Adequate protein intake and protein supplementation has a beneficial role in the prevention and treatment of sarcopenia. The achievement and quantification of the recommended total protein intake by sarcopenic older adults receiving protein supplementation has not been studied. The aim of this study was to compare the accuracy of protein intake estimated from a combination of four-day food diaries and weighed protein powders against total protein intake estimated from 24 -h urine samples.

Longitudinal data analysis of the ongoing Exercise and Nutrition for Healthy AgeiNg (ENHANce) study.

This study included community-dwelling older adults aged ≥65 years) diagnosed with sarcopenia (EWGSOP2-criteria).

The amount of protein/placebo supplement was individualized to achieve a mean total protein intake of 1.5 g/kg BW/day. Total protein intake in participants was determined by a combination of weighed protein powders and four-day food diaries and by nitrogen-excretion in 24 -h urine samples at eight different timepoints during the intervention. Mean differences and Lin’s concordance correlation coefficients were used to assess agreement between the two methods.

After 12 weeks, nitrogen analysis showed that the mean total protein intake was 1.31 g/kg BW in the protein powder group (n = 33) and 0.86 g/kg BW in the placebo group (n = 17). Mean protein intake according to the combination of food diaries and weighed powders (87.0 g/day) was overestimated by 7.7 g/day compared to the method using 24 -h urine samples (79.3 g/day). Correlation between protein intake derived from the combined method and 24 -h urine samples varied between 0.244-0.565 and 0.382-0.641 in the placebo group and protein group, respectively.

Both the 24 -h urine samples and combined food diaries with weighed protein powders demonstrated that protein supplementation increased protein intake to meet the daily recommended amount of protein intake for older adults (1.0-1.2 g/kg BW), but not that for sarcopenic older adults (1.5 g/kg BW). While a fair to moderately strong correlation was observed between the methods, there was significant variability in the protein intake estimates. Additional research is needed to assess the accuracy of other potential techniques in determining protein intake in an older population. The ENHANce study was registered on ClinicalTrails.gov (NCT03649698).