Download - Measuring Undernutrition Chapter 4
Measuring UndernutritionChapter 4
From Chapter 3What we Learned
Biggest problem, Over- & under-nutrition
Total CaloriesProteinMicronutrients
Common methods of assessing undernutrition
Clinical Assessment: Looking for physical signs of nutritional disordersBiochemical: Examine blood and urine looking for metabolic changes that accompany nutritional disorders
Common methods of assessing undernutrition (cont.)
Dietary Assessment: Track what the person eatsAnthropometric Assessment: Measuring the human body and its parts. It is the most common method of assessing nutritional disorders
Clinical AssessmentLook at:
Hair color (lighter and thinner)Ankle swellingEnlarged necksPoor eye sight
Clinical Assessment (cont.)What is each an indicator of?
Hair color (Lighter and thinner)Protein deficiency
Ankle swellingProtein deficiency causing circulation problems
Enlarged necksGoiter, iodine deficiency
Poor eye sightVitamin A deficiency
Clinical Assessment (cont.)Be aware that other things can cause these symptomsWhen these symptoms show to this extent then the problem is advancedUsed to analyze:
most severe casesSpecific types of malnutrition
Biochemical AssessmentBlood and urine testsShow micronutrient deficienciesAccurate but relatively expensive
Dietary Assessment2 Methods:
Survey – recall by the person, after-the-factReview dietary records
Dietary Assessment (cont.)
Problems with both methodsPeople can’t recall exactly People liePeople adjust their eating habits when they are in a studyBreast feeding – difficult to determine how much the baby eatsSeasonal variations (price & availability)
Dietary AssessmentUseful in:
Doing comparisons of diet and incomeAlso useful to track food allocations within the family
Anthropometric Assessment
Most commonly-used methodSize – indicator of calories & protein intake
Anthropometric (cont.)Acute undernutrition
Short-term inadequate foodCaused by famine or warPeople can recover
Chronic undernutritionLong-term inadequate foodEven moderate, effects are permanent
StuntingDef.: low height-for-age
Shows that the person has experienced chronic undernutrition during growth yearsIt is a symptom of past undernutrition
Stunting (cont.)People born in 1910 were 4 cm (1.6 in) shorter than those born in 1930People born in 1950 1 cm (1/2 in) taller than those in 1930
What does that tell you?
WastingDef.: low weight for heightThis is a symptom of current undernutrition
Under weightDef.: low weight for ageA symptom of present undernutrition
What about Inheritance?Part of people’s height is determined by their genesAre there ethnic differences?These factors are less important than other factors
Nature vs. nurture
Other FactorsPovertyPoor food intakeInfectious & parasitic diseasesOther environmental factors
Use of AntropometryMost useful in comparisons of infantsOlder children, less soIn developed countries useful in measuring overnutrition of adults
Antropometry (cont.)What is measured?
HeightWeightArm circumference
One of the better measures of fat in the body
Skin-fold thickness
Antropometry (cont.)Measurements are easy and cheapNeed:
ScaleTape measureCalipers (know what they are)
Antropometry (cont.)Training someone to recognize undernutrition by clinical means takes a lot more timeComparisons to a Reference Group
“You are shorter than average”“You weigh less than average”
What is the purpose of all this?
Identify those in need of helpEither those who are undernourishedOr Those who are overnourished
Method 1Measuring Large Groups
(Note: Method 1 is not labeled, but is described in the paragraph on p. 51 Drawing Inferences from a sample)
A continent?A country?A region?Among demographic groups
Def: characteristics of a population or segment of the pop.
Among ethnic groups
Measuring (cont.)Cannot measure everyoneStatistics – SamplingIf our sample is representative then inferences can be made of the whole population
Method 2Examine Aggregate DataLook at data on:
Birth weightInfant mortalityMorbidity
Def.: the rate of incidence of a diseaseThese are not direct measures of nutritional status
Method 3 Aggregate Nutrient IntakeOr: average nutrient intakeFAO keeps such data on each country
FAO Food and Agriculture OrganizationPart of the UN
These food-balance sheets show sources and types of food – over 100 different foods
Aggregate (cont.)FAO keeps stats on sources of food:
Beginning stocksProductionImports
Aggregate (cont.)FAO keeps stats on uses of food:
Ending stocksExportAnimal feedConsumption
Aggregate (cont.)They use the word balance sheet because sources and use are in balance
Aggregate data: These measures imply undernutrition in a region
1. High IMR 2. Low birth-weights3. High morbidity (illness) rates
Look at food availability to infer the existence of undernutritionFood balance sheets estimate human consumption1. Add up the supply of a specific food beginning stocks + production + imports
2. Subtract the amount used for: exports + livestock feed + seed + ending
stocksWhat about food stocks used for fuel?
What is left can be assumed to go for human consumption
3. Convert this to calories• do for all foods, to calculate available
calories per capita per day (a widely used measure of malnutrition)• Remember: Carbohydrate and protein
has 4 calories/gram & Fats and oils have 9 calories/gram
This is a mean, it could be that some people are consuming above the average and some people are undernourisheda. Studies of individuals need to be done to infer the percentage of the population that have inadequate food intake
IV. Undernutrition & child health
A. Undernourished mothers are likely to produce malnourished babies1. Low birth weight2. 40 times more likely to die
before their first year
B. Undernutrition leads to high under-five mortality rates
Worldwide average (1999) = 78 per 1,000 live births
• Industrialized countries = 7Developing countries = 85
• Least developed countries = 161(Sub-Saharan Africa)
C. Undernutrition results in a weakened immune system which leads to death from childhood diseasesInfant mortality rate (IMR; children who die before their 1st birthday per 1,000 live births) goes up as a child’s percent of the median weight-for-age goes down
IMR in the U.S. is 2.1%– before five = 2.5%IMR in Guinea = 21.6%– before five = 36.7%
V. Effects of undernutrition A. Mental development
impaired in undernourished children
B. Educational achievement lowered
C. Childhood undernutrition results in smaller adults who can do less physical work & who earn less money
D. Undernourished adults are less productive when working and lose more work time to sickness and so have less money to buy food
(note the cycle)
Measuring nutritional status for large groupsA. Draw inferences from a
sample using statistics1. Use info from a subset of the population to infer characteristics of the whole population2. Sample must be representative
B. Use aggregate data on the effects of undernutrition to infer how much undernutrition existsAggregate data: data compiled from several measurements