|Disease (and key nutrient involved)||Symptoms||Foods rich in key nutrient|
|xerophthalmia (vitamin A)||blindness from chronic eye infections, poor growth, dryness and keratinization of epithelial tissues||liver, fortified milk, sweet potatoes, spinach, greens, carrots, cantaloupe, apricots|
|rickets (vitamin D)||weakened bones, bowed legs, other bone deformities||fortified milk, fish oils, sun exposure|
|beriberi (thiamin)||nerve degeneration, altered muscle coordination, cardiovascular problems||pork, whole and enriched grains, dried beans, sunflower seeds|
|pellagra (niacin)||diarrhea, skin inflammation, dementia||mushrooms, bran, tuna, chicken, beef, peanuts, whole and enriched grains|
|scurvy (vitamin C)||delayed wound healing, internal bleeding, abnormal formation of bones and teeth||citrus fruits, strawberries, broccoli|
|iron-deficiency anemia (iron)||decreased work output, reduced growth, increased health risk in pregnancy||meat, spinach, seafood, broccoli, peas, bran, whole-grain and enriched breads|
|goitre (iodine)||enlarged thyroid gland, poor growth in infancy and childhood, possible mental retardation, cretinism||iodized salt, saltwater fish|
Chronic undernutrition manifests primarily as protein-energy malnutrition (PEM), which is the most common form of malnutrition worldwide. Also known as protein-calorie malnutrition, PEM is a continuum in which people—all too often children—consume too little protein, energy, or both. At one end of the continuum is kwashiorkor, characterized by a severe protein deficiency, and at the other is marasmus, an absolute food deprivation with grossly inadequate amounts of both energy and protein.
An infant with marasmus is extremely underweight and has lost most or all subcutaneous fat. The body has a “skin and bones” appearance, and the child is profoundly weak and highly susceptible to infections. The cause is a diet very low in calories from all sources (including protein), often from early weaning to a bottled formula prepared with unsafe water and diluted because of poverty. Poor hygiene and continued depletion lead to a vicious cycle of gastroenteritis and deterioration of the lining of the gastrointestinal tract, which interferes with absorption of nutrients from the little food available and further reduces resistance to infection. If untreated, marasmus may result in death due to starvation or heart failure.
Kwashiorkor is typically seen when a child is weaned from high-protein breast milk onto a carbohydrate food source with insufficient protein. Children with this disease, which is characterized by a swollen belly due to edema (fluid retention), are weak, grow poorly, and are more susceptible to infectious diseases, which may result in fatal diarrhea. Other symptoms of kwashiorkor include apathy, hair discoloration, and dry, peeling skin with sores that fail to heal. Weight loss may be disguised because of the presence of edema, enlarged fatty liver, and intestinal parasites; moreover, there may be little wasting of muscle and body fat.