Ilse Reinders, Hanneke Wijnhoven, Satu Jyväkorpi, Merja Suominen, Riikka Niskanen, Judith Bosmans, Ingeborg Brouwer, Kristien Fluitman, Michel Klein, Lothar Kuijper, Laura van der Lubbe, Margreet R. Olthof, Kaisu Pitkälä, Rachel Vijlbrief and Marjolein Visser

BMJ Open

Introduction: Short-term metabolic and observational studies reveal that protein intake above the recommended dietary allowance of 0.83 g/kg body weight /day may have positive effects on muscle mass and physical function in old age, but evidence from randomized controlled trials is not clear.

Methods: The PRevention Of Malnutrition In Senior Subjects in the EU (PROMISS) trial evaluates the effect of a personalized protein rich diet on physical function. Some participants are additionally advised to consume protein shortly after usual physical activity. A total of 264 older adults over 65 living at home with a lower protein intake (< 1.0 g/kg body weight/day) from Finland and the Netherlands will be randomized into three study groups; two intervention groups and one control group. Intervention group 1 receives personalized dietary advice in order to increase their protein intake to at least 1.2 g/kg of bodyweight/day. Intervention group 2 receives the same advice as Intervention group 1, and in addition advice to consume protein through protein rich or protein enriched foods within half an hour after performing usual physical activity. The control group receives no intervention. We will investigate the effect of increasing protein intake after 6-months looking if there’s a change in how long a person takes to walk 400-m. Other outcome measures are i.e. changes in a physical performance test, muscle strength and body composition. We also investigate cost-effectiveness by change in health care costs.

Discussion: The PROMISS trial will provide evidence whether increasing protein intake, and additionally optimizing the timing of protein intake, has a positive effect on the course of physical functioning after 6 months among older adults living at home with a lower protein intake.

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