This study aims to assess the digestibility and efficacy of the study groups previously developed innovative plant-based protein and fibre products.

Older people are at high risk of undernutrition, which leads to serious adverse health outcomes, but effective preventive strategies are lacking. Effective, new strategies should focus on the etiology of undernutrition and directly address potential causes and mechanisms underpinning undernutrition.

Reduced food intake and restricted dietary diversity are direct consequences of poor appetite. Recent studies have shown, that older persons with a poor appetite demonstrate lower intake of protein and dietary fibre, and of several nutrient-rich food groups (e.g. meat, fish, wholegrains, vegetables), after adjustment for energy intake and other potential confounders, but a higher consumption of food groups low in micronutrients (e.g. fats, oils, sweets, and sodas), compared to those with good appetite.

Enhancing dietary protein and fibre intake in older Europeans is a key objective because intake of both nutrients is sub- optimal, not only in those with poor appetite. Adequate protein intake prevents excessive decline in muscle mass and function (sarcopenia), a widespread health-issue in older persons, intensified by undernutrition. Adequate dietary fibre intake prevents constipation and impedes the development of many chronic diseases prevalent in older people. Thus, targeting adequate protein and fibre intake may be particularly beneficial in this vulnerable population.

A preparatory short-term study will be performed to assess in 10 healthy older adults the net peripheral Amino Acid (AA) appearance following ingestion of 3 selected Plant-based Proteins and Fibre (PPF) products previously developed by the wider study collaborators, compared to the reference of 30 g whey protein. Plasma concentrations of AA from arterialised blood will be measured by ion exchange chromatography in blood samples (1 drawn before and 6 during 3 hours postprandial). This step will allow the research group to compare in-vitro (previous work) and in-vivo digestibility of several PPF mixtures and identify the product with both optimal amino acid composition and sensory properties as well as optimal post-prandial plasma amino acid profile to be used in further studies.

Inclusion Criteria:

• Community-dwelling, Age 65+ years, not a heavy smoker (≤10/day), BMI 18-30 kg/m2

Exclusion Criteria:

• Medical condition or medication known to impact appetite or energy intake, consumes more than 14 (female) or 21 (male) units of alcohol per week, inability to come to study centre, self-reported cognitive impairment or diagnosis of clinical depression, heavy smoker (>10/day)