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Because of low intakes in the US and many other countries, nutrients of public health concern have been identified for older adults. These include several vitamins (choline, riboflavin, thiamin, and vitamins A, C, D, and E) and minerals (calcium, magnesium, potassium, and selenium) (Table 16.3).^7,8 In the US, several of these nutrients are added to foods, especially riboflavin, thiamin, vitamin A, vitamin D, vitamin E, and iron, while selenium is added to foods (and fertilizers) in some countries with low selenium in the soil (e.g. Finland⁹). With the exception of choline and potassium, these nutrients of concern are typically found in nutritionally significant amounts in multivitamin‐mineral (MVM) supplements (Table 16.3).

Calcium and vitamin D are widely recognized for their roles in bone health and have many other functions such as differentiation, growth, immunity, insulin secretion, blood pressure, and neuromuscular function.⁵ Menopause leads to bone loss through decreased oestrogen that increases bone resorption and decreases calcium absorption. Adequate calcium and vitamin D intake throughout life protects skeletal health. Recommended daily intakes after age 50 are 1000–1200 mg for calcium and 800 IU (20 μg) (AI) for vitamin D.³ The UL for calcium after age 51 is 2000 mg daily, and the UL for vitamin D after age 9 is 4000 IU (100 μg) daily.³ Although there is no clinical biomarker for calcium status, vitamin D status can be assessed through serum/plasma 25‐hydroxyvitamin D.¹⁰ At a minimum, 25‐hydroxyvitamin D concentrations less than 25–30 nmol/L (10–12 ng/ml) should be treated. There is no clear consensus as to what constitutes adequacy, although a concentration of 50 or more nmol/L is often used.¹⁰

Vitamin B12 (cobalamin) malabsorption is common in older adults and is often associated with atrophic gastritis.^3,5,11 About 10 to 30% of older adults malabsorb food‐bound vitamin B12, so it is recommended that those age 50 and older meet the RDA mainly by consuming foods fortified with vitamin B12 or a supplement containing B12. Pernicious anaemia is characterized by a lack of intrinsic factor and occurs in 1 to 2% of older adults. Loss of intrinsic factor markedly decreases vitamin B12 absorption in the gastrointestinal tract. Although pernicious anaemia is usually treated with intramuscular vitamin B12, oral doses are also effective.^3,5,11 Vitamin B12 deficiency is usually thought of as mainly causing anaemia (macrocytic anaemia). However, other common signs of vitamin B12 deficiency are fatigue, weakness, loss of appetite, weight loss, and neurological symptoms such as numbness and tingling in hands and feet, balance problems, depression, confusion, dementia, poor memory, and/or soreness of the mouth or tongue.

Iron deficiency is less prevalent in older people than in younger age groups.⁵ Iron deficiency can cause microcytic anaemia and should not be confused with the microcytic anaemia of chronic disease; standard laboratory tests can distinguish these two conditions (serum ferritin, C‐reactive protein). Iron‐deficiency anaemia is associated with gastrointestinal disturbances, weakness, and fatigue as well as impaired concentration, cognitive function, immune function, exercise or work performance, and temperature regulation. Atrophic gastritis, some medications, and other conditions that cause achlorhydria can impair intestinal iron absorption. For health reasons, older people may decide to avoid red meat, which contains the most bioavailable form of iron as heme iron in haemoglobin and myoglobin. Individuals of any age who follow vegetarian and vegan dietary patterns have a higher requirement for iron because of low availability and absorbability of iron from plant‐based diets. Also, MVM supplements marketed to older adults typically contain very little iron to address the lower requirement for iron among postmenopausal women, as well as hereditary hemochromatosis that involves life‐long accumulation of iron,⁵ and thus do not provide repletion for iron deficiency. In the choice of iron supplements for treatment of deficiency, the more bioavailable form, which is ferrous iron (+2), should be selected rather than ferric iron (+3).

Table 16.3 Function, deficiency, age‐related changes, food sources, and supplements.

Nutrient	Function	Deficiency diseases or symptoms	Age‐related changes in metabolism	Low intakes so of public health concern	Primary food sources	Commonly fortified or enriched foods (US)	Types of supplements (US)	Chemical forms or methods of exposure of interest
Calcium	Major mineral in bones and teeth; circulating calcium tightly regulated by parathyroid hormone (PTH)	Very low bone density (osteoporosis) and increased risk of fractures	AI increases for women at age 50 and increases for men after age 70; ageing decreases intestinal absorption	Yesa, b	Milk products, some green leafy vegetables	Milk products, most fluid milk, some yoghurts, some cereals	Single or with vitamin D, some MVMs	Calcium‐citrate better absorbed than calcium‐carbonate; calcium‐carbonate in some antacids (e.g. Tums)
Chromium	Enhances insulin action; role in metabolism and storage of carbohydrate, fat, and protein in the body	Some rare reports of chromium deficiency in hospitalized patients who were fed intravenously	AI decreases at age 51 for men and women; ageing‐associated decrease in chromium in hair, sweat, and blood		Meat, whole grains, some fruits and vegetables	Some meal‐replacement beverages (e.g. Boost Plus, Ensure Plus)	MVMs, single, complex with selected vitamins or minerals	Chromium+3 is biologically available; chromium picolinate is biologically available; but chromium+6 is toxic and not used in foods or supplements
Choline	Source of methyl groups for metabolism, phospholipids, acetylcholine, gene expression, cell signalling; liver production in liver not sufficient to meet human needs	Muscle damage, liver damage, and nonalcoholic fatty liver disease (NAFLD or hepatosteatosis)	AI does not change after age 19	Yesa	In plant and animal foods; in US, main sources are meats, poultry, fish, milk products, and eggs	Some meal‐replacement beverages (e.g. Boost Plus, Ensure Plus)	Single
Vitamin B12 (cobalamin)	Red blood cell formation, neurological function, and DNA synthesis	Megaloblastic anaemia, fatigue, weakness, loss of appetite, weight loss, neurological symptoms	Impaired intestinal absorption from atrophic gastritis or pernicious anaemia		Milk products, meat, fish, poultry, eggs	Some cereals	MVMs, single, B‐complex	After age 50, the chemical form found in supplements or fortified foods is recommended, as it is better absorbed than the protein‐bound food form
Folic acid (folate)	Coenzyme or cosubstrate in single‐carbon transfers in the synthesis of nucleic acids (DNA and RNA) and metabolism of amino acids	Megaloblastic anaemia, weakness, fatigue, difficulty concentrating, irritability, headache, heart palpitations, shortness of breath	RDA does not change after age 19		Vegetables (especially dark green leafy vegetables), fruits and fruit juices, nuts, beans, peas, seafood, eggs, milk products, meat, poultry, grains	Grains, cereals	MVMs, single, B‐complex	Folic acid in fortified foods and supplements is better absorbed than food folates
Iron	In haemoglobin, myoglobin, and numerous enzymes and protein; required for growth, neurological development, and synthesis of some hormones	Iron deficiency causes in late stages microcytic anaemia that should be distinguished from microcytic anaemia of chronic disease, exercise	RDA decreased for women after age 50; menopausal cessation of menstrual bleeding leads to lower requirement for iron		Heme iron in meat, poultry, fish, non‐heme in nuts, beans, vegetables, fortified grain products	Grains, cereals	Single, MVMs at low levels in products formulated for older adults	Heme iron from muscle foods is more bioavailable than non‐heme iron; vegetarians and vegans have higher requirement for iron because of low availability of iron in plant‐based diets
Magnesium	Cofactor in >300 enzymes, e.g. for protein synthesis, muscle and nerve function, blood glucose control, and blood pressure regulation	Numbness, tingling, muscle contractions and cramps, seizures, abnormal heart rhythms, coronary spasms; signs of severe deficiency are hypocalcemia or hypokalemia	RDA increases at age 31; intestinal absorption decreases and renal excretion increases with age	Yesa, b	Many plant and animal foods, e.g. green leafy vegetables, legumes, nuts, seeds, and whole grain	Some grains, cereals	Some MVMs, single, complex e.g. with ‘bone’ health nutrients	In some laxatives, e.g. Phillips’ Milk of Magnesia and some products for indigestion, e.g. Extra‐strength Rolaids
Niacin (vitamin B3)	Niacin as nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NDP) are coenzymes in oxidation‐reduction reactions	Severe deficiency disease is pellagra, with symptoms of dermatitis, diarrhoea, neurologic deficits, including cognitive decline	RDA does not change after age 19		Meat, fish, poultry, legumes, whole grains	Grains, cereals	MVMs, single, B‐complex	Dietary tryptophan can be metabolized to niacin; foods rich in tryptophan (e.g. dairy products) can compensate for inadequate dietary niacin
Potassium	The major intracellular cation, required for normal cellular function	Severe deficiency is hypokalemia with cardiac arrhythmias, muscle weakness, glucose intolerance	AI does not change after age 19	Yesa	Dark green leafy greens, fruits, vegetables	A food additive in some processed foods; typically not added for nutritional benefits	Less than 100 mg in over‐the‐counter supplements	Amount in supplements is low to help avoid interactions with medications that alter potassium retention or excretion
Pyridoxine (vitamin B6)	More than 100 enzymes, mainly in metabolism of one‐carbon units, protein, carbohydrates, lipids, neurotransmitters, immune function, haemoglobin, and maintaining normal homocysteine levels	Microcytic anaemia, EEC abnormalities, dermatitis, glossitis, depression, confusion, low immunity	RDA higher for adults after age 50		Fish, poultry, meat, some beans, fruits and vegetables, especially chickpeas, bananas, and potatoes	Grains, cereals	MVM, single, B‐complex
Riboflavin (vitamin B2)	In coenzymes flavin‐mononucleotide (FMN) and flavin‐adenine dinucleotide (FAD)	Skin disorders particularly, lips, mouth, throat, degeneration of liver and nervous system	RDA does not change after age 19	Yesb	Milk products, eggs, meat, poultry, fish, green vegetables	Grains, cereals	MVMs, single, B‐complex
Selenium	Selenoproteins involved in reproduction, thyroid hormone metabolism, DNA synthesis, and protection from oxidative damage and infection	Severe deficiency diseases in specific geographical regions (e.g. China, Tibet, Siberia) are Keshan (cardiomyopathy) and Kashin‐Beck (osteoarthritis)	RDA does not change after age 19	Yesb	Breads, grains, meat, poultry, fish, and eggs	Some meal‐replacement beverages (e.g. Boost Plus, Ensure Plus)	MVMs, single	Food and/or supplement forms are bioavailable and include selenomethionine, selenium‐enriched yeast, selenite, selenate
Thiamin (vitamin B1)	Coenzyme for metabolism of carbohydrates and branched‐chain amino acids	Severe deficiency is beriberi, which involves peripheral neuropathy and wasting; also Wernicke‐Korsakoff syndrome associated with chronic alcoholism	RDA does not change after age 19	Yesb	Meat, fish, poultry, legumes, nuts, seeds	Grains, cereals	MVM, single, B‐complex
Vitamin A	Immune function, vision, reproduction, and cellular communication	Blindness increases the severity and mortality risk of infections	RDA does not change after age 19, although ageing is associated with decreased clearance of vitamin A	Yesb	Milk products, fish meat, some fruits and vegetables	Milk products, grains, cereals	MVMs, single	Human diet has preformed vitamin A (retinol and its esterified form, retinyl esters, in animal source foods) and provitamin A carotenoids (beta‐carotene, alpha‐carotene and beta‐cryptoxanthin)
Vitamin C (ascorbic acid)	Synthesis of collagen, L‐carnitine, some neurotransmitters, protein metabolism, wound healing	Severe deficiency known as scurvy	RDA does not change after age 19; increased requirement for smokers	Yesa	Fruits, vegetables, especially citrus fruits, tomatoes and tomato juice	Some fruit drinks, some cereals	MVMs, single, antioxidant complex	Can be low in canned fruits and vegetables, as well as lost with prolonged cooking
Vitamin D	Bone mineralization, calcium and phosphorus homeostasis	Muscle weakness, poor immune function and bone health (osteomalacia)	RDA increased after age 70 in men and women	Yesa, b	Highest in fatty fish; small amount in meat, cheese, egg yolks	Fortified milk products, fluid milk, some yoghurts, some fruit drinks, some orange juice	MVMs, single, with calcium	Vitamin D3 (cholecalciferol) is preferred form as it is more bioavailable than vitamin D2 (ergocalciferol); high‐dose injections available under medical supervision, but lower daily doses may be preferable10
Vitamin E	Antioxidant, immune function, cell signalling, regulation of gene expression, and other metabolic processes	Rare; may occur with fat‐malabsorption with symptoms of peripheral neuropathy, ataxia, skeletal myopathy, retinopathy, poor immunity	RDA does not increase after age 19	Yesa	Vegetable oils, nuts, seeds, whole grains, and green leafy vegetables	Cereals	MVMs, single, antioxidant complex	Alpha‐tocopherol is considered the essential form; there are numerous other chemical forms
Vitamin K	Blood clotting (prothrombin), bone metabolism (osteocalcin)	Clinically relevant when prothrombin time is increased	AI does not increase after age 19		Green leafy vegetables	Boost Plus	MVMs at low levels in supplements formulated for older adults	Phylloquinone is present primarily in green leafy vegetables and is the main dietary form of vitamin K; menaquinones produced by gut bacteria may satisfy some of the requirement for vitamin K
Zinc	More than 100 enzymes, protein, immunity, protein synthesis, wound healing, cell division	Loss of appetite, impaired immunity, diarrhoea, eye and skin lesions, taste abnormalities	RDA does not change after age 19		Meats, poultry, fish, milk products, and eggs	Some cereals, grains	MVMs, single	Zinc is more bioavailable from animal‐sourced foods than from plants

AI, adequate intake; MVM, multivitamin‐mineral supplement; RDA, recommended dietary allowance; UL, tolerable upper intake level; AI, RDA, and UL are terminology used in the US and Canada.³

Source: Adapted from NASEM³; US National Institutes of Health, Office of Dietary Supplements⁵; USDA⁶; USDHHS, USDA⁷.

^a Considered nutrients of concern because of low intakes in the US.⁷

^b Considered nutrients of concern from systematic review and meta‐analysis in community‐dwelling older adults; vitamin D, thiamin, riboflavin, Ca, Mg, and Se.⁸

Vitamin C is well known for being an antioxidant and is also needed for collagen formation.⁵ The severe vitamin C deficiency disease is known as scurvy, with symptoms of petechiae, ecchymoses, purpura, joint pain, poor wound healing, hyperkeratosis, swollen and bleeding gums, and tooth loss. Vitamin C also promotes iron absorption, especially the inorganic non‐heme forms of iron. Individuals who avoid fruits and vegetables and/or consume only the canned forms of fruits or vegetables are at risk for vitamin C deficiency. Vitamin C is present in most frozen and fresh vegetables but can be lost with prolonged cooking of fruits or vegetables, so steaming as a cooking method and shorter cooking times will optimize preservation of the vitamin.

Nutrient antioxidants decrease oxidative stress by counteracting the adverse effects of reactive species, e.g. in the human body.¹² Although the most recognized antioxidant nutrients are vitamin C and vitamin E, many nutrients and other food‐derived compounds function as antioxidants.¹² Thus, dietary advice focuses first on eating a wide variety of foods with essential nutrients and other food components that have health benefits and less reliance on supplements of antioxidants.⁷ A healthy dietary pattern includes various fruits, vegetables, whole grains, calcium sources (e.g. dairy foods), and protein sources (e.g. animal‐sourced foods and/or plant foods high in protein, such as nuts and legumes).⁷