Infants and children are at particular risk for under nutrition because they need a greater amount of calories and nutrients for growth and development. They may develop deficiencies in iron, folic acid, vitamin C, and copper from inadequate diets. Insufficient intake of protein, calories, and other nutrients can lead to protein-energy malnutrition, a particularly severe form of under nutrition that retards growth and development.
A bleeding tendency in newborns (hemorrhagic disease of the newborn) caused by a deficiency of vitamin K can be life threatening. As children approach adolescence, their nutritional requirements increase because their growth rate increases.
A woman who is pregnant or breastfeeding has an increased need for all nutrients to prevent malnutrition in herself and her baby. Folic acid supplements are recommended during pregnancy to reduce the risk of brain or spinal defects (spina bifida) in the baby. Although women who have taken oral contraceptives are more likely to develop folic acid deficiency, there is no proof that the fetus will be deficient. The baby of an alcoholic woman may be physically and mentally impaired by fetal alcohol syndrome, because alcohol abuse and the resulting malnutrition affect fetal development. An infant who is breastfed exclusively can develop vitamin B12 deficiency if the mother is a vegetarian who eats no animal products (a vegan).
Elderly people may become malnourished because of loneliness, physical and mental handicaps, immobility, or chronic illness. In addition, their ability to absorb nutrients is reduced, possibly contributing to such problems as iron deficiency anemia, osteoporosis, and osteomalacia.
Aging is accompanied by a progressive loss of muscle that’s unrelated to any disease or dietary deficiency. This loss averages about 22 pounds for men and 11 pounds for women. It accounts for the slowdown that occurs in metabolism, the decrease in total body weight, and the increase in body fat from about 20 to 30 percent in men and 27 to 40 percent in women. Because of these changes and a reduction in physical activity, older people need fewer calories and less protein than younger people do.
Who Is at Risk for Over nutrition?
• Children and adults who have good appetites but don’t exercise
• People who are more than 20 percent overweight
• People on high-fat, high-salt diets
• People who take high doses of nicotinic acid (niacin) for hypercholesterolemia
• Women who take high doses of vitamin B6 (pyridoxine) for premenstrual syndrome
• People who take high doses of vitamin A for skin disorders
• People who take high doses of iron or other trace minerals without a prescription
People who have a chronic disease that causes malabsorption tend to have trouble absorbing fat-soluble vitamins (A, D, E, and K), vitamin B12, calcium, and iron. Liver disease impairs the storage of vitamins A and B12 and interferes with the metabolism of protein and glucose, a type of sugar. People, who have kidney disease, including those on dialysis, are prone to deficiencies of protein, iron, and vitamin D.
Most vegetarians are ovo-lacto vegetarians: They don’t eat meat and fish, but they do eat eggs and dairy products. Iron deficiency is the only risk from such a diet. Ova-lacto vegetarians tend to live longer and develop fewer chronic disabling conditions than people who eat meat. However, their better health may also be a result of their abstention from alcohol and tobacco and their tendency to exercise regularly. Vegetarians who consume no animal products (vegans) are at risk of developing deficiencies of vitamin B12. Oriental-style and other fermented foods, such as fish sauce, can provide vitamin B12.
Many fad diets claim to enhance well-being or reduce weight. However, highly restrictive diets are nutritionally unsound: these diets have resulted in deficiencies of vitamins, minerals, and proteins; in disorders affecting the heart, kidneys, and metabolism; and even in some deaths. Very low calorie diets (fewer than 400 calories a day) can’t sustain health for long.
Addiction to alcohol or drugs can disrupt a person’s lifestyle to the point that adequate nourishment is neglected and the absorption and metabolism of nutrients are impaired.
Alcoholism is the most common form of drug addiction, with serious effects on nutritional status. Consumed in large amounts, alcohol is a poison that damages tissue, particularly in the gastrointestinal tract, liver, pancreas, and nervous system (including the brain). People who drink beer and continue to consume food may gain weight, but people who consume a fifth of hard liquor daily tend to lose weight and become undernourished. Alcoholism is the most common cause of vitamin B1 (thiamine) deficiency in the United States and may also lead to deficiencies of magnesium, zinc, and other vitamins.