Malnutrition is the condition that develops when the body does not get the right amount of the vitamins, minerals, and other nutrients it needs to maintain healthy tissues and organ function.
Malnutrition occurs in people who are either undernourished or overnourished. Undernutrition is a consequence of consuming too few essential nutrients or using or excreting them more rapidly than they can be replaced.
Infants, young children, and teenagers need additional nutrients. So do women who are pregnant or breastfeeding. Nutrient loss can be accelerated by diarrhea, excessive sweating, heavy bleeding (hemorrhage), or kidney failure. Nutrient intake can be restricted by age-related illnesses and conditions, excessive dieting, food allergies, severe injury, serious illness, a lengthy hospitalization, or substance abuse.
The leading cause of death in children in developing countries is protein-energy malnutrition. This type of malnutrition is the result of inadequate intake of calories from proteins, vitamins, and minerals. Children who are already undernourished can suffer from protein-energy malnutrition (PEM) when rapid growth, infection, or disease increases the need for protein and essential minerals. These essential minerals are known as micronutrients or trace elements.
Two types of protein-energy malnutrition have been described-kwashiorkor and marasmus. Kwashiorkor occurs with fair or adequate calorie intake but inadequate protein intake, while marasmus occurs when the diet is inadequate in both calories and protein.
About 1% of children in the United States suffer from chronic malnutrition, in comparison to 50% of children in southeast Asia. About two-thirds of all the malnourished children in the world are in Asia, with another one-fourth in Africa.
In the United States, nutritional deficiencies have generally been replaced by dietary imbalances or excesses associated with many of the leading causes of death and disability. Overnutrition results from eating too much, eating too many of the wrong things, not exercising enough, or taking too many vitamins or other dietary replacements.
Risk of overnutrition is also increased by being more than 20% overweight, consuming a diet high in fat and salt, and taking high doses of:
- Nicotinic acid (niacin) to lower elevated cholesterol levels
- Vitamin B6 to relieve premenstrual syndrome
- Vitamin A to clear up skin problems
- Iron or other trace minerals not prescribed by a doctor.
Nutritional disorders can affect any system in the body and the senses of sight, taste, and smell. They may also produce anxiety, changes in mood, and other psychiatric symptoms. Malnutrition begins with changes in nutrient levels in blood and tissues. Alterations in enzyme levels, tissue abnormalities, and organ malfunction may be followed by illness and death.
Causes and symptoms
Poverty and lack of food are the primary reasons why malnutrition occurs in the United States. Ten percent of all members of low income households do not always have enough healthful food to eat. Protein-energy malnutrition occurs in 50% of surgical patients and in 48% of all other hospital patients.
Loss of appetite associated with the aging process. Malnutrition affects one in four elderly Americans, in part because they may lose interest in eating. In addition, such dementing illnesses as Alzheimer's disease may cause elderly persons to forget to eat.
There is an increased risk of malnutrition associated with chronic diseases, especially disease of the intestinal tract, kidneys, and liver. Patients with chronic diseases like cancer, AIDS, intestinal parasites, and other gastric disorders may lose weight rapidly and become susceptible to undernourishment because they cannot absorb valuable vitamins, calories, and iron.
People with drug or alcohol dependencies are also at increased risk of malnutrition. These people tend to maintain inadequate diets for long periods of time and their ability to absorb nutrients is impaired by the alcohol or drug's affect on body tissues, particularly the liver, pancreas, and brain.
Eating disorders. People with anorexia or bulimia may restrict their food intake to such extremes that they become malnourished.
Food allergies. Some people with food allergies may find it difficult to obtain food that they can digest. In addition, people with food allergies often need additional calorie intake to maintain their weight.
Failure to absorb nutrients in food following bariatric (weight loss) surgery. Bariatric surgery includes such techniques as stomach stapling (gastroplasty) and various intestinal bypass procedures to help people eat less and lose weight. Malnutrition is, however, a possible side effect of bariatric surgery.
Unintentionally losing 10 pounds or more may be a sign of malnutrition. People who are malnourished may be skinny or bloated. Their skin is pale, thick, dry, and bruises easily. Rashes and changes in pigmentation are common.
Hair is thin, tightly curled, and pulls out easily. Joints ache and bones are soft and tender. The gums bleed easily. The tongue may be swollen or shriveled and cracked. Visual disturbances include night blindness and increased sensitivity to light and glare.
Other symptoms of malnutrition include:
- night blindness
- irritability, anxiety, and attention deficits
- goiter (enlarged thyroid gland)
- loss of reflexes and lack of muscular coordination
- muscle twitches
- amenorrhea (cessation of menstrual periods)
- scaling and cracking of the lips and mouth.
Malnourished children may be short for their age, thin, listless, and have weakened immune systems.
Overall appearance, behavior, body-fat distribution, and organ function can alert a family physician, internist, or nutrition specialist to the presence of malnutrition. Patients may be asked to record what they eat during a specific period. X rays can determine bone density and reveal gastrointestinal disturbances, and heart and lung damage.
Blood and urine tests are used to measure the patient's levels of vitamins, minerals, and waste products. Nutritional status can also be determined by:
- Comparing a patient's weight to standardized charts
- Calculating body mass index (BMI) according to a formula that divides height into weight
- Measuring skinfold thickness or the circumference of the upper arm.
Normalizing nutritional status starts with a nutritional assessment. This process enables a clinical nutritionist or registered dietician to confirm the presence of malnutrition, assess the effects of the disorder, and formulate diets that will restore adequate nutrition.
Patients who cannot or will not eat, or who are unable to absorb nutrients taken by mouth, may be fed intravenously (parenteral nutrition) or through a tube inserted into the gastrointestinal (GI) tract (enteral nutrition).
Tube feeding is often used to provide nutrients to patients who have suffered burns or who have inflammatory bowel disease. This procedure involves inserting a thin tube through the nose and carefully guiding it along the throat until it reaches the stomach or small intestine. If long-term tube feeding is necessary, the tube may be placed directly into the stomach or small intestine through an incision in the abdomen.
Tube feeding cannot always deliver adequate nutrients to patients who:
- Are severely malnourished
- Require surgery
- Are undergoing chemotherapy or radiation treatments
- Have been seriously burned
- Have persistent diarrhea or vomiting
- Whose gastrointestinal tract is paralyzed.
Intravenous feeding can supply some or all of the nutrients these patients need.
Up to 10% of a person's body weight can be lost without side effects, but if more than 40% is lost, the situation is almost always fatal. Death usually results from heart failure, electrolyte imbalance, or low body temperature. Patients with semiconsciousness, persistent diarrhea, jaundice, or low blood sodium levels have a poorer prognosis.
Some children with protein-energy malnutrition recover completely. Others have many health problems throughout life, including mental retardation and the inability to absorb nutrients through the intestinal tract. Prognosis for all patients with malnutrition seems to be dependent on the age of the patient, and the length and severity of the malnutrition, with young children and the elderly having the highest rate of long-term complications and death.
Breastfeeding a baby for at least six months is considered the best way to prevent early-childhood malnutrition. The United States Department of Agriculture and Health and Human Service recommend that all Americans over the age of two:
- Consume plenty of fruits, grains, and vegetables
- Eat a variety of foods that are low in fats and cholesterols and contain only moderate amounts of salt, sugars, and sodium
- Engage in moderate physical activity for at least 30 minutes, at least several times a week
- Achieve or maintain their ideal weight
- Use alcohol sparingly or avoid it altogether.
Every patient admitted to a hospital should be screened for the presence of illnesses and conditions that could lead to protein-energy malnutrition. Patients with higher-than-average risk for malnutrition should be more closely assessed and reevaluated often during long-term hospitalization or nursing-home care.
- Not enough red blood cells in the blood.
- Anorexia nervosa
- Eating disorder marked by malnutrition and weight loss commonly occurring in young women.
- Pertaining to the study, prevention, or treatment of overweight.
- A unit of heat measurement used in nutrition to measure the energy value of foods. A calorie is the amount of heat energy needed to raise the temperature of 1 kilogram of water 1°C.
- Severe malnutritution in children primarily caused by a protein-poor diet, characterized by growth retardation.
- Severe malnutritution in children caused by a diet lacking in calories as well as protein. Marasmus may also be caused by disease and parasitic infection.
- Essential dietary elements that are needed only in very small quantities. Micronutrients are also known as trace elements. They include copper, zinc, selenium, iodine, magnesium, iron, cobalt, and chromium.
For Your Information
- Beers, Mark H., MD, and Robert Berkow, MD, editors. "Malnutrition." Section 1, Chapter 2. In The Merck Manual of Diagnosis and Therapy.Whitehouse Station, NJ: Merck Research Laboratories, 2004.
- Flancbaum, Louis, MD, with Erica Manfred and Deborah Biskin. The Doctor's Guide to Weight Loss Surgery. West Hurley, NY: Fredonia Communications, 2001.
- Alvarez-Leite, J. I. "Nutrient Deficiencies Secondary to Bariatric Surgery." Current Opinion in Clinical Nutrition and Metabolic Care 7 (September 2004): 569-575.
- Amella, E. J. "Feeding and Hydration Issues for Older Adults with Dementia." Nursing Clinics of North America 39 (September 2004): 607-623.
- Bryan, J., S. Osendorp, D. Hughes, et al. "Nutrients for Cognitive Development in School-Aged Children." Nutrition Reviews 62 (August 2004): 295-306.
- Grigsby, Donna G., MD. "Malnutrition." eMedicine December 18, 2003.
- Gums, J. G. "Magnesium in Cardiovascular and Other Disorders." American Journal of Health-System Pharmacy 61 (August 1, 2004): 1569-1576.
- Halsted, G. H. "Nutrition and Alcoholic Liver Disease." Seminars in Liver Disease 24 (August 2004): 289-304.
- Reid, C. L. "Nutritional Requirements of Surgical and Critically-Ill Patients: Do We Really Know What They Need?" Proceedings of the Nutrition Society 63 (August 2004): 467-472.
- American College of Nutrition. 722 Robert E. Lee Drive, Wilmington, NC 20412-0927. (919) 452-1222.
- American Institute of Nutrition. 9650 Rockville Pike, Bethesda, MD 20814-3990. (301) 530-7050.
- Food and Nutrition Information Center. 10301 Baltimore Boulevard, Room 304, Beltsville, MD 20705-2351.
- World Health Organization (WHO) Nutrition web site.