Over-nutrition, under-nutrition and other forms of out-of-balance nutrient intake, or malnutrition, can all adversely affect your health. Severe deficiency, excess and unbalanced nutrient intake each can upset your body's equilibrium and its ability to grow and flourish, but in different ways. Under-nutrition stunts growth, while over-nutrition may lead to chronic illness. A deficit or excess of specific vitamins, minerals and nutrients, such as vitamin A, iron and protein, can foster nutrient-related diseases and conditions.
Under-nutrition implies a deficiency of energy or nutrients. Malnutrition represents an imbalance, either a deficiency or an excess, in your intake of nutrients and other elements needed for health. Under-nutrition, therefore, is one form of malnutrition.
Malnutrition may manifest as hunger, a deficiency of vitamins and minerals or overfeeding. Half of the world’s 3 billion people suffer from malnutrition, as reported by the Nutrition Ecology International Center. One in five people in the developing world suffers from hunger. More than half of adults in the United States are classified as overweight or obese, as defined by a body mass index, BMI, of 25 or greater, according to Eleanor Whitney, Ph.D. and Sharon Rolfes, M.S., R.D., in the book “Understanding Nutrition.” Overweight, linked to over-nutrition, increases your risk of chronic diseases such as cardiovascular disease, diabetes and some cancers.
Specific out-of-balance nutrients also contribute to malnutrition. Too little vitamin A causes blindness; too much damages your cells. Too little iron results in anemia; too much can cause poisoning or death. Too little protein can devastate your health, and overconsumption of protein also may pose health risks.
Protein-energy under-nutrition (PEU), formerly called protein-energy malnutrition (PEM), results when people are deprived of protein, energy or both. It strikes early in childhood and is the most prevalent, devastating form of malnutrition in the world. PEU affects 500 million children in the world. Inadequate food intake results in poor growth in children and weight loss and wasting in adults. Whitney and Rolfes describe two distinct forms of PEU, marasmus and kwashiorkor.
Marasmus involves severe deprivation of food over a long period. Caused by inadequate energy, protein, vitamins and minerals, marasmus results in extreme loss of muscle and fat and gives marasmic children the appearance of having just skin and bones. Without sufficient nutrition, even your heart muscle wastes away and brain development and function falter.
Kwashiorkor, another form of PEU, results from a sudden and recent deprivation of food. In contrast to emaciated marasmic children, children with kwashiorkor typically display a swollen abdomen. Their enlarged liver and loss of fluid balance allows fluids to leak into spaces between cells and give the appearance of a swollen belly on a frame that displays some muscle wasting with swelling in the limbs and face. Loss of hair color; patchy, scaly skin; infectious disease; and sores slow to heal are other kwashiorkor symptoms.
- “Understanding Nutrition, Ninth Edition”; Eleanor Whitney, Ph.D. and Sharon Rolfes, M.S., R.D.; 2002
- Nutrition Ecology International Center: Undernutrition and Malnutrition in the World
- "The Merck Manual for Health Care Professionals": Protein-Energy Undernutrition