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Malnutrition In The Elderly

Malnutrition in the elderly has a complex and multifactorial origin; age is associated with physiological changes that cause the old person to be more vulnerable and more easily subjected to malnutrition in conjunction with risk factors, such as diseases, lifestyle, drugs, etc.

Gastrointestinal changes in aging involve motor function and therefore intestinal transit, mechanical breakdown of food and his chemical digestion. These alterations can progressively lead to the reduced ability to supply the body with adequate levels of nutrients, with the consequent development of malnutrition.

Recognizing risk factors is a fundamental step in being able to treat malnutrition.

Age is able to induce changes in the function of all organs and human physiological processes such as:

Intestinal function with a reduction in sensory perceptions, salivation, chewing, absorption of nutrients, and lactose tolerance;
Brain function with cognitive impairment and Alzheimer’s disease;
Body composition with loss of lean mass (especially in skeletal muscle tissue, a phenomenon known as sarcopenia) and increase in fat mass with variation in its distribution;
Balance of fluids;
Bones and joints with osteoporosis and/or arthritis with a consequent increased risk of falls and fractures;
Metabolism with type 2 diabetes mellitus and dyslipidemia;
The cardiovascular system with various diseases;
Cell growth with cancer (cancer in the elderly exhibits a slower growth because they show a slower rate of cell development than in young people).

For geriatric patients, European guidelines established that malnutrition is characterized by the presence of either weight loss (which reflects a catabolic state) and/or a low BMI, representing depleted physiological stores.

Three types of weight loss that may affect the elderly are wasting, cachexia, and sarcopenia.

Wasting is due to an insufficient dietary intake and leads to involuntary weight loss.

Cachexia is due to induced catabolic processes, with the production of proinflammatory cytokines. Its main consequence is a reduction of lean mass and body cell mass.

Sarcopenia is defined as a loss of muscle mass in combination with a loss of muscle strength or physical performance; these two entities often occur together, this has led to the new term “malnutrition sarcopenia syndrome”. The etiology is poorly understood, but an important role is due to physical inactivity, the induction of a pro-inflammatory response, and the dysregulation of anabolic hormones, such as testosterone or growth hormone.

Depending on the type of malnutrition, protein catabolism can be pronounced. Malnutrition leads to protein catabolism with a rapid wasting of skeletal muscles, a lower muscle mass, and reduced muscle strength. At the same time, there could be a reduced dietary protein intake with a decreased bone mineral mass. The result is an impaired musculoskeletal function, increased disability, and with reduced physical performance an increased risk of falling, with a greater risk of osteoporosis and osteoporotic fractures.

An adequate protein intake associated with a correct energy intake is essential to prevent malnutrition and sarcopenia in the elderly and if the diet is not sufficient, it is necessary to supplement any micronutrient deficiencies.

Malnutrition also leads to an impaired immune function, with reduced cell-mediated immunity, and an increased risk of infection and delayed healing.

The mechanisms that lead to malnutrition in elderly people are complex, but can ultimately result from starvation, disease, or advanced aging, alone or in combination.

The main cause is to be found in a reduced and/or unbalanced dietary intake, due to many causes that can be divided in three main categories: physiological, psychological, and social. In developed countries, the main factor of malnutrition is disease.

Physiological Causes

  • Gastrointestinal diseases

  • Dysphagia

  • Malabsorption

  • Oral problems (poor oral hygiene)/loss of smell or taste

  • Respiratory diseases

  • Endocrine diseases (diabetes mellitus)

  • Neurological/psychiatric diseases

  • Loss of autonomy with physical disability to feed self

  • Infections

  • Drugs interactions

  • Cancer

  • Poor appetite and poor diet

The gastrointestinal tract represents the primary and largest area of contact with environmental factors and ingested pathogens.

The regular functioning of the gastrointestinal tract is essential for maintaining good health of the body, as it guarantees the absorption of nutrients and drugs, and protection against external pathogens.

The multi-organ system that composes the gastrointestinal tract has large reserve capacity, and thus there is little changes in gastrointestinal function because of aging in absence of specific disease.

Nevertheless, some older older people can show a reduction of gastrointestinal functions, including immune function, with a greater frequency of bacterial and viral gastrointestinal infections compared to young people. Aging is associated with structural and functional alterations of mucosal defense, an increased oxidative stress, reduced ability to generate protective immunity, and increased incidence of inflammation and autoimmunity.

Particularly, the gastrointestinal mucosal layer represents the first line of defense against external pathogens and is equipped with multiple defense mechanisms, including the secretion of alkaline mucus, bicarbonate and antimicrobial peptides, epithelial intercellular tight junctions, antioxidants, autophagy, and antimicrobial peptides, and the innate mucosal immune system.

Mucus secretion performs multiple functions, such as protecting epithelial cells from pathogens, acids, digestive enzymes, and abrasion from food residues.

Aged mucosal surfaces are susceptible to lesions which appear to be receptive to differential levels of sex hormones.

Furthermore, in the elderly, the response to infection is often exacerbated by malnutrition; in fact, low-grade chronic inflammation can derive from the intestinal environment but with consequences even at a distance from the intestine, leading to fragility, sarcopenia, and degenerative disorders affecting various organic systems, including the central nervous system.

Microbial Digestion

With aging, physiological changes in the gastrointestinal tract are associated with major changes in the gut microbiota, with a reduced microbial stability and diversity.

In particular, low health-promoting bacteria, especially short-chain fatty acid-producing bacteria (SCFA) such as bifidobacteria, associated with an increased overgrowth of pathobionts (e.g., streptococci, staphylococci, enterobacteria, and enterococci anaerobes), can result in an overall decrease in saccharolytic production. At the same time, it seems to increase the proteolytic potential, resulting in a predominant putrefactive metabolism, with a gradual decline in immune system function and contributing to an augmented risk of infection and frailty.

This altered composition of microbiota significantly correlates with a pro-inflammatory status, and with a higher incidence of disease, frailty, co-morbidity, and undernutrition.

The reduction of short-chain fatty acids has important repercussions on the organism. They are derived from the undigested oligosaccharides and monosaccharides, which undergo bacterial degradation and fermentation, so as to be transformed into short-chain fatty acids (SCFA), i.e., acetate, propionate, and butyrate. SCFA are then almost completely absorbed in the colon, and used as energy for the colonocytes or transported to various peripheral tissues, influencing the human metabolism and exerting important anti-inflammatory and antineoplastic effects, promoting the formation and protection of the intestinal barrier from the harmful action of lipopolysaccharide (LPS); furthermore, they represent the most important drivers for microbiota change in the elderly.

Centenarians show a different and unique microbiota composition as compared to young adults and the elderly; in fact, both seem to have a similar bacterial structure, with a high composition of Bacteroidetes and Firmicutes and a minor population of Actinobacteria and Proteobacteria.

Furthermore, there is a shift of the Firmicutes population to a low diversity in terms of species composition, with an increase in Bacilli and a decrease and rearrangement of some cluster of Clostridium (i.e., the butyrate-producing bacteria Ruminococcus, Roseburia Eubacterium Faecalibacterium prausnitzii). This is very important because butyrate is a major energy source for the enterocytes and has a significant anti-inflammatory role.

Aged people with high levels of the mucin degrading Akkermansia muciniphila were found in comparison with the young adults.

In semi-supercentenarians, i.e., those aged 105–109, in comparison to adults, the elderly, and centenarians, a decrease was found in symbiotic bacteria, belonging mainly to the dominant Ruminococcaceae, Lachnospiraceae, and Bacteroidaceae families, as well as an increase in opportunistic bacteria along with age.

Ultimately, it is very important to emphasize and promote a correct diet and good life-style in light of the fact that they are considered to be the most important drivers for microbiota change in the elderly.

Intestinal Barrier and Immune System

In the elderly, modifications of the mucus could explain the reduced ability of bifidobacteria to bind to the mucosa, but, apart from H. pylori-positive subjects, the thickness of the mucus layer is not altered.

Aging is associated with “immunosenescence”, which is also a progressive reduction in the mucosal immune response of the intestine, linked to a reduced ability of the aging immune system to provide a tolerance towards antigens and a reduced production of immunoglobulin-specific antigen A, which represents the most important defensive mechanism of the mucosal immune response.

Finally, the lack of oral tolerance in old age can be explained by a decrease in the number and functionality of dendritic cells, which have the task of presenting antigens to immunocompetent B and T lymphocytes; however, in Peyer’s patches, the density of mononuclear phagocytes did not vary with aging.

Aging associated with malnutrition leads to a progressive deterioration of health in the elderly, with a consequent decrease in physical and functional abilities and a greater vulnerability of the patient, dependence in the activities of daily life, a poor quality of life, and greater morbidity and mortality.

Malnutrition also negatively affects the outcome of therapies because it reduces the immune response with a consequent increase in infections and delay in healing, reduces muscle mass, favoring inactivity and dependence, with psychological consequences leading to depression with a relative possible loss of appetite.

Elderly subjects tested with BMI, weight loss and food intake have consistently showed an association between mortality and malnutrition or nutritional risk.

A multidisciplinary team, such as geriatricians, gastroenterologists, dietitians, and other professionals, when necessary, should be assembled to treat malnutrition in older patients.

The nutritional intervention, lasting at least three months, should work on the treatment of the underlying cause of malnutrition and on the improvement of the nutritional status, monitoring weight changes and the estimation of food intake, which are key aspects to assess the effects of the intervention.

Impact of major food products on malnutrition.

Dairy Products

In old people, dairy products represent an important source of energy, protein, vitamins (A, B2, B5, B9, B12), minerals (calcium, magnesium, phosphorus, and zinc), and cholesterol; furthermore, some important nutrients, such as vitamin B9 and vitamin D, can be administered by fortifying milk.

Furthermore, probiotic yogurt showed a reduction in mutagenicity in the intestinal tract after consumption, as well as anti-inflammatory activity.

The immune system is positively influenced by dairy products containing bacteria, such as fermented milk or yogurt with added probiotic strains and/or lactic acid bacteria; data from literature show positive effects of these products in a series of pathologies such as Clostridium difficile infection, infectious airway diseases, and the common cold and reducing the development of osteoporosis when integrated with calcium and vitamin D.

This concept has been reiterated by the European Society for the Clinical and Economic Aspects of Osteoporosis and Osteoarthritis (ESCEO), which recommend in frail elderly patients at a high risk of falls and fractures the daily consumption of food products fortified with calcium and vitamin D (such as yogurt or milk).

Dairy products, in particular milk proteins, are also rich in branched-chain amino acids (BCAAs), in particular leucine, which are necessary for muscle protein synthesis; thus, preventing the onset of sarcopenia in the elderly.

Other clinical indications are constipation, relieved by yogurt supplemented with dietary fiber, non-viral gastroenteritis, where probiotic fermented milk can alleviate symptoms, and dental health that can be improved by milk intake, supplemented with fluoride and probiotics.

Finally, dairy products provide an important matrix for introducing the flavors preferred by the elderly in order to deliver nutrients tailored to their nutritional needs; in fact, the taste of food is very important as it can induce changes in preferences for food consumption and so influence food intake.

Recognizing risk factors is a fundamental step in being able to treat malnutrition.

Literature studies show how the quality of the diet is very important with respect to the risk of frailty but there are still significant gaps in the literature regarding the evidence for the non-drug treatment of malnutrition.

Resource:

Nutrition and Healthy Aging: Prevention and Treatment of Gastrointestinal Diseases