THE ROLE OF FOOD, AGRICULTURE, FORESTRY AND FISHERIES IN HUMAN NUTRITION – Vol. IV - Nutritional Assessment: Methods for Selected Micronutrients and Calcium - E.U. Wasantwisut, J.L. Rosado and R.S. Gibson NUTRITIONAL ASSESSMENT: METHODS FOR SELECTED MICRONUTRIENTS AND CALCIUM E.U. Wasantwisut Institute of Nutrition, Mahidol University, Thailand J.L. Rosado Department of Nutritional Physiology, National Institute of Nutrition, Mexico R.S. Gibson Department of Human Nutrition, University of Otago, New Zealand Keywords: Malnutrition, deficiency, toxicity, survey techniques, vitamins, minerals, holo-RBP, trace elements, assessment, calcium, micronutrients, riboflavin, Vitamin B2, folate, Vitamin B12, cobalamin, Vitamin A, retinol, iron, zinc, iodine, selenium, dietary assessment, clinical signs, biochemical indices, functional assay, anthropometry, laboratory tests, twenty-four-hour recalls, food records, food frequency, dietary history Contents 1. Introduction 2. Stages in the Development of a Nutritional Deficiency 3. Choosing the Most Appropriate Nutritional Assessment Indices 3.1. Nutritional Assessment Indices and Indicators 3.2. Criteria for Selecting Indices for use in Nutritional Assessment Systems 3.3. Classification of Indices 3.4. Impact of Confounders on Nutritional Assessment Indices 3.5. Evaluating Nutritional Assessment Indices 4. Dietary Assessment 4.1. Twenty-Four-Hour Recalls 4.2. Estimated or Weighed Food Records 4.3. Dietary History 4.4. Food Frequency Questionnaire 5. Nutritional Assessment Indices 5.1. Nutrients of Interest 5.2. VitaminUNESCO B2 (Riboflavin) µg/mL – EOLSS 5.3. Folate 5.4.Vitamin B12 5.5. Vitamin A SAMPLE CHAPTERS 5.6. Calcium 5.7. Iron 5.8. Zinc 5.9. Iodine 5.10. Selenium 6. Conclusion and Recommendations Glossary Bibliography Biographical Sketches ©Encyclopedia of Life Support Systems (EOLSS) THE ROLE OF FOOD, AGRICULTURE, FORESTRY AND FISHERIES IN HUMAN NUTRITION – Vol. IV - Nutritional Assessment: Methods for Selected Micronutrients and Calcium - E.U. Wasantwisut, J.L. Rosado and R.S. Gibson Summary Nutritional deficiency represents a continuum from the early to the late stages, which necessitates the use of different assessment methods involving subclinical and clinical indices. Selection of appropriate nutritional indices should be based upon the objectives and nature of certain factors such as population versus individual status, identification of areas/populations at risk, efficacy of intervention, tracking progress toward long- range goals, monitoring and evaluating the impact of programs, and so on. Indices used in nutritional assessment systems include: biological, ecological, and behavioral indices. Biological indices are derived from both static and functional laboratory tests and clinical measurements. Apparent clinical signs represent the last stage when the nutrient deficiency is severe. Clinical indices are useful for identifying the severity of the problem and measuring progress toward long-range goals to eradicate nutrient deficiencies. Static and functional laboratory tests are primarily used to detect subclinical nutrient deficiency states, and to confirm a clinical diagnosis. Static biochemical tests measure levels of the nutrients in biological specimens while functional biochemical tests determine the changes in the activities of enzymes dependent on a specific nutrient, or in the concentrations of specific blood components dependent on a given nutrient. Biochemical assessment provides useful information on the level of nutrients necessary to meet biological demands, bioavailability, and metabolism of nutrients, and on the impact of interventions. Functional physiological tests assess the physiological performance of an individual in vivo such as immune competence, taste acuity, night blindness, muscle function, and work capacity. None of these functional physiological tests are specific and must be interpreted along with biochemical measurements. Behavioral indices, either qualitative or quantitative, are often included in nutrition surveillance systems used to monitor the impact of nutrition intervention programs and to track progress toward attainment of long-range goals. Ecological indicators include those related to socioeconomic status, dietary intakes, anthropometry, and illness/mortality. Because inadequate dietary intake precedes the other stages of nutritional deficiency, assessment of habitual food consumption pattern or nutrient intakes (qualitatively or quantitatively) is useful in identifying community at risk of inadequate intakes of nutrients and provides a basis for dietary intervention programs. The interpretation of nutritional assessment indices may be confounded by factors such as the impact of infection, concurrent nutrient deficiencies, seasonal variation, age, sex, disease states, and so on, in addition to samplingUNESCO and measurement errors. – EOLSS To evaluate nutritionalSAMPLE assessment indices, the CHAPTERS observed values can be compared with a reference distribution or reference limits or cutoff points. This article emphasizes biological indices (static and functional biochemical tests, physiological tests, clinical signs) to assess the status of the following nutrients: Vitamin B2, folate, Vitamin B12, Vitamin A, calcium, iron, iodine, zinc, and selenium. In a setting with limited resources, selection of inexpensive yet reliable indices can provide useful information on nutritional status. Clinical indices and simplified dietary assessment and field methods of functional, physiological, and behavioral indicators should first be considered. These indices should be accompanied by biochemical indices to identify the limiting nutrient. ©Encyclopedia of Life Support Systems (EOLSS) THE ROLE OF FOOD, AGRICULTURE, FORESTRY AND FISHERIES IN HUMAN NUTRITION – Vol. IV - Nutritional Assessment: Methods for Selected Micronutrients and Calcium - E.U. Wasantwisut, J.L. Rosado and R.S. Gibson Selection of both the appropriate design and indices, together with use of subsampling procedure, should be exercised, and use of local expertise and resources optimized. 1. Introduction In the field of nutrition, a major challenge is how to identify individuals and/or populations who have nutritional problems. Appropriate nutritional assessment can provide the answer. Several texts and numerous journal articles have been written on the subject. This article does not attempt to duplicate such information nor cover assessment methods for every nutrient in detail. Instead, we highlight the following micronutrients which are of global importance: Vitamin B2 (riboflavin), folate, Vitamin B12, Vitamin A, calcium, and the trace elements iron, zinc, selenium, and iodine. The preferred methods of assessing the status of these nutrients at both the population and the individual level are described, commencing with the first stage in the development of a nutrient deficiency state: assessment of dietary intakes, followed by biochemical and functional indices and finally, clinical signs and symptoms. The application and interpretation of various indices used in research studies and/or public health programs are a major focus of this article. Finally, recommendations on how best to conduct nutritional assessment protocols in settings with both limited and sophisticated resources are indicated. 2. Stages in the Development of a Nutritional Deficiency The development of a nutritional deficiency state represents a continuum from the early to late stages. Clinical assessment may readily detect the late or severe stages of nutritional deficiencies, for example, angular stomatitis for riboflavin deficiency, and eye lesions or xerophthalmia for Vitamin A deficiency. However, before such clinical signs become apparent, "subclinical" stages of deficiency develop as summarized below: 1. Nutritional deficiency is usually initiated by an inadequate dietary intake of one or more nutrients resulting from either a low content in indigenous food sources and/or the presence of exogenous factors that interfere with ingestion, absorption, and metabolism of the nutrient(s). This stage of nutritional deficiency usually can be identified by dietary assessment. 2. When inadequate intakes persist, the tissue stores become gradually depleted of thatUNESCO nutrient, resulting in low levels – in EOLSScertain body fluids and tissues, and/or in the activity of nutrient-dependent enzymes. Often, these changes can be detected by biochemicalSAMPLE tests. CHAPTERS 3. Following nutrient depletion of body fluids or tissues, functional changes occur. Functional tests provide a measure of the biological significance of a given nutrient because they assess the functional consequences of nutritional deficiency, for example, cognitive function for iron, taste acuity for zinc, and dark adaptation for Vitamin A. Anthropometric indices such as weight for age, height for age, weight for height, and measurements such as mid-upper arm circumference and triceps skinfold, are especially useful in detecting a possible chronic imbalance of protein and energy, and can be used, ©Encyclopedia of Life Support Systems (EOLSS) THE ROLE OF FOOD, AGRICULTURE, FORESTRY AND FISHERIES IN HUMAN NUTRITION – Vol. IV - Nutritional Assessment: Methods for Selected Micronutrients and Calcium - E.U. Wasantwisut, J.L. Rosado and R.S. Gibson in certain cases, to identify moderate and severe malnutrition (see Nutritional Deficiency and Imbalances). No single index of nutritional status provides a definitive diagnosis of all levels of nutritional