The basis for nutritional interventions and assessment of their impact

Health and Social Behaviour: The basis for nutritional interventions and assessment of their impact

Basis for nutritional interventions

Diet is one of the most important and modifiable life-style determinants of human health. Under-nutrition and over-nutrition play a role in morbidity and mortality and therefore nutritional interventions are needed to reduce morbidity and
mortality through dietary change. They can be implemented at an individual, local, or national level for example through policy. Examples of nutritional interventions include:

National:

Education campaigns to improve knowledge and attitudes e.g. 5 a day campaign and Traffic Light food labelling.
Supplementation and food fortification to increase consumption e.g. fortification of salt with iodine and bread/flour with folate or other micronutrients, and fluoridation of water.
Collaboration with food manufacturers to reduce the salt, sugar or fat content of foods.
National Healthy Schools Programme (NHSP) - more than 95% of schools nationally are now involved in the programme and over 60% of schools have achieved National Healthy Schools Status

Local:

Workplace initiatives e.g. ‘healthy’ canteen, replacing vending machines with ‘healthy vending’ machines.
Skills training to allow previously uneaten foods to be consumed e.g. cooking, planning meals, managing a budget, shopping tours.

Individual:

Individual counselling - usually occurs in primary care or a health centre setting and is generally addressing a particular health problem (e.g. obesity, hypertension). Dietary advice is provided and tailored to the individual.

Assessment of their impact

There are a number of methods for assessing the impact of nutritional interventions as outlined below.

Measuring the impact of nutrition interventions on physical growth

Physical growth is measured using anthropometry, which measures the dimensions and composition of the human body (see ‘Markers of nutritional status, nutrition and food’ - anthropometric measures).
Measuring impact of nutritional interventions on biomarkers using laboratory methodologies

Laboratory measurements of the nutrient content of body fluids or tissues can provide subclinical information for evaluating the nutritional impact of nutrition interventions. Biological markers are used for each individual nutrient and are
useful for detecting dietary inadequacies prior to the appearance of clinical symptoms and signs. The major nutrient deficiencies of public health significance for which food or nutrient-specific interventions have been designed include
inadequate food energy intake, protein-energy malnutrition, iron deficiency anaemia, vitamin A deficiency, iodine deficiency, and hypercholesterolemia/hyperlipidaemia.
Measuring impact of nutritional interventions using clinical, morbidity, and mortality data
Measuring impact of nutritional interventions using dietary assessments

Dietary assessments estimate food and/or nutrient intakes. This type of assessments is challenging and prone to inaccuracies - see ‘Markers of nutritional status, nutrition and food’.
Measuring impact on physical activity and physical fitness

Some nutritional interventions may focus on both diet and physical activity. In such circumstances, an impact of physical activity and physical fitness should be measured. Measuring physical activity determines the amount of energy expended per
day by an individual and thus sets the requirement for food. Physical fitness depends on a number of factors: genetics, past and present nutritional state and level of habitual activity, and disease. Physical activity or energy expenditure is
measured using ‘direct’ or ‘indirect calorimetry’. Direct calorimetry measures the heat output of the body and therefore requires laboratory conditions, whilst indirect calorimetry measures oxygen uptake by the body. Physical activity
diaries, heart rate monitors and pedometers are other methods for recording energy expenditure.

It is also worth noting that some nutritional interventions are evaluated using behavioural change and psychological indicators. For example, interventions tackling obesity will record the impact on self esteem.

References

Gibney M.J., Margetts B.M., Kearney J.M. and Arab L. Public Health Nutrition. The Nutrition Society.
Lewis, G. Sheringham, J. Kalim, K. Crayford, T. (2008) Mastering Public Health: A postgraduate guide to examinations and revalidation. The Royal Society of Medicine Press Limited.