Plain language summary
Undernutrition in older adults is a problem and the recommendation of increased protein intake may prevent this. However, dietary protein can increase feelings of being full and subsequently reduce the amount of food eaten, which is counterproductive. It is thought that it does this through modulation of the gut microbiota and appetite regulation in the brain. This subgroup analysis of a randomised control trial of 90 older adults with protein intake of <1.0g/kg of adjusted body weight/day aimed to determine if protein intakes of 1.2g/kg of adjusted body weight/day affect gut microbiota composition and appetite. The results showed that gut microbiota composition, brain activity in response to food, and appetite were unaffected by increased protein intake for 6 months. It was concluded that increased protein intake in older adults has no negative effects on gut microbiota or appetite. This study could be used by healthcare professionals to recommend a higher protein diet to older adults with decreased muscle mass or who are undernourished without concerns that it will decrease dietary intake of other nutrients.
Abstract
Expert groups argue to raise the recommended daily allowance for protein in older adults from 0.8 to 1.2 g/kg/day to prevent undernutrition. However, protein is thought to increase satiety, possibly through effects on gut microbiota and central appetite regulation. If true, raising daily protein intake may work counterproductively. In a randomized controlled trial, we evaluated the effects of dietary advice aimed at increasing protein intake to 1.2 g/kg adjusted body weight/day (g/kg aBW/day) on appetite and gut microbiota in 90 community-dwelling older adults with habitual protein intake <1.0 g/kg aBW/day (Nintervention = 47, Ncontrol = 43). Food intake was determined by 24-h dietary recalls and gut microbiota by 16S rRNA sequencing. Functional magnetic resonance imaging (fMRI) scans were performed in a subgroup of 48 participants to evaluate central nervous system responses to food-related stimuli. Both groups had mean baseline protein intake of 0.8 ± 0.2 g/kg aBW/day. At 6 months’ follow-up this increased to 1.2 ± 0.2 g/kg aBW/day for the intervention group and 0.9 ± 0.2 g/kg aBW/day for the control group. Microbiota composition was not affected, nor were appetite or brain activity in response to food-related stimuli. Increasing protein intake in older adults to 1.2 g/kg aBW/day does not negatively impact the gut microbiota or suppress appetite.
Methodological quality
Jadad score
:
2
Allocation concealment
:
No
