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Undernutrition in the community

Sarah Schenker
British Nutrition Foundation

Undernutrition is the consequence of a dietary intake that does not meet nutritional needs as a result of one or more of the following:

  • Decreased dietary intake.
  • Increased nutritional requirements/losses.
  • Impaired ability to absorb or utilise nutrients.

Undernutrition usually has a slow onset, resulting from a period of weeks or months where intake has not matched requirements. However, in conditions of acute metabolic stress, where nutritional demands are high, utilisation of energy and nutrients is disturbed and oral intake is likely to be compromised, nutritional depletion can occur rapidly and be severe.
Undernutrition can adversely affect every system of the body, such as the muscular system (resulting in fatigue, lethargy and decreased peripheral and respiratory muscle strength), the immune system (predisposing to and delaying recovery from infection) and psycho-social function (causing anxiety, depression and self-neglect).
As a consequence, undernutrition consumes a disproportionate amount of healthcare resources. It is estimated that 70% of undernutrition in the UK goes unrecognised and untreated. The presence of undernutrition in adults is often assessed in terms of degrees of weight loss. An easy (but not the best) index is body mass index (BMI), and it has been shown that 10% of the community population have a BMI less than 20kg/m(2). Table 1 gives values for defining adult grades of undernutrition.

It is important to recognise that not all people with low BMI are undernourished and that some may be perfectly healthy. Difficulties exist in defining undernutrition, as the anthropometric measurements used are neither age- nor disease-specific. Ranges and cut-off points to define normal or ideal have been based on healthy young individuals and are applied to the whole population. However, the three key elements that help define undernutrition or risk of undernutrition are:

  • Assessment of chronic protein-energy status.
  • History of weight loss.
  • Underlying risk factors, including disease and disabilities.

Causes of undernutrition
People may be undernourished as a result of a variety of disease-related, social or psychological factors. Mental illnesses such as depression and dementia cause anorexia. Malignancy and acute or chronic physical disease reduce appetite and alter the taste, smell and preferences for different types of food. Infections and malignant disease may also increase nutritional requirements. Neurological and mechanical impairment of swallowing and diseases of the gastrointestinal tract affect nutritional intake. Factors such as social isolation and poverty can play an important role, and disability and immobility can interfere with food purchase and preparation. Taste appreciation also alters with ageing.

Low income as a cause of undernutrition
One in four of the UK population, nearly 14 million people, live in households with incomes below the European poverty line of half the average income. Approximately 9.6 million are in households that receive income support, and the remainder live on low or insecure wages. A study found that food insecurity was common in households with incomes at the level of the UK national minimum wage or lower.(1) Diets of low income households are characterised by less dietary variety that is associated with poorer nutrient profiles.
Previous national food survey results have consistently shown lower nutrient intakes in the lowest income groups compared with the highest. In addition, the Dietary and Nutritional Survey of British adults found that men and women who were unemployed, or living in households claiming benefit, or in social classes IV and V, had significantly lower intakes of many vitamins (especially vitamin C, carotene and vitamin E) and minerals (especially iron) than people not in these categories.(2)
In the related study of schoolchildren, those who received free school meals  (and were, therefore, from households in receipt of benefits) had lower vitamin and mineral intakes than those not from benefit households.(3,4)
In terms of the variety of the diet and overall dietary patterns, poorer households consume less fruit juice, lean meat, oily fish and wholemeal products, and fewer salads, and are more likely to eat white bread, potatoes, cheaper fatty meats, beans, eggs and chips.(5) Those on lower incomes have a much less diverse food base, so their diet is more likely to lack variety.
Many foods that are integral to a healthy diet are perceived as a luxury by those with low incomes and are an expensive form of energy; such foods include fruits, vegetables and fish. In addition, many healthier alternatives to everyday foods carry a price premium, for example wholemeal bread, fats and spreads low in saturates, and lean meat. However, in addition to price, many factors influence the purchasing and consumption patterns in low-income households that are related to their poor financial status, such as limited food preparation facilities. Low income is also often associated with lack of knowledge and skills related to food, nutrition and cooking.

Healthy food choices
It was recently reported that the three key elements of a "food desert" - fruit and vegetable price, socio-economic deprivation and lack of locally available supermarkets - were not factors influencing fruit and vegetable intake, as has been previously suggested.(6) It has been suggested that the causes of food insecurity affecting many people that are living in deprived areas of the UK are more complex than simply resources and that government programmes aimed at alleviating food insecurity must address complex issues such as attitudes to healthy eating and food choice.(7)

The cost of undernutrition
It is estimated that undernutrition in the UK costs in excess of £7.3bn each year, more than double the projected £3.5bn cost of obesity.(8) The bulk of the cost of undernutrition arises from the treatment of undernourished patients in hospital (£3.8bn) and in long-term care facilities (£2.6bn). Other associated costs arise from GP visits (£0.49bn), outpatient visits (£0.36bn), and enteral and parenteral nutrition, tube feeding and oral nutritional supplementation in the community (£0.15bn).

The benefits of correcting undernutrition
There is clear evidence that correcting undernutrition has many benefits.(9) Improvements in body weight and anthropometric parameters have been shown to be associated with improvements in immune function, wound healing and muscle function, and in clinical outcomes such as recovery time from illness.(10-13)
Therefore the presence of disease, whether in hospital or community-based patients, should be seen as an indication of the need for nutritional screening to identify those at particular risk and those who might benefit from some form of nutritional intervention. In which case, implementing measures, such as improved staff training, nutritional screening and assessment, and monitoring, combined with better catering practices for those living in institutions, will result in most patients' nutritional requirements being met.
BAPEN has developed MUST - the Malnutrition Universal Screening Tool - which provides a simple and quick solution to screening, enabling health and care professionals in hospitals, care homes and the community to identify those already suffering or at risk of malnutrition (see Resources).

Initiatives to prevent undernutrition
The government has set up a number of schemes and initiatives to help prevent or combat malnutrition in the community. These initiatives include the establishment of the Neighbourhood Renewal Unit for deprived neighbourhoods, Sure Start set up to operate local programmes for children and parents living in areas of high poverty, and Healthy Living Centres set up to run schemes such as luncheon clubs for older people. The Department of Health published its report Tackling Health Inequalities: A Programme for Action in 2003.(14) It set out plans to tackle health inequalities up until 2006, which would establish the foundations required to achieve the national target for 2010 to reduce the gap in infant mortality across social groups, and raise life expectancy in the most disadvantaged areas faster than elsewhere. In this time, numerous individual projects have also been set up in local areas, which include:

  • Food cooperatives and mobile shops.
  • Cookery and shopping skills courses.
  • Development and provision of healthy recipe leaflets.
  • Community cafes and lunch clubs providing healthy food at low cost.
  • Food and nutrition education courses.
  • Meal provision for those with special needs.
  • Food coupons.
  • Transport to shops.

The overall aim is to reduce inequalities and improve health, including nutritional status, thereby reducing the incidence and prevalence of undernutrition in the community. Details of these projects and information about their effectiveness can be found on Sustain's website and the Health Development Agency's website (see Resources).

Undernutrition in hospitals
It is reported that 40% of all patients admitted to hospitals are undernourished, half of them severely so. Nutritional status tends to worsen during hospital stay and is associated with a worse outcome for the disease and prolonged hospital stay. Studies have shown that 40% of hospital food is wasted, resulting in patients receiving only 70% of their energy and protein requirements. Since many patients are discharged from hospital in a worse nutritional state than they entered it, this then injects into the community a further group of undernourished individuals, setting up a vicious circle. This can largely be prevented or treated with appropriate screening and management both in hospitals and the community.



  1. Tingay RS, Tan CJ, Tang S, Teoh PF, Wong R, Gulliford MC. Food insecurity and low income in an English inner city. J Public Health Med 2003;25:156-9.
  2. Henderson L, Gregory J, Irving K, et al. The National Diet and Nutrition Survey: adults aged 19 to 64 years. Volume 2: Energy, protein, carbohydrate, fat and alcohol intake. London:The Stationery Office; 2003.
  3. Gregory J, Lowe S, Bates C, et al. National diet and nutrition survey:children aged 4 to 18 years. London:The Stationery Office; 2000.
  4. Buttriss J. Findings of the National Food Survey for 2000. Nutr Bull 2002;27:37-40.
  5. Henderson L, Gregory J, Swan G. The National Diet and Nutrition Survey: adults aged 19 to 64 years. Volume 1: Types and quantities of foods consumed. London: The Stationery Office; 2002.
  6. Pearson T, Russell J, Campbell MJ, Barker ME. Do "food deserts" influence fruit and vegetable consumption? A cross-sectional study. Appetite 2005;42:195-7.
  7. Bukhari HM, Margetts BM, Jackson A. Food insecurity in the UK; determinants and consequences.Asia Pac J Clin Nutr 2004;13:167.
  8. Elia M, Stratton R, Russell C, Green C, Pan F. The cost of disease-related malnutrition in the UK and economic considerations for the use of oral nutritional supplements (ONS) in adults. London: BAPEN; 2005.
  9. Potter J, Langhorne P, Roberts M. Routine protein energy supplementation in adults: systematic review. BMJ 1998;317:495-501.
  10. Dionigi R, Zonta A, Dominioni L, et al. The effects of total parenteral nutrition on immunodepression due to malnutrition. Ann Surg 1988;185:467-74.
  11. Chandra RK. Effect of vitamin and trace element supplementation on immune responses and infection in elderly subjects. Lancet 1992;340:1124-7.
  12. Haydock DA, Hill GL. Improved wound healing response in surgical patients receiving intravenous nutrition. Br J Surg 1987;74:320-4.
  13. Fiatarone MA, Evans WJ. The etiology and reversibility of muscle dysfunction in the aged. J Gerontol 1993;48:77-83.
  14. Department of Health. Tackling inequalities: a programme for action. London: DH; 2003.

Malnutrition Universal Screening Tool
Health Development Agency