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XNN001 Nutrition assessment in individuals and populations

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XNN001 Nutrition assessment in individuals and populations

  1. 1. XNN001 Semester 2 2013
  2. 2.  The first step before planning and evaluating the nutritional care of individuals or groups  Determined on the basis of multiple kinds of information  A systematic method for obtaining, verifying & interpreting information
  3. 3. Individual Nutrition Assessment Anthropometry Biochemistry (Laboratory analysis) Clinical Dietary Energy Requirements Population Assessment & Monitoring Food Supply Data Food Prices Household & Dietary Surveys Mortality & Morbidity Data Anthropom etric Data Birth wt, infant feeding & mortality Monitoring & Surveillanc e System
  4. 4. Four main components 1. Anthropometry 2. Biochemistry (Laboratory assessment) 3. Clinical assessment 4. Dietary intake 5. Energy requirements
  5. 5.  Study of physical dimensions of the body  Standardised equipment & procedures essential  Body size  direct measurements  height, weight, circumferences  derived values  Body shape  Waist hip ratio, body weight distribution  Body composition  size of lean tissue and fat compartments
  6. 6.  One of the most commonly used measurements for assessing nutritional status  Ratio of weight to height  Caution – BMI not ideal for determining health risk as it does not reflect amount of muscle compared to fat
  7. 7. # WHO 2000, AIHW (2004) * Ideal body wt (IBW) or desirable wt for ht (US Metropolitan Life Insurance data) 9 Classification # BMI (kg/m2) IBW % * Risk of Chronic Disease Underweight <18.5 >10% below* Low (but other risks) Normal range 18.5-24.9 desirable Average Overweight >25 pre-obese 25.0-29.9 (10-19% above*) Increased obese class I 30.0-34.9 (>20% above*) Moderate obese class II 35.0-39.9 Severe obese class III >40 Very severe
  8. 8. BMI classification in kg/m2 10 Asian Pacific Is. <18.5 <19.9 Underweight 18.5-23.9 20.0 - 26.9 Normal weight 24.0-26.0 27.0-32.9 Overweight 27.0-39.0 33.0-39.9 Obesity
  9. 9.  The International Obesity TaskForce (IOTF) published BMI thresholds defining paediatric overweight and obesity in 2000.  Centile equivalents for children aged 2–18 were derived statistically by extrapolation from adult cutoffs at BMI 25 and 30 kg/m2, respectively.  They were not intended for clinical use but to assess trends and to compare populations.
  10. 10.  Height requires a stadiometer – a ruler calibrated in cm and m, which is fixed to the wall and has a movable head plate
  11. 11.  Infants up to 36 months should be measured in cm, using recumbent length if they are unable to stand
  12. 12.  Chumlea has developed formula to estimate knee height in those who are unable to stand  Men = 64.19 – (0.04 X age) + (0.02 X knee height)  Women = 84.88 – (0.24 X age) + (1.83 X knee height) Chumlea WC, Steinbaugh ML, Roche AF, Mukherjee D, Gopalaswamy N. (1985) Nutritional anthropometric assessment in elderly persons 65 to 90 years of age. Journal of Nutrition for the Elderly. 4:39-51.
  13. 13.  Is measured on scales which are on a hard, firm surface and calibrated daily  Weight is usually measured to the nearest 0.5kg
  14. 14. 1. Waist circumference (AIHW, 2005) > 18 y  >94 cm (M) >80 cm (F) – abdominal overweight  >102 cm (M) >88 cm (F) – abdominal obesity 2. Waist: hip ratio  visceral fat around organs vs. subcutaneous fat on hips  optimal WHR is < 1 (M) or < 0.8 (F)  varies with: genes, age, ethnicity, sex  increased by 'stress', smoking, alcohol  decreased by physical activity 19
  15. 15. NHMRC Obesity guidelines
  16. 16.  Metabolically active tissue determines energy requirements  Lean body mass or muscle mass is the most metabolically active tissue  Bodies are made up of water and fluids, bone, muscle and fat  80% of energy requirements are determined by height, weight, sex and age
  17. 17.  Body fat – skinfold thicknesses and Dual X ray Absorptiometry (DEXA)  Body water – Bioelectrical impedance (BIA)  Body cell mass – Total body potassium, DEXA (bone, muscle)
  18. 18. Fat Fat-free Mass (FFM) Fat Water (TBW) Protein Mineral Fat Ex-cellular fluid Body Cell Mass Ex-cellular solids Adapted from Wang et al (1992) and Heymsfield et al (1996), cited K Campbell, PhD thesis Skinfold DXA BIA TBK Body Composition Assessment Weight
  19. 19. DEXA
  20. 20.  Blood tests  Readily obtained (so often used)  Vary little (homeostatic control)  Should be used in conjunction with nutrient and supplementation history  Tissue testing  May include hair & nails for information about trace elements  Other tissues only acceptable under exceptional circumstances (invasive)  Urine testing  Varies between nutrients and influenced by variety of factors (including volume of urine)  Multiple samples required  Functional tests  Ability to perform specific functions (e.g. muscle response, immunological response)
  21. 21.  Advantages:  Provide the earliest indications of some nutrient deficiencies & excesses  Can confirm a nutritional diagnosis made on the basis of signs & symptoms  Can be used to assess the effect of nutritional therapy
  22. 22.  Information obtained includes:  Socio-demographic details (age, gender, occupation)  Medical history (including family history)  Dietary intakes  To help identify patients at risk of nutritional deficiency  Signs & symptoms important
  23. 23. Assessment of populations
  24. 24.  Infant birth weight  Provides information on:  maternal health & nutritional status  risk of infant mortality  Is influenced by:  maternal body size, infection, smoking, alcohol consumption, maternal nutrition during pregnancy  Infant mortality data  % related to prevalence of low birth weight (populations with high rates of low birth weight usually have high rates of infant mortality) e.g. Indigenous Australians Also affects
  25. 25.  Inappropriate infant feeding practices influences growth & development esp. in the 1st 4 to 6 mths  Decrease in breastfeeding since 1945 (21% 1971, above 50% since 1985)  Breastfeeding or correctly prepared infant formula  infant morbidity & mortality
  26. 26.  Provide information on:  the diseases & conditions that are reported as causes of death/hospital admissions  possibly on chronic conditions such as cancer & diabetes  Reflect:  the major social & health problems of the community  And can be used as:  clues to the most likely causes of mortality & morbidity  measures of the prevalence of specific nutrition related conditions
  27. 27.  Only provide information on:  Indirect measures of the kinds of nutritional problems most likely to be encountered in a population Multi-factorial aetiology of conditions in developed countries  Current burden of disease statistics available from the AIHW Disability adjusted life years (DALYs) are the years of life lost due to premature mortality & disability & measure the number of healthy years of life lost as a consequence of death or newly diagnosed disease or injury in the population.
  28. 28.  Weight & height are used in population studies as they:  provide an overall measure of nutritional status  are non-invasive  are quick to carry out  use minimal (& cheap) equipment  Provide information on:  the growth of children  the prevalence of obesity or underweight

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