Within the PROMISS consortium, low protein intake is considered a relevant marker of being at higher risk of developing protein-energy malnutrition. PROMISS shows, using international observational data from five international aging cohorts and three national dietary surveys, that 22% of older Europeans does not meet the current European recommendation of protein intake which is set at 0.8 grams of protein per kilogram body weight per day (g/kgBW/d). If this recommendation is set at 1.0 or 1.2 as is the case for some EU countries, the percentage would increase to 47% or 71%. Older adults with one of the following characteristics are more likely to have a lower protein intake: having a poor appetite, poor smell, swallowing problems or financial limitations, being female, being physically inactive, following a diet (e.g. low salt) and being obese. The Protein Screener can be used to quickly screen older adults for a high risk of low protein intake. Based on a European-wide survey, PROMISS showed that while most older adults know that protein is important for health and muscles, knowledge on the recommended intake is rather poor.
Importantly, based on data from several large cohort studies, PROMISS showed that a higher protein intake in older adults, and especially a protein intake greater than 1.0 g/kgBW/d, is associated with a lower incidence of developing mobility limitations and slower decline in physical performance. The causality of this relationship was confirmed in the PROMISS trials, showing that dietary advice to increase protein intake to 1.2 g/kgBW/d in older adults with a low habitual protein intake is feasible, and is associated with a slower 6-months decline in 400 m walk time and leg muscle strength. Persuasive technology during the trial (a provided tablet with individually-tailored application to count daily protein intake, with and without gamification) was well-appreciated by the older participants, but did not enhance compliance to the dietary advice. PROMISS also highlighted that the dietary changes induced by the dietary advice made the diet of the older participants less environmentally sustainable. However, modelling studies based on habitual dietary intake data from Dutch older adults showed that an increase in protein intake to 1.2 g/kgBW/d with a parallel 50% reduction in environmental burden is feasible without unrealistic dietary changes while maintaining a sufficient intake of essential amino acids.
Several studies, including gnotobiotic mouse experiments, were performed to investigate the role of the oral and gut microbiome in appetite and malnutrition. Furthermore, the effect of increased protein intake on the oral and gut microbiome in older adults was investigated in the PROMISS trial. The in-depth methodological study was resumed after the COVID-19 lockdown with the aim to validate physical activity data collected using different accelerometers.
The industry/SME partners in collaboration with the applied sciences universities have developed protein-(en)rich(ed) food products and successfully tested them in older persons. PROMISS has also developed several explainer videos targeting industry to start product innovation and a roadmap based on the Stage-gate model to guide new food product development according to the needs and preferences of older adults to prevent malnutrition and enhance active and healthy aging.
