Dietary protein adequacy is crucial for muscle health in aging individuals, posing a particular challenge for vegetarian seniors. This randomized controlled trial (RCT) investigates the impacts of protein-enriched lacto-vegetarian soup supplementation on body composition, muscle strength and physical performance, functional assessment as well as cardiometabolic risk, and inflammatory biomarkers in older adults.

We enrolled 100 participants ≥65 years with sarcopenia risk (SARC-F ≥4 or SARC-CalF ≥11) and at risk for malnutrition (MNA ≤ 11) in this RCT. Participants were randomized assigned to receive a daily protein-enriched lacto-vegetarian soup (24-30 g protein) or usual diet. Primary outcomes of interest including 1) body composition (anthropometric measurements and body composition measured by bioimpedance analysis (BIA), 2) physical performance (Short Physical Performance Battery, SPPB) and muscle strength (hand grip strength), and 3) functional assessments (including sarcopenia risk scales and nutritional status) as well as secondary outcomes of interests including cardiometabolic and inflammatory biomarkers were assessed at baseline and the 12^th week of follow-up.

Data of 97 participants (intervention: n = 48, control: n = 49) were analyzed. Despite no significant changes in body composition were observed in the intervention group, compared to the usual diet, those who received protein-enriched lacto-vegetarian soup supplementation had an improved physical performance including an increase in SPPB score (β = 0.83 (95% CI 0.15 to 1.51), p = 0.02), a decrease in time to complete the 5 times chair rise test (β=-2.25 (-4.04 to -0.44), p = 0.01). Some functional assessments, including improved sarcopenia risk scale (e.g., SARC-F score (β=-0.68, p = 0.04)) and nutritional status (e.g., MNA-SF score (β = 0.44, p = 0.03)) were also observed.

Daily supplementation with protein-enriched lacto-vegetarian soups enhanced physical performance and functional assessments (such as sarcopenia risk scale and nutritional status) among older adults at risk of malnutrition and sarcopenia. Further study is needed to explore the long-term benefits of protein-enriched lacto-vegetarian soup supplementation for healthy aging.