1.4.1 Functional consequences -

1.4.1 Functional consequences

Malnutrition has functional consequences in adults and older people

Malnutrition is associated with decreased muscle function and impaired functional status. In adult hospital patients, decreased hand-grip strength is a predictor of loss of functional status.²⁷⁷ Reduced muscle strength and fatigue can lead to falls, reduced ability to self- care, and poor recovery from chest infection.¹²² Muscle atrophy and loss of strength can occur rapidly during extended periods of disuse or mechanical unloading, such as after acute hospitalization or bed rest.²⁷⁸ Even brief periods of disuse, though sometimes necessary for recovery from illness or injury, may have adverse health effects.In individuals who are already malnourished, these effects can further intensify the functional consequences associated with malnutrition. A systematic review analysing the effects of short-, medium-, and long-term bed rest (ranging from 5 to 120 days) in a pooled sample of 318 healthy adults found significant strength loss and muscle atrophy in the knee extensor muscles. The most substantial decline in strength and muscle mass occurred in the early stages of bed rest, after which the decline plateaued.²⁷⁸ In another study examining short-term disuse (<10 days), ten healthy young men underwent one week of strict bed rest. The results showed an average loss of 1.4 ± 0.2 kg in lean tissue and a 3.2 ± 0.9% reduction in quadriceps cross-sectional area (both P < 0.01).²⁷⁹

Malnutrition leads to significant muscle wasting and weakness, resulting in inactivity and reduced ability to perform daily activities such as working, shopping, cooking, and self-care. In a recent study among community-dwelling older adults, higher daily protein was associated with a slower decline in walking speed and a reduced likelihood of developing mobility limitations, independent of physical activity levels.²⁸⁰
Low plasma vitamin D levels (< 20 ng/ml) have been associated with poorer physical performance and a greater decline in physical performance than with plasma vitamin D levels of at least 30 ng/ml.⁵⁹ In addition, low plasma vitamin D concentrations have been associated with a greater risk of future nursing home admission, and they are independently associated with an increased risk of falling in older people, particularly in those aged 65–75 years.^281,282
The clinical criteria for frailty (‘shrinking’ [i.e. unintentional weight loss/sarcopenia], weakness, poor endurance, and low activity) are associated with chronic under-nutrition resulting in loss of weight and muscle mass and poor muscle function.²⁸³
One study highlights the that over one-third of hospitalised older adults had disease-related malnutrition or sarcopenia, both of which were significantly associated with higher hospital readmissions, mortality, and reduced quality of life, high prevalence of disease-related malnutrition and sarcopenia in older adults, reinforcing the link between undernutrition and frailty in older adults.²⁸⁴ Malnutrition is further described as part of a spectrum that includes cachexia and sarcopenia in cancer patients, all of which contribute to muscle wasting and worsening physical function.²⁸⁵ It has also been emphasised that low muscle mass and malnutrition significantly impact overall health status, increasing morbidity and the risk of disability in older adult patients with cancer.²⁸⁶ Without appropriate intervention, frail older people are likely to experience functional limitations and disability, increased morbidity and use of healthcare resources, and mortality.²¹⁴ Therefore, it is essential to address the risk of malnutrition early and provide appropriate treatment, as this will improve overall patient outcomes and reduce related healthcare costs.
A review of the links between nutrition and frailty suggested that loss of appetite, weight loss, sarcopenia, low energy and protein intake, low intake, and blood levels of vitamins (B, C, D, E, folate), antioxidants (carotenoids) and trace elements (selenium and zinc) influence the development or aggravation of frailty.²⁸⁷
Maintaining function in older people is considered a high priority by the WHO with an objective to prevent decline and institutionalisation (see Figure 1.23). Indeed, through the UN Decade of Action on Nutrition (2016–2025), the WHO aims to combat all forms of malnutrition by promoting sustainable food systems, improving healthcare interventions, and strengthening nutrition policies.¹³² This is important, given that frailty and malnutrition are associated with increased healthcare utilisation and higher rates of hospital readmission. Overall economic burden is higher than compared to well-nourished individuals.^288,289
A systematic review and meta-analysis of 19 studies examining the relationship between malnutrition and cognitive frailty in older adults revealed that 57% of older adults with cognitive frailty were malnourished. The meta-analysis demonstrated that malnourished older adults had a 3.77 times higher risk of developing cognitive frailty compared to well-nourished individuals (OR = 3.77, 95% CI: 2.49–5.69).²⁹⁰

Maintaining functionality and independence