Dong-Ki Hong

Age-associated reductions in muscle strength and physical function have become an important public health concern among older adults, and gut microbiome-targeted interventions have emerged as a potential strategy to mitigate these declines. We evaluated the effects of Lactiplantibacillus plantarum HY7715 ( L. plantarum HY7715) on lower-limb muscle function, serum vitamin B ₂ , and gut microbiome profiles in older adults exhibiting reduced muscle strength. In this 12-week, randomized, double-blind, placebo-controlled trial, 100 adults aged 50–85 years were assigned to receive HY7715 (5.0 × 10 ⁹ CFU/day) or placebo. Compared with placebo, HY7715 supplementation was associated with greater increases in multiple measures of quadriceps strength, with the left and bilateral mean measures remaining significant after baseline adjustment. Selected hamstring strength and quadriceps muscle power outcomes also showed significant improvements in the unadjusted analyses. Overall, the most consistent findings were observed for quadriceps strength, whereas the hamstring strength and quadriceps muscle power findings were less consistent after baseline adjustment. Serum vitamin B ₂ concentration increased significantly following HY7715 supplementation, and the between-group difference remained significant after adjustment for baseline dietary riboflavin intake. Microbiome analyses demonstrated increased Chao1 alpha diversity, significant within-group shifts in beta diversity, and increased relative abundances of Lactiplantibacillus and L. plantarum . HY7715 supplementation was associated with greater increases in selected quadriceps strength measures and serum vitamin B ₂ concentrations in adults with reduced muscle strength.

Maintaining probiotic effectiveness represents the most important task for the development of functional foods. Gastrointestinal stability and intestinal adhesion properties comprise one criterion for probiotic selection. Here, we investigated the benefits of milk fermented with Lactobacillus casei HY2782 at different fermentation times. The probiotic strain used was L. casei HY2782 and the reference strain was L. casei ATCC393 for comparisons. The samples were fermented for 7 days at 30 °C. We determined the pH, CFU/mL, survival rate during simulated gastrointestinal digestion, adhesion ability to HT-29 cells, and gene expression of tight-junction proteins known to regulate intestinal permeability in Caco-2 cells. L. casei HY2782 exhibited significantly higher survival rates in simulated gastrointestinal digestion during long-term fermentation than L. casei ATCC393. The adhesion ability to HT-29 cells was significantly increased with L. casei HY2782 (3.3% to 8.7%) after 7 days of fermentation; however, only a slight increase was observed for L. casei ATCC393 (3.1% to 4.7%). In addition, L. casei HY2782 can significantly increase the expression of genes encoding tight-junction proteins during long-term fermentation of milk. In conclusion, we confirmed that long-term fermentation could be a novel manufacturing process for fermented milk containing L. casei HY2782 and showed the beneficial effects.

Journal of Milk Science and Biotechnology (J. Milk Sci. Biotechnol., ISSN 2384-0269; eISSN 2508-3635) publishes original papers or review articles covering topics of chemistry, biotechnology, processing and microbiology of milk and milk products since 1981