Introduction

older adults, probiotic supplementation is considered promising for improving cognitive function and metabolic health, especially in conditions such as diabetes, cardiovascular disease, and hypertension. However, the extent and consistency of these effects are not yet well established in the scientific literature. In older adults, probiotic supplementation is considered promising for improving cognitive function and metabolic health, especially in conditions such as diabetes, cardiovascular disease, hypertension and neurodegenerative diseases like Alzheimer’s and Parkinson’s disease.

Objective

this study aims to evaluate the cognitive and metabolic effects of probiotic use in older adults through a meta-umbrella review.

Methods

a meta-umbrella review was conducted following the JBI methodology and the Reporting Guideline for Overviews of Interventions in Health (PRIOR). A systematic search was performed in databases including Web of Science, PubMed, Scopus, EMBASE, Cochrane, Epistemonikos, and CINAHL. Studies included systematic reviews and meta-analyses evaluating the cognitive and metabolic effects of probiotic supplementation in elderly individuals. Data extraction, quality assessment (using AMSTAR and ROBIS tools), and statistical analyses, including heterogeneity tests and meta-analytical synthesis, were performed.

Results

from an initial pool of 287 studies, 24 systematic reviews and meta-analyses were included. The findings suggest that probiotic supplementation significantly improves cognitive function, particularly in individuals with neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease (SMD = 1.34, 95% CI: 0.51–2.16, p < 0.01). Regarding glycemic control, probiotics led to a reduction in fasting glucose levels (MD = -0.98 mmol/L, 95% CI: -1.17 to -0.78, p < 0.00001) and glycated hemoglobin (HbA1c) (MD = -0.19%, 95% CI: -0.32 to -0.07, p = 0.003). Probiotic supplementation also improved lipid metabolism by lowering total cholesterol (MD = -8.43 mg/dL, 95% CI: -12.57 to -4.28, p < 0.001) and LDL cholesterol (MD = -5.08 mg/dL, 95% CI: -7.63 to -2.53, p < 0.01), while increasing HDL cholesterol levels (MD = +1.14 mg/dL, 95% CI: 0.28–2.00, p = 0.009). Blood pressure regulation showed moderate benefits, with reductions in systolic blood pressure (MD = -3.10 mmHg, 95% CI: -5.04 to -1.16, p = 0.002) and diastolic blood pressure (MD = -1.98 mmHg, 95% CI: -3.84 to -0.12, p = 0.04). Additionally, probiotics significantly reduced inflammatory biomarkers, including C-reactive protein (CRP) (MD = -0.62 mg/L, 95% CI: -0.91 to -0.33, p < 0.001) and tumor necrosis factor-alpha (TNF-α) (MD = -0.27 pg/mL, 95% CI: -0.49 to -0.05, p = 0.02). Despite these promising findings, heterogeneity across studies was moderate to high, with I2 values ranging from 40% to 85%, indicating variability in study populations, intervention durations, and probiotic strains used.

Conclusion

probiotic supplementation appears to be a promising intervention for improving cognitive and metabolic health in older adults. The modulation of the gut microbiota plays a key role in regulating inflammation, energy metabolism, and neurotransmission, which may contribute to these health benefits. However, due to variations in study designs and probiotic formulations, further high-quality randomized clinical trials are needed to establish optimal strains, dosages, and treatment durations.