Micronutrient Status and Protein-Energy Malnutrition in Free-Living Older Adults: A Current Perspective

Abstract

Purpose of review:

This review addresses the newest findings on micronutrient status and protein-energy malnutrition in the increasingly aging global population; understanding the nutritional challenges they face is vital for healthcare, well-being, and public health.

Recent findings:

The review examines deficiencies in macro- and micronutrients among nonhospitalized, free-living older adults, revealing significant associated health consequences, including frailty, cognitive decline, and reduced quality of life. Deficiencies in fat-soluble vitamins such as A, D, and E, are common in older populations, emphasizing the need for close monitoring for status of these. Furthermore, water-soluble vitamin deficiencies, especially vitamins B12 and C are also common, and pose health risks, including neurological disorders and cognitive decline. Iron and iodine deficiencies contribute to nutrient deficiency, anemia, and neurocognitive disorders. Finally, protein-energy malnutrition is common in older adults living in high-resource countries and may occur concomitant with depletion of one or more micronutrients.

Summary:

Addressing specific nutritional deficiencies is fundamental to enhancing the wellbeing and quality of life for free-living older adults. Protein-energy malnutrition, impacting over 25% of those aged 65 and above, results in a range of health issues, including poor wound healing, susceptibility to infections, anemia, and delayed convalescence. These concerns are aggravated by inadequate energy, macronutrient, and micronutrient intake, affecting muscle strength and overall health. Future research should focus on tailored appropriate monitoring of at-risk individuals, specific nutritional interventions, and dietary strategies to mitigate these issues and improve health outcomes among older adults.

Introduction

The global population of older adults is experiencing a remarkable surge, with projections indicating that by 2050, approximately two billion people will be aged 65 and above [1, 2]. This demographic transition represents a profound shift in the age composition of most societies, with significant implications for healthcare, nutritional status, and overall well-being. In 2022, the world already housed 780 million individuals over age 65 [3], constituting 10% of the global population, with a notable gender distribution: approximately 56% were women and 44% were men [4,5].

This demographic transformation and an overall increase in life expectancy present a multifaceted nutritional challenge in free-living older adults. Aging inherently carries a gradual risk of nutritional imbalances. These imbalances encompass compromised micronutrient and macronutrient status, affecting various vitamins (fat-soluble and water-soluble) and trace elements such as iron, copper, iodine, and zinc [6]. Additionally, protein-energy malnutrition is another concern within this context. The increasing demand for micronutrients, energy and protein in some individuals further exacerbates this, as free-living older adults experience multiple chronic disease conditions, including a variety of gastrointestinal disorders affecting nutrient digestion and/or absorption, as well as difficulties in maintaining adequate food intake, particularly in low-resource settings [7].

This review summarizes recent papers enhancing our understanding of the incidence and prevalence of micronutrient status and protein-energy malnutrition in free-living older adults.

Specific nutrient deficiency in free-living older adults

Among older adults, the deficiency of protein, energy, and/or micronutrients contributes to various states of malnutrition that may result in a cascade of adverse outcomes. These include muscle weakness, wasting and sarcopenia, general frailty, decreased immunocompetence, osteoporosis, cognitive impairment, impaired convalescence after illness or injury, and diminished quality of life [1, 6, 7]. Neglecting these deficiencies can lead to delayed treatment and result in complications, including poor wound healing, pressure ulcers, falls, hospitalization, and nursing home admissions.

Nutrient depletion among free-living older adults is attributed to various factors, including age-related changes affecting taste, digestion, chewing, and swallowing, which can reduce motivation to eat, and chronic illnesses, which are often multiple, that can affect nutrient requirements and assimilation. Also, reduced mobility can result in social isolation and loneliness, decreasing appetite and food intake, and increasing the risk of malnutrition. Additionally, financial hardships due to outliving savings, retirement, and limited employment opportunities push older adults to choose less healthy, cost-effective, and nutritionally deficient foods to cut living expenses [8].

Fat-soluble vitamins

Vitamins are vital micronutrients that are not synthesized endogenously in sufficient amounts, which highlights their importance in our diet at all life stages - playing a crucial role in maintaining health. However, older adults are particularly susceptible to deficiencies in fatsoluble vitamins, including vitamins D, A, and E [7].

The production and metabolism of vitamin D change with aging [9]. For instance, the concentration of 7-dehydrocholesterol in the skin decreases by more than 50% from ages 20 to 80 years, resulting in 40% less vitamin D synthesis in older adults [10]. Deficiency in this vitamin is a widespread issue among older adults. In the United States, with an estimated 35% of older adults exhibiting serum 25-hydroxyvitamin D concentrations lower than 50 ng/mL; a recent study in Iran, 51% of adults aged ≥60 exhibited similarly low levels [11]. Moreover, a retrospective analysis recently determined that more than 40% of the European older adult population had insufficient vitamin D levels, over 13% experienced acute deficiency, and nursing home residents being at significantly higher risk [12]. Older women are at even higher risk of suffering from vitamin D deficiency; in a large epidemiological cohort, women aged over 80 years from nine European countries exhibited frank deficiency when considering the 30 ng/ml threshold [13].

These statistics highlight the urgent need to address vitamin D inadequacy in older adults to prevent osteoporosis, cardiovascular diseases, autoimmune disorders (such as multiple sclerosis), kidney diseases, and fatigue [9–13].

Vitamin A has a fundamental role in the development and homeostasis of many organ systems, including the nervous and immune systems, and the development of proper immunity against viral infections [14]. Adult deficiency of vitamin A in common in low-resource settings, with cases reaching 14 per 100 inhabitants in Sub-Saharan Africa and 43 cases per 100 inhabitants in Somalia. In Europe, more than 6,000 cases of deficiency per 100,000 older adults were demonstrated, while data from Latin America reported 5,000 cases of low vitamin A levels per 100,000 older adults. Such deficiencies increase the risk of infections and may worsen visual acuity in the aging population [15].

Although deficiency of vitamin E is less studied, a recent report from Asia documented deficiencies of vitamin E among the elderly, with a range from 27% to 55% of individuals having low vitamin E concentrations in blood, based on a plasma α-tocopherol concentration cutoff of 12 to 14 mmol/L [16].

Water-soluble vitamins

Water-soluble vitamin deficiencies in older adults are common and present a significant health concern. Deficiencies in specific vitamins can result in various health issues, including megaloblastic anemia, mental status changes, and neurologic issues, and are related to rates of disorders common in older adults including Alzheimer’s disease, Type 2 diabetes, and cognitive decline [16–20].

Vitamin B12 deficiency is a prevalent condition among the elderly population, often due to factors such as autoimmune destruction of parietal cells (pernicious anemia), atrophic gastritis (achlorhydria), and prolonged antacid or proton pump inhibitor use, which may lead to malabsorption of the vitamin via decreased production of intrinsic factor. Vitamin B12 deficiency in the elderly can lead to demyelinating neurological disorders affecting the central and peripheral nervous systems [17]. While the general population’s estimated B12 deficiency prevalence ranges from 1% to 2%, in the United States and the United Kingdom, it has been reported that approximately 6% of older adults (>60 years) experience a deficiency in this vitamin. Symptoms of B12 deficiency include sensory abnormalities, impaired balance, and a decline in skeletal muscle mass with muscle weakness [18].

Numerous studies have shown a lower vitamin C status and a higher prevalence of deficiency in individuals with various acute and chronic conditions, which are common among older people [19]. While there is limited up-to-date information on the vitamin C status in older adults, data from the U.S. National Health and Nutrition Examination Surveys (NHANES 2003– 2006 and 2017–2018) indicate a higher vitamin C status and a lower or comparable prevalence of deficiency (<11 µmol/L) in people aged ≥60. This increased vitamin C nutriture in older individuals was primarily attributed to higher vitamin C supplement intake [20].

Trace elements

Depletion of iron and iodine are some of the most prevalent trace element deficiencies worldwide. Iron deficiency is considered a significant contributor to nutrient deficiency anemia in older individuals. Previous studies among older adults have indicated that reduced iron stores, regardless of anemia status, are often linked to inflammation, an increased risk of physical and cognitive impairment, and decreased overall morbidity and mortality [21].

Secondary analysis of the DO-HEALTH trial in Europe has reported the prevalence of iron deficiency among older adults aged 70 and above [21]. Portugal exhibited the highest prevalence, ranging from 8.5% based on serum ferritin levels >30 µg/L to 49.8% when considering the soluble transferrin receptor (sTfR)–ferritin index > 1.5. In contrast, France showed the lowest prevalence, with 2.0% based on ferritin and 27% based on the sTfR-ferritin index. Austria, Switzerland, and Germany also exhibited iron deficiency prevalence rates of 4.6%, 3.9%, and 3.2%, respectively, based on blood ferritin level. Over a three-year follow-up period, this European study recorded 390 cases of iron deficiency, resulting in an overall incidence rate of 9.2 per 100 person-years when iron deficiency was defined by sTfR > 28.1 nmol/L. This data highlights the necessity for monitoring and addressing iron deficiency at a population level, considering geographical disparities and the specific definition of iron deficiency [21].

Iodine plays a critical role in regulating body growth and development, primarily through the synthesis of thyroid hormones. Additionally, imbalances in iodine levels can contribute to neurocognitive disorders and narcolepsy in older adults [22]. Iodine deficiency represents a substantial public health concern, with roughly 30% of the global population being susceptible to deficiency [23]. Although there is limited evidence regarding iodine’s role in brain function in older adults, cognitive impairment in older adults encompasses conditions such as Alzheimer’s disease/dementia, and mild cognitive impairment. A recent study from China fond a significant association between iodized salt intake and cognitive functions in older adults [24].

Protein-energy malnutrition in older adults

Older adults are more susceptible to malnutrition (nutritional deficiencies) and unhealthy lifestyles. Globally, protein-energy malnutrition in older adults varies considerably due to variations in the assessment tool and the population studied, with prevalence ranging from 3% to over 27% of community-dwelling older adults [25]. Such generalized malnutrition in older adults can lead to serious health consequences, including poor wound healing, increased susceptibility to infections, fatigue, and weakness. Delay in nutritional repletion can result in complications including higher rates of hospitalization and impaired convalescence after illness. Causes include the effects of acute and chronic diseases, chewing and swallowing difficulties, food availability and cost, and socioeconomic factors [26].

Cross-sectional studies conducted among older adults (>60 years of age) have revealed a high rate of inadequacies in dietary energy, protein, and fiber, as well as 63% of evaluated micronutrients, low body mass index (BMI), and sarcopenia. Vitamins and trace element status, including vitamin B6, vitamin D, vitamin E, and iron, correlated with muscle strength, while protein and dietary fiber inadequacies were prevalent at 69% and 97%, respectively [25,26]. Over 50% of the population needed more intake of vitamin B6, vitamin B12, phosphorus, and selenium, with vitamin D, vitamin E, copper, magnesium, potassium, and calcium showing inadequacies exceeding 80% among participants [25].

In high-resource countries, studies have indicated that malnutrition affects a significant portion of free-living older adults aged 60 and above, with reported prevalence rates ranging from 10% to 30%. Moreover, approximately 16% of the older adults, comprising 17% of males and 15% of females, were identified as having moderate nutritional risk [8]. This risk is often associated with various factors, including gastrointestinal and other chronic diseases, altered taste perception, as some older adults have reported a reduced enjoyment of consuming nutrient-dense foods, and other factors such as anorexia.

Conclusions

The aging global population faces significant challenges related to micronutrient status and protein-energy malnutrition, which can lead to various adverse outcomes, including frailty, cognitive impairment, and a lower quality of life. Deficiencies in essential vitamins and trace elements, including vitamin D, vitamin A, vitamin E, vitamin B12, and iodine (and likely others), highlight the need for routine monitoring and intervention as needed to prevent associated health issues. Furthermore, protein and dietary fiber inadequacies are common among older adults, impacting muscle strength and overall health. These concerns are exacerbated by the high prevalence of malnutrition in this population, with many older adults at moderate nutritional risk. Addressing these nutritional deficiencies is essential for enhancing the well-being and quality of life of free-living older adults. Table 1 summarizes important issues related to selected nutritional deficiencies in older adults outlined in this paper. Future research should focus on developing targeted interventions and dietary strategies to mitigate these issues and improve overall health outcomes in this growing demographic.

Table 1.

Overview of Selected Nutritional Deficiencies in Older Adults

Nutrient	Some Concerns and Impacts	Status in Older Adults Based on Recent Reports	Some Clinical Symptoms of Deficiency
Vitamin A	Crucial role in organ system development, cell differentiation, and immunity. Increases infection risk and may impact visual acuity in the aging population. A serum retinol level should be obtained in patients with suspected vitamin A deficiency. Patients with fat malabsorption at particular risk.	Common deficiency in low-resource settings: Sub-Saharan Africa (14/100), Somalia (43/100), Latin America (5,000/100,000).	Night blindness, xerophthalmia (dryness and inflammation of the cornea), conjunctivitis (pink eye), corneal ulcers. Other symptoms: corneal opacity (cloudiness), photophobia (sensitivity to light), blurred vision, decreased visual acuity (sharpness). Susceptibility to infections, impaired wound healing, and increased risk of bone fractures.
Vitamin D	Aging alters vitamin D production and metabolism to the active 1,25 hydroxyvitamin D hormone. Patients with fat malabsorption at particular risk. There is an urgent need for intervention to prevent osteoporosis; impact on cardiovascular diseases, kidney diseases, type 2 diabetes, mental illness, autoimmune disorders, respiratory infections and others is unclear. Hypovitaminosis D increases the risk of respiratory infections. 7-dehydrocholesterol concentrations in the skin decrease by more than 50% from ages 20 to 80 years, resulting in 40% less vitamin D synthesis in older adults.	Widespread deficiency: in general US (approx. 35%), Iran (approx. 50%), Europe (>40%). Higher deficiency risk in older women, emphasizing the 30 ng/mL threshold for sufficiency.	Fractures, falls, muscle weakness (low knee flexion strength and reduced postural stability). Symmetric low back pain, proximal muscle weakness, muscle aches, and throbbing bone pain elicited with pressure over the sternum or tibia. Fatigue, depression, cognitive impairment.
Vitamin E	Higher risk due to factors such as reduced dietary intake, malabsorption, liver disease, and medication use. Treatment options include dietary supplementation of vitamin E or analogs (alpha-tocopherol or mixed tocopherols).	Limited studies, but some recent data from Asia showed deficiency in 27–55% of older adults, based on plasma α-tocopherol concentration of 12–14 mmol/L.	Most common clinical finding is peripheral neuropathy. Muscle weakness, muscle damage (myopathy), ataxia (loss of coordination), difficulty walking, anemia, and skin changes. Vision problems (retinopathy), impaired immune function (immunosuppression), and risk of infections.
Vitamin B12	Demyelinating neurological disorders, sensory abnormalities, impaired balance. Neurological symptoms resulting from B12 deficiency may take several months or even years to resolve completely. Deficiencies can also result in megaloblastic anemia, mental status changes, and are related to rates of disorders common in older adults, including Alzheimer’s disease, Type 2 diabetes, and cognitive decline. Patients with ileal resection at particular risk.	Higher prevalence in the US and UK, with approximately 6% deficiency in older adults (>60 years old) compared to the general population with 1–2% deficiency.	Paresthesia in the hands, legs, or feet, and difficulty with gait. Anemia: fatigue and weakness. Psychiatric symptoms: difficulty concentrating, memory loss, severe depression, and paranoia. Digestive symptoms, swollen, inflamed reddish tongue (glossitis).
Vitamin C	Lower vitamin C status in various acute and chronic conditions, including malnutrition and malabsorption.	Higher deficiency prevalence in individuals with chronic health conditions.	Spontaneous petechiae and ecchymoses, friable gingiva and loose teeth, bone pain, and joint effusions. Other symptoms include fatigue, weakness. vague muscle and joint aches, depression and cognitive issues.
Iron	Iron deficiency anemia common in older individuals. Reduced iron stores linked to inflammation, increased risk of physical and cognitive impairment, and overall higher morbidity/mortality.	Prevalence varied across Europe (e.g., Portugal: 8.5% to 49.8%) Austria, Switzerland, and Germany also exhibited iron deficiency prevalence rates of 4.6%, 3.9%, and 3.2%, respectively, based on blood ferritin levels. Incidence rate: 9.2 per 100 person-years (trans-European study).	Fatigue, weakness, bleeding, irritability, and lack of energy. Other symptoms: dry mouth, cheilitis, atrophic glossitis.
Iodine	Critical role in regulating body growth and development through thyroid hormones. Deficient iodine levels can contribute to neurocognitive disorders in older adults. Public health concern; significant association between iodized salt intake and cognitive functions in older adults (China study).	Roughly 30% of the global population is susceptible to deficiency.	Neurocognitive disorders and narcolepsy Cognitive impairment (Alzheimer’s disease, dementia) Goiter, hypothyroidism, cretinism, puffy skin, a hoarse voice, dry and scaly skin, sparse and coarse hair, intolerance to cold, and weight gain. Severe symptoms: confusion, disorientation, slow breathing, a slow heart rate, low blood pressure, hypothermia, or coma.
Protein-Energy Malnutrition	Older adults are more susceptible to malnutrition and unhealthy lifestyles. Protein-energy malnutrition linked to severe health consequences including higher rates of hospitalization and impaired convalescence after illness. Causes include effects of acute and chronic diseases, chewing/swallowing difficulties, food availability, and cost, and socioeconomic factors. Association with malabsorption and other chronic diseases, acute catabolic illness, anorexia.	Globally, prevalence varies (3% to over 27%) among community-dwelling older adults. Cross-sectional studies reveal inadequacies in dietary energy, protein associated with micronutrient depletion. In high-resource countries, prevalence ranges from 10% to 30% in hospital patients; while approx. 20% of older adults identified as having moderate risk for depletion.	Loss of appetite, impaired wound healing, weight loss, muscle weakness/atrophy, edema, cognitive impairment, dry or flaky skin, brittle hair and nails.

Key points.

1. The global population of older adults is rapidly increasing, with projections indicating two billion people aged 65 and above by 2050.

2. Older adults are at risk of micronutrient deficiencies, including fat-soluble vitamins, water-soluble vitamins, and essential trace elements.

3. Deficiencies in micronutrients and macronutrients contributes to weakness, frailty, cognitive impairment, delayed recovery from illness or injury, and a lower quality of life, with potentially severe consequences including immune system decline and neurological disorders.

4. A significant percentage of older adults worldwide are affected by protein-energy malnutrition.

5. Routine screening for micronutrient depletion and protein-energy malnutrition is important in older adults worldwide.