Nutrition for Older Adults
Age-Related Dementia: Risk Factors
-Age. The risk increases with advanced age. -Alcohol use. Consuming large amounts of alcohol increases the risk of dementia, while drinking a moderate amount may be protective. -Atherosclerosis. This inflammatory process leads to a thickening of the vessel walls, which can reduce the flow of blood that reaches the brain, leading to stroke or another brain injury. High levels of LDL cholesterol can raise the risk for vascular dementia and Alzheimer's disease. -Diabetes. Poorly controlled diabetes is a risk factor for stroke and cardiovascular disease-related events, which in turn increase the risk for vascular dementia. -Down syndrome. Many people with Down syndrome develop early-onset AD by the time they reach middle age. -Genetics. Some types of dementia are inherited. -Hypertension. Chronic high blood pressure has been linked to cognitive decline, stroke, and types of dementia that affect the regions of the brain involved in cognition. -Smoking. Smokers often develop circulatory problems that can interfere with normal blood flow to the brain.
The following suggestions can help improve nutrient intakes of older persons
-Emphasize nutrient-dense foods when planning daily menus. -Try new foods, seasonings, and ways of preparing foods. -Serve meals in well-lit or sunny areas, and plan appealing meals by using foods with different flavors, colors, shapes, textures, and smells. -Plan occasions for the older adult to share cooking responsibilities and eat meals with friends or relatives. -Encourage the older person to eat at a senior center whenever possible. -Investigate community resources for helping the older adult obtain groceries, cook, or manage other daily care needs. -Encourage the older adult to be physically active. -If biting and chewing are difficult for an older person, chop, grind, or blend tough or crisp foods.
Factors That Contribute to Reduced Food Intake Among Older Adults
-Reduced ability to taste and smell food -Dysphagia -Loss of teeth -Loss of normal cognitive function -Low income -Depression -Reduced mobility and flexibility
Depression
About 1 to 5% of community-dwelling older persons and almost 12% of older persons living in hospital settings suffer from major depression. Situations that contribute to depression among the older adult population include chronic illness, loss of mobility, and isolation and loneliness as family members and friends die or move away. If the depressed person loses interest in cooking and eating, weight loss and nutrient deficiencies are likely to occur. In many instances, depression can be managed with medication, but social support and psychological counseling may be necessary as well. Without proper treatment, depressed persons are at risk of alcoholism and suicide.
Diet and Vision protection
According to experts with the American Optometric Association, a diet high in fruits and vegetables that contain the carotenoids lutein and zeaxanthin may protect against age-related vision problems, particularly age-related macular degeneration and cataracts. Some of the richest food sources of lutein and zeaxanthin are dark green, leafy vegetables, such as spinach, collards, and kale.
Obesity
After a person reaches 50 years of age, his or her metabolic rate declines by approximately 4% per decade. Most older adults are less physically active than when they were younger. Thus, older persons generally need fewer calories for basal metabolism and physical activity than when they were 25 years of age. If older individuals do not reduce their caloric intake to accommodate their reduced energy needs, they experience an increase in body fat. The aging body tends to gain fat tissue in the intra-abdominal region and lose subcutaneous fat in other areas of the body, especially the legs and face. Increased abdominal fat results from hormonal changes, overeating, and lack of physical activity; but even athletic and lean people usually gain some central body fat after they are 50 years of age. In 2011-2014, approximately 37% of Americans who were 60 years of age and older were obese. Being overweight or obese may be beneficial to the survival of older adults. Elderly persons are prone to falls, but having excess body fat may protect bones from being fractured when they fall. In older adults, obesity reduces the likelihood of hip and spine fractures, but excess body fat increases the risk of ankle and upper arm fractures. Having extra body fat can provide a source of energy to sustain the older person when his or her appetite declines. Obese nursing home residents are more likely to live longer than leaner residents
Steps to take to reduce the risk of AD
Although there are a few medications that can be prescribed to slow the progression of Alzheimer's disease, there is no way to prevent or cure the disease. Some steps people can take that might reduce their risk of AD and, possibly, other forms of irreversible dementia include: -Eating foods that are rich sources of omega-3 fatty acids -Being physically active -Keeping intellectually and socially active.
Macronutrients
Americans generally consume adequate amounts of carbohydrates, fats, and proteins. Diets of most older Americans meet or exceed the Recommended Dietary Allowance (RDA) for protein (0.8 g/kg body weight). However, as much as 1.6 g protein/kg body weight may be required to maintain muscle mass in older adults. Foods that provide high-quality protein, such as beef, chicken, and fish, are often more expensive and difficult to prepare than carbohydrate-rich foods. Older adults who are on limited incomes, live alone, or are physically unable to shop for and cook food are at risk of developing protein malnutrition.
Parkinson's Disease
Another possible cause of dementia is Parkinson's disease, a disease that affects as many as 1 million people in the United States. Parkinson's disease usually strikes people who are over 50 years of age. The disease is a neurological disorder that results from the loss of dopamine-producing cells in the brain. Without dopamine, the nerve cells of the brain cannot send messages properly, which leads to the loss of muscle function, shaking (tremors), stiffness, and impaired balance. As the disease progresses, the affected person eventually has difficulty swallowing, chewing, and speaking. There is no cure for Parkinson's disease, but the medications levodopa and carbidopa often provide relief for some signs of the condition. The brain converts levodopa to dopamine. Because levodopa is an amino acid, it competes with certain other amino acids for absorption. Therefore, foods high in protein should not be eaten close to the time that levodopa is taken.
The Aging Digestive Tract
As a person ages, his or her gastrointestinal tract usually secretes less digestive juices, and the muscles of the digestive tract weaken. The result of such changes can be the development of gastrointestinal disorders and a reduced ability to digest food and absorb nutrients.
Energy
As the human body ages, its need for energy decreases from a combination of physical inactivity and reduced metabolic rate. The Estimated Average Requirement for energy is 2000 kcal for older men and 1600 kcal for older women. In 2013-2014, average energy intakes of Americans who were 70 years of age or older were quite close to these values: 2022 kcal for men and 1604 for women. Hypothyroidism, which contributes to a slower metabolic rate and weight gain, is common among older adults. According to findings of various studies, 1 to 10% of the older adult population has hypothyroidism; the condition is more likely to develop in women. Signs and symptoms of hypothyroidism include fatigue, lack of concentration, depression, dry skin, puffy eyes (edema), cold sensitivity, constipation, and weight gain. Because these signs and symptoms can be physiological aspects of the normal aging process, physicians may overlook the possibility that an older adult patient has hypothyroidism. Therefore, it is important for physicians to screen older adults for the condition and consider treating affected patients with oral medication, usually L-thyroxine, the synthetic form of thyroid hormone.
Age-Related Dementia
As the name implies, the risk of developing an age-related dementia increases with advancing age. Alzheimer's disease (AD) is the most common form of irreversible, degenerative, age-related dementia among older Americans. In 2016, AD affected about 15% of people who were 65 to 74 years of age, but the prevalence increased to 37% of the population who were 85 years of age and older. AD is the fifth leading cause of death in persons age 65 years and older. Although AD is more likely to occur in older adults, the condition can begin in persons who are younger than 60 years of age. During the early stages of AD, the degree of cognitive impairment is mild; affected individuals may have difficulty following directions or become lost while driving in an area that was formerly familiar to them. As the disease progresses, persons with AD may forget where they live and names of family members. Eventually, individuals with AD are unable to care for themselves and need 24-hour care. Death usually occurs 3 to 20 years after the disease is first suspected, depending on how quickly the disease worsens. People with AD usually die as a result of complications from infection or organ failure. Physicians often have difficulty diagnosing AD because many of the disease's signs and symptoms are the same as those of other forms of dementia. Medical practitioners need to rule out other causes of dementia, such as stroke or brain tumor. Currently, the only way to determine whether a person had AD is to microscopically examine a sample of his or her brain tissue after death to find specific signs of tissue degeneration.
Age-Related Physiological Changes
Body System Changes -Digestive Reduced saliva, gastric acid, and intrinsic factor secretion; increased likelihood of heartburn and constipation; reduced number of taste buds; and delayed swallowing rate -Integumentary (skin, hair, and nails) Reduced skin elasticity, increased wrinkles and dryness; decreased efficiency in vitamin D synthesis from sun exposure; decreased hair thickness; reduced hair color (graying) -Musculoskeletal Decreased activity of osteoblasts, resulting in bone loss that can lead to tooth loss and bones that fracture easily Decreased joint flexibility Decreased muscle mass, resulting in loss of strength and stamina -Nervous Decreased brain weight; reduced production of neurotransmitters; delayed transmission of nerve impulses; loss of short-term memory; and reduced sensory abilities (e.g., vision, hearing, smell, and taste) -Lymphatic (immune) Reduced functioning, resulting in increased vulnerability to cancer and infections -Circulatory Reduced flexibility of arteries, reduced cardiac output, and increased risk of blood clots Endocrine Decreased production of growth and thyroid hormones Respiratory Reduced lung capacity and increased vulnerability to respiratory infections -Urinary Increased loss of functional kidney cells, resulting in decreased blood filtration rate -Reproductive Men: Decreased male hormone production and sperm count Women: Decreased female hormone production, resulting in cessation of menstrual cycles and loss of fertility
Heart Failure
By age 65 years, most Americans have some form of cardiovascular disease (CVD), which causes progressive damage to the heart. Heart disease, a form of CVD, is the number one cause of death of older adults. As the heart becomes too weak to pump an adequate amount of blood throughout the body, heart failure (HF) develops. Signs and symptoms of HF include shortness of breath, fatigue, and edema, especially in the legs. The prevalence of heart failure increases with advancing age, and the majority of cases are diagnosed in people who are 75 years of age and older. Treatment of heart failure consists of medications and dietary modifications. Medications such as beta-blockers and ACE inhibitors may improve heart function. Diuretics such as furosemide are prescribed to increase urine output, and anticoagulants such as warfarin are given to reduce the likelihood of developing blood clots. A healthy eating pattern, such as the DASH diet, is generally recommended for people with heart failure. Patients with HF may need to consult with a registered dietitian nutritionist for individualized medical nutrition therapy.
Tips for people who have dementia
Caregivers of people who have an irreversible form of dementia can consider the following tips when feeding the affected person: -Limit distractions. Serve meals in a quiet area of the house. -Use plain plates and placemats to avoid visual confusion. -Limit utensils. Prepare easy-to-eat meals that require either a fork or a spoon. -Serve only one food at a time. Offering too many food choices may overwhelm the individual. -Be patient during meals. As the dementia progresses, the person may forget how to chew and swallow, so gently remind him or her to chew and swallow carefully. -Eat with the person who has dementia and provide directions on how to use utensils.
Diabetic Eye Disease
Cataracts, glaucoma, and diabetic retinopathy are collectively referred to as diabetic eye disease because these conditions may be complications of poorly controlled diabetes. Diabetic retinopathy is the most common type of diabetic eye disease. This condition is caused by elevated blood glucose and subsequent AGEs damage to the small blood vessels of the retina. In some cases, the tiny blood vessels in the retina swell and leak fluid into the vitreous, the gel-like substance that fills much of the inner eye. In other cases, the vessels become blocked, which signals the development of new blood vessels in the retina. The new vessels, however, are delicate and may leak blood, which interferes with vision. In the early stages of diabetic retinopathy, people usually do not have any symptoms, but as the condition worsens, affected individuals report seeing floating "spots" or having blurry vision. Long-term good control of blood pressure, cholesterol, and glucose levels reduces the risk that diabetic retinopathy will progress to blindness. Laser eye surgery and/or medications that are injected into the eye are often used to treat advanced cases of diabetic retinopathy.
Damage or Error Theories
Damage or error theories have the premise that organs simply wear out with use and abuse, largely from a combination of damage that results from lifestyle, which may include poor diet, smoking, and excessive alcohol consumption. One particular damage or error theory focuses on the effects of free-radical injury to cells. Such injury causes the accumulation of damaged material in cells that interferes with their ability to function normally, and eventually, organ failure occurs as a result. The nucleic acids, lipids, and proteins that are within cells are susceptible to free-radical attack and destruction. If this theory is correct, following a diet that is high in antioxidants might delay the aging process. Another damage or error theory proposes that an increase in the number of cross-linked proteins in cells causes damage to tissues and organs, slowing down bodily processes, which results in senescence. The glycation theory suggests that elevated blood levels of glucose or other sugars in the body bind to proteins, lipids, and nucleic acids (glycation). Advanced glycation end products (AGEs) form in people who have poorly controlled diabetes. Eventually, AGEs cause inflammation and disrupt organ functioning. Thus, maintaining healthy blood glucose levels throughout one's lifetime may reduce AGEs damage and extend one's life expectancy.
Gout
Gout is a form of inflammatory arthritis that is caused by a buildup of crystals that contain uric acid in joints, particularly a joint in the big toe. Uric acid is derived from the breakdown of purines, which are nitrogen-containing compounds made in the body and found in animal foods. The condition affects an estimated 6 million American adults and is more common in men than women. People who are overweight or obese, have hypertension, consume alcohol, take diuretics, and/or consume high amounts of meat and seafood are more likely to develop gout than people who do not have these characteristics. Although gout is a chronic disease, people with the condition tend to have times when they are free of symptoms (remission). An acute bout of the disease is called a "flare," which is characterized by joint pain and swelling of the affected joint. Treatment usually includes anti-inflammatory medication, such as NSAIDs and steroids. To prevent flares, gout patients may need to take medications (allopurinol, for example) that lower blood uric acid levels.
Longevity
Growing old is a normal and natural process; however, some people show the signs of aging at an earlier age than others. Scientists have found a strong genetic component to human longevity, the capability of living a long life. A person who has ancestors who are very old or lived to be 95 years of age or older may have inherited genes that contribute to longevity. Such characteristics could be having an immune system that functions better than average or cells that can divide more times to replace themselves without becoming cancerous. You can also contribute to your longevity by making responsible healthy lifestyle decisions while he or she is still young, such as selecting a nutritious diet, exercising regularly, and avoiding tobacco. The focus should not be simply on living longer but rather on living longer and healthier.
Having multiple chronic diseases in older adults
Having multiple chronic diseases results in high health care expenditures; almost 13% of older American adults' total expenditures are for health care, which is higher than for any other age bracket. Lower-income older adults must often decide between paying for food or paying for medications and other health-related expenditures.
Defining Older Adult
In 1900, only 3% of the U.S. population were 65 years of age or older. In 2015, 14.9% of the U.S. population were 65 years of age or older. By 2050, government experts estimate that 22% of Americans will be in this age group. Americans who are the "oldest old"—85 years of age or older—comprise one of the fastest-growing segments of the U.S. population. In 1900, only 0.1% of Americans were 85 years of age or older. By 2015, almost 2% of Americans were members of that age group.3 The percentage of Americans who will be 85 years of age or older is expected to be nearly 5% by 2050.
What Is Life Expectancy?
In 1900, the life expectancy of a baby born in the United States was only 47 years. Life expectancy is the average length of time a person born in a specific year, such as 1900, can expect to live. A newborn's life expectancy reflects death rates that occur across all age groups in a particular population, including infancy and adolescence. In the early 1900s, many American infants and older children did not live to reach adulthood. At that time, the top three leading causes of death for Americans were pneumonia, influenza, and other infectious diseases. By 2015, life expectancy in the United States had risen to almost 79 years. During the 20th century, several factors contributed to increased life expectancy, including improved diets, housing conditions, and public sanitation, as well as advances in medical care such as the development of antibiotics, vaccines, and reliable ways to diagnose diseases. Poor diet, physical inactivity, and other typical lifestyle habits of Americans are largely responsible for our nation's unimpressive world ranking for life expectancy. Unhealthy lifestyles increase the risk of serious chronic diseases, including heart disease, cancer, and stroke. Such diseases are the leading causes of death among older American adults. Healthy life expectancy is the number of years a person can expect to spend without being disabled or having serious diseases. Although more Americans are living longer than their ancestors, they are not necessarily living well. Many older adult Americans are in poor health, have limited mobility (ability to move around), and depend on others for their care.
Food Insecurity Among Older Adults
In 2015, almost 9% of Americans over 65 years of age were living below the poverty level; rates were higher among African-American and Hispanic older adults. An impoverished person is at risk of food insecurity, the situation that occurs when the individual is concerned about running out of food or not having enough money to buy more food. Food insecurity can result in poor nutritional status because the food-insecure person does not have enough money to buy nutrient-dense foods. Consuming nutritionally inadequate diets often worsens existing chronic diseases and impairs physical and cognitive functioning. If, for example, an older adult's diet is low in protein, vitamin B-12, and iron, he or she is likely to experience sarcopenia and anemia, which limit the person's ability walk, shop, and prepare foods. As the older adult's nutritional status deteriorates, his or her immune system function becomes weakened. Lowered immunity makes a person susceptible to infections such as pneumonia, a leading cause of death among older Americans.
Calorie-Restricted Diets and Longevity
In the 1930s, researcher Clive McKay proposed that the life span could be prolonged by following a calorie-restricted (CR) diet. In his studies of laboratory rats, the rodents that were given a CR diet (30% fewer kcal) lived longer and had fewer cases of age-related diseases than controls that ate a standard diet. Since McKay's work, results of other studies involving nonprimates indicate that CR diets prolong life, as long as the diet provides all essential nutrients. Whether CR will extend lifespan in humans is not yet known, but it appears that moderate CR coupled with adequate micronutrient intake may protect against many of the chronic conditions associated with old age, such as hypertension, cancer, type 2 diabetes, and obesity.
Teeth and Mouth
In the 1950s, surveys of Americans indicated that the majority of older adults had lost all their natural teeth. Since then, the percentage of older persons who retain all or most of their teeth has increased in the United States. In 2011-2012, nearly 50% of Americans who were 20 to 64 years of age had all of their teeth. However, almost 20% of Americans who were 65 years or older had lost all their natural teeth (edentulism). Excessive tooth loss can lead to poor nutrition. People who lack teeth often avoid crisp or chewy foods, such as fresh fruits, vegetables, whole-grain cereals, and meat. Although dentures that replace natural teeth can enable some people to chew normally, many older adults do not like to wear them because they can be uncomfortable. When a person has difficulty chewing food, serving soft foods such as ground meats, cooked vegetables, pureed fruits, and puddings can stimulate the individual's appetite. By following recommended dental hygiene practices, obtaining regular dental care, and avoiding tobacco use, people can greatly increase their chances of keeping most of their teeth as they age. Xerostomia (zeer-o-sto′-me-ah), or "dry mouth," results from hyposalivation, the lack of saliva secretion. A review of the medical literature shows that up to 29% of people have xerostomia; older adults, particularly older women, are more likely to have the condition than young persons. X-rays of the oral cavity, chemotherapy, and certain medications are common causes of dry mouth, although the condition may develop spontaneously, that is, without a clear cause. Saliva makes food easier to swallow and increases the flavor and palatability of foods. Thus, xerostomia interferes with a person's ability to taste food, which generally results in reduced intake.
Sodium and Potassium
In the United States, adults who are 70 years of age or older consume more than recommended amounts of sodium. This population, however, consumes less than recommended amounts of potassium. This mineral imbalance is of particular concern because 65% of adults who are 60 years of age or older have hypertension. The best dietary approach to treating hypertension is the DASH diet. which is low in sodium and recommends fruits and vegetables that are rich sources of potassium. Excessive dietary sodium is also associated with loss of calcium from bones; inadequate potassium intake increases the risk of osteoporosis, stroke, and kidney stones.
Older Adults
In the United States, people who are over 65 years of age are a diverse population. Many members of this population are healthy, have adequate incomes, and live independently, whereas others suffer from multiple chronic diseases, live in poverty, and cannot care for themselves. -People age at different rates. Senescence refers to declining organ functioning and increasing vulnerability to disease that occur with advanced age. -Geriatrics is the medical specialty that focuses on health care needs and medical conditions that are associated with older adults.
Physiological Aspects of Normal Aging
In the last stage of life, most cells lose their ability to regenerate their organelles, and they die (apoptosis). As the number of dying cells in an organ increases and are not replaced, the organ begins to lose its functional capacity. When one organ fails, the other organs begin to fail, and eventually, the body's organ systems are adversely affected to the extent that the person dies.
Weight Loss
It is not unusual for people to lose some weight after they are 70 years of age. Several factors can contribute to weight loss among older adults. For example, older persons may eat less because they have lost the ability to taste and smell food. In addition, loss of teeth and difficulty swallowing (dysphagia) can result in decreased food consumption.
Who Are the Centenarians?
Life span refers to the maximum number of years an organism can live. To date, Frenchwoman Jeanne Calment (1875-1997) had the longest documented human life span (122 years). Very few people live to be 100, but the number of centenarians (people who have reached the age of at least 100 years) is increasing in the United States. In 2015 approximately 72,000 centenarians were in the United States. Compared to other regions in the world, Okinawa, Japan, may have the highest concentration of centenarians (five per 10,000 people).8 Much of the longevity that occurs among Okinawans may be related to their traditional diet, which is low in calories yet nutrient dense. The traditional Okinawan diet is very high in carbohydrate (90% of total calories) and consists primarily of abundant vegetables and fruits that are rich sources of micronutrients and phytochemicals.
Esophagus, Stomach, and Intestines
Older adults are more likely to develop gastroesophageal reflux disease (GERD) than any other disorder of the upper gastrointestinal tract. As an adult grows older, the lower esophageal sphincter may "wear out" and lose its ability to constrict, which enables acidic gastric juice to enter the esophagus. Medications that reduce stomach acid production are often used to control GERD. As a person ages, his or her stomach secretes less hydrochloric acid and intrinsic factor. These changes can contribute to poor absorption of vitamin B-12 and the development of vitamin B-12 deficiency and pernicious anemia. Many older adults are able to meet their vitamin B-12 needs by eating foods that have been fortified with the micronutrient or by taking vitamin B-12 supplements. Other persons with vitamin B-12 deficiency must take injections of the vitamin to prevent pernicious anemia Older persons are also at risk of iron deficiency because reduced stomach acid production may hinder iron absorption. Furthermore, many older adults take aspirin regularly, and this practice can cause intestinal bleeding that can lead to iron deficiency anemia. Intestinal ulcers and cancer can also cause blood loss from the digestive tract. The discovery of blood in bowel movements needs to be reported to a physician. Constipation is a major complaint of older adults. By increasing their intake of fiber-rich foods, such as whole-grain products and vegetables, older adults may be able to have more regular bowel movements. Dehydration also contributes to constipation, so older persons should make sure their fluid intake is adequate.
Nutrient Needs of Healthy Older Adults
Older adults tend to consume more than recommended amounts of sodium, saturated fat, and added sugars. Their diets, however, generally do not provide enough fiber, calcium, magnesium, potassium, zinc, folate, and vitamins A, B-6, C, D, and E. In 2015, fewer than half (38.5%) of older adults consumed 2 or more servings of fruit each day, and only about 19% of this population ate 3 or more servings of vegetables each day.
Sarcopenic Obesity
Older people may develop sarcopenic obesity: the loss of skeletal muscle mass and strength combined with an excessive increase in body fat. A combination of lack of exercise and a surplus of calories contributes to the development of sarcopenic obesity. People with sarcopenic obesity are more likely to experience mobility problems and other physical limitations than people who do not have the condition. Healthy people are never too old to gain some benefits from aerobic and strength-training exercise.
Chronic Health Conditions in older adults
Over fifty percent of older Americans suffer from one or more chronic health conditions. In 2013-2014, the most frequently occurring chronic medical conditions among older persons were diagnosed arthritis, heart disease, cancer, diagnosed diabetes, and hypertension.
Polypharmacy and Food-Drug Interaction
Polypharmacy (condition that occurs when a person takes multiple medicines each day) is a common practice among older adults, especially in individuals who have multiple chronic diseases. In 2009-2012, about 39% of Americans aged 65 years or older reported using five or more prescription drugs during the past 30 days. An 88-year-old woman, for example, may take hydrochlorothiazide to lower her blood pressure, lovastatin to reduce her elevated cholesterol level, citalopram to combat depression, metformin to help control her diabetes, and levothyroxine to boost her level of thyroid hormone. Additionally, she takes over-the-counter products that contain vitamin D to treat her vitamin D deficiency and low-dose aspirin to reduce inflammation. Among older adults, cholesterol-lowering medications (statins), beta-blockers, and diuretics are among the most frequently prescribed drugs. Beta-blockers help regulate heartbeat, and diuretics help reduce elevated blood pressure. Although diuretics can be very effective, these medications can cause serious side effects, including dizziness and dehydration. Although medications can improve health and quality of life of older persons, some drugs interfere with the body's absorption and/or use of certain nutrients. Prescription medications can have a variety of effects on a person's nutritional status, such as by: -Altering taste (dysgeusia); -Causing gastrointestinal bleeding or diarrhea -Causing anorexia (loss of appetite) or increased appetite -Altering blood glucose levels. Certain dietary supplements, including herbal products, can reduce or amplify the effects of prescribed medications. Therefore, older adults should notify their physicians about their use of all dietary supplements. A few foods also interfere with the metabolism of prescribed drugs. Grapefruit juice, for example, can alter the potency of certain statins that are used to lower blood cholesterol.
Programmed Theories
Programmed theories imply that aging is genetically programmed and follows a biological sequence, similar to the milestones of a child's growth and development. Programmed theories may include the following notions: -Over time, the activity of certain genes results in aging -Shortening of telomeres at the ends of chromosomes, which limits the number of times cells can divide -Changes in hormones, particularly decreases in estrogen or growth hormone levels, act as biological "clocks" that contribute to aging -The immune system is programmed to decline over time, which makes people more susceptible to diseases and ultimately results in their death. According to programmed theories, aging is inevitable and healthy dietary and lifestyle choices have little influence on the rate at which the aging process occurs.
Physiological Changes
Some of the physiological changes that are associated with the normal aging process can have adverse effects on the older adult's nutritional state. For example, declines in digestive system functioning can interfere with the older person's ability to chew, swallow, and digest food. Other changes may negatively influence the older adult's appetite. To enjoy eating, for example, people must be able to taste the flavor and smell the aroma of foods. With advancing age, a person's senses of smell and taste typically become less acute. More than 50% of people who are between 65 and 80 years of age have signs of reduced olfactory function. As many as 80% of people who are more than 80 years of age are unable to smell odors effectively. The sense of taste, especially the ability to taste sweet and salty foods, also tends to decrease after 60 years of age. Common causes of taste disorders among older adults include the use of certain medications and deficiencies of zinc or vitamin B-12. As a person's ability to enjoy the aroma and flavor foods declines, his or her caloric and nutrient intake usually declines as well. Adding spices to foods may help enhance their taste and stimulate an older adult's interest in eating.
Vitamin B-12
The DRI for vitamin B-12 is 2.4 μg for all individuals who are over 14 years of age. On average, older Americans consume more than this amount of vitamin B-12 from food sources. However, low vitamin B-12 status is common among the older adult population, because absorption of vitamin B-12 is diminished in older persons. Dietary supplements contain unbound ("free") vitamin B-12, which is easier to absorb than the natural form. Many adults ages 50 and older are encouraged to consume foods that have been fortified with free vitamin B-12, such as fortified grain products, or take vitamin B-12 supplements. Increasing the daily intake of vitamin B-12 to between 6 and 10 μg may be beneficial for older adults who have adequate absorption of the micronutrient. Higher doses of vitamin B-12 and even injections of the vitamin may be appropriate for people with impaired absorption.
Theories on Aging
The aging process begins at conception and is characterized by a number of predictable physical changes. What causes people to age is unclear, but medical researchers have proposed various theories to explain why aging occurs.
Water
The body's water content decreases with advancing age: About 60% of the body weight of younger adults is water, whereas water comprises about 50% of the body weight of healthy older adults. With advancing age, thirst sensation declines, kidneys are less able to conserve fluids, and frail older persons may find it difficult to drink water regularly because they lack good mobility. Poor mobility can limit an older adult's ability to get to sources of water. Additionally, some medications, such as furosemide, which is taken to control high blood pressure, increase urination and/or depress thirst perception. Many older adults avoid drinking fluids simply because they want to avoid frequent trips to the bathroom or urinary incontinence. Urinary incontinence is a condition characterized by urine leaking out of the bladder. Dehydration is a common problem, especially among people who are 85 years of age and older. Signs of dehydration include weakness, constipation, and mental confusion. If untreated, dehydration can lead to coma and death. To avoid dehydration, older adults often need to be reminded to drink water and other fluids.
Calcium
The calcium RDA for adults ages 70 years and above is 1200 mg/day. Most older adults do not meet their RDA for calcium by consuming foods. Therefore, calcium supplementation among older Americans is common: 62% of people over age 70 take a daily calcium supplement. Prevention of osteoporosis and related bone fractures is the main reason older adults should be concerned about their calcium intake. Recovery after any broken bone may require months of rehabilitation, especially for frail older adults. Many older persons are unable to walk without assistance after recovering from a broken hip or spine.
Dementia
The number of functioning neurons (nerve cells that transmit information) in the brain decreases with age. A reduction in the number of neurons in the brain negatively affects mental functioning (cognition). Memory, language skills, and the abilities to reason, pay attention, and solve problems are cognitive functions. Dementia results from the decline in cognition. Some people with dementia also lose control over their emotions. Dementia can be so severe that it interferes with the person's ability to carry out tasks of daily living. Age-related dementia is associated with advancing age, but it is important to recognize that dementia is not a normal feature of the aging process. Some forms of dementia are reversible and not related to advanced age. Reversible dementia might result from poor dietary practices, hormonal imbalances, or medications. For example, a deficiency of thiamin or vitamin B-12, or dehydration can cause reversible dementia. Treating reversible dementia may simply involve modifying the diet of the older adult to improve its thiamin content or giving the person a vitamin B-12 supplement. Most forms of age-related dementia, including vascular dementia and Alzheimer's disease, are irreversible. This section of the chapter focuses on common forms of age-related dementia.
Sarcopenia
The weight loss that often occurs after the age 70 years is partially a result of the loss of muscle mass (sarcopenia). In people with sarcopenia, some muscle cells shrink or die, and loss of muscular strength results. Among older adults, sarcopenia is a major cause of reduced mobility and independence. The loss of muscular mass also increases the risk of falls and diminished ability to recover from serious illness.
Administration for Community Living's Nutrition Program
To combat food insecurity and undernutrition among older Americans, the federal government provides funds for nutrition assistance programs. Title III of the Older Americans Act of 1965 authorized nutrition services for older adults. Goals of the Nutrition Program of the Administration for Community Living (ACL) are to: -Reduce hunger and food insecurity -Promote socialization -Promote good health -Delay the development of poor health in older adults. The ACL's nutrition programs focus on serving people who are over 60 years of age and have the greatest economic and social needs. To learn more about the government-sponsored nutrition-related programs for older adults, visit the following websites: National Institute on Aging, www.nia.nih.gov; American Geriatrics Society, www.americangeriatrics.org; and Administration for Community Living www.acl.gov.
Diseases and Conditions That Affect Vision
To obtain food and prepare meals, a person must be able to drive (or walk) to the store, select groceries from the aisles, take the groceries home, and use the stove to cook the foods. Visual impairments negatively affect all aspects of meal preparation, from grocery shopping to cooking. By the age of 40 years, the lens of the eye begins to harden and the muscle fibers around the lens lose their ability to control the shape of the lens. As a result of these normal changes, it becomes more difficult for the eyes to focus on objects that are close, such as print on the pages of a book. The loss of this focusing ability is called presbyopia. With advancing age, the likelihood of presbyopia increases, and eventually, everyone's eyes lose some ability to focus on close objects clearly. Reading glasses or contact lenses often can correct presbyopia and enable older people to read food labels and recipes, and prepare meals. Other more serious vision problems can lead to permanent blindness. A cataract develops when proteins in the lens of the eye are damaged, causing the lens to become translucent or opaque. About 25% of Americans who are 65 to 69 years of age have a cataract; the prevalence of cataract increases to almost 70% of the population who are 80 years of age or more. Cataracts occur more frequently in smokers and people with diabetes. Exposure to sources of ultraviolet light, including sunlight, also contributes to cataract formation. A cataract can be treated by surgically removing the clouded lens and replacing it with an artificial lens. As a result of the surgery, vision is usually restored. Age-related macular degeneration (AMD) is characterized by loss of vision in the center of the visual field (the macula) of the eye. A healthy macula is necessary for sharp central vision. People with AMD cannot see a clear image when they look straight ahead. Only 3% of Americans who are 75 to 79 years of age have AMD, but the prevalence of the condition increases to almost 12% of the population who are 80 years of age or older. AMD is more common in people who smoke, have a family history of the disease, and have elevated blood pressure or elevated blood cholesterol levels. Glaucoma occurs when the fluid pressure in the anterior chamber of the eye is higher than normal. The increased pressure damages the optic nerve, which can result in blindness. About 8% of Americans who are 80 years of age and older have glaucoma.
Vascular-Degenerative Dementia
Vascular dementia occurs when the blood supply to the brain is reduced, which damages brain tissue. This form of dementia usually occurs after a person has had several small strokes. Vascular dementia is more common in people with hypertension or atherosclerosis. Therefore, dietary strategies to control these diseases may reduce a person's chances of developing this form of dementia. The majority of people who were at least 80 years of age and had dementia when they died probably had "mixed dementia" (mixed vascular-degenerative dementia). Results of some studies indicate that mixed vascular-degenerative dementia is the most common cause of severe cognitive decline in older adults.
Arthritis
inflammation of a joint that is usually accompanied by pain, swelling, and stiffness. In the United States, an estimated 52.5 million adults have been diagnosed with arthritis. Arthritis is the most common cause of physical disability among American adults. Arthritis can strike people of any age, but it is more common in older adults. Osteoarthritis, the most common form of arthritis, is estimated to affect at least 27 million Americans. The condition results from progressive degeneration of the bones and cartilage, particularly in the fingers, wrists, knees, hips, and spine. The pain of osteoarthritis can be so severe, it interferes with a person's ability to shop, prepare food, and eat. The primary risk factor for osteoarthritis is obesity, but the condition also develops in people who have experienced trauma to a joint earlier in life. For example, after years of overuse and injury, joggers and retired professional football and soccer players often develop osteoarthritis in their knees. Treatment of osteoarthritis includes controlling pain, improving joint function, and weight loss in individuals who are obese. Pain is treated by NSAIDs (nonsteroidal anti-inflammatory drugs), which increase the risk of gastrointestinal bleeding and subsequent anemia. According to results of a major study, dietary supplements that contain glucosamine and/or chondroitin sulfate were not effective for reducing the discomfort and slowing the joint damage that occur in osteoarthritis.
Vitamin D
vitamin D3 must be hydroxylated in the liver and the kidneys to become the active calcitriol form of the vitamin. As one ages, the liver and kidneys become less able to activate the vitamin D3 precursor. Furthermore, most older adults do not obtain sufficient exposure to sunlight, so they are unable to synthesize adequate amounts of vitamin D. Thus, the RDA for vitamin D increases from 15 to 20 μg (600 to 800 IU) for people who are over 70 years of age. Therefore, health experts often recommend that older adults take a daily supplement that supplies 400 IU of vitamin D. Supplements that contain the calcitriol form of the vitamin are a good choice for older adults because the vitamin is in the active form.