Public health nutrition


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Public health nutrition

  1. 1.  the evaluation of the nutritional status of individuals or populations through anthropometry, biochemical, clinical and dietary measurements. the measurement of indicators of dietary status and nutrition- related health status to determine the possible occurrence, nature and extent of impaired nutritional status which can range from deficiency to toxicity (US Department of Health and Human Services).Types or Forms of Nutritional Assessment Systems1. Nutritional survey - an epidemiological investigation of the nutritional status of a population by various methods; may include an evaluation of factors affecting nutritional status. useful in establishing baseline nutritional status and/or ascertaining the overall nutritional status of the population; if cross-sectional, can identify and define those population sub-groups at risk of chronic malnutrition.
  2. 2.  less likely to identify acute malnutrition if socio-economic, ecologic and demographic information are simultaneously collected, possible causes of malnutrition may be identified through statistical analysis of data.2. Nutritional surveillance - continuous monitoring of the nutritional status selected population groups. unlike surveys, data are collected, analyzed and utilized for an extended period of time. useful in identifying causes of malnutrition, hence can be used in formulating and initiating intervention measures.3. Nutrition screening - involves comparing an individual’s measurements with predetermined risk levels or “cut-off” points.• usually less comprehensive than survey or surveillance;• useful in identifying individuals in need of immediate intervention. Operation Timbang collects only age and weight data, targets only preschoolers, and is used to screen children for inclusion in food assistance programs.
  3. 3. Purposes of Nutritional Assessment1. Define nutritional problems that need attention; as an integral part of situational analysis, it is the first step in the nutrition program planning and management cycle.2. Provide baseline data for planning and evaluation of programs.3. Help identify priorities and responsibilities of the public health system at all administrative levels (i.e. from national to barangay level).Methods of Nutritional Assessment1. Methods that provide direct information on nutritional statusa) clinical examinationb) biochemical examinationc) anthropometryd) biophysical methods (e.g. measures of body composition, bone density)2. Methods that provide indirect informationa) food consumption studiesb) studies on health conditions and vital statistics (special on infant and child mortality rates)c) studies on the food supply situation
  4. 4. d) studies on socio-economic conditionse) studies on cultural and anthropological influences Factors Affecting Choice of Nutritional Assessment System and Method1. Objectives of nutritional assessment, e.g.• to define current overall nutritional status, a nutrition survey using clinical, biochemical, anthropometric and dietary (food consumption) methods is essential.• to evaluate the impact of nutrition intervention, a monitoring system is used and the choice of method depends on the objective of the intervention, e.g., - anthropometric methods for feeding programs; - clinical or biochemical methods for nutrient supplementation programs.• to identify malnourished or individuals needing immediate intervention, a screening system using indices of past and present nutrition must be used.2. Unit to be assessed, e.g. household, individuals, population groups• biochemical methods may not be feasible for household level assessment.
  5. 5. 3. Type of information required for program planning and evaluation purposes, e.g.• for nutrition education, food consumption data4. Degree of reliability and accuracy required – usually requires a combination of at least two methods (clinical, biochemical, anthropometric, dietary methods), preferably all four.5. Facilities and equipment available. Biochemical and biophysical methods require facilities and equipment which may not be readily available.6. Manpower resources and training required, e.g.• clinical methods require a medical nutritionist trained in the detection of deficiency signs and symptoms;• biochemical methods require a biochemist, chemist or medical technologist;• anthropometric methods require trained technicians;• dietary methods require nutritionist-dietitians trained in food consumption data collection and analysis methods.
  6. 6. 7. Time reference: season of the year, week-end, week day, numbers of days of data collection.8. Funding and financial support available.CLINICAL ASSESSMENTA. Description : deals with the examination of changes that can be seen or felt in superficial tissues, such as skin, eyes, hair, etc.B. Advantages more coverage in a short time inexpensive, no need for sophisticated equipmentC. Disadvantages1. non-specificity of signs (signs may be due to non-nutritional causes)2. Overlapping of deficiency states (dietary deficiencies are not restricted to an isolated nutrient)3. Bias of the observer (observations of two examiners are most often not consistent with each other)
  7. 7. Clinical Signs of Value in Nutrition Assessment and Their InterpretationTissue/body part Signs Associated Disorder or Nutrient1. Hair Lack of lustre Kwashiorkor, less Thinness and sparseness commonly, marasmus Straightness Dyspigmentation Flag sign Easy pluckability naso-labial dyssebaccea2. Face Moon-face Riboflavin Kwashiorkor Pale conjunctiva Anemia (iron etc.) Bitot’s spots3. Eyes Conjunctival xeroxis Corneal xeroxis Keratomalacia Vitamin A Angular palpebritis Angular stomatitis Angular scars4. Lips Cheilosis Riboflavin
  8. 8. Predominant Clinical Symptoms of Common Nutritional Problems1. Protein-energy malnutritiona) Mild to moderate – low weight and/or height for ageb) Severe (marasmus and kwashiorkor)2. Xerophthalmia – affects the eyes, gradually beginning with an impairment of night vision. Symptoms include:a) Night blindnessb) Cornea softening and ulcerationc) Skin changes are usually non-specific3. Anemia – clinical symptoms are non-specific (may be due to other conditions) and should be confirmed with biochemical test, e.g. for blood hemoglobin level. Symptoms include:a) Paleness under the eyelidsb) Paleness under the nails
  9. 9. 4. Beriberi – symptoms include:a) Muscle weakness, fatigabilityb) Heart enlargement, tachycardia, edema (in wet type)5. Goiter – symptoms include:a) Swelling of the neckb) Lassitude and easy fatigability6. Ariboflavinosis – symptoms are non-specific and may include:a) Magenta red tongueb) Sores at the angles of the mouth and folds of the nose. Interpretations Guides1. WHO Criteria for determining whether a significant public health problem of xerophthalmia and vitamin A deficiency exists in a population
  10. 10.  Night blindness (XN) – greater than 1% Bitot’s spots (XIB) – greater than 0.5% Corneal xeroxis/corneal ulceration/keratomalacia (X2/X3A/X3B) – greater than 0.05% Plasma vitamin A of less than 10 ug/dl – greater than 5%
  11. 11. Biochemical AssessmentDescription: estimation of tissue desaturation, enzyme activity or blood composition.1. Tests are confined to two fairly easily obtainable fluids; blood and urine.2. Results are generally compared to standards, i.e., normal levels for age and sex.Advantages1. objectivity, i.e., independent of the emotional and subjective factors than usually affect the investigator.2. can detect early subclinical states of nutritional deficiency (i.e., before clinical symptoms appear).Disadvantages1. costly, usually requiring expensive equipments2. time consuming3. difficulty in collecting samples4. lack of practical standards of sample collection
  12. 12. Factors Affecting Accuracy of Results1. method of sample collection2. method of transport and storage of samples3. techniques employedBiochemical Measurements Which May be Done in Nutritional Status Surveys1. Protein statusa. Urea nitrogen/creatine nitrogen ratio – determined from a 3 to 4 hour or 24 hours urine sample• A ratio of 30 or lower is indicative of malnutritionb. Amino acid imbalance test – the ratio of four dispensable amino acids and four indispensable amino acid is determined by paper chromatography.• A high ratio of 5-10 is indicative of kwashiorkor.• The ratio is low (less than 2) in well-fed children.c. Hydroxyproline excretion in random urine sample.• Low (0.5 – 1.5) in clinically malnourished• Normal level: 2.0 – 2.5
  13. 13. d. Serum albumin – most common biochemical test for protein nutriture.• Guide to interpretation (g/100ml): - High: 4.25 - Acceptable: 3.52 – 4.24 - Low: 2.80 – 3.51 - Deticient: less than 2.802. Protein – Energy status:3. Vitamin A statusa. Serum vitamin A• Guide to interpretation: a serum level of 10-20 ug/dl is considered low, while <10 ug/dl is considered deficient.• A prevalence rate of 10% for “deficient” serum levels and 15% of “low” serum levels indicate the existence of a public health problem in the community.b. Serum carotene• Guide to interpretation. A serum level of equal or less than 39 ug/dl is considered low.• Low serum carotene levels per se are not indicative of vitamin A deficiency but reflect current intake of carotene which is a precursor of the vitamin.
  14. 14. 4. Thiamine statusa. Urinary thiamine – less preferred test.b. Erythrocyte transketolase activity (ETKA) with and without addition of thiamine triphosphate (TPP) in vitro.c. Blood pyruvate level – increased I thiamine deficiency.5. Riboflavin statusa. Urinary riboflavin – less preferred testb. Erythrocyte glutathione reductase activity coefficient (EGR- AC)• Guide to interpretation: normal EGR-AC value is 1.0 – 1.3; higher values indicate riboflavin deficiency.6. Ascorbic acid statusa. Serum ascorbic acid• Interpretation guide: a serum ascorbic acid level of 0.8 mg/dl is considered “acceptable” or “ good”. Lower levels indicate ascorbic acid deficiency.
  15. 15. 7. Iron statusa. Hemoglobin• Values below which anemia is said to exist - infants and children, 6 mos. To 6 years: 11 grams % - children and adolescents, 6 years to 14 years: 12 grams % - adult males: 12 grams % - adult females, non-pregnant: 12 grams % - adult females, pregnant: 11 grams %b. Hematocrit• Normal values - females: 37-47% - males: 45-52%c. Total iron binding capacity (TIBC)• Normal value: 250-425 mg/dld. Transferrin saturation• Normal value: 20-50%e. Ferritin• Normal level: 30-250 mg/dl
  16. 16. Iodine statusa. Urinaru iodine• Guide to interpretation – epidemiological criteria for assessing severity of IDD based on median urinary iodine levels.
  17. 17. Median ug/L
  18. 18. ANTHROPOMETRY The measurement of variations of physical dimensions and gross composition of the human body at different age levels and degrees of nutrition.Common Anthropometric Measurements1. Weight (for age) Uses weighing scales such as beam balance scales or clinical scales which are ideal, but a bar scale could be used in their absence. Assesses body mass; an indicator of current nutritional status of preschoolers. Advantages: