Effect of pea protein-enriched snacks and vitamin D supplementation on the progression of sarcopenia in elderly subjects: study protocol of the SARC-PEA randomised controlled trial

The progressive ageing of the population (age > 65 years) underscores the urgent need for effective strategies for the prevention of sarcopenia, a condition characterised by the gradual loss of muscle mass and muscle strength and a decline in physical performance. Adequate intake of dietary protein and vitamin D (VD) has been identified as a key factor in mitigating the progression of this condition. The SARC-PEA study aims to evaluate the efficacy of a nutritional intervention involving the consumption of a pea protein-enriched snack, coupled with VD supplementation, in slowing the progression of sarcopenia. The use of plant proteins is necessary from the perspective of a protein transition. However, human intervention studies to date have primarily focused on the effects of animal proteins (mainly whey) on the progression of this disease. A study of the effects of plant proteins, particularly pea proteins, has not yet been conducted and will gather information on their effectiveness in modulating disease-related markers. We propose a monocentric, single-blind, parallel randomised clinical trial to evaluate the efficacy of consuming a snack enriched with pea proteins and supplementing VD in slowing the progression of sarcopenia. Patients who met the inclusion criteria and signed the informed consent form would be randomly assigned to the intervention group or the control group. The intervention will last 3 months, with no follow-up. The primary outcome is the appendicular skeletal muscle mass index measured by bioimpedance analysis. Secondary outcomes include muscle strength by measuring grip strength and leg strength (chair stand test); physical performance by the “Short Physical Performance Battery”; and inflammatory response and other blood biomarkers related to sarcopenia, such as CRP, IL-6, TNF-alpha, ox-LDL, IGF-1, 25-hydroxycholecalciferol, albumin, leptin, triglycerides, haemoglobin, and C-terminal fragment of agrin. In addition, the following will be assessed: eating habits using a food frequency questionnaire and repeated 3-day food records, and their quality of life using the SarQoL questionnaire. Finally, the effect of the nutritional intervention on modulation of the gut microbiome and its metabolites (SCFA) will be evaluated using 16S rRNA sequencing, bioinformatic analysis and high-performance liquid chromatography. The results will provide insights into the effectiveness of the consumption of a pea protein functionalised palatable snack paired with VD supplementation. Moreover, including a variety of outcome measures—such as muscle mass, strength, physical performance, biomarkers, and gut microbiome composition—in a single trial allows for a thorough evaluation of the intervention’s effects across multiple physiological systems. ClinicalTrials.gov, NCT07356440. Registered on 12/01/2026, available at https://clinicaltrials.gov/study/NCT07356440 .