Nutritional Assessment Methods

Study Notes

Nutritional status is influenced by several factors including food intake, quantity, and quality, and physical health.
Nutritional assessment identifies individuals or populations at risk of malnutrition and those who are malnourished.
Nutritional assessment helps develop healthcare programs to meet community needs and measure the effectiveness of nutritional programs.

Direct methods focus on individual data and objective criteria.
- Anthropometric methods: Measure body height, weight, and proportions. Used clinically to evaluate under and overnutrition.
- Biochemical/Laboratory methods: Assess blood, urine, and tissue samples for nutrient levels and metabolic activity. Helpful in detecting early changes in metabolism.
- Clinical methods: Examine physical signs related to malnutrition, such as hair, skin, and nail changes.
- Dietary evaluation methods: Assess food intake through various methods like 24-hour recall, food frequency questionnaires, and dietary history.
Indirect methods use community health indicators that reflect nutritional influences.
- Ecological variables: Include factors like crop production.
- Economic factors: Consider per capita income, population density, and social habits.
- Vital health statistics: Analyze infant and under-five mortality rates, and fertility indices.

Height: Measured using a stadiometer with the subject standing erect, barefoot, and touching the wall with their heels, buttocks, shoulders, and back of the head.
Weight: Measured using a calibrated electronic or balanced-beam scale with the subject wearing light clothing and no shoes.
Body Mass Index (BMI): Calculated using the formula: BMI = Weight (kg) / Height (m²).
- BMI is an international standard for assessing body size in adults.
- High BMI is associated with type 2 diabetes and increased cardiovascular risk.
Skin fold thickness: Measures subcutaneous adipose tissue using calipers at specific body sites. Provides an indirect measure of body fat percentage.
Mid-arm circumference (MAC): Measured around the upper arm at the midpoint between the shoulder and elbow. Reflects muscle protein reserves.
Mid-arm muscle circumference (MAMC): Calculated using MAC and triceps skin fold thickness measurements. Correlates with lean body mass.
Waist/Hip Ratio: Calculated by dividing waist circumference by hip circumference. Used to predict mortality risk and assess obesity.

Inter-observer errors in measurement.
Limited in diagnosing specific nutritional deficiencies.
Challenges with reference standards, particularly when comparing local and international standards.
Arbitrary cut-off levels for determining abnormal values.

Initial Laboratory Assessment: Includes tests like:
- Haemoglobin estimation: Provides information about overall nutritional status, including anemia and protein and trace element deficiencies.
- Haematocrit or packed cell volume (PCV): Measures the percentage of red blood cells in the blood volume, important for anemia diagnosis.
- Red cell counts and blood films: Assess the size and uniformity of red blood cells, aiding in diagnosing malaria, hemoglobinopathies, and parasites.
- Stool examination: Detects ova (eggs) and/or intestinal parasites, quantifying parasite load.
- Urine examination: Uses dipsticks and microscopy to detect albumin, sugar, and blood.
Specific Lab Tests: Measure individual nutrient levels in body fluids (e.g., serum retinol, serum iron, urinary iodine), detect abnormal metabolite amounts in urine (e.g., urinary creatinine), and analyze hair, nails, and skin for micronutrients.

Essential feature of all nutritional surveys.
The simplest and most practical method for assessing a group's nutritional status.
Uses physical signs associated with malnutrition and vitamin and micronutrient deficiencies.

Methods:
- 24-hour dietary recall: Asks the subject to recall all food and drinks consumed in the previous 24 hours. Quick and easy, but relies on short-term memory and may not be representative.
- Food Frequency Questionnaire: Provides a list of food items and asks the subject to report their frequency of consumption. Inexpensive, more representative, and easy to use.
- Dietary history: Collects detailed information about food intake, including types, amounts, frequency, and timing, over a longer period. Accurate but time-consuming.
- Food dairy technique: Subjects record their food intake at the time of consumption. Reliable but can be difficult to maintain.
- Observed food consumption: Directly observes food intake, providing real-time data.