Protein or branched-chain amino acid intake at breakfast for muscle mass gain in older persons: A protocol for systematic review and meta-analysis

In recent years, prevention of sarcopenia and frailty is a matter of concern for community dwelling older persons. The recommended protein daily intake is not fulfilled by 10% of community-dwelling elderly and 35% of residents in aged-care facilities. Furthermore, the optimum time of protein consumption is unclear because of the varying combinations of intake timing and exercise. Although it is desirable to increase protein intake at breakfast and lunch without reducing intake at supper to maximize muscle protein synthesis, this is not clear for older people. Therefore, before considering whether protein consumption at breakfast is superior to other times of the day, its effectiveness needs to be clarified in older adults. The inclusion criterion will be healthy or frail adults older than 60 years. This protocol of systematic review adhered to the PRISMA 2020 statement. A comprehensive study strategy is designed for PubMed, EMBASE, CENTRAL, and Clinical Trials.gov. Search strategies will be made using Boolean Search Logic by an experienced librarian in systematic review search formula design. Two authors will carry out independent screening of titles, abstracts, and data extraction for randomized controlled trials. Statistical heterogeneity will be assessed by meta-analysis. Assessment of the risk of bias will be conducted using the Risk-of-bias 2 tool. Integrated data will be analyzed using Review Manager software to create summary tables. Findings summary tables for primary and secondary outcomes will be produced in accordance with the procedures in the Cochrane Handbook. We believe that the effects of protein or BCAA intake at breakfast in older people analysed in this review will provide evidence that contributes to the establishment of treatment strategies to prevent frailty and sarcopenia. The benefits of protein intake at breakfast for the elderly will be clarified. This will encourage hospitals and elderly care facilities to review the content of the diet and encourage the elderly to change their own behavior. This is expected to ultimately reduce healthcare costs.