MALNUTRITION. Malnutrition results from the chronic dietary intake of nutrients or energy that provides considerably less or more than is required to be considered adequate or appropriate to support the everyday needs of the human body. Such adverse nutrient intakes are detrimental to human health and may lead to a state of deficiency, dependency, toxicity, or obesity. Malnutrition includes undernutrition, which means the body is not receiving nearly enough nutrients, and overnutrition, which means the intake of nutrients is grossly excessive.

Undernutrition

Undernutrition continues to be a significant cause of malnutrition in developing countries, although it is relatively rare in developed countries. Poverty in developing countries contributes more to undernutrition than a lack of global food production and is considered the chief cause of malnutrition. Families that are poor do not have the economic, social, or environmental resources to purchase or produce enough food. Poor soil conditions may also contribute to a family's inability to grow enough food to prevent malnutrition and the accompanying complications to health. Additionally, for the urban poor, low wages, underemployment, and food prices beyond the reach of families also contribute to undernutrition.

Prolonged dietary intakes deficient in energy or calories, protein, fat, vitamins, and minerals lead to illness and eventually death if not corrected. Undernutrition may also be the result of psychological disorders, such as anorexia nervosa, which manifests as an unwillingness to eat enough food to sustain life. Elderly adults often have a decrease both in appetite and intestinal function and are at an increased risk for undernutrition. Children, particularly infants and those under five years of age are also at an increased risk for undernutrition due to a greater need for energy and nutrients during periods of rapid growth and development. Infants born to undernourished mothers are more likely to be low birth weight infants. Addiction to alcohol or drugs may also lead to undernutrition when the addicted individuals favor alcohol and/or drug intake over adequate food intake. Severe, prolonged diarrhea, renal failure, infection, or diseases that cause the malabsorption of nutrients in the small intestine also may cause undernutrition even if dietary intake is adequate. It is obvious that the causes of undernutrition are varied and complex, requiring solutions that may also be complex.

Nutrients Required to Prevent Undernutrition

The nutrients required in adequate amounts by the body to prevent undernutrition are carbohydrates, fat or lipids, protein, vitamins, minerals, and water. Carbohydrates provide the body with energy (about 4 kilocalories per gram of carbohydrate consumed). Carbohydrates also protect protein stores in the body. A minimal intake of 50 to 100 grams (1.8 to 3.5 oz.) of carbohydrates is required to prevent the development of ketones that the brain can use somewhat inefficiently for energy. The brain optimally uses carbohydrate for energy, but when carbohydrate intake is inadequate for several weeks, the body does not metabolize fatty acids completely in order to produce ketones for energy. In addition to ketone formation resulting from insufficient carbohydrate consumption, body protein will also be lost, and the body will generally become weakened.

Fats or lipids provide essential fatty acids upon metabolism following consumption. Essential fatty acids are obtained from dietary lipids and are termed essential because the human body cannot synthesize them. Essential fatty acids are important for human health because they participate in immune processes, vision, are an integral part of cell structures, and participate in hormone-like compound production. If an inadequate intake of lipids is routinely consumed, the body becomes deficient in essential fatty acids. This results in skin problems, diarrhea, and an increase in infections with a corresponding decrease in the ability of the body to heal wounds. Lipids also provide energy for the body (about 9 kilocalories per gram (28 kilocalories per ounce of fat consumed), can be stored for future use as energy, insulate the body and protect body organs, and aid in the absorption and transport of fat-soluble vitamins (vitamins A, D, E, and K) throughout the body. The fat-soluble vitamins are important for vision (vitamin A), bone metabolism (vitamin D), providing antioxidant protection from free radicals (vitamin E), and blood coagulation (vitamin K), among other functions.

Protein is a very important nutrient because so many substances in the body are made from it. Proteins are made when amino acids are combined in specific sequences to form specific proteins. The sequence of the amino acids determines the shape of the protein, and the shape of the protein, in turn, determines the function of the protein. Amino acids can be obtained from plant or animal sources. There are nine essential amino acids: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. The human body is not able to synthesize these amino acids, so they must be derived from the foods we eat. There are eleven nonessential amino acids that the human body is able to make: alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine. As stated previously, amino acids are necessary for protein synthesis, but they are also important because they provide the body with a special form of nitrogen that the body cannot get from carbohydrates or lipids. Protein, like carbohydrate, provides approximately 4 kilocalories per gram of protein consumed, but requires much more metabolizing and processing by the liver and kidneys to put the energy from protein to use. Protein is a part of every cell in the human body. Blood proteins enable the body to maintain the right balance of fluid inside and outside of cells. When adequate protein is not consumed, there is a lower concentration of blood proteins in the bloodstream, which causes the balance of fluids inside and outside of cells in tissues to be thrown off, resulting in swelling of tissues or edema, which can lead to serious medical problems. Proteins also help regulate the pH, or acid-base balance, in the blood, are necessary for the synthesis of many hormones and enzymes, and participate in important cell formation for cells vital for the immune system. Amino acids from protein can also be used to produce glucose, which is a positive thing for providing glucose after an overnight fast. But in the case of starvation, excessive muscle tissue is wasted and results in diminished health. Protein-energy malnutrition results from near starvation and may be seen in the body tissues in either a wet, dry, or combined form. The dry form, marasmus, is caused by deficiency of protein and nonprotein nutrients, with the individual being very thin from the loss of muscle and body fat. The wet form, kwashiorkor, is caused primarily by protein deficiency, with energy deficiency being secondary, and is accompanied by edema. The combined form, marasmic kwashiorkor, results from protein and energy deficiency with edema and more body fat than is seen in marasmus.

There are also water-soluble vitamins in addition to the fat-soluble vitamins. Because water-soluble vitamins are not stored in any appreciable amounts in the body, but are excreted readily in urine, it is relatively easy to become depleted of them. Fat-soluble, in contrast, are stored in adipose tissue and the liver, and consequently it is more difficult to become deficient of them. The water-soluble vitamins are the B vitamins and vitamin C. The B vitamins are thiamin, riboflavin, niacin, pantothenic acid, biotin, pyridoxine, folate, and vitamin B₁₂. All of the water-soluble vitamins except vitamin C have coenzyme functions and are involved in a variety of reactions including energy metabolism, DNA synthesis, nerve function, protein and carbohydrate metabolism, and fat synthesis. Vitamin C is involved in protecting the body from oxidative damage caused by substances called free radicals. It also functions in connective tissue synthesis, hormone synthesis, and neurotransmitter synthesis. Physiological consequences of deficiency include inflammation of the mouth and tongue (riboflavin deficiency); diarrhea, dermatitis (niacin deficiency); edema, weakness (thiamin deficiency); tongue soreness, anemia (biotin deficiency); fatigue, tingling in hands (pantothenic acid deficiency); poor growth, inflammation of the tongue (folate deficiency); poor nerve function, macrocytic anemia (vitamin B₁₂ deficiency); and poor wound healing, bleeding gums (vitamin C deficiency).

Minerals are important nutrients that must be obtained from foods consumed, as the human body is unable to synthesize them. Some factors that influence mineral bioavailability (the extent to which minerals in food consumed is available for the body to put to use) are the amount of mineral content in the soil in which the food providing the mineral was grown; dietary fiber consumed in the same meal as a food containing the minerals; mineral-mineral interactions; and vitamin-mineral interactions. Sodium, potassium, chloride, calcium, phosphorus, magnesium, and sulfur are the major minerals. Deficiencies of these minerals lead to such symptoms as muscle cramps (sodium), irregular heartbeat (potassium), convulsions in infants (chloride), an increased risk for osteoporosis (calcium), diminished bone support (phosphorus), and poor heart function (magnesium). There are also so-called trace minerals that are only required in very small amounts to contribute to optimal health. These trace minerals are iron, zinc, selenium, iodide, copper, fluoride, chromium, manganese, and molybdenum. When inadequate amounts of foods containing the trace minerals are consumed, symptoms begin to appear. These symptoms include low blood iron (iron), skin rash/poor growth and development (zinc), muscle weakness (selenium), goiter (iodide), anemia/poor growth (copper), increased risk for dental cavities (fluoride), and high blood glucose after eating (chromium).

Developed countries typically have water supplies that are monitored for safety by government agencies and are provided in large enough quantities that a lack of drinking water is not the norm. Developing countries, however, may not have water that is free from contamination, or because of drought or other natural disasters do not have a large enough water supply for human consumption or to provide water for livestock or crops. Water is vital for life and, without it, an adult can survive only a few days because the human body does not have the ability to store water. Water is found inside of cells as intracellular fluid and outside of cells as extracellular fluid. A proper balance between intracellular and extracellular water is necessary to prevent complications such as edema. Water also is responsible for regulating body temperature, most notably through the cooling-off process accomplished by perspiration. Water is necessary to provide lubrication for joints such as the knees. Without adequate water in the form of amniotic fluid in the womb of a pregnant woman, the growing fetus does not have sufficient support to prevent injury should the mother fall or be otherwise jarred abruptly. Water is also the primary avenue utilized by the body to rid itself of waste products. While water does not supply energy as carbohydrates, protein, and fats are able to do, it is still a very important nutrient necessary to prevent malnutrition.

Overnutrition

Overnutrition results when energy expenditure is grossly exceeded by energy intake and leads to overweight and obesity. Developed countries, with their abundant food supplies and processed foods, are most afflicted with overnutrition and the medical complications associated with it. Due to the excessive intake of food products, the amount of fat-soluble vitamins and minerals in the body can rise to toxic levels because they are stored in the body. Developed countries have greater incidences of cardiovascular disease, blood lipids, diabetes mellitus, hypertension, respiratory problems, gallbladder disease, arthritis, and cancer, all of which are connected to complications stemming directly from overnutrition.

Methods of Evaluating Malnutrition

Malnutrition is diagnosed based on the findings of a medical and diet history, physical examination, and laboratory tests. The results are then compared with norms of weight for height, body mass index (body weight in kilograms divided by height in meters squared), dietary intake, physical findings, and plasma levels of nutrients and nutrient-dependent substances such as hemoglobin. The physical examination would necessarily include anthropometric measurements, as well as close examination of the skin, hair, and mouth for symptoms of malnutrition. For example, depigmentation of the hair is indicative of undernutrition, and a body weight that is 20 percent above the average desirable body weight as determined by insurance company standardized charts would indicate overnutrition. A triceps skinfold test may be utilized to determine the body's energy stores. Laboratory tests are used to reveal the extent to which amino acid nutrition is meeting the body's needs to determine undernutrition, or plasma lipids in the diagnosis of overnutrition. In the field when assessing nutritional status, the medical and diet history and physical examination may be the only tools accessible to the physician or nurse, particularly in developing countries.

Who is at Increased Risk for Malnutrition?

The risk for malnutrition is increased for a variety of reasons. Increased nutritional needs during growth, pregnancy, lactation, old age, infection, certain cancer therapies, or immune deficiency disorders increase the risk of malnutrition. Diets that focus on a narrow range of foods may not provide the variety of nutrients required and lead to deficiencies. Those experiencing famine, with the accompanying reduction in available food, are at great risk for malnutrition in the form of undernutrition. Lack of money to purchase an adequate diet or cultural practices that dictate which members in the family get a large or small amount of food may also lead to malnutrition. Any medical condition that effects the absorption of nutrients from foods, or requires medication that has adverse consequences on appetite, may cause malnutrition if the condition is long term. Taking megadoses of vitamin/mineral supplements may result in toxic levels of the substances taken in the body with the outcome being a state of overnutrition.

Correcting Malnutrition in the United States

Since the Great Depression of the 1930s, the federal government of the United States has undertaken the task of alleviating and/or preventing malnutrition. In the 1960s, President John F. Kennedy reestablished the federal government's efforts to end debilitating hunger. Individuals and families who have low incomes may take advantage of several federally sponsored programs to ensure a better quality of nutrient intake. Food stamps are available to those who are usually employed but having difficulty purchasing an adequate food supply by using coupons to purchase food from grocery stores. The Commodity Supplemental Food Program distributes U. S. Department of Agriculture surplus foods through county agencies to such low-income populations as pregnant women and families with young children. The School Lunch and Breakfast Programs offer free or reduced-priced meals based on the Food Guide Pyramid to children of low-income families, with the cost of the reduced-priced meals being based on family income. The Summer Food Service Program offers free, nutritious meals and snacks to low-income children and distributes the meals from a central location during lower and secondary school vacations. There are also programs targeted specifically at different age groups. Preschool children enrolled in organized child-care programs receive meals at no cost, and the child-care program receives reimbursement for the meals through participation in the Child-Care Food Program. For individuals 60 years or older, a free noon meal is provided at centralized sites as part of the Congregate Meals for the Elderly Program. Homebound individuals over 60 years of age can take advantage of home-delivered meals at no cost or for a fee, depending on income, at least five days per week.

World Hunger: Addressing a Global Problem

In 1798 the English clergyman and political economist Thomas Malthus suggested that the world's population was growing at a rate faster than the food supply. The year 2002 finds world population growth exceeding economic growth, and poverty on the rise. Globally less than one-half of 1 percent of the world's yearly production of goods and services goes exclusively to economic development assistance, yet 6 percent goes to support the world's military operations. Civil wars in some countries have substantially retarded progress of the poor and continue to contribute to massive undernutrition. Environmental factors such as soil erosion or lack of fresh water for irrigation of crops exacerbate the problem of providing sufficient quantities of foods for many countries. What is being done to overcome all of these detriments to feeding the world's hungry? Since the 1960s, an American program, the Peace Corps, has been instrumental in providing education, distributing food and medical supplies, and building structures for locals to use in developing nations. National surveys such as the National Family Health Survey conducted in India are valuable tools in the determination of whether any progress is being made to improve the nutritional status of the nation. Advances in biotechnology to genetically alter plants and animals to improve the nutritive quality of the foods produced from them may help to meet increasing food needs both now and in the future. The United Nations and the World Health Organization cry out for governments in developed countries to facilitate greater strides in improvements in malnutrition in undeveloped countries by financial, educational, and scientific interventions. What will be required to eradicate malnutrition in this world is a coming together of the leaders of rich and poor nations to the same degree. Globally, there is an adequate food supply and the technical expertise necessary to address the problems and complications of malnutrition. All that is lacking is the political cooperation to address this devastating situation.

See also Anorexia, Bulimia; Aversion to Food; Body Composition; Caloric Intake; Disease: Metabolic Diseases; Eating: Anatomy and Physiology of Eating; Fasting and Abstinence; Fluoride; Food Politics: United States; Hunger, Physiology of.

Rebecca J. (Bryant) McMillian