Assessment of nutritional status

Nutritional Status: It is the result obtained from the relationship between the body's demand for nutrients and the nutrients obtained from the diet. It is known that both deficits and excesses of nutrients are detrimental to health, so the key to an adequate nutritional status lies in the balance between nutrient intake and the body's demand.

Knowledge of nutritional status allows:

• Determine the existence of risk groups that maintain inadequate eating habits.
• To verify the relationship between some consumption patterns and some chronic degenerative diseases.

• To know the nutritional status of vulnerable groups such as the elderly, children and women during pregnancy and breastfeeding.

• To outline health policies aimed at the prevention of risk situations associated with food consumption.

• Promote and encourage nutrition education.

The nutritional status of a person or population group depends on a wide variety of factors, so for an accurate assessment, studies should be carried out from a multiple perspective, including:

• Dietetics.

• Anthropometry.

• Biochemistry.

• Immunology.

• Other ways.

There are not always the resources, nor the personnel prepared to face such challenges, so many times only the essential methods are used to assure an acceptable diagnosis.

Dietary surveys: Dietary surveys are a quick and practical method to obtain information on the nutrient intake of an individual or group. The data obtained on the composition of food can be compared with the recommended intakes and nutritional objectives, where different indices are assessed, allowing to form a general criterion of nutritional status from the diet.

Limitations of dietary surveys:

• It is an inaccurate method in terms of the quantities and quality of nutrients ingested.
• The results are not very accurate because only dietary data are used in the assessments.

Some criteria to classify dietary surveys, according to the area where it is applied:

• National surveys.

• Family or small group surveys.

• Individual surveys.

According to the intake data taken, current or past, Prospective. Techniques that study current intake. Examples:

• Chemical analysis.

• Food composition tables (TSA).

Retrospective. Techniques that study past intake. They can measure immediate, recent or distant past intake. Examples:

• 24-hour recall.

• Frequency of consumption.

• Dietary history.

According to the ways of collecting the data, they are classified as follows:

• Indirect: Through balance sheets.

• Direct: They can be: Records and interviews.

Anthropometric measurements: The determination of body structure and composition is done by taking parameters of length and weight of the organism, and then comparing them with reference values that take into account age, sex, as well as the pathophysiological states in which individuals are found.

Although anthropometric measurements depend to a great extent on genetic factors, they are also related to environmental factors, and within these, nutrition plays a primordial role, especially during the growth stages.

The following indexes can be calculated from anthropometric measurements:

• body mass index (BMI): The body mass index allows the classification of individuals into underweight, normal weight, overweight and obese, based solely on the height and weight of the individual.

• Basal energy expenditure (BEE): This is the energy expenditure we would have at rest.

• Body fat: Through the measurement of the subcutaneous folds at different points of the body, an estimate of the subcutaneous fat mass can be made, which represents approximately 50% of the total fat mass.

• Muscle mass: This is done by measuring the muscle perimeter of the arm.

Biochemical data: These are based on the study of different biological samples used to evaluate nutritional status. They are characterized by a high degree of objectivity due to the rigorous quality control required in each laboratory.

Types of analysis performed:

• Static: They measure the actual value of nutrient in a specific sample. For example, they measure serum iron.

• Functional: Determine the nutrient content by quantifying the activity of an enzyme that depends on the nutrient of interest. For example, they measure plasma homocysteine.

Immunological parameters: These consist of the measurement of certain immunological parameters that allow the detection of malnutrition in patients who appear healthy. Nutritional status affects the immune system, which is why it has been demonstrated that apparently healthy patients with normal anthropometric parameters, but suffering from subclinical malnutrition, have decreased cellular immunity.

Immunological parameters analyzed:

• T lymphocyte count.

• Delayed hypersensitivity skin reactions.

• Lymphoblastic transformation tests.

• Determination of immunoglobulins.

Other ways to determine nutritional status:

• Clinical assessment of nutritional status: used when the level of nutrient-specific or generalized malnutrition is so evident that clinical signs are manifested in certain organs or areas of the body such as the eyes, lips, gums, etc.

• Functional tests: The most characteristic example is the respiratory function test, which is used to indirectly assess muscle mass through the functioning of the respiratory muscles.