6 Chapter 5: Nutrient Requirements for Older Adults

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

Chapter 5 Learning Objectives

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

Learning Objectives

  • Explain how energy and macronutrient needs change into older adulthood.
  • Describe how intakes of fat-soluble vitamins may change into older adulthood.
  • Describe how intakes of water-soluble vitamins may change into older adulthood.
  • Explain the importance of major and trace minerals in older adulthood.
  • Understand how fluid intake changes for older adults.

Nutrient needs change as adults get older. For example, people become less active, their metabolism slows, and energy requirements decrease. Older adults’ ability to absorb and utilize many nutrients becomes less efficient, increasing their nutrient requirements. Chronic conditions and medications can affect nutrition requirements as well. The Dietary Reference Intakes (DRIs) have been adjusted to reflect these changes and can be found at the following link: Government of Canada Dietary Reference Intakes


Maintaining a nutrient-dense diet promotes healthy aging. This chapter provides a summary of dietary recommendations for older adults.

5.1 Energy and Macronutrients

Due to lean body mass and metabolic rate reductions, older adults have lower caloric needs than younger adults. An estimated energy requirement range for people ages fifty-one and over are 1,600 to 2,200 calories for women and 2,000 to 2,800 calories for men, depending on activity level. Generally, food intake decreases with advancing age due to decreased appetite, feeling full for longer, and a lower metabolic rates. The Basal Metabolic Rate (BMR) decreases with age due to age-related declines in muscle mass, increase in fat mass, hormonal changes, and decreased physical activity. The Acceptable Macronutrient Distribution Ranges, or AMDRs, for carbohydrates, protein, and fat remain the same. Therefore, a common issue that older adults experience is maintaining macro- and micronutrient requirements as energy requirements decrease.


Older adults should focus on unrefined carbohydrates, such as whole grains over refined ones. Fibre is a plant-derived long-chain polysaccharide with important roles in the body as it aids in delaying gastric emptying and helps to reduce postprandial blood glucose levels. Fibre is important in preventing constipation and diverticulitis, which is more common as people age and may also reduce the risk of colon cancer.


Fats provide energy and help with nutrient absorption, mood, and brain function. Focusing on healthy fats such as omega-3 fatty acids can help lower triglycerides, reducing the risk of heart disease and stroke. Some foods high in omega-3 fatty acids include oily or fatty fish such as salmon, sardines, nuts and seeds such as walnuts, chia seeds, and ground flaxseeds, avocados, and foods fortified with omega 3, such as eggs, yogurt, and soy beverages. Margarine that contains trans fats may be worse for your heart than fats that contain saturated fat, such as butter. The healthiest fats are oils, such as olive and canola. The healthiest soft tub margarine are non-hydrogenated.


Protein has many important roles, even in the aging body. This macronutrient helps build and repair tissues and is a constituent of antibodies, hormones, and enzymes. Overall energy needs decrease while protein needs remain the same, making it more challenging to obtain adequate protein. Adequate protein intakes are recommended for older adults to discourage muscle wasting and decrease the risk of sarcopenia. Sources of protein for older adults should be lean to avoid the overconsumption of saturated fats.

5.2 Micronutrients

The recommended intake levels of several micronutrients are increased in older adulthood while others are decreased. Nutrient changes in older adulthood are most commonly a result of physiological changes due to aging. For example, calcium and Vitamin D recommendations increase for both men and women to slow bone loss. Higher iron levels are no longer needed post-menopause for older women, and recommendations decrease as a result. 

Fat-Soluble Vitamins

Fatsoluble vitamins are absorbed along with dietary fat. Low fat meals impair fat-soluble vitamin absorption. Once fat-soluble vitamins have been absorbed in the small intestine, they are packaged and incorporated into chylomicrons and other fatty acids and transported by the lymphatic system to the liver. The liver stores and exports these vitamins as needed, releasing them into the blood to transport them to the cells. 

Vitamin A

Vitamin A can be found in plant and animalderived food sources and is converted in the body to the biologically active forms of the vitamin: retinal and retinoic acid. Retinol is the preformed Vitamin A from animal-derived sources such as egg yolks, butter, liver, and fish liver oils; while carotenoids, including beta-carotene, come from plant-derived sources such as pumpkin, carrots, squash, spinach, tomatoes, and more. Carotenoids are not absorbed as well as retinols but are similar as they require fat in the meal for absorption. Retinoids are named for their primary function to aid in vision within the retina of the eye, especially in low-light conditions. Vitamin A is required for bone health, helps maintain vision, and has a significant role in immunity. The Recommended Daily Allowance (RDA) of Vitamin A for those aged 51+ is 900 RAE or 4500 IU for men and 700 RAE or 3500 IU for women. Intake above RDA is not advised due to the risk of accumulation. 


A deficiency in Vitamin A results in the decreased detection of low-level light, also defined as night-blindness. Insufficient intake of dietary Vitamin A over time can also cause complete vision loss. The beta-carotene form of Vitamin A also has antioxidant roles in the body as it is protective against heart disease, dementia, and cancer.


For further information on the effects of vitamin A on vision, immunity, growth and development, and cancer, here is a link to the Vitamin A section in Chapter 5B. 

Vitamin D

Vitamin D3 (calcitriol) helps regulate blood calcium levels in concert with the parathyroid hormone. Less than 15% of calcium is absorbed from foods or supplements without adequate Vitamin D intake. Therefore, the effects of Vitamin D on calcium status are significant for overall bone health. Adequate Vitamin D intake promotes muscle health and reduces the risk of cancer and cardiovascular disease. Food sources of Vitamin D include fatty fish, egg yolks, and fortified foods. Vitamin D can also be synthesized from sunlight. The ability to synthesize Vitamin D from sunlight into activated calcitriol decreases with age, so older adults need more exposure to sunlight to produce the required amount. The RDA for those aged 51+ increases from 15ug (600 IU) to 20ug (800 IU) for both men and women. Vitamin D deficiency is quite common among the older population due to reduced production in the skin and limited food sources. Chronic low levels of Vitamin D can cause low bone density and lead to other physiological issues.  


For further information on the health benefits of Vitamin D, here is a link to the Vitamin D section in Chapter 5B. 

Vitamin E

Alpha-tocopherol is the only form of Vitamin E recognized to meet human requirements among the eight chemical forms it occurs in. Alpha-tocopherol is primarily responsible for protecting cell membranes against lipid destruction caused by free radicals, making it an antioxidant for the human body. Vitamin E helps boost the immune system by helping fight off bacteria and viruses. It also enhances the dilation of blood vessels and inhibits the formation of blot clots. Because of its role in inhibiting clot formation, higher dosages of Vitamin E may interfere with the role of Vitamin K (blood clotting) and cause symptoms of toxicity such as nausea and vomiting. For dietary intake, vegetable oils, nuts and seeds, whole grains and dark leafy vegetables are sources of Vitamin E. The RDA for those aged 50+ is 15mg for both men and women, the same as for younger adults. Vitamin E deficiency is rare and usually is a result of underlying conditions.  

Vitamin E and Dementia

The brain’s high glucose consumption makes it more vulnerable than other organs to oxidative stress. Oxidative stress has been implicated as a significant contributing factor to dementia and Alzheimer’s disease. Some animal and non-interventional studies suggest Vitamin E supplements might have a role in preventing or treating Alzheimer’s disease and cognitive decline. However, a 2017 Cochrane review, concluded that Vitamin E did not reduce the number of people who developed dementia in intervention trials.


More studies are needed to better assess the dose and dietary requirements of Vitamin E and, for that matter, whether other antioxidants lower the risk of dementia, a disease that devastates the mind and puts a substantial burden on loved ones, caretakers, and society in general (Farina, Llewellyn, Isaac & Tabet, 2017).

Eye Conditions

Oxidative stress plays a role in age-related vision loss, called macular degeneration. Age-related macular degeneration (AMD) primarily occurs in people over age fifty. It is the progressive loss of central vision resulting from damage to the center of the retina, referred to as the macula. There are two forms of AMD, dry and wet, with wet being the more severe form.


In the dry form, deposits form in the macula; the deposits may or may not directly impair vision, at least in the early stages of the disease. In the wet form, abnormal blood vessel growth in the macula causes vision loss. Clinical trials evaluating the effects of Vitamin E supplements on AMD and cataracts (clouding of the lens of an eye) did not consistently observe a decreased risk for either. However, scientists do believe Vitamin E, in combination with other antioxidants such as zinc and copper, may slow the progression of macular degeneration in people with early-stage disease.

Vitamin K

Vitamin K is critical for blood function as it acts as a coenzyme, playing an essential role in blood coagulation. Therefore, a deficiency in Vitamin K can lead to bleeding disorders. Vitamin K deficiency is rare but can occur among people with diseases that cause malabsorption of nutrients, such as celiac disease or pancreatic cancer. Vitamin K is also required to maintain bone health as it modifies proteins involved in bone remodelling. Food sources of Vitamin K include green leafy vegetables, broccoli, brussels sprouts, cabbage, plant oils and margarine. The RDAs of Vitamin K for those aged 51+ are 120ug for men and 90ug for women, the same as younger adults.


For further information on the health benefits of vitamin K, here is a link to the Vitamin K section in Chapter 5B. 

Water Soluble Vitamins

Water-soluble vitamins are absorbed in the small intestine and transported to the liver through blood vessels. Most water-soluble vitamins are required as functional parts of enzymes involved in energy release and storage and are referred to as coenzymes.

Vitamin C

Vitamin C, commonly called ascorbic acid, is a water-soluble micronutrient essential in humans’ diets. Vitamin C is an effective antioxidant as it can easily donate electrons, effectively scavenging free radicals. It also protects lipids by disabling free radicals and aiding in the regeneration of Vitamin E. Vitamin C is required as a part of several enzymes for signaling molecules in the brain, hormones, and amino acids. Vitamin C levels in the body are affected by the amount consumed, influencing how much is absorbed and excreted. There also may be reduced absorption with increasing age. The RDAs for older adults are 90mg for men and 75 mg for women, the same as younger adults. Because Vitamin C is effective at scavenging free radicals, the Institute of Medicine (IOM) increased the RDA for smokers by 35 milligrams, as tobacco smoke is an environmental and behavioural contributor to free radicals in the body. Sources of Vitamin C include raw fruit and vegetables, as cooking can leach Vitamin C out of food.  

Cardiovascular Disease and Vitamin C

Vitamin Cs ability to prevent disease has been debated for many years. Overall, higher dietary intakes of Vitamin C (via food intake, not supplements) are linked to decreased disease risk. A 2019 review concluded that there is a limited role for Vitamin C supplementation in specific population groups (older people, individuals with lower Vitamin C status, and those at higher risk of cardiovascular disease) to improve cardiovascular health (Ahor et al., 2019). Vitamin C levels in the body have been shown to correlate well with fruit and vegetable intake, and higher plasma Vitamin C levels are linked to a reduced risk of some chronic diseases. 

Cancer and Vitamin C

There is some evidence that a higher Vitamin C intake is linked to a reduced risk of mouth, throat, esophagus, stomach, colon, and lung cancers, but not all studies confirm this. As with the studies on cardiovascular disease, the reduced cancer risk results from eating foods rich in Vitamin C, such as fruits and vegetables, not from taking Vitamin C supplements. In these studies, the specific protective effects of Vitamin C are inseparable from the many other beneficial constituents in fruits and vegetables. 

Immunity and Vitamin C

Vitamin C has several roles in the immune system, and many people increase Vitamin C intake either from diet or supplements when they have a cold. Many others take Vitamin C supplements routinely to prevent colds. However, contrary to this widespread practice, no good evidence exists that Vitamin C prevents a cold. A review of more than fifty years of studies published in 2004 in the Cochrane Database of Systematic Reviews concluded that taking Vitamin C routinely does not prevent colds in most people. Vitamin C deficiency, or Scurvy, impairs immunity, so while Vitamin C may not be able to prevent colds completely, adequate amounts will support immune function, such as reducing cold severity and duration (Carr et al., 2017). Moreover, taking mega doses (up to 4 grams per day) at the onset of a cold provides no benefits. In individuals hospitalized with pneumonia who had a low Vitamin C status, increasing their Vitamin C intake positively impacted reducing their symptoms (Carr et al., 2017). Vitamin C adequacy is important among the older population as their risk for disease and infection is already increased, and vitamin C has many positive health impacts.


Gout is a disease caused by elevated circulating levels of uric acid and is characterized by recurrent attacks of tender, hot, and painful joints. There is evidence that a higher Vitamin C intake reduces the risk of gout.

Vitamin B1 (Thiamin)

Thiamin is an essential vitamin for glucose metabolism. It acts as a cofactor for enzymes that break down glucose for energy production. Thiamin plays a key role in nerve cells as the glucose that is catabolized by thiamin is needed for an energy source. The brain and heart are most significantly affected by thiamin deficiency. Thiamin deficiency, also known as beriberi, can cause symptoms of fatigue, confusion, movement impairment, pain in the lower extremities, heart failure, and swelling of the heart. These symptoms are especially dangerous for older adults due to lower immune function. 


If thiamin deficiency (beriberi) progresses, it can lead to Wernicke-Korsakoff syndrome (NIH, 2023). Wernicke-Korsakoff syndrome is a neurological disorder that consists of two different stages: Wernicke’s encephalopathy, a degenerative brain disorder due to a Vitamin B1 deficiency associated with alcoholism (NIH, 2023), due to alcohol’s impairment of thiamin absorption (NIH, 2021). Wernicke encephalopathy presets as acute confusion, often reversible. Left untreated, this can lead to Korsakoff syndrome, which includes gait abnormalities and memory loss, which is often irreversible. Without intervention, Wernicke-Korsakoff may progress to coma and death. Other individuals at risk include those who consume diets typically low in micronutrients, such as those with eating disorders, older adults, and those who have undergone gastric bypass surgery (NIHb, 2019).


For further information on the dietary sources and fortification guidelines of Thiamin, here is a link to the Thiamin section of Chapter 5B. 

Vitamin B6 (Pyridoxine)

Overall, the B vitamins play especially important roles in metabolism. Vitamin B6 is the coenzyme involved in a wide variety of functions in the body, and most commonly aids in the synthesis and metabolism of proteins. The requirements for Vitamin B6 are affected by age as the aging body experiences a decline in active forms of the vitamin, more rapid hydrolysis, and longer times for Vitamin B6 repletion. The DRIs for Vitamin B6 are higher for older age groups to aid in metabolic turnover, especially since deficits are common in this age group. The RDAs for adults aged 70+ are 1.7 mg for men and 1.5 mg for women. Food sources of this vitamin include fortified cereals, fish, meats, bananas, beans, peanut butter, and most vegetables.


For further information on the dietary sources of Vitamin B6, here is a link to the Vitamin B6 section of Chapter 5B. 


Folate is a required coenzyme for synthesizing methionine and making RNA and DNA. Therefore, rapidly dividing cells are most affected by folate deficiency, such as red and white blood cells and platelets. When folate is deficient in the body, cells cannot divide normally. Low folate levels result in macrocytic or megaloblastic anemia- unusually large, abnormal, immature red blood cells containing less hemoglobin. OTC medications such as aspirin and antacids can interfere with the bodys uptake and handling of folate. Therefore, the prevalence of deficiency among older adults can be quite high. Low levels of folate in older adults are often associated with cognitive impairment. For adults aged 70+, the RDA for folate is 400ug per day, the same as for younger adults. Avoiding folate toxicity is important as higher levels of this micronutrient can mask Vitamin B12 deficiency and speed up cognitive decline in those who are Vitamin B12 deficient. Food sources of folate include liver, leafy greens, fortified grain products and citrus fruits.  

Vitamin B12 (Cobalamin)

Vitamin B12 is essential for coenzymes for fat and protein catabolism, folate coenzyme function, and hemoglobin synthesis. A folate-dependent enzyme needs an enzyme requiring Vitamin B12 to synthesize DNA. Thus, Vitamin B12 deficiency has similar consequences as folate deficiency and can lead to macrocytic anemia. Higher levels of folate in the body can also mask deficiency of Vitamin B12. Food sources of Vitamin B12 are animal sources and fortified foods.


The aging process causes changes in the gut, which in turn can affect the absorption of Vitamin B12. Low amounts of hydrochloric acid (HCl) in the stomach affect the ability to cleave Vitamin B12 from its protein sources. Cells in the stomach secrete a protein called intrinsic factor (IF), necessary for Vitamin B12 absorption, which occurs in the small intestine. Secretion of IF can be compromised by an autoimmune disease or chronic stomach inflammation (such as that occurring in some people with H.pylori infection), leading to pernicious anemia, a type of macrocytic anemia. Vitamin B12 malabsorption is most common in older adults, who may have impaired functioning of digestive organs, a normal consequence of aging. Pernicious anemia is treated by large oral doses of Vitamin B12 or by putting the vitamin under the tongue, where it is absorbed into the bloodstream without passing through the intestine. In patients who do not respond to oral or sublingual treatment, Vitamin B12 is given by injection.


Older adults are much more susceptible to Vitamin B12 deficiency as absorption becomes less efficient with aging (Dietitians of Canada, 2019). Older adults may have decreased acid secretion in the stomach, or atrophic gastritis, diminishing its capacity to free Vitamin B12 from food proteins (Stover, 2010). Some pharmaceuticals, such as proton pump inhibitors, decrease gastric acid secretion, inhibiting B12’s ability to be freed from protein, resulting in decreased absorption (Stover, 2010). However, these drugs do not affect supplemental B12 as it is not bound to protein (Stover, 2010). Prolonged Vitamin B12 deficiency can contribute to cognitive decline, such as dementia (Stover, 2010). Health Canada advises adults over 50 to consume foods fortified with Vitamin B12 or a supplement containing Vitamin B12, to meet the RDA (Dietitians of Canada, 2019).

5.5 Minerals


Calcium is the most abundant mineral in the body, and over 99% of it is stored in bone tissue. Though less than 1% of calcium in the human body is found in the blood and soft tissues, this is where calcium performs its most critical functions. Here calcium is required for blood clotting, nerve transmission, muscle contraction and relaxation, cell membrane permeability and enzyme activation. Blood calcium levels are regulated so that if blood levels drop, the body will rapidly respond by stimulating bone breakdown, which releases stored calcium from the bones to the blood. Therefore, bone health depends on dietary calcium intake, yet blood calcium levels do not respond to dietary calcium intake. Increased calcium intake helps to increase the mineralized content of bone tissue. Greater mineralized bone tissue corresponds to a greater bone mineral density (BMD) and bone strength. The active form of Vitamin D, calcitriol, is the active hormone that acts on the intestinal cells and increases dietary calcium absorption. As a result, adequate Vitamin D intake is important for maintaining bone health.


As people age, calcium bioavailability is reduced, the kidneys lose their capacity to convert Vitamin D to its active form, the kidneys are no longer efficient in retaining calcium, the skin is less effective at synthesizing Vitamin D, there are changes in overall dietary patterns, and older people tend to get less exposure to sunlight. Thus, the risk of calcium inadequacy and bone loss are great (NIH, 2019). Due to this, a negative calcium balance is common among older people. Age-related bone loss can occur, so RDA for calcium increases from middle adulthood to older adulthood. The RDA for women over the age of 50 and men 71 years and older is 1200 mg, greater than the 1000 mg recommended for women under 50 and men under 70. Estrogen enhances calcium absorption, so the decline in this hormone during and after menopause puts postmenopausal women at risk for calcium deficiency. Decreases in estrogen production are responsible for an increase in bone resorption and a decrease in calcium absorption. During the first years of menopause, annual decreases in bone mass range from 3–5 percent. After age sixty-five, decreases are typically less than 1 percent (NIH, 2011). Calcium food sources include dairy products, fortified plant-based milks, edamame, seeds, canned sardines and salmon, beans, lentils, and squash.

Other Health Benefits of Calcium in the Body

Besides forming and maintaining strong bones and teeth, calcium has been shown to have other health benefits for the body, including:

Cancer: The National Cancer Institute reports that there is enough scientific evidence to conclude that higher intakes of calcium decrease colon cancer risk and may suppress the growth of polyps that often precipitate cancer. Although higher calcium consumption protects against colon cancer, some studies have looked at the relationship between calcium and prostate cancer and found higher intakes may increase the risk for prostate cancer.  However, the data is inconsistent, and more studies are needed to confirm any negative association.

Blood pressure: Multiple studies provide evidence that higher calcium consumption reduces blood pressure. A review of twenty-three observational studies concluded that for every 100 milligrams of calcium consumed daily, systolic blood pressure is reduced 0.34 millimeters of mercury (mmHg) and diastolic blood pressure is decreased by 0.15 mmHg.1

Kidney stones: Another health benefit of a high dietary calcium intake (not supplemental) is that it blocks kidney stone formation. Calcium inhibits the absorption of oxalate, a chemical in plants such as parsley and spinach, which is associated with an increased risk of developing kidney stones. Calcium’s protective effects on kidney stone formation occur only when you obtain calcium from dietary sources. Calcium supplements may increase the risk of kidney stones in susceptible people.

Osteoporosis is the excessive loss of bone over time. It leads to decreased bone strength and increased susceptibility to bone fracture. Loss of bone mass leads to reduced bone strength and breaks and fractures happen easily. Bone mass refers to the total weight of bone tissue in the human body. It is estimated that more than 200 million people have osteoporosis. According to recent statistics from the International Osteoporosis Foundation (IOG), worldwide, 1 in 3 women over 50 years and 1 in 5 men will experience osteoporotic fractures in their lifetime (Sozen et al., 2017). Bones grow and mineralize during infancy, childhood, and puberty. During this time, bone growth exceeds bone loss. By age twenty, bone growth is complete, and only a small amount (about 10 percent) of bone mass accumulates in the third decade of life. By age thirty, bone mass is at and then gradually declines after age forty. Bone mass refers to the total weight of bone tissue in the human body. The greatest quantity of bone tissue a person develops during their lifetime is called peak bone mass. The decline in bone mass after age forty occurs because bone loss is greater than bone growth. Several factors lead to loss of bone quality during aging, including reduced hormone levels, decreased calcium absorption, and increased muscle deterioration. It is comparable to being charged with maintaining and repairing the structure of your home without having all the necessary materials to do so. However, there are many ways to maximize bone health at any age.  


Osteoporosis is a silent disease, like high blood pressure, because symptoms are rarely exhibited until a serious problem occurs. Someone with osteoporosis may not know they have the disease until they experience a bone break or fracture. Detection and treatment of osteoporosis before fracture occurrence can significantly improve the quality of life. A dual x-ray absorptiometry (DEXA) scan measures bone mineral density to detect osteopenia or osteoporosis.


Osteoporosis is categorized into two types that differ by the age of onset and the type of bone tissue most severely deteriorated. Type 1 osteoporosis, also called postmenopausal osteoporosis, most often develops in women between the ages of fifty and seventy. Estrogen plays a role in maintaining bone mass by increasing calcium bioavailability and increasing osteoblast (bone formation) activity. Reduced estrogen levels lead to increased osteoclast activity, accelerating bone loss. Trabecular tissue is more severely affected because it contains more osteoclasts cells than cortical tissue. Type 1 osteoporosis is commonly characterized by wrist and spine fractures. Type 2 osteoporosis is also called senile osteoporosis and typically occurs after seventy. It affects women twice as much as men and is most often associated with hip and spine fractures. In Type 2 osteoporosis, both the trabecular and cortical bone tissues are significantly affected. Not everybody develops osteoporosis as they age.


During both types of osteoporosis, bone mineral density decreases, and the bone tissue microarchitecture is compromised. Excessive bone resorption in the trabecular tissue increases the size of the holes in the lattice-like structure, making it more porous and weaker. A disproportionate amount of resorption of the strong cortical bone causes it to become thinner. The deterioration of one or both types of bone tissue causes bones to weaken and become more susceptible to fractures.

Calcium Supplements: Which One to Buy

Many people choose to fulfill their daily calcium requirements by taking calcium supplements. Calcium supplements are sold primarily as calcium carbonate, calcium citrate, calcium lactate, and calcium phosphate, with elemental calcium contents of about 200 milligrams per pill. It is important to note that calcium carbonate requires an acidic environment in the stomach to be used effectively. Although this is not a problem for most people, it may be for those on medication to reduce stomach acid production or for older adults with a reduced ability to secrete acid in the stomach. For these people, calcium citrate may be a better choice. Otherwise, calcium carbonate is the cheapest. The body can absorb about 30 percent of the calcium from these forms. 

Calcium Bioavailability

In the small intestine, calcium absorption primarily takes place in the duodenum (first section of the small intestine) when intakes are low, but calcium is also absorbed passively in the jejunum and ileum (second and third sections of the small intestine), especially when intakes are higher. The body does not completely absorb all the calcium in food. Interestingly, the calcium in some vegetables such as kale, Brussel sprouts, and Bok choy is better absorbed by the body than dairy products. About 30 percent of calcium is absorbed from milk and other dairy products.


The greatest positive influence on calcium absorption comes from having an adequate intake of Vitamin D. People deficient in Vitamin D absorb less than 15 percent of calcium from the foods they eat. The hormone estrogen is another factor that enhances calcium bioavailability. Thus, as a woman ages and goes through menopause, during which estrogen levels fall, calcium absorption decreases, and the risk for bone disease increases. Some fibres, such as inulin in jicama, onions, and garlic, also promote intestinal calcium uptake.


Chemicals that bind to calcium decrease their bioavailability. Substances negatively affecting the bioavailability of calcium absorption include oxalates in certain plants, tannins in tea, and phytates in nuts, seeds, grains, and some fibres. Oxalates are found in high concentrations in spinach, parsley, cocoa, and beets. Calcium bioavailability is inversely correlated to the oxalate content in foods. High-fibre, low-fat diets also decrease the amount of calcium absorbed, an effect related to how fibre and fat influence the time food stays in the gut. Anything that causes diarrhea, including sickness, medications, decreases the transit time of calcium in the gut and, therefore, reduces calcium absorption. As we get older, stomach acidity sometimes decreases, diarrhea occurs more often, kidney function is impaired, and Vitamin D absorption and activation are compromised, all of which contribute to a decrease in calcium absorption.


Sodium is vital in maintaining fluid balance and many other essential bodily functions, such as muscle function. In contrast to many minerals, sodium absorption in the small intestine is highly efficient and in a healthy individual, the kidneys excrete all excess sodium. In fact, little sodium is required in the diet (about 200 milligrams) because the kidneys actively reabsorb it. A typical North American diet today is  high in sodium, especially if a person consumes many processed and pre-packaged foods. High sodium intake can have profound consequences for people with compromised kidney function. In addition, during aging, the kidneys often become less efficient at excreting excess sodium from the blood. Adequate Intake (AI) for sodium is 1500mg/day for all individuals above the age of 14, and it is recommended to keep intake below 2300mg/day. There are links between sodium and calcium in the body since the same cellular systems regulate both minerals. When the body tries to excrete excess sodium from the body, it also removes calcium. Calcium excretion in the urine can increase one’s risk for kidney stones and osteoporosis.


The typical Canadian diet today is quite high in sodium, often providing > 2,300 milligrams daily. This is especially true if a person eats a lot of processed or packaged foods. Excess sodium intake may not be a problem for young people with healthy kidneys. However, high sodium intake can seriously affect people with compromised kidney function. In addition, during the normal aging process, the kidneys often become less efficient at excreting excess sodium from the blood. In either case, compromised kidney function results in fluid retention in the blood, leading to higher pressure within the blood vessels. This condition is known as high blood pressure or hypertension. With age, salt sensitivity- how sensitive the body is to increasing blood pressure in response to high sodium intake- increases, putting more strain on the kidneys. This can be  addressed by decreasing sodium intake.


Most of the body’s magnesium stores are in the skeleton, contributing to bone structure. Magnesium is needed to produce and release parathyroid hormone. This hormone increases calcium levels when they are low by stimulating the release of calcium from bones, increasing intestinal absorption, and decreasing urinary calcium losses. Not surprisingly, higher intakes of magnesium are associated with higher bone mineral density, reducing the risk of osteoporosis.


Magnesium status can change as a person ages. The body’s ability to absorb magnesium declines with age, and urinary excretion increases. The RDAs of magnesium for males over 19 is 420mg/day, and for females over 19 is 320mg/day. The upper limit for magnesium is specific to supplemental magnesium and is 350 mg. High-dose supplements can cause diarrhea, nausea and cramping when used in excess. Dietary sources of magnesium include green leafy vegetables, fruits, grains, nuts, pork, beef, poultry, and fish. Seafood such as clams, shrimp and crab meat are also good sources of magnesium. Magnesium absorption problems can occur with certain medications, a restrictive diet or malnutrition, laxative use, chronic alcohol abuse, kidney disease, and antiacid toxicity.

5.6 Trace Minerals


Red blood cells contain the oxygen-carrier protein hemoglobin, composed of four globular peptides, each containing a heme complex. Iron is in the center of each heme. Many electron-transport chain proteins have iron-sulfur clusters involved in transferring high-energy electrons, leading to ATP synthesis. Iron is also involved in numerous metabolic reactions that take place in the liver and work to detoxify harmful substances. When blood cells are decommissioned, the body recycles the iron back to the bone marrow, where red blood cells are made. The body stores some iron in the bone marrow, liver, spleen, and skeletal muscle. A small amount of iron is excreted when cells lining the small intestine and skin cells die and during blood loss, such as during menstrual bleeding. Lost iron must be replaced with dietary sources.


The bioavailability of iron is highly dependent on the dietary source. Animal-based foods have higher iron bioavailability than plant-based sources, as animal-derived iron contains heme iron. Some plants contain phytochemicals that inhibit the uptake of iron. Other conditions, such as celiac disease, Crohn’s disease and some cancers, can cause iron malabsorption. The RDA for iron does not change for men as they age. Postmenopausal women see decreases in RDAs for iron since they no longer experience loss from their menstrual cycle. A deficiency of iron in the body can lead to microcytic, hypochromic anemia and can be caused by bleeding, chronically low energy intakes, low intake of protein-rich food sources, and low stomach acid levels.


For further information on enhancers and inhibitors of iron absorpotion, here is a link to the Iron section of Chapter 5B. 


Zinc is a cofactor for over two hundred enzymes in the body and plays a direct role in RNA, DNA, and protein synthesis. In addition, zinc is a cofactor for enzymes involved in energy metabolism. Absorption of zinc is high in diets rich in animal protein. Food sources of zinc include meat, seafood, whole grains, and legumes. Higher intakes of zinc can cause copper deficiency and impair the immune system, while low intakes of zinc affect immune response and wound healing abilities. The RDA for all adults, including older adults, for zinc is 11mg/day for men and 8mg/day for women.


Older adults are at an increased risk of developing pressure ulcers, along with other changes to their gastrointestinal tract and muscles. Also, older adults are at an increased risk of developing zinc deficiency due to malabsorption in the intestine, low intake in the diet, or disease that develops with age {Nakamura et al., 2019}. Those who develop pressure ulcers have a lower serum zinc concentration, contributing to a prolonged healing time (Nakamura et al., 2019).


For further information on Zinc, here is a link to the Zinc section in Chapter 5B. 

5.7 Water

Water is an essential nutrient for metabolic reactions and is a transport medium. Water supports vital bodily functions; therefore, inadequate water intake can cause problems such as increased vulnerability to drug toxicity, susceptibility to heat exhaustion, constipation, and issues in the kidneys. One’s body composition influences total body water; a drop in bodily water composition is seen with aging. Older adults are more at risk for dehydration, which can be fatal in some circumstances. Recommendations are set to meet metabolic and functional needs and to avoid dehydration. For those aged 51+, men should consume 3.7L/day, and women should consume 2.7L/day. These fluid intakes are expected to come from water, though other beverages and food naturally contain water too. 


This chapter was adapted from ‘Nutrition 100: Nutritional Applications for a Healthy Lifestyle’ by Lynn Klees: https://psu.pb.unizin.org/nutr100/

Creative Commons Attribution: BY NC SA


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Chapter 5: Nutrient Requirements for Older Adults 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.

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