Malnutrition is a broad term which refers to both undernutrition (subnutrition) and overnutrition.
Individuals are malnourished, or suffer from undernutrition if their diet does not provide them with adequate calories and protein for maintenance and growth, or they cannot fully utilize the food they eat due to illness.
People are also malnourished, or suffer from overnutrition if they consume too many calories
Malnutrition can also be defined as the insufficient, excessive or imbalanced consumption of nutrients.
Several different nutrition disorders may develop, depending on which nutrients are lacking or consumed in excess.
According to the World Health Organization (WHO), malnutrition is the gravest single threat to global public health.1
Contents of this article:
What is malnutrition?
This text will focus more on the undernutrition aspect of malnutrition, rather than overnutrition.
Subnutrition occurs when an individual does not consume enough food. It may exist if the person has a poor diet that gives them the wrong balance of basic food groups.
Obese people, who consume more calories than they need, may suffer from the subnutrition aspect of malnutrition if their diet lacks the nutrients their body needs for good health.
Though scurvy is a very rare disease, it still occurs in some patients - usually elderly people, alcoholics, or those that live on a diet devoid of fresh fruits and vegetables. Similarly, infants or children who are on special or poor diets for any number of economic or social reasons may be prone to scurvy.
According to the National Health Service (NHS), UK, it is estimated that around three million people in the UK are affected by malnutrition (subnutrition).2
According to the Food and Agriculture Organization (FAO), the number of people globally who were malnourished stood at 923 million in 2007, an increase of over 80 million since the 1990-92 base period.3
The World Health Organization (WHO) says that malnutrition is by far the largest contributor to child mortality globally, currently present in 45 percent of all cases.4
Underweight births and inter-uterine growth restrictions are responsible for about 2.2 million child deaths annually in the world. Deficiencies in vitamin A or zinc cause 1 million deaths each year.
WHO adds that malnutrition during childhood usually results in worse health and lower educational achievements during adulthood. Malnourished children tend to become adults who have smaller babies.
Globally, as well as in developed, industrialized countries, the following groups of people are at highest risk of malnutrition (subnutrition):
- Elderly people, especially those who are hospitalized or in long-term institutional care
- Individuals who are socially isolated
- People on low incomes (poor people)
- People with chronic eating disorders, such as bulimia or anorexia nervosa
- People convalescing after a serious illness or condition.
Symptoms of malnutrition
A symptom is something the patient feels and reports, while a sign is something other people, such as the doctor detect. For example, pain may be a symptom while a rash may be a sign.
Signs and symptoms of malnutrition (subnutrition) include:5
- Loss of fat (adipose tissue)
- Breathing difficulties, a higher risk of respiratory failure
- Higher risk of complications after surgery
- Higher risk of hypothermia - abnormally low body temperature
- The total number of some types of white blood cells falls; consequently, the immune system is weakened, increasing the risk of infections.
- Higher susceptibility to feeling cold
- Longer healing times for wounds
- Longer recover times from infections
- Longer recovery from illnesses
- Lower sex drive
- Problems with fertility
- Reduced muscle mass
- Reduced tissue mass
- Tiredness, fatigue, or apathy
In more severe cases:
- Skin may become thin, dry, inelastic, pale, and cold
- Eventually, as fat in the face is lost, the cheeks look hollow and the eyes sunken
- Hair becomes dry and sparse, falling out easily
- Sometimes, severe malnutrition may lead to unresponsiveness (stupor)
- If calorie deficiency continues for long enough, there may be heart, liver and respiratory failure
- Total starvation is said to be fatal within 8 to 12 weeks (no calorie consumption at all).
Children who are severely malnourished typically experience slow behavioral and intellectual development, which may lead to intellectual disabilities. Even when treated, undernutrition may have long-term effects in children, with impairments in mental function and digestive problems persisting - in some cases for the rest of their lives.
Adults whose severe undernourishment started during adulthood usually make a full recovery when treated.
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 problems
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.
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.
MUST (Malnutrition Universal Screening Tool)
MUST has been designed to identify adults, especially elderly people, who are:
- At risk of malnutrition (undernutrition)
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
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.
STEP 2 (Weight Loss Score)
Unplanned weight loss in past 6 months
- 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 1
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.
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.
Treatments for malnutrition
The type of malnutrition treatment recommended depends mainly on its severity, and whether the patient has an underlying condition/illness which is a contributory factor. If so, that underlying illness/condition needs to be treated or addressed.
NICE (National Institute for Health and Clinical Excellence), UK, has guidelines for malnutrition treatment.8
They state that the needs and preferences of the patient need to be taken into account. The patient, along with healthcare professionals, should be able to make informed decisions about care and treatment.
NICE guidelines say that individuals who are receiving nutritional support, as well as their caregivers (UK: carers):
- Should be fully informed about their treatment
- Should be given tailored information
- Should be given the opportunity to discuss diagnosis, treatment options and relevant physical, psychological and social issues.
- Should be given contact details of relevant support groups, charities and voluntary organizations.
When a diagnosis of either malnutrition or malnutrition risk has been made, the healthcare professional (either a doctor or dietician) who is responsible for the patient will devise a targeted care plan.
The care plan
Aims for treatment will be set out, which should include the treatment for any underlying conditions/illnesses which are contributory factors to the malnutrition.
Typically, treatment will include a feeding program with a specially planned diet, and possibly some additional nutritional supplements.
Severely malnourished patients, or individuals who cannot get sufficient nutrition by eating or drinking may need and should receive artificial nutritional support.
The patient will be closely monitored for progress. Their treatment will be regularly reviewed to make sure their nutritional needs are being met.
A good healthcare professional will discuss eating and drinking with the patient and provide advice regarding healthy food choices. The aim is to make sure the patient is receiving a healthy, nutritious diet.
The doctor or dietitian will work with the patient to make sure enough calories are being consumed from carbohydrates, proteins, fats and diary, as well as vitamins and minerals. If the patient cannot get their nutritional requirements from the food they eat, oral supplements may be needed. An additional 250kcal to 600kcal may be advised.
Artificial nutritional support
There are two main types of artificial nutritional support, mainly for patients with severe malnutrition:
- Enteral nutrition (tube feeding) - a tube is placed in the nose, the stomach or small intestine. If it goes through the nose it is called a nasogastric tube or nasoenteral tube. If the tube goes through the skin into the stomach it is called a gastrostomy or percutaneous endoscopic gastrostomy (PEG) tube. One that goes into the small intestine is called a jejunostomy or percutaneous endoscopic jejunostomy (PEJ) tube.
- Parenteral feeding - a sterile liquid is fed directly into the bloodstream (intravenously). Some patients may not be able to take nourishment directly into their stomach or small intestine.
The patient will be regularly monitored to check that he/she is receiving the right amount of calories and nutritional needs. This may be adjusted as the patient's requirements change. Patients receiving artificial nutritional support will be switched over to normal eating as soon as they are able to.
Malnutrition is caused mainly by not consuming what the National Health Service (NHS), UK, calls "the right balance of nutrients from major food groups". These include:
- Fruit and vegetables
- Dairy - vegans are able to find abundant nutrients from non-animal sources (see: The Vegan Diet)
The average human should drink at least 1.2 liters of fluid per day.
A fairly common chronic (long-term) disease that causes inflammation of the colon (the large intestine). It is a form of inflammatory bowel disease. When inflammation is only in the rectum the disease is called ulcerative proctitis. The inflammation may extend into the upper parts of the colon. Universal colitis or pancolitis is when the whole colon is involved.
Patients with ulcerative colitis commonly lose weight because their body is unable to absorb nutrients properly. Consuming plenty of fluids, and eating regularly (five or six small meals daily), as well as taking food supplements may help to prevent ulcerative colitis.
An ongoing condition that causes inflammation of the digestive tract, or the GI (gastrointestinal) tract (the gut). Crohn's disease may also be called ileitis or enteritis. Crohn's disease can affect any part of the gut, from the mouth all the way down to the anus. In the majority of cases the lower part of the small intestine - the ileum - is affected. Patients with Crohn's disease can feel pain; the condition makes the intestines empty frequently, resulting in diarrhea. Although preventing Crohn's disease is unlikely, following treatment carefully helps prevent malnutrition considerably.
Celiac disease (UK: Coeliac disease) is also known as gluten intolerance. If you suffer from Celiac disease you have a genetic disorder that makes you intolerant to gluten. It is caused by a reaction to gliadin (a gluten protein found in wheat). It can affect all types of people. However, it seems to be more prevalent among people of Northern European descent. Patients who follow a well-balanced, healthy, gluten-free diet are less likely to suffer from malnutrition.
People who are addicted to alcohol and abuse alcohol may sometimes suffer from malnutrition. The only effective way to address this is to treat the alcoholism. There are several ways of treating alcoholism. The first step for the alcoholic it to acknowledge that there is an alcohol dependency problem. The next step is to get help.
Video: further information
This video by World Vision explains the potential lifelong deadly effects of malnutrition, especially among children.
Effects include a "starved" brain, unhealthy heart, the accumulation of dangerous toxins in the liver which leads to kidney failure and a poor immune system. Cracked skin, another consequence of malnutrition significantly increases the risk of infection, while weakened bones prevent proper growth.