APpETITE Publications
Innovating plAnt Protein fibre and Physical activity solutions to address poor appEtite and prevent undernutrition in older adults – APPETITE.
Older adults with poor appetite are at higher risk of undernutrition due to the role of appetite as a key driver of food intake. Dietary protein and fibre are particularly critical nutrients in this population, and enhancing their intake is vital to preventing undernutrition and maintaining organ function and health.
In APPETITE, experts from eight institutions in six European countries are collaborating to design potentially effective interventions to enhance protein and fibre consumption of community-dwelling older adults with poor appetite. The aim is to address undernutrition through a targeted personalised nutrition and physical activity-based strategy. Older adults with poor appetite will be evaluated using a mixed-methods approach to gain insights into their nutritional and behavioural preferences.
APPETITE aims to create knowledge in three important areas: (1) How we can make healthy and inexpensive foods that are sensorily appealing by combining plant-based proteins and dietary fibres, (2) how well the body digests these food products, (3) how we can use these food products combined with structured physical activity and regular social contact, through dietary counselling and group training sessions, to overcome undernutrition.
The research involves examining the impact of selected products and physical activity on digestibility, amino acid bio-availability and whole-body protein metabolism. In a multi-centre, randomised controlled intervention trial, the impact of two new food products, provided as part of a personalised diet, a physical activity programme, and their combination will be determined.
They will create new knowledge on how these products can be used in a whole-diet approach together with physical activity and regular social contact to overcome undernutrition and contribute to a better quality of life for older Europeans.
Exploring the experience of appetite loss in older age: insights from a qualitative study
Poor appetite occurs frequently in older age, with an estimated prevalence ranging between 15-30% in community-dwelling populations. Despite known links between poor appetite and adverse health outcomes, appetite is not routinely assessed and the causes and impact of appetite loss in older age are poorly understood. This study aimed to improve understanding of appetite loss in older age and to consider the implications for prevention and treatment opportunities.
Thirteen older adults aged 60-93 years (9 women, 4 men) identified as having poor appetite using the Simplified Nutritional Appetite Questionnaire (SNAQ) and took part in semi-structured interviews. Open-ended questions focused on influences on and experiences of appetite and appetite loss in older age. Interviews were transcribed; reflective thematic analysis was conducted using an inductive approach.
The researchers found three main themes: 1) there are many reasons for loss of appetite - these include biological, psychological and social factors; 2) people experience appetite loss in different ways and can have different attitudes towards losing their appetite 3) social interactions and the environment influence the appetite of older adults.
In summary, this study demonstrated that each person's experience of appetite loss is distinct, that there are numerous reasons for appetite loss in older adults and that the effects of appetite loss, as well as how people feel about them, differ greatly between older adults.
Future research should concentrate on understanding older adults’ experiences and perspectives to devise solutions to help older adults experiencing appetite loss.
Characterisation of community‑dwelling older adults with poor appetite
Poor appetite affects 27% of community-dwelling older adults in Europe. This poor appetite leads to lower energy and protein intake which can result in weight loss, under- or malnutrition, and sarcopenia (loss of muscle strength). These conditions can result in older adults becoming less independent and decreasing their quality of life. This study aimed to understand the physiological, emotional, cognitive, social and lifestyle characteristics that coexist with poor appetite.
In this study, 850 older adults were recruited, and their appetite over the previous week was ranked as “normal” or “poor”. Of all participants examined, almost 16% (15.6%) were considered to have a poor appetite.
Those with poor appetite tended to report chewing problems, unintentional weight loss and feeling lonely. 25% of those who reported being in hospital within the last 6 months, smoking, having reduced cognitive function, poor health, sleep quality or satisfaction with life, also reported poor appetite. Females were twice as likely as males to have a poor appetite. Those on greater than five medications (polypharmacy) were also seen to have a poor appetite.
These results indicate the complexity of regulating appetite in older adults and highlight some of the factors involved.
Peripheral Amino Acid Appearance Is Lower Following Plant Protein Fibre Products, Compared to Whey Protein and Fibre Ingestion, in Healthy Older Adults despite Optimised Amino Acid Profile
The APPETITE Project is a research initiative aimed at older people (+65yrs) to improve and maintain adequate nutrition, thus reducing the risk of poor outcomes. Protein intake and bioavailability are essential in older adults as they require more protein than younger adults to prevent conditions such as sarcopenia.
A pilot study carried out in Ireland and Italy in 2022, aimed to investigate how three different plant protein and fibre (PPF) products affect the number of Amino Acids (AA) (building blocks of protein) in the blood of healthy older adults, compared to whey protein with added fibre (WPF). The population studied was 12 adults aged 65+ living in the community. Plant-based protein options can be more environmentally friendly than animal-based options. However, they have lower amino acid content, aren’t as easily digestible, and are believed to be less effective in muscle maintenance.
Study participants consumed a test meal enriched with protein powder (PPF or Whey). Their blood was taken before, and after eating to compare amino acid profiles. There were four separate test days, a week apart, until all varieties of PPF, and whey-enriched meals were consumed. In each meal, the energy content was kept consistent, with protein content adjusted to match total leucine.
The results showed that all the plant-based protein and fibre products increased the appearance of amino acids in the blood, indicating their potential to stimulate the anabolic muscle response to maintain muscle health in older adults. It was evident that plant-based diets and protein sources have the potential for enhancing the vitality and nutritional status of older adults. However, the results of this study add to those previously reported that the absorption and utilisation of whey protein is higher than plant-based proteins, regardless of how much is consumed. The study concluded that WPF remained more efficient at increasing AA concentrations after meals, even when PPF contained 32% more total protein. Leucine concentration was highest after whey protein in comparison to plant protein. Leucine is essential for building and maintaining muscle mass. Further research is needed to assess the anabolic properties of innovative protein and fibre blends and whole foods in older adults to determine if moving towards higher plant protein consumption should be accompanied by higher protein requirements or other novel strategies.