Background: As individuals age, there is a gradual loss of muscle mass and strength, which not only impairs physical functionality but also heightens the risk of falls and diminishes independence among older adults. Probiotics have emerged as a focus of recent research due to their potential role in enhancing muscle health via the gut–muscle axis. This study evaluates the effects of live and heat-treated Lacticaseibacillus paracasei PS23 (PS23) supplementation on muscle strength and mass in the elderly. Methods: This study recruited 119 participants, aged 65–85 years, and randomly assigned them to receive a placebo (0 × 10¹⁰ CFU/day), L-PS23 (live PS23, 2 × 10¹⁰ CFU/day), or HT-PS23 (heat-treated PS23, 2 × 10¹⁰ cells/day) for a duration of 12 weeks. Assessments of blood pressure, body composition, muscle strength, functional physical fitness, and biochemical parameters were conducted at baseline, 6 weeks, and 12 weeks. Results: Among the 100 subjects who completed the trial, supplementation with both L-PS23 and HT-PS23 significantly enhanced lower limb muscle strength and endurance compared to the placebo (p < 0.05), although no significant differences were observed in muscle mass or upper limb muscle strength across the groups. Additionally, while most muscle anabolism-related markers showed no significant changes, both supplements effectively decreased inflammatory markers related to aging—C-reactive protein (CRP: L-PS23, p = 0.016; HT-PS23, p = 0.013) and interleukin-6 (IL-6: L-PS23, p = 0.003; HT-PS23, p < 0.001)—and increased interleukin-10 levels (L-PS23, p = 0.014; HT-PS23, p = 0.005). Notably, only the HT-PS23 group demonstrated a significant increase in testosterone levels (p = 0.029). Conclusions: 12 weeks of supplementation with L-PS23 and HT-PS23 improved lower limb muscle strength and endurance but did not significantly enhance muscle mass in older adults. Both supplements also proved effective in reducing inflammatory markers and elevating testosterone levels. HT-PS23, administered as a heat-treated probiotic, provided more pronounced benefits to the elderly compared with its probiotic counterpart, L-PS23.

Probiotics are posited to enhance exercise performance by influencing muscle protein synthesis, augmenting glycogen storage, and reducing inflammation. This double-blind study randomized 88 participants to receive a six-week intervention with either a placebo, Lactococcus lactis subsp. lactis LY-66, Lactobacillus plantarum PL-02, or a combination of both strains, combined with a structured exercise training program. We assessed changes in maximal oxygen consumption (VO_2max), exercise performance, and gut microbiota composition before and after the intervention. Further analyses were conducted to evaluate the impact of probiotics on exercise-induced muscle damage (EIMD), muscle integrity, and inflammatory markers in the blood, 24 and 48 h post-intervention. The results demonstrated that all probiotic groups exhibited significant enhancements in exercise performance and attenuation of muscle strength decline post-exercise exhaustion (p < 0.05). Notably, PL-02 intake significantly increased muscle mass, whereas LY-66 and the combination therapy significantly reduced body fat percentage (p < 0.05). Analysis of intestinal microbiota revealed an increase in beneficial bacteria, especially a significant rise in Akkermansia muciniphila following supplementation with PL-02 and LY-66 (p < 0.05). Overall, the combination of exercise training and supplementation with PL-02, LY-66, and their combination improved muscle strength, explosiveness, and endurance performance, and had beneficial effects on body composition and gastrointestinal health, as evidenced by data obtained from non-athlete participants.

Background: Insomnia is prevalent and difficult to treat safely over the long term. Given the role of the microbiota–gut–brain axis in melatonin and hypothalamic–pituitary–adrenal (HPA) regulation, and preclinical evidence for Limosilactobacillus fermentum PS150, we evaluated whether a heat-treated formulation (HT-PS150) could improve sleep and modulate endocrine/circadian markers in adults with poor sleep. Methods: In a randomized, double-blind, placebo-controlled trial, 84 adults aged 20–60 years with PSQI ≥ 5 and ISI < 22 were assigned to receive either placebo or HT-PS150 for eight weeks. Outcomes included patient-reported sleep (PSQI, ISI), anxiety/depression (GAD-7, PHQ-9), quality of life (QLESQ-SF), gastrointestinal symptoms (VAS-GI), wrist actigraphy (Fitbit Inspire 3), and sleep-relevant biomarkers measured from urine, saliva, and/or blood samples (melatonin, cortisol, orexin, serotonin, GABA, and/or norepinephrine). Repeated measures were analyzed using generalized estimating equations. An exploratory proportional regulation analysis classified individual biomarker changes as up- or down-regulated and compared proportions between study arms. Per-protocol analyses required ≥80% compliance. Results: Improvements in the primary outcomes, PSQI and ISI, were observed over time in both groups, while no significant group × time interactions were detected. In exploratory proportional analyses, a higher proportion of participants in the HT-PS150 group exhibited up-regulated nocturnal melatonin secretion and improved daytime plasma orexin levels, as well as a tendency toward greater reductions in nocturnal salivary cortisol compared with placebo. In subgroup analyses with higher baseline insomnia severity (ISI ≥ 8), HT-PS150 was associated with greater improvements in PSQI (notably sleep duration and efficiency) and reduction in anxiety (GAD-7) upon post hoc testing. Conclusions: Although group mean scores on sleep symptom scales did not differ significantly in the full cohort, HT-PS150 appeared to modulate sleep–wake regulation by enhancing nocturnal melatonin secretion, attenuating HPA-axis activity, and stabilizing wakefulness. Clinical benefits were most evident among participants with greater baseline symptom burden, suggesting potential utility in more symptomatic populations.

Background: Exercise-induced fatigue arises primarily from energy substrate depletion and the accumulation of metabolites such as lactate and ammonia, which impair performance and delay recovery. Emerging evidence implicates gut microbiota modulation—particularly via probiotics—as a means to optimize host energy metabolism and accelerate clearance of fatigue-associated by-products. Objective: This study aimed to determine whether live or heat-inactivated Lacticaseibacillus paracasei NB23 can enhance exercise endurance and attenuate fatigue biomarkers in a murine model. Methods: Forty male Institute of Cancer Research (ICR) mice were randomized into four groups (n = 10 each) receiving daily gavage for six weeks with vehicle, heat-killed NB23 (3 × 10¹⁰ cells/human/day), low-dose live NB23 (1 × 10¹⁰ CFUs/human/day), or high-dose live NB23 (3 × 10¹⁰ CFUs/human/day). Forelimb grip strength and weight-loaded swim-to-exhaustion tests assessed performance. Blood was collected post-exercise to measure serum lactate, ammonia, blood urea nitrogen (BUN), and creatine kinase (CK). Liver and muscle glycogen content was also quantified, and safety was confirmed by clinical-chemistry panels and histological examination. Results: NB23 treatment produced dose-dependent improvements in grip strength (p < 0.01) and swim endurance (p < 0.001). All NB23 groups exhibited significant reductions in post-exercise lactate (p < 0.0001), ammonia (p < 0.001), BUN (p < 0.001), and CK (p < 0.0001). Hepatic and muscle glycogen stores rose by 41–59% and 65–142%, respectively (p < 0.001). No changes in food or water intake, serum clinical-chemistry parameters, or tissue histology were observed. Conclusions: Our findings suggest that both live and heat-treated L. paracasei NB23 may contribute to improved endurance performance, increased energy reserves, and faster clearance of fatigue-related metabolites in our experimental model. However, these results should be interpreted cautiously given the exploratory nature and limitations of our study.

Background/Objectives: Aging is characterized by progressive physiological and metabolic decline. Aerobic exercise mitigates age-related impairments, and nicotinamide mononucleotide (NMN), a precursor in the NAD⁺ salvage pathway, has emerged as a nutritional intervention to promote healthy aging. This study investigated whether NMN supplementation combined with aerobic exercise provides synergistic benefits on physical performance and metabolic regulation in aged mice. Methods: Forty male C57BL/6J mice, including eight young (8 weeks) and thirty-two aged (85 weeks) mice, were randomly assigned to five groups: young sedentary (YS), aged sedentary (AS), aged with exercise (AE), aged with NMN (ASNMN; 300 mg/kg/day), and aged with combined NMN and exercise (AENMN). Interventions lasted six weeks. Assessments included grip strength, muscle endurance, aerobic capacity, oral glucose tolerance test (OGTT), and indirect calorimetry, followed by biochemical and molecular analyses of NAMPT and SirT1 expression. Results: The AENMN group demonstrated significant improvements in maximal strength and aerobic endurance compared with the AS group (p < 0.05). Both NMN and exercise interventions increased blood NAMPT concentrations, with the highest levels observed in the AENMN group (p < 0.05). SirT1 expression was elevated in the ASNMN and AENMN groups relative to YS (p < 0.05). Glucose tolerance improved in the ASNMN and AENMN groups (p < 0.05). Enhanced energy metabolism in the AENMN group was indicated by increased oxygen consumption, elevated energy expenditure, and reduced respiratory quotient. Conclusions: NMN supplementation, particularly when combined with aerobic exercise, effectively improved aerobic performance, glucose regulation, and systemic energy metabolism in aged mice. These findings suggest that NMN, in synergy with exercise, may serve as a promising nutritional strategy to counteract age-associated metabolic and functional decline.

Chronic psychological stress impairs neuroendocrine balance and increases the risk of mental health disturbances, including anxiety, sleep disruption, and low mood. The gut–brain axis has emerged as a promising target for stress modulation, particularly through psychobiotic interventions. This randomized, double-blind, placebo-controlled trial evaluated the effects of a combined psychobiotic formulation (Neuralli Mood), comprising live Lactiplantibacillus plantarum PS128 (PS128) and heat-treated Lacticaseibacillus paracasei PS23 (HT-PS23), on the psychological and physiological stress responses in a high-stress occupational population. A total of 116 healthy participants with elevated perceived stress (PSS ≥ 14), primarily firefighters, were randomly assigned to receive the dual-strain supplement or placebo for 8 weeks. Stress-related outcomes were assessed by using validated psychological scales and serum biomarkers. Compared with placebo, the psychobiotics group showed significantly greater reductions in overall job stress perception (JSS), state anxiety (STAI), and insomnia severity (ISI) (all p < 0.05). Additionally, serum adrenocorticotropic hormone (ACTH) and norepinephrine levels were significantly reduced post-intervention, whereas cortisol levels remained unchanged. These findings suggested that combining live and heat-treated psychobiotic strains may provide a safe and effective strategy for alleviating psychological stress and regulating neuroendocrine function in high-risk populations.