the term “edematous malnutrition” is preferred.
d Below the median National Center for Health Statistics (NCHS)/World Health Organization (WHO) reference; the SD-score is defined as the deviation of the value for an individual from the median value of the reference population, divided by the standard deviation of the reference population. S-score observed value median reference value standard deviation of reference population, D = ( )-( ).
e Percentage of the median NCHS/WHO reference (see footnote in Appendix 1).
f This corresponds to marasmus (without edema) in the Wellcome clinical classification (2, 3) and to grade III malnutrition in the Gomez system (4). However, to avoid confusion, the term “severe wasting” is preferred.
Any patient with symmetrical edema is considered severely malnourished; this underscores the grave danger of kwashiorkor and the importance of prompt recognition and treatment. In addition, any patient with a weight-for-height or height-for-age less than three SDs below the mean is considered severely malnourished. Children between two and three SDs below the mean are classified as moderately malnourished. Additional important medical history and clinical examination findings relevant to assessment of malnutrition are provided in Box 5.2 .
Checklist of points for taking the child’s medical history and conducting the physical examination
Medical history
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Usual diet before current episode of illness
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Breastfeeding history
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Food and fluids taken in past few days
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Recent sinking of eyes
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Duration and frequency of vomiting or diarrhea, appearance of vomit or diarrheal stools
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Time when urine was last passed
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Contact with people with measles or tuberculosis
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Any death of siblings
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Birth weight
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Milestones reached (sitting up, standing, etc.)
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Immunizations
Physical examination
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Weight and length or height
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Edema
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Enlargement or tenderness of liver, jaundice
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Abdominal distension, bowel sounds, “abdominal splash” (a splashing sound in the abdomen)
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Severe pallor
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Signs of circulatory collapse: cold hands and feet, weak radial pulse, diminished consciousness
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Temperature: hypothermia or fever
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Thirst
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Eyes: corneal lesions indicative of vitamin A deficiency
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Ears, mouth, throat: evidence of infection
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Skin: evidence of infection or purpura
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Respiratory rate and type of respiration: signs of pneumonia or heart failure
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Appearance of feces
Modified from World Health Organization. Management of Severe Malnutrition: A Manual for Physicians and Other Senior Health Workers. Geneva, Switzerland: World Health Organization; 1999.
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