A problem underestimated for a long time

Although malnutrition is a significant problem in clinical practice, particularly in the elderly, it is often unrecognized and even less often treated. Malnutrition has a decisive influence on the mobility, independence and cognition of geriatric patients. Here, the key is to be mindful.

Although malnutrition is a significant problem in clinical practice, particularly in the elderly, it is often unrecognized and even less often treated. Depending on the study, it is estimated that in German-speaking countries 17-30% of geriatric patients have malnutrition and 38-65% are at least at risk for malnutrition, but only about one-third of cases are recognized as such and only a portion of these receive targeted therapy [1].

However, awareness of the importance of malnutrition has increased in recent years, on the one hand due to demographic developments with a corresponding rise in geriatric case numbers in hospitals, and on the other hand due to increased awareness of the links between malnutrition, mortality and serious complications, particularly in hospitalized patients. Therefore, the registration of the affected persons as well as the optimization of the nutritional status is of great importance. Malnutrition also has a decisive influence on the mobility, independence and cognition of geriatric patients.

Malnutrition – a geriatric syndrome

There is a close correlation between malnutrition on the one hand and other geriatric syndromes such as sarcopenia (physiological reduction of muscles with increasing age), cognitive impairment, gait and balance disorders, polypharmacy or frailty on the other. These syndromes influence each other and, if left untreated, lead to a negative spiral. For example, if malnutrition is present, there is a high probability that muscle atrophy will be particularly pronounced and, accordingly, that there will be an increased risk of falls. Falls, in turn, can exacerbate malnutrition through the associated immobility and limitation in daily living. This interdependence and influence is also called the network of syndromes (Fig. 1) . To break through this tendency, it is important not only to clarify and treat a geriatric syndrome, but also to consider the associated consequences. Early detection of the syndromes is crucial for the success of the therapy.

Causes of malnutrition in old age

There are numerous physiological as well as pathological causes of malnutrition.

Physiological causes

Decreased feeling of hunger and thirst in old age: In the context of sarcopenia, muscle tissue is replaced by adipose tissue, the proportion of fat in the body increases, while at the same time the proportion of water decreases. As a result of these physiological changes, as well as the fundamental increase in immobility, the energy requirement decreases in old age by up to 30%, which corresponds to approx. 500 kcal per day.

In addition, the physiological changes in the gastrointestinal tract lead to an increase in cholecystokinin, a peptide hormone that is produced in the duodenum and jejunum and, among other things, is involved as a neurotransmitter in the brain in triggering the feeling of satiety.

The need for fluids hardly changes with age. However, the feeling of thirst and thus the need to drink something diminishes. In addition, incontinence or the administration of diuretics with frequent water loosening can lead to consciously drinking less in order to also have to go to the toilet less. Furthermore, diseases such as diabetes mellitus, renal insufficiency, chronic diarrhea or pulmonary diseases with increased respiratory rate can lead to water deficiency. According to a study from Germany, 10-20% of seniors are thought to have mild to severe fluid deficiency [2].

Presbyphagia: Physiological changes in the oro-pharyngeal area such as slowed peristalsis in the esophagus, increased drying of the mucous membranes and slowing of the swallowing reflex lead to dysphagia in old age. This occurs frequently (approximately 70% in geriatric inpatients) but is often not recognized because symptoms such as increased coughing while eating are nonspecific and rarely interpreted by patients as a medical problem [3]. However, presbyphagia should not be underestimated and is considered an independent risk factor for serious complications, especially in older age, and is associated with an increased risk of mortality. Smoking and poor oral hygiene are also considered risk factors.

Changes in the sense of taste and smell: By the age of 80, about 50% of the taste buds are lost due to age-related physiological changes. These changes do not affect all flavors equally, but primarily the salty. For this, the detection threshold may be up to 11× higher than in younger individuals [4]. Since salty dishes are no longer palatable, there is a preference for sweet, sugary foods with the associated unbalanced diet.

Similarly, there is a 20% decrease in the sense of smell by the age of 70, and the ability to discriminate between different odors may also be reduced by up to 75% (Fig. 2) [5]. The cause is thought to be a loss of neurons in the olfactory bulb during the normal aging process. But diseases such as dementia or Parkinson’s disease can also affect the sense of smell.

Changes in the gastrointestinal tract: The gastrointestinal tract has a large reserve capacity and therefore ages less compared to other organs. Nevertheless, it plays an important role in malnutrition in old age. Thus, there is a breakdown of neurons in the myenteric plexus and, as a consequence, a delay in gastrointestinal emptying with a correspondingly faster and longer lasting feeling of satiety.

Age-related atrophy of the gastric mucosa results in decreased secretion of pepsin (needed for the breakdown of proteins from food) and intrinsic factor (a prerequisite for the absorption of vitamin B12). Furthermore, the secretion of gastric acid decreases. This leads to an increase in pH. This impairs the absorption of vitamin B12, calcium, iron or beta-carotene, as these substances require the most acidic pH possible for absorption.

However, medications that are frequently administered in old age, such as calcium antagonists or opioids, can also influence gastrointestinal emptying.

Dental status: Often underestimated in connection with malnutrition is the deterioration of dental status. This leads to the inability to chew certain foods, which can thus lead to an unbalanced diet. The problem is supported by the physiological decrease in saliva production, which can be additionally intensified by medications such as anticholinergics or psychotropic drugs.

Vibro-tactile sensitivity: From the age of 40, there may be an increase in the tactile sensitivity threshold by 2-3 times. In combination with any arthritic changes in the hands, this can lead to considerable difficulty in preparing meals.

Pathological causes

Hospitalization: Patients lose weight especially during hospitalization because they have less appetite in the context of an acute illness, but due to the catabolic metabolic state they have a higher nutritional requirement than in health.

Multimorbidity: Multimorbid patients, e.g. with COPD or malignant diseases, show a higher stress metabolism. The resulting increased energy demand is ensured by breaking down the body’s own proteins, primarily from the muscles. In addition, illnesses such as stroke, depression, polyarthrosis or even visual impairments, among others, lead to functional limitations with the associated difficulties in food procurement and preparation.

Chronic inflammatory diseases: Patients with chronic inflammatory diseases such as rheumatoid arthritis or Crohn’s disease have a fundamentally catabolic metabolic state with a correspondingly increased basal metabolic rate in the body. There is a release of amino acids for gluconeogenesis and for the synthesis of acute-phase proteins from endogenous proteins, resulting in muscle breakdown.

Polypharmacy: More than 250 drugs can affect the sense of taste and smell. These include numerous drugs that are frequently administered in old age, such as ACE inhibitors, calcium antagonists, diuretics, but also psychotropic agents. Proton pump inhibitors and antacids increase the pH in the stomach and can thereby negatively affect the absorption of micronutrients, as described above. Lipid-lowering drugs, in turn, reduce the absorption of fat-soluble vitamins D, E and K.

Dysphagia: In contrast to the above-mentioned presbyphagia, dysphagia is based on pathological changes in the swallowing act, primarily in the context of neurological diseases such as after stroke, in Parkinson’s disease or in multiple sclerosis. Dysphagia is particularly common in dementia patients. Here, the prevalence is around 80%.

Social problems

Financial constraints or loneliness in old age can promote malnutrition. Cooking a whole menu just for yourself is not much fun.

Malnutrition and dementia

Decreasing body weight is an important clinical sign of dementia and may occur up to a year before diagnosis. The causes of weight loss in early dementia are poorly understood, and a multifactorial etiology is thought to exist. Neurodegenerative changes can lead to brain atrophy in regions of appetite regulation at an early age, resulting in altered sensations of hunger and thirst. Dysphagia, which is common in dementia, may also play a role. In addition, due to cognitive deficits, patients can no longer adequately purchase and prepare food. In a study from the USA, it was shown that there is a significant difference in muscle mass between patients in the early stages of Alzheimer’s dementia and the healthy control group (Tab. 1) [6].

Partly as a result of this work, the European Society for Clinical Nutrition and Metabolism (ESPN) has included regular nutritional screening in all cognitively impaired patients in its guidelines [7].

Detection of malnutrition

Despite the growing evidence regarding the importance of malnutrition, no standard diagnostic criteria currently exist. For the screening of malnutrition, the Nutrition Risk Score (NRS 2002) has become established in Swiss hospitals, which correlates well with the further course in terms of mortality and complications [8]. It has a sensitivity of 98% and a specificity of 53% and was recommended as a screening tool by the Swiss Society for Clinical Nutrition (SSNC) and the European Society for Clinical Nutrition and Metabolism (ESPN) not least for this reason [9]. Risk for malnutrition is present when the NRS is ≥3 points. From this value onwards, nutritional counseling should be involved, which carries out a targeted nutritional assessment to identify the deficiency symptoms in detail and, based on this, set individual nutritional targets in terms of calories, proteins, vitamins and nutrients. Based on these results, individualized nutritional therapy is initiated.

The Mini-Nutritional Assessment (MNA) has been developed specifically for elderly patients and is accordingly used specifically by nutrition counselors in this age segment [10].

In each case, the development of the screening tools examined which nutritional parameters correlated with mortality and complications. They therefore have primarily a prognostic value and say nothing about whether a patient also benefits from nutrition therapy.

Another way to assess nutritional status is to determine body mass index (BMI). In principle, the informative value of the BMI with regard to malnutrition is rather limited, since only body weight and length are measured. However, a correlation between BMI on the one hand and NRS or MNA on the other hand could be shown. Thus, it can be assumed that with the BMI, which is easy to collect, at least a rough impression of the nutritional status can be achieved.

With regard to laboratory values, albumin in particular has clinical relevance as a prognostic factor. Thus, it has been shown that serum albumin determined preoperatively is a strong predictor of perioperative complications and mortality [8]. However, laboratory values alone cannot be used to diagnose malnutrition.

Consequences of malnutrition in old age

Decreased protein intake and the associated breakdown of proteins from skeletal muscle accelerates the progression of the aforementioned sarcopenia. Corresponding to the reduced muscle strength, the risk for falls and the associated, often immobilizing injuries increases.

Postoperatively, malnourished patients are at risk of poorer wound healing and the occurrence of the dreaded decubiti . The mobilization of patients is delayed and the hospitalization time increases.

Anemia in the elderly occurs frequently. One third of these are the result of substrate deficiency in the context of malnutrition, in particular due to iron deficiency in every third case [11].

Malnourished patients exhibit decreased immunocompetence with a consecutive higher incidence of infections. For example, a study from Geneva showed that a decrease in caloric intake below 70% of individual needs was associated with a significant increase in hospital-associated infections (Fig. 3) [12].

A recent study from Zurich and Vienna was able to show that in 135 geriatric patients in an acute hospital, the calorie requirement was basically met in well-nourished patients. Even in the case of mild malnutrition, however, it was on average only 55% covered, well below the 70% limit. In the case of severe malnutrition, only 36% of the energy requirement was covered (Table 2) [13]. These results show that the occurrence of nosocomial infections in malnourished geriatric patients in hospital is a serious problem.

In a cohort study, also in Switzerland, with over 3000 patients, the impact of malnutrition (measured with the NRS 2002) on medical outcome was investigated. Regarding 30-day mortality, there was a significant difference of 4% in patients with NRS <3 versus 33.7% in patients with NRS >3. Also, patients with a higher NRS had to be re-hospitalized more frequently within 30 days (9.8% versus 17.3%) (Table 3) [14].

Despite the demonstrated importance of malnutrition in elderly patients, especially hospitalized ones, it remains understudied. According to the Swiss Federal Statistical Office, malnutrition was coded in only 1.1% of hospitalizations in Switzerland in 2012. In the following years, this figure increased only slightly (in 2018, it was 4.5%). Unfortunately, once patients with malnutrition are recorded, appropriate therapy still often fails to occur. In the nutrition report of the German Nutrition Society (DGE), it was shown that in Germany, only 10-22% of cases of severe malnutrition receive nutritional intervention in the form of fortified food. In Europe, it is 21-50% (Fig. 4) [15].

Therapy of malnutrition

Detection of possible causes and their treatment

Medications can affect the nutritional status of the elderly in several ways. It is therefore of particular importance, especially in the context of any polypharmacy, that the list of medications is checked at each visit to the doctor with regard to the indication and dosage of the active ingredients. For example, proton pump inhibitors or antacids should only be used when clearly indicated and should be discontinued as soon as possible. The same applies to antihypertensives, psychotropic drugs, anticholinergics or diuretics (influence on the sense of taste and smell, influence on fluid balance, impairment of saliva production). Another example is avoiding concomitant administration of calcium supplements and thyroid hormones. In these cases, complex formation can occur, which prevents the absorption of the active ingredients. For this reason, the drugs should be taken with a minimum time interval of two hours. Last but not least, taking numerous medications can basically lead to malaise and inappetence.

To optimize dental status, patients should be encouraged to visit the dentist regularly. For the detection and treatment of presbyphagia or dysphagia, a logopedic evaluation is advisable when suspicious symptoms occur, such as frequent coughing while eating.

If there is evidence of pronounced sarcopenia or gait instability, as well as after fall events, it is imperative that muscle development be sought with the help of physical therapy. If arthritic changes or limited vibro-tactile sensitivity of the hand are present, consider registration with occupational therapy. Finally, referral to nutrition counseling can be of great help in the outpatient setting as well.

Protein intake in old age

According to various bodies, including the WHO, the daily protein requirement is 1-1.3 g/kg body weight. Postoperatively, in case of illness or pronounced sarcopenia, the intake must be increased up to 1.5 g/kg body weight. In patients with renal insufficiency or on dialysis, 0.8 g/kg body weight is recommended. It is important to note that not simply as much protein as possible should be consumed per meal. Studies have shown that a protein amount of 25-30 g per meal appears to optimally stimulate postprandial muscle protein synthesis (Review 1) [16].

Especially whey proteins enriched with leucine (parmesan, camembert, brie, peanuts, soy, peas, beans liver, poultry) have a good potential to improve muscle mass and strength in old age. This was also confirmed in the Provide study from Germany, in which vitamin D and leucine-enriched whey proteins were administered as dietary supplements to independently living older adults with low skeletal muscle mass index. After 13 weeks, it was found that compared to baseline, the intervention group had an average of 170 grams more muscle than the control group (Fig. 5) [17].

Energy supply in old age

According to the Swiss Society for Nutrition (SGE), the recommended daily energy intake for geriatric women is 1800 kcal/day and for men 2400 kcal/day. A daily energy intake of less than 21 kcal/kgKG is significantly associated with frailty. The fact that these values are often not achieved is shown by a study from the USA, in which 16% of people over 65 living at home consume less than 1000 kcal/d [18].

Additional dietary recommendations

Omega-3 fatty acids exhibit a stimulating effect on muscle-protein metabolism and are found more abundantly in Brussels sprouts, spinach, beans, avocado, raspberries, hazelnuts, peanuts and chestnuts.

A major problem in old age is constipation as a result of a low-fiber diet. Per day, the intake of 30 g of fiber is recommended. These are found in heaps in whole grain and rye products, legumes, potatoes, oatmeal, apples, plums or figs. However, it must be mentioned that the high-fiber foods tend to quickly lead to a feeling of satiety, which in turn can have a negative impact on energy and protein intake.

Enrichment of meals

The natural enrichment of meals can be done, for example, with milk powder, curd or grated cheese to improve the protein content and with sugar or honey to optimize the carbohydrates.

Dairy products are particularly suitable as snacks, as they contain calories and protein, as well as vitamins and minerals. Accordingly, studies have shown that an increased intake of dairy products in old age is associated with better physical performance [19].

Therapy for inpatients: Individualized, conservative nutrition therapy

In individualized conservative nutrition therapy, patients’ nutritional deficiencies and needs, particularly with regard to calories, ice whites, vitamins and minerals, are recorded by means of assessment by the nutritional counselor and taken into account in collaboration with the hospital kitchen when preparing the personalized meal. In addition, depending on the situation, supplements such as multivitamin preparations or protein drinks are also used as a snack.

Combined with the results of previous smaller studies and observational research, the results of the large-scale, multicenter, Swiss, eight-hospital EFFORT study strongly support this concept. After 30 days of treatment of proven malnourished patients using the individualized nutrition therapy, mortality was 7.2% in the intervention group versus 9.9% in the control group. The number needed to treat (NNT) was 37 patients. Severe complications occurred in 22.9% in the intervention group and 26.9% in the control group (NNT=25) (Fig. 6 ) [9]. These results are confirmed by other studies. Thus, in a meta-analysis by Gomes et al. 2019, an analogous 25% reduction in mortality will be shown under individualized nutritional therapy [20]. This contrasts with the modest therapy costs, which amount to 15 Swiss francs per patient per day.

Take-Home Messages

• Malnutrition is an important factor in the treatment approach in old age, as there is a significant association with the occurrence of complications, mortality, as well as a decrease in independence.
• There are numerous physiological as well as pathological causes of malnutrition. Recognizing them is often the first therapeutic step.
• Even a decrease in individual caloric requirements below 70% is associated with a significantly higher incidence of nosocomial infections in hospital.
• Consistent detection of malnourished patients in the hospital with subsequent implementation of individualized conservative nutrition therapy is associated with a significant decrease in mortality and serious complications.

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GASTROENTEROLOGIE PRAXIS 2023; 1(1): 12–18