Nutritional assessment of groups and individuals is a prerequisite to planning for the prevention or solution of nutrition-related health problems. It represents a broad area within the field of nutrition and is only highlighted here. Resources related to the selection of appropriate nu-tritional assessment techniques and their implementation are listed at the end of this chapter.
Nutritional status may be assessed for a population group or for an individual. Community-level assessment identifies a population’s status using broad nutrition and health indicators, whereas individual assessment pro-vides the baseline for anticipatory guidance and nutrition intervention.
Community-Level Assessment
A target community’s “state of nutritional health” can generally be estimated using existing vital statistics data, seeking the opinions of target group members and local health experts, and making observations. Knowledge of average household incomes; the proportion of families participating in the Food Stamp Program, soup kitchens, school breakfast programs, or food banks; and the age distribution of the group can help identify key nutrition concerns and issues. In large communities, rates of infant mortality, heart disease, and cancer can reveal whether the incidence of these problems is unusually high.
Information gathered from community-level nutritional assessment can be used to develop community-wide pro-grams addressing specific problem areas, such as childhood obesity or iron-deficiency anemia. Nutrition programs should be integrated into community-based health programs.
Individual-Level Nutritional Assessment
Nutritional assessment of individuals has four major components:
Clinical/physical assessment
●
Dietary assessment
●
Anthropometric assessment
●
Biochemical assessment
●
Data from all of these areas are needed to describe a per-son’s nutritional status. Data on height and weight provide information on weight status, for example, and knowl-edge of blood iron levels tells you something about iron status. It cannot be concluded that people who are normal
Registered Dietitian An individual who has acquired food and nutrition knowledge and skills necessary to pass a national registration examination and who participates in continuing professional education.
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questions that hone the accuracy of information pro vided by interviewees about the food they ate the previous day.
The five-step interview process used by the automated multiple-pass method consists of the following:
1. The Quick List Quickly collect a list of foods and beverages consumed the previous day.
2. The Forgotten Foods List Probe for foods forgot-ten during development of the Quick List.
3. Time and Occasion List Collect information on the time and eating occasion for each food.
4. The Detail Cycle Collect detailed information on the description and amount of food consumed using USDA’s interactive Food Model Booklet and measuring guides.
5. Final Probe Review Review 24-hour recall and ask about anything else consumed.
Additional information on this advanced method for assessing dietary intake can be found at www.ars.usda. gov/
Services/docs.htm?docid=7710.
The Healthy Eating Index The HEI (Healthy Eating Index) assesses a person’s reported dietary intake based on 10 dietary components that cover intake of the Pyramid’s five basic food groups, and the Dietary Guidelines for Americans recommendations for fat and sodium intake, and dietary variety. The components are assigned scores based on the extent to which diets meet recommended standards of intake. The HEI is primarily used for population monitoring of dietary quality, evaluation of interventions, and research. It has been shown to be a valid tool for assessing dietary quality.63
Additional information about the HEI is available online from the USDA at www.cnpp.usda.gov/Healthy EatingIndex.htm.
frequency questionnaire that confirms 24-hour usual dietary intake information. Results must be coded, checked, and processed. Although expensive, diet histories provide more complete and accurate data than most other dietary assessment methods.59
Food Frequency Questionnaires Food frequency questionnaires are often used in epidemiological studies to estimate food and nutrient intake of groups of people. These tools are considered semiquantitative because they force peo-ple into describing food intake based on a limited number of food choices and portion sizes (Illustra tion 1.12). Validated food frequencies are relatively inexpensive to administer and tabulate, and they provide good enough estimates of dietary intake to rank people by their food and nutrient intake levels. They tend to underestimate food intake and pro-vide data that are more likely to fail to identify nutrient and health relationships than are quantitative assessment techniques such as the dietary history.60
Web Dietary Assessment Resources Several high-quality computer programs and Internet resources are avail-able for dietary assessment. My Pyramid Tracker, developed by the U.S. Department of Agriculture (USDA), is an ex-ample of a high-quality Internet resource. This interactive program provides an analysis of nutrient and food intake.
MyPyramid Tracker can be found at www.mypyramid.gov.
USDA’s Automated 5-step Multiple-Pass Method A computerized, interactive method for collecting interviewer-administered 24-hour dietary recalls either in person or by telephone has been validated by several studies.61,62 It’s called the Automated Multiple-Pass Dietary Recall and is being used in government-sponsored nutri-tional studies. It utilizes a five-step multiple-pass 24-hour recall. The term multiple pass refers to the repeated use of
Illustration 1.12 Example component of a food frequency questionnaire.
1. a. Broth-type soups, 1 cup b. Tap water, 1 cup
c. Sparkling or mineral water, 1-cup serving d. Decaffeinated black tea, iced or hot, 1 cup e. Herbal tea, (no caffine) iced or hot, 1 cup 2. Custard or pudding, 1/2 cup
3. Onions, 1/4 cup, alone or in combination
Never or less than once per month
1–3 per month
1 per week
2–4 per week
5–6 per week
1 per day
2–3 per day
4–5 per day
6+
per
Food day
Frequency of Consumption
source: J. Brown, University of Minnesota; Diana Project form, adapted from W. Willett’s Food Frequency Questionnaire.
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assessment of nutritional status. Which nutrition biomark-ers are measured depends on what problems are suspected, based on other evidence. For example, a young child who tires easily, has a short attention span, and does not ap-pear to be consuming sufficient iron based on dietary assessment results may have blood taken for analyses of hemoglobin and serum ferritin (markers of iron status).
Suspected inborn errors of metabolism that may underlie nutrient malabsorption may be identified through DNA or other tests. Such results provide specific information on a component of a person’s nutritional status and are very helpful in diagnosing a
particular condition. Table 1.18 provides examples of normal levels of various nutrition biomarkers that
may be used as part of a biochemical assessment of a nu-tritional status, or to help diagnose a particular deficiency or nutrient-related health problem.
Anthropometric Assessment
Individual measures of body size (height, weight, percent body fat, bone density, and head and waist circumferences, for example) are useful in the assessment of nutritional status—if done correctly. Each measure requires use of standard techniques and calibrated instruments by trained personnel. Unfortunately, anthropometric measurements are frequently performed and recorded incorrectly in clini-cal practice. Training on anthropometric measures is often available through public health agencies and programs such as WIC (Special Supplemental Nutrition Program for Women, Infants, and Children), and courses and training sessions are sometimes presented at universities.
Biochemical Assessment
Nutrient and enzyme levels, DNA characteristics, and other biological markers are components of a biochemical
Anthropometry The science of measuring the human body and its parts.
Table 1.18 Examples of normal levels of various nutrition biomarkers that may be used as part of a biochemical assessment of nutritional statusa, 64-67
Nutrient Women Men
Red blood cell (erythrocyte) count, whole blood 4.0–5.23106/mm3 4.5–5.93106/mm3
Ferritin, serum 12–150 ng/mL 15–300 ng/mL
Folate, serum or plasma >4.0–17.5 ng/mL
(9.0–39.7 nmol/L)
3.1–17.5 ng/mL (7.0–39.7 nmol/L)
Folate, red blood cell >187–645 ng/mL
>424–1,426 nmol/L
150–450 ng/mL 340–1,020 nmol/L
Hematocrit, whole blood 36–46% 41–53%
Hemoglobin, whole blood 12–16 g/dL
(7.4–9.9 mmol/L)
13.5–17.5 g/dL (8.4–10.9 mmol/L)
Iron, serum 40–150 μg/dL
(7.2–27.0 μmol/L)
50–160 μg/dL (9.0–28.7 μmol/L) Mean corpuscular hemoglobin, whole blood 26–34 pg/cell 26–34 pg/cell Vitamin B12, serum or plasma >250 pg/mL
(>185 pmol/L)
>250 pg/mL (>185 pmol/L)
Vitamin A, serum 20–100 μg/dL
(0.7–3.5 μmol/L)
20–100 μg/dL (0.7–3.5 μmol/L)
Riboflavin, serum 4–24 μg/dL
(106–638 nmol/L)
4 –24 μg/dL (106–638 nmol/L)
Vitamin B6, plasma 5–30 ng/mL
(20–121 nmol/L)
5–30 ng/mL (20–121 nmol/L)
Vitamin C, serum 0.4–1.0 mg/dL
(23–57 μmol/L)
0.4-1.0 mg/dL (23–57 μmol/L) Vitamin D3 (25 hydroxy-vitamin D), plasma 30–68 ng/mL
(75–170 nmol/L)
30–68 ng/mL (75–170 nmol/L)
Vitamin E, serum 5–18 μg/mL
(12–42 μmol/L)
5–18 μg/mL (12–42 μmol/L)
Vitamin K, serum 0.13–1.19 ng/mL
(0.29–2.64 nmol/L)
0.13–1.19 ng/mL (0.29–2.64 nmol/L)
aSI units given in parentheses. Refer to the second page of Appendix B for factors used to convert convention units to SI units. Nutritional biomarker values and reference ranges are affected by many variables, including sample and method of analysis used and population characteristics. They change as more information becomes known about nutrient biomarker levels and health relationships.
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After the fact-finding phase of nutritional assessment, the nutritionist or other professionals must “apply their brains to their clients’ problems.” There is no “one size fits all” approach to solving nutrition problems—each has to be figured out individually.
In the future, biochemical assessments will include a nutrigenomics profile to identify health risks due to interactions among an individual’s genetic makeup, gene functions, and components of food.68