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Impact of Dietary Protein on Disability in ageing Europeans

Periodic Reporting for period 1 - InDEPENDEnt (Impact of Dietary Protein on Disability in ageing Europeans)

Reporting period: 2019-07-15 to 2021-07-14

Older adults (≥65y) comprise, on average, 18% of the total population of the European Union (EU). As of 2014, there were 22 countries in Europe with a life expectancy at birth higher than 80 years and 17 countries with a life expectancy at age 65 higher than 20 years. Life expectancy has not only been rising from birth but also at age 65. For example, life expectancy at age 65 in Portugal has increased from 20.0 years in 2004 to 21.7 in 2015 for women, and from 16.3 years to 18.0 for men during the same period, placing Portugal 0.5 years and 0.1 years above the EU28 for women and men, respectively. However, the increase in Healthy Life Years (HLY), the number of years an individual can expect to live disability-free, has not kept pace; HLY in Portugal has remained constant since 2006 and lower than the EU28 average for women and men by 4.0 and 2.8 years, respectively. Bridging the gap between life expectancy and HLY by compressing morbidity into the later years of life is of special interest; not only to increase quality of life, but also to relieve the immense strain on the healthcare systems of European countries. Diet is a major modifiable risk factor for the development and management of a range of age-related diseases that are frequently the leading causes of morbidity, disability and death in Europe. Specifically, dietary protein may slow the decline of muscle mass and function with ageing, making it a sensible candidate to prevent or modulate disability progression.
Protein malnutrition is a cause for concern in older adults in Europe since protein intake is lower in European older men (87 g/d) and women (69 g/d) than in their younger counterparts (97 g/d and 73 g/d respectively) due to multimorbidity, changes in oral health, changes in taste perception and loss of independence. Another compounding issue is that the current protein recommended dietary allowance is based largely on short-term nitrogen balance studies conducted in mainly healthy young adults, thereby failing to take into account functional outcomes, such as disability, or the higher prevalence of multimorbidity in older adults both of which can offset protein requirements due to disease-related tissue catabolism and inflammation. The InDEPENDEnt project addressed these issues by providing a robust estimate of the association between protein intake and physical function in older European and North-American adults, as well as investigating the synergistic effect of physical activity. InDEPENDEnt also reproduced these analyses on Portuguese young-old adults as well as providing up-to-date estimates on the prevalence of mobility limitations in Portugal.
After a thorough quality check, selected variables were harmonised prior to merging of all cohorts. The secondment at Vrije Universiteit with Prof. Marjolein Visser was essential to speed up this process. With the cohorts merged we could carry on with the pooled analysis of individual participant data. The last stage of InDEPENDEnt was replicating the analysis on a Portuguese nationally-representative sample of young-old adults and estimating the prevalence of mobility limitations.
The main results of project were that a) higher daily protein intake may reduce physical function decline in community-dwelling older adults not only in those with a protein intake <0.8 g/kg bodyweight/d but also in those with protein intake that is already considered sufficient, in a dose-dependent manner; b) we also found that in our sample there was no association between protein intake and physical activity in relation to physical function; c) in addition there was no association between animal foods and mobility limitations in a Portuguese sample of young-old adults.

InDEPENDEnt directly resulted in 3 published or submitted scientific publications and indirectly to others:

• Salvador C … Mendonça N. (2021) Animal foods and mobility limitations in community-dwelling young-old adults: longitudinal analysis of the EpiDoC cohort (submitted).
• Mendonça et al. (2021) Protein intake, physical activity and grip strength in European and North American community-dwelling older adults: a pooled analysis of individual participant data from four longitudinal ageing cohorts. (submitted).
• Mendonça N et al. (2021) Low protein intake, physical activity and physical function in European and North American community-dwelling older adults: a pooled analysis of four longitudinal aging cohorts. Am J Clin Nutr. doi:10.1093/ajcn/nqab051.

I have delivered several oral presentations at international and national conferences, as well as created a project’s website, shared lay summaries of the published articles on Twitter, LinkedIn, the project’s website as well as another H2020 project’s website (PROMISS) (www.promiss-vu.eu).
InDEPENDEnt was recently finalised and all the findings are still being published and/or disseminated. However, it will be essential to inform the development of age-specific guidelines for protein intake in older adults in Europe and elsewhere. We have also supplied up-to-date prevalence on mobility limitations in Portugal which may help the national health system to allocate resources and develop better dietary strategies to prevent mobility limitations. This project has the potential to compressing morbidity into the later stages in life and therefore increasing quality of life and alleviating the immense strain on the European healthcare systems. This aligns well with the EU’s societal challenges of demographic change, health and food security and addresses the WHO’s focus on maintaining maximum health and functional capacity of ageing people.
Cohorts used
Updated simple GANTT chart
Logo for InDEPENDEnt project