Carbohydrates

Carbohydrates include the familiar sugars and starches that compose approximately half of the standard American diet. A ready source of energy for the body, carbohydrates are usually divided into two categories: simple and complex. Simple carbohydrates are used most readily by the body because their bonds are easily broken. Table sugar, honey, syrup, and candy are examples of simple carbohydrates. Complex carbohydrates must be broken down into simple sugars before they can be used by the body. This breakdown requires time and energy. Foods such as vegetables, whole grains, and fruits contain complex carbohydrates. Foods that contain complex carbohydrates usually also contain other nutrients (e.g., minerals and vitamins), making them more nutritious than foods containing simple carbohydrates only. The American Heart Association recommends that 55% to 60% of calories should come from carbohydrates, with an emphasis on complex carbohydrates. This recommendation appears to be appropriate for the aging population.

In addition to providing essential nutrients, complex carbohydrates usually contain significant amounts of soluble fiber, a substance humans cannot digest, which forms bulk and aids bowel elimination. Fiber is recommended as helpful in preventing constipation, diverticulosis, and diverticulitis. A diet high in complex carbohydrates is recommended as part of the control of many disease processes. The soluble fiber in complex carbohydrates has been shown to reduce blood cholesterol levels, which is helpful for individuals who are at risk for coronary artery disease. Complex carbohydrates also play an important role in the control of diabetes, because they effectively meet energy needs without causing rapid increases in blood glucose levels the way simple sugars do.

Proteins

Tissue replacement and repair continue throughout life. Any condition in which tissue integrity is altered (e.g., surgery and pressure ulcers) increases the amount of protein needed to aid in tissue repair. Red meats, poultry, fish, eggs, and dairy products are good sources of complete proteins, which contain all of the amino acids necessary for making and repairing tissues. Plant foods such as legumes (peas and beans), nuts, and cereals (whole grains and rice) contain smaller amounts of incomplete proteins, which do not individually contain all of the necessary amino acids. Incomplete proteins must be combined carefully to meet protein needs.

Some foods that are high in protein such as steak, ham, organ meats, egg yolks, hard cheese, and whole milk also contain large amounts of fats. Excessive consumption of proteins with a high fat content can contribute to elevated blood levels of cholesterol and triglycerides, which, in turn, contribute to plaque formation and atherosclerotic changes in the blood vessels. Atherosclerosis often results in hypertension and heart disease. For this reason, many physicians and dietitians recommend that high-fat protein foods be restricted. A person who is on a fat-restricted diet should consume low-fat proteins such as fish and lean poultry, as well as protein from plant sources such as peas and beans.

Fats

It is recommended that fats be limited to approximately 25% to 30% of the total daily caloric intake. This recommendation does not change with aging. A certain amount of fat is necessary and desirable in the diet to aid in the absorption of fat-soluble vitamins and to provide adequate amounts of essential fatty acids. Fat is desirable because it adds flavor to food and provides a sense of fullness with a meal. Foods with no fat would be unappealing, poor tasting, and not very satisfying.

When considering fat intake in the diet, it is important to watch the type of fats ingested. The body incorporates fats into substances called lipoproteins, which contain cholesterol and proteins. There are three important types of lipoproteins: high-density lipoprotein (HDL), low-density lipoprotein (LDL), and very-low-density lipoprotein (VLDL). LDL is primarily composed of cholesterol and is believed to contribute to blood vessel disease. VLDL is primarily composed of triglycerides and may contribute to vessel disease but not as significantly as does LDL. HDL, the so-called healthy fat, is primarily composed of protein that appears to protect against blood vessel disease.

Some individuals who have been eating high-cholesterol foods for their entire lives may be reluctant to change their eating habits as they age. They may find it difficult or unpleasant to shop for and prepare foods in new ways. Others can successfully alter their dietary intake to avoid foods high in these substances.

Vitamins

The benefits of vitamins for older adults are being closely examined. Some researchers who subscribe to the free radical theory of aging are studying the effects of the so-called antioxidant vitamins. It is theorized that antioxidant vitamins can block or neutralize free radicals and prevent cell damage, thereby slowing the effects of aging and preventing a number of diseases such as cancer and heart disease. Although research into this area is promising, many experts are not yet convinced of the effectiveness of antioxidant vitamins or satisfied that we have an adequate understanding of their method of action, therapeutic dosage, and long-term effects. Vitamins A, C, and E are considered antioxidants.

Older adults who consume well-balanced diets may not require supplemental vitamins. Those with increased risk factors such as gastrointestinal (GI) problems or inadequate nutritional intake may benefit from selected vitamin supplements. Supplements should be used with caution and under the direction of a physician or dietitian. Excess amounts of the water-soluble vitamins are quickly eliminated from the body and pose few risks. Excess amounts of the fat-soluble vitamins (A, D, E, and K) are retained in fatty tissue or stored in the liver. Overconsumption of these vitamins can lead to toxic symptoms and even permanent liver damage.

Minerals

Minerals are inorganic chemical elements that are required in many of the body’s functions. Minerals make up a small proportion of total body weight, yet a slight mineral imbalance can have serious effects.

Calcium, the most abundant mineral in the body, is necessary for bone and tooth formation, nerve impulse transmission and conduction, muscle contraction (including cardiac function), and blood clotting. The main dietary sources of calcium are milk and dairy products. Calcium is normally retained in bone, with only a small amount (1%) found in the tissues and blood. With aging and with immobility, the bones tend to lose calcium, resulting in osteoporosis. In certain disease states, abnormal amounts of calcium leave the bone, enter the bloodstream, and cause hypercalcemia, which is an elevated level of calcium in the blood. Hypercalcemia is seen with hyperparathyroidism, disuse atrophy, metastatic bone tumors, and vitamin D excess.

Individuals experiencing hypercalcemia may manifest symptoms, including confusion, abdominal pain, muscle pain, weakness, and anorexia. These symptoms may be easily missed in older individuals because they are vague and common to many other conditions. Extremely high levels of calcium in the blood can result in shock, kidney failure, and even death. When the kidneys attempt to rid the body of excess calcium, hypercalciuria (increased calcium in the urine) results, and the risk for renal calculi (kidney stone) formation is increased.

Adequate calcium intake is important throughout life, but it is particularly important for those at risk for developing osteoporosis, especially postmenopausal women. Calcium may arrest the progress of osteoporosis. Vitamin D aids in the absorption of calcium. For this reason, vitamin D is added to milk products and fortified margarine.

Phosphorus is needed for normal bone and tooth formation, activation of some B vitamins, normal neuromuscular functioning, metabolism of carbohydrates, regulation of acid-base balance, and other physiologic processes. Inadequate nutritional intake of phosphorus can result in weight loss or anemia. The typical dietary sources of phosphorous compounds are dairy products, meat, egg yolks, peas, beans, nuts, and whole grains. Because of its wide availability, meeting the dietary requirements of this mineral normally is not a problem unless the individual is on a highly restricted diet.

Iron-deficiency anemia results from inadequate intake of dietary iron. Rich sources of dietary iron include red meat, particularly organ meats such as liver; shellfish; egg yolks; leafy green vegetables; and dried fruits. Red meat is expensive and, unless properly prepared, can be difficult for older adults to chew. Many people do not like the taste of liver and organ meats and refuse to eat them. In addition, organ meats and egg yolks are high in cholesterol, which is often restricted from the diet. This can make meal planning difficult. In addition to increased nutritional intake of iron rich foods, folic acid and iron supplements are commonly prescribed.

It should be remembered that a concentrated iron formulation (liquid or solid) administered orally can irritate the GI tract. To reduce GI irritation, iron supplements should be taken during or after meals. Iron solutions can stain the teeth, so a straw should be used with liquid iron preparations. If iron is given by injection, it is important to use the Z-track method for deep intramuscular administration. Foods rich in vitamin C should be given in conjunction with iron to enhance its absorption. Patients should be told that iron will probably turn the stool a dark green or black color, and nurses should keep this in mind when assessing the stool of individuals receiving iron supplements. Concentrated iron supplements can also cause diarrhea.

Pernicious anemia is caused by a deficiency in intrinsic factor secreted by the stomach. Without this factor, vitamin B₁₂, which is required for red blood cell maturation in the bone marrow, is not absorbed. In addition, there are fewer white blood cells and there may be cellular changes in the existing cells. Individuals suffering from pernicious anemia may manifest weakness, numbness, or tingling in the extremities; anorexia; or weight loss. Treatment typically consists of cyanocobalamin injections and possibly oral folic acid and iron supplements.

Sodium is a commonly occurring mineral and is one of the important elements in the body. Sodium ions are involved in acid-base balance, fluid balance, nerve impulse transmission, and muscle contraction. Sodium is mostly found in extracellular fluid. Sodium levels are regulated by the kidneys, which retain or eliminate sodium according to the body’s needs. Sodium interacts with potassium as part of the fluid exchange through cell membranes. Sodium is naturally present in many foods. The most common, most familiar concentrated form is sodium chloride, or table salt, which is used to flavor and preserve food. The typical American diet tends to be higher in sodium than is nutritionally required. Prepared foods such as canned soups or vegetables and frozen dinners are common in the diet of many older adults. In addition, older adults may use excessive amounts of salt to compensate for the decreased ability to perceive the taste of foods. Excessive blood levels of sodium, or hypernatremia, can cause fluid retention, which in body tissue is manifested as edema. People with hypertension, renal failure, or cardiac conditions are often placed on sodium-restricted diets, and many (especially older adults) report that food is less appetizing when prepared with reduced amounts of sodium. With less appetite, these individuals may eat less.

Potassium is the major intracellular ion in the body. Potassium ions play an important role in acid-base balance, fluid and electrolyte balance, and (with sodium) normal neuromuscular functioning. Potassium is not as abundant in the diets of older adults as are some of the other minerals. Dietary sources of potassium include citrus fruits, milk, bananas, and apple juice. Potassium deficiency, or hypokalemia, is a common problem in older adults. Many diuretic and antihypertensive medications deplete the body of potassium, as can prolonged or frequent diarrhea. Symptoms of hypokalemia include muscle weakness, anorexia, apprehension, irritability, drowsiness, depression, and disorientation. Severe muscle weakness is the most common observation related to decreased potassium levels. Hypokalemia with digitalis therapy is often a cause of cardiac arrhythmias. Because not all patients who have decreased levels of potassium demonstrate observable symptoms, nurses must check laboratory studies to verify levels of the electrolytes. Supplements are often prescribed to increase low blood potassium levels.

Zinc is a trace mineral that plays a role in protein synthesis. In adults, insufficient zinc may result in delayed wound healing, impaired immune function, lethargy, skin changes, diminished sense of smell and taste, and decreased appetite. Certain conditions, including some that are common in older adults, may result in zinc deficiency (e.g., cirrhosis of the liver, kidney disease, malignant cancers and alcoholism). Supplemental zinc may be administered. Dietary sources of zinc include meat, shellfish, and nuts.

Trace elements such as magnesium, copper, iodine, fluorine, chromium, selenium, nickel, and sulfur are necessary in very small amounts for normal body functioning. Selenium is gaining importance as an antioxidant mineral believed to promote heart health; improve tissue elasticity; and decrease the risk of colorectal, lung, and prostate cancer.