How to establish increased protein intake in a blended lifestyle intervention in community-dwelling older adults?: subgroup-analysis of the VITAMIN RCT

Rationale: The dietary protein counselling of the VITAMIN trial showed to be effective in increasing the protein intake in community-dwelling older adults up to 1.41 g/kg/day after 6-months intervention and sustaining this intake up to 1.24 g/kg/day at 12-months. In this sub-analysis we determine how the increased protein intake was established. Methods: The VITAMIN (VITal AMsterdam older adults IN the city) RCT randomised older adults into: control, exercise, or exercise plus dietary counselling (protein) group. The dietary counselling intervention was blended, by use of face-to-face contacts and videoconferencing during a 6-month intervention, followed by a 6-month follow-up. Dietary intake was measured by a 3d dietary record at 0, 6 and 12 months (m). Sub-group analysis included characterisation of protein sources, product groups, resulting amino acid intake, and intake per meal moment. Linear Mixed Models were performed with SPSSv25; whereas time and time*group interaction were defined as fixed factors, and the protein group as reference. Results: In total 212 subjects were eligible for analysis (72.2 ± 6.3y), with an average protein intake at baseline of 77.8 (20) g/day and 1.08 (0.3) g/kg/day. Animal protein (g) accounted as major source (6m +25.6 (2.7) p<0.001 | 12m +15.6 (2.8) p<0.001), with the main increase in dairy products (g) (6m +14.2 (1.5) p<0.001 | 12m +10.0 (1.5) p<0.001), followed by fish and meat. This resulted in significant changes in amino acid intake: e.g. leucine (g) 6m +2.3 (0.3) p<0.001 | 12m +1.1 (0.3) p<0.001. Significant increased intake for the protein group was seen at all 6 meal moments, and particularly at breakfast (g) 6m +6.2 (1.0) p<0.001 | 12m +6.5 (1.1) p<0.001) and lunch (g) 6m +7.2 (1.3) p