What is malnutrition?

Malnutrition is a state of nutrition in which a deficiency or excess (or imbalance) of energy, protein and other nutrients causes measurable adverse effects on tissue / body form (body shape, size and composition) and function and clinical outcome. The term malnutrition does include obesity, however BAPEN is focussed on the problem of “undernutrition”. The term “malnutrition” is used on this website to mean “undernutrition”. For further information on obesity please go to NHS Choices website

What are the symptoms of malnutrition?

Malnutrition can often be very difficult to recognise, particularly in patients who are overweight or obese to start with. Malnutrition can happen very gradually, which can make it very difficult to spot in the early stages. Some of the symptoms and signs to watch out for include:

  • Loss of appetite
  • Weight loss – clothes, rings, jewellery, dentures may become loose
  • Tiredness, loss of energy
  • Reduced ability to perform normal tasks
  • Reduced physical performance – for example, not being able to walk as far or as fast as usual
  • Altered mood – malnutrition can be associated with lethargy and depression
  • Poor concentration
  • Poor growth in children

Who is at risk of malnutrition?

  • Older people over the age of 65, particularly if they are living in a care home or nursing home or have been admitted to hospital
  • People with long-term conditions, such as diabetes, kidney disease, chronic lung disease
  • People with chronic progressive conditions – for example, dementia or cancer
  • People who abuse drugs or alcohol

There are also social factors that can increase the risk of malnutrition including:

  • Poverty
  • Social isolation
  • Cultural norms – for example, hospitals and care homes may not always provide food that meets particular religious or cultural needs and so increase the risk of malnutrition whilst a person is away from their normal environment

Physical factors can also increase the risk of malnutrition. For example:

  • Eating may be difficult because of a painful mouth or teeth
  • Swallowing may be more difficult (a stroke can affect swallowing) or painful
  • Losing your sense of smell or taste may affect your appetite
  • Being unable to cook for yourself may result in reduced food intake
  • Limited mobility or lack of transport may make it difficult to get food

It is also important to realise that if an older person is less able to feed themselves and becomes malnourished, this will make them more susceptible to disease, which in turn will make their nutritional state worse and impair recovery. The Malnutrition Carousel below describes this downward vicious spiral.

The Malnutrition Carousel

What are the consequences of malnutrition?

Malnutrition affects every system in the body and always results in increased vulnerability to illness, increased complications and in very extreme cases even death.

Immune system
Reduced ability to fight infection


  • Inactivity and reduced ability to work, shop, cook and self-care
  • Inactivity may also lead to pressure ulcers and blood clots
  • Falls
  • Reduced ability to cough may predispose to chest infections and pneumonia
  • Heart failure

Impaired wound healing

Inability to regulate salt and fluid can lead to over-hydration or dehydration

Malnutrition causes apathy, depression, introversion, self-neglect and deterioration in social interactions

Malnutrition reduces fertility and if present during pregnancy can predispose to problems with diabetes, heart disease and stroke in the baby in later life.

Impaired temperature regulation
This can lead to hypothermia

Consequences of malnutrition in children and adolescents

  • Growth failure and stunting
  • Delayed sexual development
  • Reduced muscle mass and strength
  • Impaired intellectual development
  • Rickets
  • Increased lifetime risk of osteoporosis

Consequences of specific micronutrient deficiencies

There are very many of these and so only the commonest are given below:

  • Iron deficiency can cause anaemia
  • Zinc deficiency causes skin rashes and decreased ability to fight infection
  • Vitamin B12 deficiency can cause anaemia and problems with nerves
  • Vitamin D deficiency causes rickets in children and osteomalacia in adults
  • Vitamin C deficiency causes scurvy
  • Vitamin A deficiency causes night blindness

How is “undernutrition” recognised?

The best way to detect malnutrition is by the use of malnutrition screening tools, such as the ‘Malnutrition Universal Screening Tool’ (‘MUST’).This tool consists of three parts:

  • Body Mass Index (BMI) – this is calculated from an individual’s weight and height. A BMI of less than 18.5kg/m2 suggests a significant risk of malnutrition.
  • A history of recent weight loss that has happened without any intention to lose weight. The unintentional loss of more than 10% of normal body weight in the last 3 -6 months suggests a significant risk of malnutrition.
  • An “acute disease effect” associated with being acutely ill and unable to eat for more than five days.

This tool assesses patients as being at low, medium or high risk of malnutrition and guides the user to develop individualised care plans for treatment if required and further monitoring.

What is the size of the problem in the UK?

It has been estimated that malnutrition (or “undernutrition”) affects over 3 million people in the UK.  Of these about 1.3 million are over the age of 65. Whilst most of those affected are living in the community (about 93% or 2.8 million people) BAPEN’s Nutrition Screening Week surveys (2007-11) have shown that:

  • 25-34% of patients admitted to hospital are at risk of malnutrition
  • 30-42% of patients admitted to care homes are at risk of malnutrition
  • 18-20% of patients admitted to mental health units are at risk of malnutrition

Surveys of the 700,000 people living in sheltered housing using ‘MUST’ criteria have shown that 10-14% are at risk of malnutrition.

How much does it cost?

In November 2015, a new report published by the National Institute for Health Research Southampton Biomedical Research Centre (NIHR Southampton BRC) and the British Association for Parenteral and Enteral Nutrition (BAPEN), estimated that the cost of malnutrition in both adults and children in England in 2011-12 was £19.6 billion and is only set to increase with an aging population and the rising cost of health and social care. This new figure represents almost a 50% increase in estimated costs compared with the £13 billion stated in the 2007 report.

In primary care, disease related malnutrition results in

  • Increased dependency
  • Increased GP visits
  • Increased prescription costs
  • Increased referrals to hospital
  • Increased admissions to care homes

In secondary care, disease related malnutrition results in

  • Increased complications such as wound  infections, chest infections, pressure ulcers
  • Increased length of hospital stay
  • Increased numbers of patients who are readmitted to hospital
  • Increased numbers of deaths

How is malnutrition treated?

Recognising the problem is the most important first step. Once individuals and those involved in their care are aware of the problem, often simple measures to increase food intake may be enough to reverse the downward cycle. We know for example that giving nutritional supplements to malnourished patients reduces complications such as wound breakdown by 70% and death by 40%.

Once an individual has been assessed as being at risk of malnutrition it is always necessary to assess the problem in more detail and identify any other factors that are contributing to the problem. Treatment should always be tailored to the needs of the individual, but in general, if a person is able to eat and does not have a diminished appetite, then the first step would to encourage this with a “Food first” approach. This may be in the form of advice on meals, snacks, nourishing drinks and food fortification, but should include setting goals of treatment and a plan for monitoring to ensure that these goals are met.

If simple measures are not working or where the patient has a reduced appetite, then an assessment and support from a dietitian may be needed.  In addition to fortifying food and increasing what you eat , there are many different oral nutritional supplements. These should usually only be used under the supervision of a dietitian or doctor. It is also possible that you may need to take a vitamin and mineral supplement – but only if advised to do so by the professional treating you.

For patients who are unable to eat, nutrition can be provided by tube feeding – either into the gut (Enteral) or directly into the bloodstream via a vein (Parenteral). In the UK, both Enteral and Parenteral feeds are manufactured to contain all the nutrients your body needs.

Enteral tube feeding (Enteral Nutrition / EN)

The commonest type of enteral tube feeding uses a tube that is passed through the nose and down into the stomach (a nasogastric tube).  This is usually for short term feeding (less than 4 weeks) to provide nutritional support as a patient recovers from illness.

For longer term feeding into the stomach, a tube is usually placed through the abdomen directly into the stomach (a PEG tube, or Percutaneous Gastrostomy tube).

If it is not possible to use the stomach, it is also possible to place tubes into the jejunum (the first part of the small intestine or small bowel). These can either be nasojejunal tubes (short –term) or jejunostomy tubes which are place through the abdominal wall directly (long-term).

For more information on enteral feeding please visit the PINNT website.

Parenteral Nutrition (PN)

If it is not possible to use your gut for nutrition (for example in patients who have lost part of their gut or in whom the gut does not work properly to be able to absorb nutrients) then nutrients can be given directly into the blood stream.  The sterile feed is given through a small tube (catheter) placed in a vein and is tailored to ensure that you are given all the nutrients that your body needs. For most patients this is done whilst they are in hospital for no more than a few weeks as they recover from illness. However for some patients, this is their only means of nutrition and they learn to do this themselves at home (Home Parenteral Nutrition or HPN).

For more information on Parenteral Nutrition please visit the PINNT website.

Malnutrition Videos

BAPEN 2016 – how can we improve Nutritional Care in our hospitals?

Optimal Nutritional Care For All

Malnutrition in the UK – what BAPEN is doing to address the problem

Newscaster Martyn Lewis interviews Professor Mike Stroud, former Chair of BAPEN on malnutrition in the UK and how the charity is addressing the issue

Screening for Malnutrition – BAPEN ‘MUST’ App Explained (2010)

Prof Marinos Elia explains how 'MUST' and the 'MUST' App identify those at risk of malnutrition in community, care and hospital. The 'MUST' App for the iPhone enables more health and care staff to cascade information about the impact of malnutrition and how it can be identified and treated.  'MUST' App - Get it - Use it - Share it!

Dr Mike Stroud speaks at the QIPP Summit Event Oct 12th 2011. The contribution of nutrition and hydration to the ‘Q’ in QIPP.

Dr Ailsa Brotherton talking at a Patient Safety Express event 15th March 2011 on “Malnutrition in the UK: The importance of Nutritional Screening”

Nutrition in the Patient Safety Express Programme (2011)

Dr. Nicola Simmonds – a short fly on the wall video talking about nutrition in the Patient Safety Express Programme and some of the issues about data collection relating to nutritional care.

The future of nutritional care

Dr Tim Bowling talking at the Patient safety express coalition summit, 12th October 2011. He outlines the importance of strategic planning of nutritional care, particularly in the community.

Go To Top