4 Chapter 4: Physiology of Aging and Nutritional Implications

Tracy Everitt; Brittany Yantha; Megan Davies; and Sayuri Omori

Chapter 4 Learning Objectives

At the conclusion of this chapter, students will be able to:

Learning Objectives

  • Describe the physiological changes associated with aging and how these changes impact nutrition and health status.
  • Identify strategies to address physiological changes of aging.


Aging is a normal physiological and psychological process that includes all the changes throughout a persons life. As people age, many changes occur in the body, mind, and behaviour.  


While all humans go through the same stages of development, no two humans will have the same development experience. People vary greatly in the rate and extent to which their body ages. Psychological, environmental, and social factors such as stress and financial situations impact the pattern of peoples development. Biology or genetics also strongly influence how people develop and the physical changes that occur. Diseases such as heart disease, infections, strokes, and the use of substances such as alcohol and drugs all affect physical changes in the human body. It is important to understand the general physical and psychological changes and stages of development that humans go through as they age. 


4.1 Common Health and Nutritional Concerns for Older Adults

Aging is a normal process; it is not a disease state or a sentence that a person will end up with a disability. Optimizing physical, mental, and cognitive health is important for healthy aging. Dietary choices can help improve and support optimal aging.   


The processes associated with aging compromises immune system function, increasing susceptibility to illness. Chronic or acute conditions, in turn, have greater impacts on the body, which can deplete nutrient reserves, contributing to more issues. The aging process leads to physiological changes, such as decreased hormone production, bone density, muscle mass, and strength, and contributes to changes in body composition. As a result, older people can experience an increased occurrence of chronic diseases such as cancer, heart disease, and diabetes.


Health challenges in older adults may be related to nutritional habits, which can further impact diet and activity levels. Decreased food intake may be due to conditions such as arthritis, impacting the person’s physical abilities, such as standing at the stove, opening a jar or can, or using a knife to chop foods. Many older adults skip at least one meal each day, making it challenging to meet nutrient requirements. Additionally, older adults have a decreased thirst response, and the kidneys have a reduced ability to concentrate urine, both of which can lead to dehydration.

4.2 The Immune System

The immune system naturally loses functionality as people age, increasing infection risk and prolonging recovery time. There are two parts to the immune system: the innate immune system and the adaptive immune system. As people age, changes occur in both systems. The innate immune system consists of barriers that protect from infection, such as skin, mucous membranes, stomach acid, the cough reflex and the ability to develop a fever. The process of aging causes a loss of collagen and elasticity in the skin, made worse with increased sun exposure and skin thinning, leading to skin becoming drier, thinner, and more fragile. Fragile skin may lead to skin tears and openings, which allow bacteria to enter and cause infection. Reduced sensory perception leads to reduced pain sensation and may delay identifying problem areas. The aging immune system may be unable to support appropriate wound healing. 


The adaptive immune system is more complex and includes the spleen, thymus, tonsils, bone marrow (which makes white blood cells), and the circulatory and lymphatic systems. T cells are white blood cells that help fight infection. As people age, their bodies produce fewer T cells, diminishing their ability to fight off bacteria and viruses. Lymph nodes decrease in size and number, making it harder for the body to develop a fever and fight infection. An older adult may not develop a fever, making it harder to detect an infection. Immune aging is a risk factor for and amplifies many of the pathologies associated with the aging process. 

4.3 Dentition

Poor oral health in older adults is an important public health issue increasing worldwide (Dietitians Association of Australia and Dental Health Services Victoria, 2015). Healthy teeth and gums are essential for enjoying a variety of foods. As people age, they will experience a decreased thirst mechanism, leading to reduced saliva production and quality. Dry mouth, or xerostomia, contributes to gum disease and dental caries, as saliva is essential to protect the teeth. Xerostomia can also make dentures fit uncomfortably, decreasing older adults’ eating ability (Dietitians Association of Australia and Dental Health Services Victoria, 2015). Fewer teeth and dentures can lead to chewing and swallowing difficulties, making it hard to maintain a healthy diet and increasing the risk of poor digestion, weight loss, and malnutrition. Dental issues can also lead to difficulty speaking, which can lower self-esteem and overall quality of life.


Oral hygiene practices are important to avoid the build-up of plaque, which contributes to periodontal disease or inflammation of the gums (Dietitians Association of Australia and Dental Health Services Victoria, 2015). Older adults may have physical and mental difficulties that make it difficult to maintain oral hygiene, such as stroke, arthritis, dementia, and depression (Dietitians Association of Australia and Dental Health Services Victoria, 2015). In addition, many older adults are on a variety of medications, which can have many side effects, including dry mouth (Carter & Roe, 2019). It is important to note that older adults from low-income brackets are more likely to experience these issues due to a lack of access to dental care, transportation, and nutritional help. Interestingly, long-term care residents may also be at increased risk of oral disease if there is a lack of funding, staffing issues, and a lack of training (Dietitians Association of Australia and Dental Health Services Victoria, 2015).


To maintain good oral hygiene, it is recommended that older adults brush their teeth twice a day with a high-fluoride toothpaste and drink plenty of water with meals to clear food debris from the mouth (Dietitians Association of Australia and Dental Health Services Victoria, 2015). Using dentures or eating chopped foods are adaptation strategies that may help to optimize nutrition intake. However, dentures must be cleared daily and removed at night (Dietitians Association of Australia and Dental Services Victoria, 2015). Using broth or gravy to soften foods can be helpful for individuals who have chewing difficulties or a sore mouth (Carter & Roe, 2019). It is also important to promote a healthy diet, including limiting sweet foods between meals, encouraging the consumption of dairy foods after meals, and drinking lots of water to prevent dry mouth (Dietitians Association of Australia and Dental Health Services Victoria, 2015).

4.4 Sensory Issues


Physiological changes that occur with increasing age impact senses, including taste and smell. Decreases in the ability to taste start at about age sixty, when taste buds begin to decrease in size and number. It is sometimes argued that they do not necessarily decrease in size and number, but in function. As a result, the taste threshold is higher in older adults, meaning that more of the same flavour must be present to detect the taste. Many older adults lose the ability to distinguish between salty, sour, sweet, and bitter flavours, making make food less appealing and decreasing appetite. The reduced desire to eat is called anorexia of aging. Older people may respond by increasing their intake of foods high in sugar and sodium due to an inability to discern those tastes.


Along with taste, the sense of smell decreases as a person ages, impacting how food is experienced and influencing which foods are appealing. The sense of smell allows for detecting, recognizing, and identifying odours and contributes to the anticipation of eating and the enjoyment of food (Bernstein & Munoz, 2019). Olfactory loss commonly occurs as a person ages. It may be caused by changes in the anatomy of the olfactory structures, such as a decrease in the number of olfactory receptor cells (Bernstein & Munoz, 2019). There is a decrease in the number of sensory cells that detect aromas because the replacement process of these cells diminishes with aging. Sense of smell is also diminished by decreased nerve function, reduced mucous production, thinning of the nose lining, hormonal changes with age, environmental exposures such as tobacco smoke, age-related disease, and some medications (Bernstein & Munoz, 2019). As with the sense of taste, smell declines gradually over time. Food intake and appetite may diminish, contributing to nutrition problems among older people who do not meet their nutritional needs (Bernstein & Munoz, 2019). Changes in taste may also lead to other nutritional concerns, such as when individuals seek foods higher in salt or over-salt their foods to improve taste. This increase in salt in the diet can compromise cardiac or renal conditions in older adults.


The impact of sensory changes reaches beyond changes in food intake. These changes may also affect digestion because the taste and smell of food stimulate digestive enzyme secretion in the mouth, stomach, and pancreas. A drier mouth, for instance, can affect one’s ability to swallow.


Some older people suffer from vision problems and a loss of vision. Age-related macular degeneration, for example, is the leading cause of blindness in those over age sixty in North America. This disorder can make food planning and preparation extremely difficult, and people who suffer from it may require assistance preparing their meals. Self-feeding may be difficult if a person is unable to see their food. Friends and family members can help older adults with shopping and cooking.


A diet high in antioxidants may help to prevent macular degeneration. Consuming colourful fruits and vegetables increases the intake of lutein and zeaxanthin, and several studies have shown that these antioxidants protect the eyes. Lutein and zeaxanthin are green, leafy vegetables such as spinach, kale, collard greens, corn, peaches, squash, broccoli, brussels sprouts, orange juice, and honeydew melon.


Cataracts are another eye condition that is common as one ages. A cataract occurs when the lens, which is normally clear, becomes cloudy. Normally, the lens refracts light as it passes through. Looking through cataracts, however, is like looking through a fogged-up window, making things look blurry, hazy or less colourful and can make completing tasks difficult. They develop slowly and progressively interfere with vision over time and may require surgery to treat.


Sensory changes impacting the smell and taste of foods will be discussed below as they fall within the gastrointestinal system.

4.5 Gastrointestinal Changes

Difficulty Swallowing Foods

Some older adults have difficulty getting adequate nutrition because of swallowing difficulties or dysphagia. Dysphagia can be any disruption in normal swallowing and can develop because of aging, frailty, and muscular, endocrine and psychiatric diseases that are common co-morbities in older adults (Bernstein & Munoz, 2019). Dysphagia is common in older adults, especially those with neurodegenerative disorders. Any damage to the parts of the brain that control swallowing, such as stroke, can result in dysphagia. Medications such as narcotics, antidepressants, anticholinergics, benzodiazepines, and antiepileptic drugs can cause confusion, decrease alertness, or affect consciousness or swallowing and thus may cause a delay in the swallowing response (Bernstein & Munoz, 2019). Physiologic changes in swallowing, including delayed upper esophageal sensory discrimination, decreased lingual strength, and delayed upper esophageal sphincter relaxation during swallowing may contribute to the development of dysphagia.


The impact of dysphagia on the health of older people is greater than that of other chronic conditions and complications (Berstein & Munoz, 2019). Adults with dysphagia feel anxiety and panic during mealtimes and can avoid eating with others because of this condition. Avoiding meats, fresh fruits, and fresh vegetables because they are difficult to chew and swallow can compromise nutritional status. Dehydration is also a concern because older adults with dysphagia may be less able to drink water and other fluids.


Altering food consistency can help older adults with dysphagia. For example, a liquid can be thickened, slowing its flow and giving the client better swallowing control (INESSS, 2022). Or, solid foods can be chopped, ground, or pureed to facilitate safer swallowing. Modifying the texture of foods when someone has trouble swallowing decreases the risk of aspiration, which occurs when food goes into the respiratory tract instead of the esophagus. Preventing aspiration is important because it can lead to pneumonia,  which can be serious because older adults already have compromised immune function. Speech therapists, physicians, and dietitians work together to determine the appropriate diet for dysphagia patients.


An available resource to meet patient food texture needs is the IDDSI framework. The IDDSI framework is a classification system used to measure the consistency of foods and drinks. For liquids, a vertical flow test is used (INESSS, 2022). For foods, a flow test, a fork pressure test, a fork dip test, a spoon tilt test, etc. are used (IDDSI, 2019).

Stomach Changes

Gastrointestinal changes that occur due to aging impact the entire length of the gastrointestinal tract.  As we age, the ability of our stomach to maintain proper motility often declines. In most cases, this results from the development of comorbid disease (Orr & Chenn, 2022). However, as we age, the cells of the enteric nerve system die, leading to the inability to control the sphincters, the smooth muscle of the digestive system, and the ability to regulate the digestive process. Eating food activates the release of hormones, which activates the digestive process. As individuals age, there is a loss in this regulation of hormones, which slows the digestion process  (Serra-Prat et al., 2013). The inability to move the contents from the stomach to the intestines efficiently impacts the individual’s nutritional status, as most nutritional absorption occurs in the small intestine (Chung, 2008). If nutrients move too quickly, they will fail to break down into an absorbable form. After the age of 80, small intestine motility decreases, negatively affecting the absorption of nutrients (Orr & Chen, 2002).   

Gastrointestinal Reflux Disease

Older adults commonly experience the relaxation of muscles in the esophagus as they age. These changes can cause the lower esophageal sphincter to relax, which may lead to acid reflux. Gastroesophageal reflux disease (GERD) occurs when gastric acid and fluids from the stomach repeatedly enter the esophagus. Exposure to stomach acid can cause damage to the mucous membranes in the esophagus, leading to coughing, hoarseness and pain when swallowing. GERD can also increase risk for other health complications, including esophagitis, esophageal stricture, and Barretts esophagus. GERD requires changes in diet and lifestyle for treatment and prevention. Weight loss and food management can decrease GERD symptoms as common risk factors are obesity, use of tobacco, alcohol, and certain medications, and consumption of coffee, chocolate, and peppermint, all of which can reduce lower esophageal muscle tone.It is also recommended to eat meals 2-3 hours before you lie down, as the stomach acid and fluids are more present after consuming food. This helps prevent the acids and fluids from splashing back into the esophagus. Certain medications may also be used in the treatment.  

Atrophic Gastritis

Atrophic gastritis is a complex syndrome that can arise from long-standing H.pylori infection (multifocal atrophic gastritis) or with an autoimmune process that progressively destroys the oxyntic mucosa (autoimmune atrophic gastritis) (Neumann, Coss, Rugge & Genta, 2013). Atrophic gastritis is a relatively prevalent illness, common in older adults but also often present in younger adults, which may arise as a long-term consequence of H.pylori infection or due to long-term inflammation caused by gastric autoimmunity. Atrophy is a synonym for wasting. When applied to the gastric mucosa, atrophy is defined as the reduction or disappearance of the native gastric glands, whether they have been replaced by nothing, fibrosis, or a type of epithelium that would not normally be there (metaplasia).


The decrease or disappearance of parietal cells results in reduced or absent acid production and loss of intrinsic factor, a glycoprotein needed to absorb Vitamin B12. An increased gastric pH enables the colonization of the stomach by bacteria that might produce nitrites and promote carcinogenesis. In addition, higher stomach pH interferes with the absorption of certain indispensable substances (such as iron and vitamin B12); and by continuously stimulating the gastrin-secreting cells of the antrum it induces the proliferation of endocrine-like cells in the corpus (largest section in the stomach), which might give rise to neuroendocrine tumors (Neumann, Coss, Rugge & Genta, 2013). The progressive depletion of native gastric structures in scattered patches throughout the stomach, one of the results of long-standing H. pylori infection, is known as multifactorial atrophic gastritis.


Autoimmune gastritis is a chronic progressive inflammatory condition that results in the replacement of the parietal cell mass by atrophic and metaplastic mucosa. It is a condition that progresses at an unknown pace from mild chronic inflammation of the gastric corpus to an advanced stage associated with severe form of vitamin B12 deficiency anemia, also known as pernicious anemia (Neumann, Coss, Rugge & Genta, 2013). Traditionally autoimmune atrophic gastritis has been viewed as a disease affecting predominantly elderly women of Northern European descent, but growing evidence suggests that there might be no racial specificity. The diagnosis of autoimmune gastritis rests on demonstrating its characteristic histopathological features and having autoantibodies against intrinsic factor and parietal cells (Neumann, Coss, Rugge & Genta, 2013). The prevalence of atrophic gastritis increases with age. It affects approximately 8% of the population aged 70-74, while in the 50-54 age category, only 4% are affected (Weck et al., 2017). Additionally, a strong association exists between atrophic gastritis and H. pylori infections. Approximately ¼ of atrophic gastritis cases have H. pylori infections (Weck et al., 2007). Management of the early stages of autoimmune atrophic gastritis is focused on preventing vitamin B12 folate and iron deficiencies. Adequate supplementation of these substances will effectively prevent cobalamin depletion and the development of anemia. If the anemia is left untreated, cognitive impairment can develop (Berstein & Munoz, 2019), impacting a person’s psychological aging. Cognitive impairments may have negative effect on the persons mentality around aging, especially if atrophic gastritis or Vitamin B12 deficiency is not treated.


Aging causes gastrointestinal changes in the body. A common change is reduced motility of the large intestine increasing the risk of constipation. Transit times for stool slow down and spend longer in the large intestine causing more water to be reabsorbed by the body. According to the National Institute of Health, in people aged 65, about 26% of women and 16% of men suffer from constipation (Berstein & Munoz, 2019). The rate continues to increase as we age. For 84 years and older, rates rise to 34% for women and 26% for men (Berstein & Munoz, 2019). Constipation can be a side effect of medication, low fluid intake, low activity, or a low fibre diet, and many times, it is a mix of some or all these issues. If not adequately addressed, these issues can lead to intestinal blockage. Possible treatments for constipation include bowel retraining, enemas, bulking agents, stool softeners and adequate fibre and fluid intake.  

4.6 Renal Changes

As the body ages, the kidneys experience changes such as shrinkage and decreased functionality. Shrinkage of the kidneys is due to a decrease in the number of glomeruli and a reduction in filtration rate, decreasing their ability to concentrate urine. The bladder’s muscle tone becomes weaker, and some older adults may have difficulty holding the same amount of urine as they did when they were younger. They may need to urinate more frequently and wake up during the night to do so. Since the bladder is weaker, it may also not empty completely. This leads to urine remaining stagnant in the bladder, which makes the person more at risk for a urinary tract infection. These are all contributing factors to incontinence. Incontinence is the loss of bladder control, which can cause urine leakage. The increased frequency of urination may contribute to dehydration, which can be dangerous for older adults. Prevention and treatment strategies for urinary incontinence include weight management, physical activity, pelvic floor strengthening, restriction of smoking and alcohol use, modifying fluid intake, and decreasing caffeine intake. 

Urinary Tract Infections

A Urinary tract infection (UTI) is a common infection of the urinary tract that affects 150 million people each year across the globe (Zeng et al., 2020). UTIs occur when bacteria enter the urethra and infect the urinary tract, which includes the bladder, kidneys, ureters, and urethra, with the most common site of infection being the bladder (CDC, 2021). Due to the physiological changes noted above, UTIs are highly prevalent among older adults, leading to an increased susceptibility to infection and urinary bacterial overgrowth (Zeng et al., 2020). UTIs are the most common infection for older women –  in hospitalized older women and those in long-term care (Rodriguez-Manas, 2020). While it is more common among women, clinically diagnosed UTIs increase with age, irrespective of gender (Rodriguez-Manas, 2020). Some risk factors for UTIs in older adults include urinary incontinence, cognitive impairment, immunological abnormality, urinary catheters, diabetes mellitus, and urologic obstruction (Zeng et al., 2020). 


Urinary incontinence is the involuntary loss of urine, a common and undertreated problem in older adults. The prevalence of urinary incontinence increases with age, and with individuals living longer, the impact of urinary incontinence on society and the healthcare, system continues to increase (Shaw & Wagg, 2016). Incontinence is often the result of multiple risk factors and modifiers. Older adults tend not to seek help from healthcare providers for various reasons, including perceived stigma and social embarrassment, belief that incontinence is a normal part of aging and an assumption that there is no available effective treatment. Several disorders result in urinary incontinence, but the majority is accounted for by stress incontinence (involuntary loss of urine on effort or physical exertion) and urgency incontinence (involuntary loss of urine associated with urgency). Several medications for chronic conditions common in older adults can worsen urinary incontinence (Shaw & Wagg, 2016).


Several general management strategies apply to all forms of incontinence but can have varying results depending on the circumstances. Managing fluid intake is important, aiming to balance dehydration, excessive drinking, and avoiding alcohol and caffeine. Weight loss through dieting or medication can be beneficial but difficult to achieve. Good blood sugar control for those with diabetes allows patients to manage the hyperglycemia that can lead to urinary incontinence (Shaw & Wagg, 2016). Conservative management techniques include:

Prompted voiding – using prompts to use the lavatory with encouragement when successful can increase patients’ self-initiating or request to toilet and decrease the number of incontinence episodes.

Habit retraining – the incontinent person’s voiding pattern is identified, usually through a bladder diary. A schedule is then devised to pre-empt incontinence episodes.

Timed voiding – the patient has lavratory visits at fixed intervals, such as every 3 hours. This  is considered a passive toileting program.

Combined prompted voiding and exercise therapy – functional intervention training involves direct caregivers incorporating strengthening exercises into toileting routines.

Adapted from Shaw & Wagg, 2016

4.7 Osteoporosis

Skeletal changes that occur naturally with aging include decreases in bone density, the wearing down of cartilage in joints and vertebral changes caused by weakening bones. Sodium, caffeine, and alcohol negatively impact bone density, while calcium, Vitamin D, and Vitamin K promote bone health. Osteoporosis occurs when osteoclasts break down bone faster than osteoblasts can rebuild it, increasing the risk of fractures. Therefore, having adequate calcium stores early in life impacts later fracture risk. Many older people with osteoporosis who break a hip never recover fully. Approximately 15% die within one year due to complications as their health further declines due to the injury (Berstein & Munoz, 2019). The elderly need to continue participating in strength-bearing exercises and get adequate amounts of Vitamin D and calcium to help support bone health. The most effective prevention for osteoporosis involves building strong bones early in life and maintaining bone mineral density during aging. A diet rich in calcium and Vitamin D paired with weight-bearing exercise helps maintain bone density throughout life. A more in-depth look into osteoporosis can be found in Chapter 5 – Nutrient Requirements. 

4.8 Sleep Changes

As with many other physiologic processes, there are a number of age-related changes in sleep that occur across the lifespan. Sleep requirements decrease as a person gets older. Total sleep time decreases from 10-14 hours a night for children to 6.5-8.5 hours a night for young adults, decreasing even further as a person ages to 5-7 hours a night (Bernstein & Munoz, 2019). It is important to distinguish the difference between age-appropriate changes and sleep problems.


Other elements that impact sleep may also change with age. Three changes may occur during aging that affect sleep: waking during the night, less REM sleep (restorative), and a decreased ability to compensate for reduced sleep hours. Sleep latency refers to the time it takes to fall asleep at the beginning of the night. Sleep latency often increases with age, causing older adults to need longer to fall asleep. Time spent awake at night often increases with age, along with prominent increases in wakefulness after sleep onset (being awake in the middle of the night) (Gooneratne & Vitiello, 2014). The odds of having sleep disturbances increase with poor health, suggesting that poor health may be a major driver of sleep problems. A final consideration is the degree of sleep debt – the difference between the actual amounts of sleep an individual obtains and the amount of sleep they need. Older adults may have fewer daytime symptoms from fragmented nocturnal sleep due to increased flexibility from retirement, allowing time for daytime naps.


Sleep disorders can impact health status by increasing the risk of health conditions and psychiatric disorders. Sleep disorders can be categorized into insomnia, hypersomnia, circadian rhythm disorders, sleep-breathing disorders, narcolepsy, and sleep movement disorders. The two most common of these found in older adults are insomnia and sleep apnea (a sleep-breathing disorder) (Gooneratne & Vitiello, 2014).


Insomnia is broadly defined as dissatisfaction with sleep. All insomnia diagnostic approaches generally include symptoms of difficulty falling asleep at bedtime, waking up in the middle of the night with difficulty going back to sleep, or waking up too early in the morning with difficulty returning to sleep (Gooneratne & Vitiello, 2014). Other symptoms may include daytime symptoms of fatigue or impaired concentration (Gooneratne & Vitiello, 2014).


Understanding the etiology of insomnia can be complicated as predisposing, precipitating and perpetuating factors must be identified (Gooneratne & Vitiello, 2014). These factors combine to raise the likelihood of experiencing insomnia. Examples of predisposing factors are demographic characteristics. Women over 45 are approximately 1.7 times more likely to have insomnia than men (Gooneratne & Vitiello, 2014). Divorced, separated or widowed individuals are also more likely to have insomnia. Lower levels of education attainment or income have also been linked to higher rates of insomnia (Gooneratne & Vitiello, 2014). Smoking and alcohol use has been linked to higher rates of insomnia in older adults. Precipitating factors are generally acute life stressors or medical conditions that may disrupt sleep. For example, individuals with respiratory symptoms, physical disability and fair to poor perceived health are at increased risk of developing insomnia (Gooneratne & Vitiello, 2014). Medications may contribute to developing insomnia. Perpetuating factors result in a persistence of insomnia. Once someone with predisposing and precipitating factors has developed acute insomnia, this will not necessarily develop into chronic insomnia unless perpetuating factors are present such as behavioral or cognitive changes resulting from acute insomnia. For example, a person may develop increased pre-sleep anxiety due to fear of having another night of insomnia (Gooneratne & Vitiello, 2014).


Effective management of insomnia requires setting realistic goals with the patient experiencing insomnia. Insomnia can be significantly improved, but patients may relapse or have occasional nights of poor sleep. There are several non-pharmacologic options to help treat insomnia. The most used include sleep hygiene and cognitive behavioural therapy. Sleep hygiene consists of several interventions that promote a stable sleep pattern and a non-disruptive environment (Gooneratne & Vitiello, 2014). These interventions can include maintaining a regular sleep/wake schedule, encouraging a non-disruptive sleep environment, reducing pre-sleep tension, and dietary/lifestyle modifications such as maintaining a healthy diet or not going to bed hungry (Gooneratne & Vitiello, 2014). Cognitive behavioral therapy for insomnia generally consists of six to ten sessions with a trained therapist to address counterproductive behaviours and cognitive beliefs that perpetuate insomnia. Pharmacological options include benzodiazepine sedatives, nonbenzodiazepine sedatives, melatonin-receptor agonists, and anti-depressants. There are risks associated with using pharmacologic methods to manage insomnia, including symptoms such as next-day sedation, confusion, falls and worsening depression and medication dependence.

Sleep Apnea

Sleep apnea, also referred to as sleep-disorded breathing and sleep-related breathing disorder, is a condition in which respiration ceases or decreases considerably in volume during sleep. This can be due to either upper airway obstruction, dysfunction in the neurological drive to breathe, or a combination of these two (Gooneratne & Vitiello, 2014). Risk factors for sleep apnea include excess weight, being male, being older, family history, and alcohol abuse. There is a clear age-related increase in the prevalence of sleep apnea since only 10% of young adults experience sleep apnea (Gooneratne & Vitiello, 2014). Sleep apnea has also been found to increase the risk of other medical conditions. The diagnosis of sleep apnea requires overnight polysomnography at an in-lab sleep facility (Gooneratne & Vitiello, 2014). Obstructive sleep apnea is characterized by complete cessation of breathing with evidence of upper thoracic effort, whereas in central sleep apnea, there are at least five central apneas per hour (cessation of breathing with absence of thoracic effort indicating a central origin).


Treatments for sleep apnea include a CPAP device, avoidance of alcohol and sedatives, and sleeping on one’s side and not one’s back. The impact of less sleep in older adults can increase the risk of cardiovascular disease, stroke, high blood pressure, and diabetes since it is more difficult to maintain a healthy weight without proper sleep. Lack of sleep also increases hunger, overall carbohydrate intake, and reduced physical activity levels (Gooneratne & Vitiello, 2014). Therefore, finding treatment options for sleep apnea in older adults is essential for good quality of life and nutritional status.

4.9 Anemia

Anemia is a condition where the body has an insufficient amount of red blood cells. Anemia caused by dietary intake are referred to as nutritional anemials. Anemia may also be related to chronic diseases. Almost 10% of older adults have some type of anemia (Bernstein & Munoz, 2019). Anemia is associated with substantial morbidity, including functional impairment and physical decline, increased rates of hospitalization, reduced mobility, and overall decreased quality of life (Berstein & Munoz, 2019). 

Iron-Deficiency Anemia

Iron-deficiency anemia rates are relatively low in the elderly population. In older adults, iron-deficiency anemia is commonly caused by chronic bleeding from the GI tract. Common causes of GI bleeding include peptic ulcers, hiatal hernias, gastritis, hemorrhoids, and cancers that affect the GI tract (Bernstein & Munoz, 2019). Signs and symptoms of iron-deficiency anemia include fatigue, shortness of breath, feeling cold, confusion, depression, dizziness or weakness, brittle nails, changing food taste, headache, sore tongue, pale coloured skin, dry and easily bruised skin, restless legs syndrome, and fast heartbeat. Eating iron-rich foods like red meat, pork, poultry, seafood, legumes, fortified grain products, and dark green vegetables can help maintain iron stores in the body. 

Anemia of Inflammation and Chronic Disease

The anemia of inflammation, traditionally known as anemia of chronic disease, is associated with medical conditions prevalent in the older adult population such as infection, thaumatological disorders, diabetes, liver disease, heart failure, and malignancy. Evaluation of nutrition status in the older adult population plays an important role in the diagnostic approach to anemia. Identifying underlying issues such as inadequate dietary folate, alcohol use and/or abuse, and reduction of cobalamin absorption secondary to atrophic gastritis, H. pylori infection, and use of gastric-acid-suppressing agents can help determine whether a nutritional approach will affect the underlying anemia (Bernstein & Munoz, 2019). To further complicate matters, older adults may have multiple causes of their anemia. Therefore, a full evaluation and several forms of treatment may be required to address the cause of the anemia (Bernstein & Munoz, 2019). 


This chapter has been adapted from ‘Nutrition Essentials’ by Stephanie Green and Kellie Shallal: https://open.maricopa.edu/nutritionessentials/

Creative Commons Attribution: BY NC SA


American Medical Association. (2008). Complete Guide to Prevention and Wellness. Hoboken, NJ: John Wiley & Sons, Inc.; 2008, 512.

Bernstein, M., & Munoz, N. (2019). Nutrition for the Older Adult. Jones & Bartlett Learning.

Carter, L. & Roe, A. (2019). Eating well in later life: Tips for looking after yourself as life changes. Malnutrition Task Force.

 CDC. (2021). Suffering from a urinary tract infection? https://www.cdc.gov/antibiotic-use/uti.html   

Centers for Disease Control (2017). Deaths and Mortality, National Center for Health Statistics. http://www.cdc.gov/nchs/fastats/deaths.htm.

Chung, J. I. (2008). Gastrointestinal Motility Variation and Oral Drug Absorption. [Thesis]. http://deepblue.lib.umich.edu/handle/2027.42/58439   

Dietitians Association of Australia and Dental Health Services Victoria (2015). Joint Position Statement on Oral Health and Nutrition.

Ehrlich, R., Harris, A., Kheradiya, N. S., Winston, D. M., Ciulla, T. A., & Wirostko, B. (2008). Age-related macular degeneration and the aging eye. Clinical Interventions in Aging, 3(3), 473.

Gooneratne, N. S., & Vitiello, M. V. (2014). Sleep in Older Adults. Clinics in Geriatric Medicine, 30(3), 591–627. https://doi.org/10.1016/j.cger.2014.04.007 

McMillan, B. (2008). Illustrated Atlas of the Human Body. Sydney, Australia: Weldon Owen, 2008, 260.

Neumann, W. L., Coss, E., Rugge, M., & Genta, R. M. (2013). Autoimmune atrophic gastritis—pathogenesis, pathology and management. Nature reviews Gastroenterology & Hepatology, 10(9), 529-541.

Orr, W. C., & Chen, C. L. (2002). IV. Clinical and physiological aspects of gastrointestinal motility and aging. American Journal of Physiology-Gastrointestinal and Liver Physiology, 283(6), G1226–G1231. https://doi.org/10.1152/ajpgi.00276.2002   

Rodriguez-Mañas, L. (2020). Urinary tract infections in the elderly: A review of disease characteristics and current treatment options. Drugs in Context, 9, 2020-4–13. https://doi.org/10.7573/dic.2020-4-13   

Rivlin, R. S. (2007). Keeping the young-elderly healthy: Is it too late to improve our health through nutrition? The American Journal of Clinical Nutrition, 86(5), 1572S-1576S.

Serra-Prat, M., Mans, E., Palomera, E., & Clavé, P. (2013). Gastrointestinal peptides, gastrointestinal motility, and anorexia of aging in frail elderly persons. Neurogastroenterology & Motility, 25(4), 291-e245. https://doi.org/10.1111/nmo.12055   

Shaw, C., & Wagg, A. (2017). Urinary incontinence in older adults. Medicine, 45(1), 23-27.

U.S. National Library of Medicine (2020, June 23). Nutrition for Older Adults. MedlinePlus. Retrieved August 18, 2020, from https://medlineplus.gov/nutritionforolderadults.html

Weck, M. N., Stegmaier, C., Rothenbacher, D., & Brenner, H. (2007). Epidemiology of chronic atrophic gastritis: Population-based study among 9444 older adults from Germany. Alimentary Pharmacology & Therapeutics, 26(6), 879–887. https://doi.org/10.1111/j.1365-2036.2007.03430.x 

Weyand M., Goronzy J. (Dec. 13, 2016). Aging of the immune system. Mechanisms and therapeutic targets. Annals of the American Thoracic Society. Suppl 5(Suppl 5):S422-S428. doi: 10.1513/AnnalsATS.201602-095AW. PMID: 28005419; PMCID: PMC5291468.

Zeng, G., Zhu, W., Lam, W., & Bayramgil, A. (2020). Treatment of urinary tract infections in the old and fragile. World Journal of Urology, 38(11), 2709–2720. https://doi.org/10.1007/s00345-020-03159-2   

Media Attributions

  • Screen Shot 2022-12-20 at 10.36.48 AM

About the authors


Icon for the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License

Chapter 4: Physiology of Aging and Nutritional Implications Copyright © 2023 by Tracy Everitt; Brittany Yantha; Megan Davies; and Sayuri Omori is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

Share This Book