Causes of malnutrition

Malnutrition, the result of a lack of essential nutrients, resulting in poorer health, may be caused by a number of conditions or circumstances.6

In many developing countries long-term (chronic) malnutrition is widespread - simply because people do not have enough food to eat.

In more wealthy industrialized nations malnutrition is usually caused by:

1) Poor diet
If a person does not eat enough food, or if what they eat does not provide them with the nutrients they require for good health, they suffer from malnutrition. Poor diet may be caused by one of several different factors. If the patient develops dysphagia (swallowing difficulties) because of an illness, or when recovering from an illness, they may not be able to consume enough of the right nutrients.

2) Mental health problem
Some patients with mental health conditions, such as depression, may develop eating habits which lead to malnutrition. Patients with anorexia nervosa or bulimia may develop malnutrition because they are ingesting too little food.

3) Mobility problems
People with mobility problems may suffer from malnutrition simply because they either cannot get out enough to buy foods, or find preparing them too arduous.

4) Digestive disorders and stomach conditions
Some people may eat properly, but their bodies cannot absorb the nutrients they need for good health. Examples include patients with Crohn's disease or ulcerative colitis. Such patients may need to have part of the small intestine removed (ileostomy).

Individuals who suffer from Celiac disease have a genetic disorder that makes them intolerant to gluten. Patients with Celiac disease have a higher risk of damage to the lining of their intestines, resulting in poorer food absorption.

Patients who experience serious bouts of diarrhea and/or vomiting may lose vital nutrients and are at higher risk of suffering from malnutrition.

5) Alcoholism
Alcoholism is a chronic (long-term) disease. Individuals who suffer from alcoholism can develop gastritis, or pancreas damage. These problems also seriously undermine the body's ability to digest food, absorb certain vitamins, and produce hormones which regulate metabolism. Alcohol contains calories, reducing the patient's feeling of hunger, so he/she consequently may not eat enough proper food to supply the body with essential nutrients.

In the poorer nations malnutrition is commonly caused by:

1) Food shortages
In the poorer developing nations food shortages are mainly caused by a lack of technology needed for higher yields found in modern agriculture, such as nitrogen fertilizers, pesticides and irrigation. Food shortages are a significant cause of malnutrition in many parts of the world.

2) Food prices and food distribution
It is ironic that approximately 80% of malnourished children live in developing nations that actually produce food surpluses (Food and Agriculture Organization). Some leading economists say that famine is closely linked to high food prices and problems with food distribution.

3) Lack of breastfeeding
Experts say that lack of breastfeeding, especially in the developing world, leads to malnutrition in infants and children. In some parts of the world mothers still believe that bottle feeding is better for the child.

Another reason for lack of breastfeeding, mainly in the developing world, is that mothers abandon it because they do not know how to get their baby to latch on properly, or suffer pain and discomfort.

Diagnosis of malnutrition
Prompt diagnosis is key to preventing complications. There are several ways of identifying adults who are malnourished, at risk of malnutrition, or obese.

Below is BAPEN's (British Association for Parenteral and Enteral Nutrition's) MUST (Malnutrition Universal Screening Tool) - a quick to use screening tool to identify those at risk of malnutrition:7

MUST (Malnutrition Universal Screening Tool)

MUST has been designed to identify adults, especially elderly people, who are:

  • Malnourished
  • At risk of malnutrition (undernutrition)
  • Obese.

MUST also includes management guidelines which can be used to develop a care plan. It is a five-step tool for use in hospitals, community and other care settings and can be used by all care workers to identify those at risk from malnutrition.

MUST 5-step plan:
Step 1 - Measure height and weight to get a BMI (body mass index) score.
Step 2 - Note percentage unplanned weight loss and score.
Step 3 - Establish acute disease (any underlying illness, such as a psychological condition) effect and score.
Step 4 - Add scores from steps 1, 2 and 3 together to obtain overall risk of malnutrition.
Step 5 - Use management guidelines and/or local policy to develop care plan.
MUST is only used for identifying malnutrition or risk of malnutrition in adults. It is not designed to identify deficiencies/excesses in vitamin and/or mineral intake.

STEP 1 (BMI kg/m2 Score)

  • BMI >20 (>30 obese), score 0
  • BMI 18.5 to 20 - score 1
  • BMI <18.5 - score 2

If there are problems measuring BMI:

If height cannot be measured - use recently documented or self-reported height (if reliable and realistic). If the subject does not know or is unable to report their height, use one of the alternative measurements to estimate height (ulna, knee height or demispan).

If height and weight cannot be obtained - use mid upper arm circumference (MUAC) measurement to estimate BMI category.

[B]STEP 2 (Weight Loss Score)[/B]

Unplanned weight loss in past 6 months

  • <5% - score 0
  • 5% to 10% - score 1
  • 10% - score 2

If recent weight loss cannot be calculated, use self-reported weight loss (if reliable and realistic).

STEP 3 (Acute Disease Effect Score)

If the patient is acutely ill and there has been or is likely to be no nutritional intake for over 5 days - score 3.

STEP 4 (Overall Risk of Malnutrition)

STEP 1 + STEP 2 + STEP 3 = STEP 4

Add Scores together to calculate overall risk of malnutrition

  • Low Risk - Score 0
  • Medium Risk - Score 1
  • High Risk - Score 2 or more

STEP 5 - Management Guidelines

Low risk, score 0

Repeat hospital screening weekly
Repeat care home screening monthly
Repeat community screening annually for special groups, e.g. those age over 75 years

  • ]]Medium risk, score


Document dietary intake for 3 days if subject is in hospital or care home.
If improved or adequate intake - little clinical concern; if no improvement - clinical concern - follow local policy.
Repeat hospital screening weekly
Repeat care home screening at least monthly
Repeat community screening at least every 2 to 3 months

High risk, score 2 or more Treat (Unless detrimental or no benefit is expected from nutritional support e.g. imminent death)

Refer to dietitian, Nutritional Support Team, or implement local policy.
Improve and increase overall nutritional intake
Monitor and review care plan:
Hospital - weekly
Care home - monthly
Community - monthly.

All risk categories:

Treat underlying condition and provide help and advice on food choices, eating and drinking when necessary.

Record malnutrition risk category.

Record need for special diets and follow local policy.


Record presence of obesity. For those with underlying conditions, these are generally controlled before the treatment of obesity.

Subjective criteria:

If height, weight or BMI cannot be obtained, the following criteria which relate to them can assist your professional judgment of the subject's nutritional risk category. Use of these criteria is not designed to assign a score.

  • BMI - clinical impression: thin, acceptable weight, overweight. Obvious wasting (very thin) and obesity (very overweight) can also be noted.
  • Unplanned weight loss - clothes and/or jewelry have become loose fitting (weight loss). History of decreased food intake, reduced appetite or swallowing problems over 3-6 months and underlying disease or psycho-social/physical disabilities likely to cause weight loss.
  • Acute disease effect - no nutritional intake or likelihood of no intake for more than 5 days.