Malnutrition is a medical condition that results from eating too few or too many nutrients. It is best known as the lack of adequate food supplies seen in developing countries and is the biggest killer of children in the world. However, in the United States malnutrition is becoming more common in elderly people. Malnutrition can be defined as both undernutrition and overnutrition. Undernutrition occurs when the body is lacking certain nutrients due to poor diet or malabsorption. Overnutrition is where the body is ingesting too many nutrients or there is an imbalance in nutrient levels.

Malnutrition can be caused by many factors, including lack of food, chronic illness, loss of appetite, alcoholism and lack of nutritional education. Signs and symptoms can also vary depending on the type of deficiency or toxicity. However, most who are malnourished experience symptoms such as extensive weight loss or gain, lethargy, hair and skin problems and poor wound healing. More serious types of malnutrition, such as protein-energy malnutrition and starvation, can affect the body more severely and even lead to death.

Malnutrition can take months or years to develop, and diagnosis of the underlying causes for malnutrition can be complex. Patients may be required to complete a diet journal in addition to a medical history and physical examination. Other tests, such as a complete blood count or x-rays, may be conducted. In many cases, malnutrition can be treated by replacing or restricting nutrients through the diet. In some extreme cases, physicians may recommend parenteral nutrition through an intravenous (I.V.) drip and liquid diets fortified with nutrients. Most complications of malnutrition can be reversed following treatment.

Malnutrition is a deficiency or toxicity in at least one macronutrient or micronutrient. The body requires a certain level of macronutrients and micronutrients to function effectively. Macronutrients are carbohydrates, protein and fat and are required to give the body energy. Micronutrients consist of vitamins and minerals that are required in small amounts for good health. Deficiency or toxicity in either macronutrients or micronutrients can lead to malnutrition.

When a person is malnourished, the body attempts to compensate for the deficiency. In cases of undernutrition, the body uses up stores of nutrients before drawing upon other sources such as muscle tissue and essential body fat. Obesity can be a form of malnutrition (overnutrition) because the body struggles to function effectively with excess body fat, high cholesterol levels and gross imbalances in nutrients.

Malnutrition is best known as a major problem affecting developing countries and areas affected by famine or war. It is the major cause of death for children under the age of 5 throughout the world. In the United States, it is difficult to estimate the number of people affected by malnutrition. Certain types of malnutrition such as obesity and protein-energy malnutrition are becoming more common, especially among the poor and the elderly.

Malnutrition in developed countries is more common in:

• Infants and children
• Adolescents
• Pregnant and lactating women
• Elderly people
• People of lower socioeconomic status
• Substance abusers

The effects of malnutrition can differ in type and severity depending on the underlying cause. One of the most prevalent effects of malnutrition is a decrease in immune function. This can often cause other conditions such as respiratory infections, viral diseases and gastroenteritis. These infections can lead to changes in metabolic function and a decrease in appetite, which perpetuates the problem of malnutrition. If left untreated, malnutrition can lead to physical and mental disability, an increased risk of other illness and an increased risk of death.

There are many types of malnutrition that vary in severity. Some of the most severe types of malnutrition include:

• Protein-energy malnutrition (PEM). Malnutrition characterized by a deficiency in protein, a macronutrient. It is often also accompanied by a deficit in many micronutrients. It is most common in developing countries, where it is one of the biggest killers of children. PEM is relatively rare in children in the United States, although it is becoming more prevalent in elderly people, often due to poor diet. Kwashiorkor is a severe type of PEM that results from a deficiency in protein with an adequate intake of calories and is often associated with edema (swelling). The best known marker of kwashiorkor is an abnormally swollen stomach. Marasmus is another type of PEM, more severe than kwashiorkor. It involves a deficiency in both protein and calories and can result in emaciation, starvation and, eventually, death.
  
  
• Starvation. The most extreme form of malnutrition. It results from a partial or total lack of essential nutrients for a long time. It can be caused by fasting, famine, anorexia nervosa or an event that suddenly upsets eating patterns or absorption, such as coma, stroke or severe gastrointestinal disorders. In the event of starvation, the body uses its own tissue as an energy source, often resulting in intestinal and muscle tissue loss. Left untreated, it can result in death in as little as eight weeks.
  
  
• Obesity (a body mass index of greater than 30 with an excess of body fat). Obesity is often caused by a sedentary lifestyle and chronic overconsumption of calories, although there are medical conditions such as hypothyroidism and Cushing’s syndrome that can also cause obesity. Obesity has been shown to increase the risk of hypertension, type 2 diabetes and cardiovascular diseases. Obesity is usually associated with an overconsumption of calories, but an imbalance of nutrients in the diet can make obesity a form of malnutrition.

The causes of malnutrition are diverse, because both a deficit and a surplus of nutrients can cause malnutrition. Undernutrition is the condition most people associate with malnutrition, which is usually caused by inadequate food supplies. However, overnutrition, particularly obesity, is one of the fastest-growing health concerns in the United States.

One of the most common causes of undernutrition is malabsorption, which is the inability of the body to absorb nutrients. It can be caused by numerous factors, some of which are hereditary and some of which relate to existing health problems. For example, chronic diseases such as cystic fibrosis, liver disease, kidney disease, cancer (especially of the gastrointestinal system), AIDS and inflammatory bowel disease (IBD) can all cause malabsorption of certain nutrients into the bloodstream. Malabsorption also often occurs following gastric bypass surgery. In addition, some medications used to treat conditions such as epilepsy, high blood pressure and acid indigestion can cause malabsorption.

Some cases of malabsorption are temporary and the body is able to effectively absorb nutrients after the source of malabsorption is treated. Other cases of malabsorption are permanent. People suffering from pernicious anemia (a deficiency in vitamin B12 which causes anemia) cannot absorb B12 and have to undergo regular supplementation for life.

Another cause of undernutrition is loss of appetite. Although this may seem trivial, the body relies on appetite to instruct it when and how much to eat. The disruption of this natural mechanism can cause undernutrition. There are many reasons why people lose their appetite, including:

• Mental health conditions. Conditions such as depression or dementia may cause people to be apathetic about food or to simply forget to eat. Also, eating disorders such as anorexia nervosa and bulimia can cause severe malnutrition.
  
  
• Dietary restrictions. Special diets, such as low-salt or low-fat diets, can cause everyday meals to become bland and unappealing, therefore contributing to under-eating.

Other causes of undernutrition include:

• Hospitalization. Most people suffer from some degree of malnutrition after major surgery. This is especially the case if nutrients are being supplied through an intravenous (I.V.) drip, as patients are sometimes released before the body has recovered from the loss of nutrients.
  
  
• Diarrhea. During prolonged periods of diarrhea, the body is unable to retain all the nutrients it ingests, often resulting in malnutrition.
  
  
• Sensory or dental problems. As the body ages, it becomes less sensitive to taste and smell, which can lead to a lack of interest in eating. In addition, conditions such as dysgeusia (taste disorder) can make some foods taste unpleasant. Dental problems such as pain while chewing or swallowing can make some people reluctant to eat.
  
  
• Substance abuse. People who abuse alcohol may eventually develop malabsorption. Alcohol impedes the absorption of folate, thiamine and other nutrients. It can also cause tissue injury and liver and kidney disease, which can have implications for absorbing nutrients. Heavy drug users may find that the need to eat is suppressed by the substances they are taking. Also, some drug users lose interest in self-preservation, often resulting in malnutrition.

Overnutrition can be caused by the following:

• Overeating. The most common cause of obesity and overnutrition is an imbalanced, overindulgent diet. This type of diet can leave the body deficient in many vitamins and minerals. For example, a diet that lacks fresh fruit and vegetables can be deficient in vitamin C, folate and other vitamins. In addition, eating disorders such as binge-eating can cause serious overnutrition problems.
  
  
• Excess intake of micronutrients or macronutrients. The over-consumption of any one micronutrient or macronutrient can cause an imbalance in nutrients, placing undue stress on the body. This is often the result of excessive vitamin supplementation. For some vitamins – especially the fat-soluble vitamins A, D, E, and K – excess levels are stored in the body for longer and toxicity can easily occur if these levels are then added to by supplements.
  
  
• Overuse of diets. Diets that concentrate on one food type, as many fad diets do, may lead to malnutrition because other nutrients are ignored. Some people, particularly those who are recovering from surgery or serious illness, are prescribed high-calorie or high-protein diets in order to facilitate faster recovery. Although these diets may be effective for short periods of time, staying on a high-calorie or high-protein diet for longer than necessary can cause severe overnutrition and eventually obesity.

In addition to the above causes, there are a number of risk factors for malnutrition. The most important of these are age and socioeconomic status.

Age is a significant risk factor for malnutrition because of the constantly changing nutritional needs of people throughout their life. The following life stages are most at risk for malnutrition:

• Infancy. In infancy, the body requires large quantities of protein, calories and other nutrients in order to grow at a steady and healthy rate. If infants do not receive adequate amounts of nutrients from breast milk or formula they are at serious risk for protein-energy malnutrition and other life-threatening conditions.
  
  
• Childhood and adolescence. As children grow and become more active, they require larger amounts of energy. However, many children in these stages begin to adopt unhealthy lifestyle habits that can cause overnutrition and obesity. It is essential that children and teenagers are encouraged to maintain an active lifestyle that efficiently burns the calories that they consume. Anorexia nervosa, a form of starvation, may affect adolescent girls.
  
  
• Pregnancy and lactation. Pregnant and breastfeeding women have extra nutritional needs. During pregnancy, nausea and vomiting may make proper nutrition difficult to maintain. Breastfeeding women must nourish themselves enough to continue to produce breast milk for their infants.
  
  
• Later life. As the body ages, its nutritional requirements change. The body’s metabolism, which regulates the rate at which nutrients are broken down for energy, slows down. This often results in a decline in appetite and a reduction of muscle, bone and organ mass. A diminished sense in taste and smell, loneliness, physical and mental handicaps, immobility, and chronic illness can result in inadequate intake and malnutrition in the elderly.  However, older people still require certain levels of nutrients, especially micronutrients. In some cases, requirements for nutrients increases with age. In addition to metabolism changes, many of the diseases that accompany old age and the medications to treat them cause malabsorption, which is one of the major causes of malnutrition.
  
  
• Socioeconomic status may also be considered a risk factor for malnutrition. One of the biggest non-medical causes of malnutrition is poverty. It is estimated that 4.4 million American households experience hunger, according to the U.S. Department of Agriculture (USDA). In addition, obesity rates are higher in poor areas, possibly because there is less access to nutritious foods and easier availability of less healthy foods.

Researchers continue to study the causes of malnutrition. For example, one recent study found that infants and children who are placed on elimination diets are at heightened risk of malnutrition. These diets are used to pinpoint the source of food allergies.

Malnutrition develops in stages over time. Therefore, the signs and symptoms of malnutrition can sometimes take weeks or even months to manifest. The signs and symptoms of malnutrition vary greatly depending on the type of deficiency. In general, this may include:

• Weight loss or gain
• Fatigue
• Dizziness
• Hair loss
• Dermatitis
• Amenorrhea (lack of menstruation)
• Poor wound healing
• Easy bruising
• Dental problems
• Irritability

Protein-energy malnutrition may also involve signs and symptoms such as:

• Diarrhea
• Lethargy
• Growth retardation in children
• Swollen organs and tissue (edema)
• Swollen stomach
• Thinning and reddening of the hair
• Irritability
• Decreased muscle mass
• Changes in skin pigment
• Vitiligo (white spots on the skin)
• Failure to gain weight
• Increased number of infections related to damaged immune system
• Shock (late stage)
• Coma (late stage)

Individuals are advised to consult a physician if any of the above symptoms are experienced, especially if they are accompanied by sudden weight loss or weight gain. More information on signs and symptoms of specific types of nutrient deficiency or toxicity can be found in the Health Guide for that nutrient, including:

Because malnutrition can be caused by many factors and conditions, diagnosis can be complex. More than one test is often required to determine in which nutrient the body is deficient or toxic. If a physician suspects malnutrition, the following tests may be performed:

• Medical history. A detailed medical history can reveal clues as to the underlying cause of malnutrition.
  
  
• Physical examination. This may be conducted to look for signs and symptoms of nutrient deficiency. For example, severely dry, cracked lips (cheilosis) can indicate a deficiency in vitamin C or riboflavin and an enlarged thyroid gland (goiter) can be a sign of iodine deficiency.
  
  
• Body measurements (measures of the physical dimensions of the patient). Height and weight are measured to establish the body mass index (BMI). BMI is a formula that calculates approximate body fat levels. A patient’s BMI is then compared to a scale that reflects whether the BMI is healthy based on the patient’s age and height. For adults, a BMI between 18.5 and 24.9 is healthy. A BMI under 18.5 is a sign of undernutrition and a BMI over 30 is classified as obese. However, the BMI is not always a reliable indicator of malnutrition as it does not take into account how much of the body is composed of muscle and how much is composed of fat. For this information a physician may measure the skin folds along the triceps or the circumference of the mid-arm muscle.
  
  
• Diet history. A physician may require the patient to complete a diet journal over the course of one or several days. This could include a simple record of foods eaten or a more complete record which includes emotional states and activity levels. Other diet histories include a food frequency questionnaire, where the patient is asked to note the frequency of certain food groups in the diet.
  
  
• Laboratory tests. A physician may conduct a complete blood count (CBC) to look for signs of anemia, which may be an indicator of malnutrition. Other blood tests may be conducted to check micronutrient and macronutrient levels. A urine test may also be recommended to measure the excretion of nutrients. In addition, x-rays, MRIs and CAT scans may be conducted to measure bone density and other signs of malnutrition.

Treatment for malnutrition varies depending on the type and severity of the condition. Many cases of malnutrition can be treated by replacing or limiting nutrients through the diet, treating symptoms as needed, and treating any underlying medical condition. This is especially the case for mild malnutrition that has been caused by a poor diet. A physician may recommend an eating plan for the patient to restore the balance of nutrients. Food must be reintroduced slowly, with carbohydrates first to supply energy, followed by protein foods. Supplements may also be advised for people who may consistently fail to consume a satisfactory amount of nutrients, such as vegetarians or people with substance addictions.

If the malnutrition is severe and accompanied by diarrhea, a physician may recommend that the patient receive parenteral nutrition through an intravenous (I.V.) drip. This is common for hospitalized patients and is necessary to replace the electrolytes that may have been lost through undernutrition and diarrhea. This is usually a short-term treatment. Following the parenteral treatment, the patient may be placed on a diet of liquid that has been fortified with protein, calories and micronutrients. If these diets are successful, the patient will be allowed to return to a strictly monitored diet of solid food.

Severe malnutrition requires close follow-ups to monitor the amount of nutrients being ingested. For those who have problems with absorption, it may be necessary to receive regular injections of supplements. Most signs and symptoms of undernutrition are reversed following adequate treatment.  

It can be more difficult to treat those who are overnourished. People who are obese are encouraged to lose weight by sticking to a healthy diet and engaging in regular activity. Losing as little as 5 to 7 percent of total body weight can result in a dramatic decrease in risk for health conditions such as diabetes, cardiovascular disease and stroke. If conventional weight-loss treatments (a healthy diet, exercise, stress management) do not help, a physician may recommend weight management medication or surgical intervention.

More information on treatment methods for malnutrition can be found by referring to the Health Guide for the specific nutrient.

Eating a healthy, well-balanced diet is the key to avoiding many types of malnutrition. The U.S. Department of Agriculture (USDA) offers personalized dietary requirements through MyPyramid, its recently revised food guide pyramid. Following this guide can help to ensure that the body receives all the nutrients it requires. For those who are aware that they may suffer from malabsorption of a specific nutrient, it may be possible to receive those nutrients through regular oral or parenteral supplements.

Loss of appetite can sometimes be prevented by putting more emphasis on the act of eating. For example, taste sensitivity can sometimes be enhanced by chewing food longer or using different flavor elements such as lemon juice or flavored vinegars. Low-salt or low-sugar diets can be enhanced by using salt and sugar substitutes. However, people are encouraged to consult a physician before introducing new substitutes into their diet. Salt substitutes often contain potassium, which can interfere with some medications and diseases, increasing the risk of hyperkalemia. It is advisable to check with a physician before using salt substitutes. And some sugar substitutes may not be appropriate during pregnancy or for people with other conditions.

It can be especially difficult for older people who live alone to receive adequate amounts of nutrients. Dietitians advise that older people make an effort to cook simple meals and keep healthful snacks, such as nuts and fruit, around the house. It is also beneficial to keep an active social life, including events that involve food, such as lunch or dinner appointments.  

Prevention of obesity requires a healthy lifestyle, including a well-balanced diet that is high in fiber, and low in fat and refined sugars. Time after time, studies have shown that weight loss and exercise can significantly reduce the risk of developing serious diseases. It is especially important to take steps toward preventing obesity in children. Parents are urged to provide their children with healthy meals and to encourage an active lifestyle. Simply increasing the amount of physical activity can help children to achieve a healthy weight without dieting, which can deprive children of nutrients and calories that are essential to growth and development.

Preparing questions in advance can help patients have more meaningful discussions regarding their conditions. Patients may wish to ask their doctor the following questions related to malnutrition:

1. Am I at risk from malnutrition?
   
   
2. Is my elderly parent at risk from malnutrition?
   
   
3. Should I consult a dietitian? Can you recommend one?
   
   
4. Could malnutrition be the cause of my existing medical conditions?
   
   
5. Could any of my existing medical conditions be causing malnutrition?
   
   
6. Could any of my medications be causing malnutrition?
   
   
7. Can my malnutrition be treated with dietary changes?
   
   
8. Will my malnutrition affect my pregnancy?
   
   
9. How much weight do you advise I gain/lose?
   
   
10. Are there any over-the-counter medications that could treat my malnutrition?
    
    
11. Would you recommend any dietary supplements for me? Which ones?