Systematic review of probiotic supplementation in Alzheimer’s patients with results on cognitive function, health biomarkers, and microbiota

The gut–brain axis has emerged as a potential therapeutic target in migraine management. Several randomized controlled trials (RCTs) have evaluated probiotic supplementation in migraine, yet their findings remain heterogeneous. The aim of this study was to systematically assess and quantitatively synthesize the effects of probiotics on migraine-related outcomes. A systematic review and meta-analysis of randomized controlled trials was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and registered in PROSPERO (CRD420261327461). Electronic databases were searched from inception to January 2026. Random-effects meta-analyses were performed to calculate pooled standardized mean differences (SMD) with 95% confidence intervals (CI). Primary outcomes included migraine attack frequency, migraine duration, and migraine severity. Secondary outcomes comprised inflammatory biomarkers, including high-sensitivity C-reactive protein (hs-CRP) and tumor necrosis factor-alpha (TNF-α). Risk of bias was assessed using the Cochrane Risk of Bias 2 (ROB 2) tool. Six RCTs involving 422 participants were included. Overall, probiotic supplementation significantly improved migraine-related outcomes compared with placebo (p<0.00001). Subgroup analyses demonstrated significant reductions in migraine attack frequency (p=0.002), migraine duration (p=0.0003), migraine severity (p=0.0006), and migraine disability assessment (MIDAS) score (p= 0.04). Substantial heterogeneity was observed across studies (I²=91%). Regarding inflammatory biomarkers, probiotic supplementation was not associated with significant reductions in hs-CRP (p=0.24) or TNF-α (p=0.66). The pooled analysis of inflammatory markers also showed no significant overall effect (p=0.28). Most trials were judged as having a low risk of bias or some concerns. In conclusion, probiotic supplementation is associated with significant improvements in migraine frequency, duration, severity, and disability, supporting its potential as an adjunctive therapeutic strategy in migraine management. The absence of significant effects on inflammatory biomarkers suggests that these clinical benefits may be mediated through alternative pathways within the gut–brain axis rather than systemic inflammation.

The microbiota-gut-brain axis (MGBA) has been implicated in the pathophysiology of Alzheimer's Disease (AD).Probiotics reduced the progression of ADin different mouse models, possibly through MGBA modulation, but human data are still limited. Here, we evaluated whether differences in the gut microbiome (GM), pro-inflammatory markers and other MGBA mediators were associated with probable AD (pAD). We also assessed the impact of a 12-week probiotic treatment on MGBA. Forty-five pAD patients and 47 healthy subjects (HC) were recruited at IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli of Brescia (Italy). An uncontrolled clinical investigation was performed to test the effects of 12-week probiotic supplementation in the pAD group. Fecal microbiota composition, intestinal and blood inflammatory markers, and microbiota-related metabolites were assessed before supplementation in all participants and after only in pAD. pAD patients showed intestinal inflammation, an altered GM profile, blood changes in the tryptophan metabolism, and reduced glutamate levels compared with HC (p-value<0.049). Probiotic supplementation partially modulated these alterations, determining a reduction in several pro-inflammatory mediators, and an increase of GM-related protective factors, such as butyrate (p-value<0.040) in pAD. These findings confirmed the presence of MGBA alterations in AD and suggested a potential beneficial effect of probiotic supplementation through modulation of GM functionality rather than composition. Further research is required to confirm these results and their clinical relevance.

Through modulating effects on the gut-brain axis, probiotics are an effective adjuvant treatment for Alzheimer's disease (AD), one of our century's most important medical care challenges (Agahi et al. Front Neurol 9:662, 2018). This trial aimed to examine the effects of two different single-strain probiotics on oxidative stress and inflammation in patients with mild and moderate AD. This was a 12-week placebo-controlled, double-blind, randomized clinical trial performed on 90 patients with AD. Eligible patients were randomly assigned to two different interventions (Lacticaseibacillus rhamnosus HA-114 (7.5 × 109) or Bifidobacterium longum R0175 (7.5 × 109)) and a placebo group, supplemented twice daily. We used mixed-effect models to examine the probiotic's independent effects on clinical results. Significant improvements in serum inflammatory and oxidative stress markers were observed at the end of the trial (P < 0.05). Probiotic supplementation for 12weeks had beneficial effects on oxidative stress, inflammation, quality of life, and physical activity in patients with mild and moderate AD.

Preoperative biofluid biomarkers reflecting pathophysiological, neuronal injury, and inflammation as well as those for Alzheimer's disease (AD) may be valuable tools for the risk stratification of perioperative neurocognitive disorders (PNDs) in older adults. We summarized current evidence relating these preoperative biomarkers to PND beyond 7 days, in older surgical participants aged ≥60 years. Studies that evaluated the association of preoperative biomarkers with cognitive decline as an outcome, beyond 7 days, were identified through searches of 6 databases and 3 trial registries to 17 January 2024. Preclinical studies, intracranial surgical, or studies with participants aged <60 years were excluded. Studies varied widely in the assessment of PND, so a wide range of cognitive outcomes was accepted, including those using the term postoperative cognitive dysfunction (POCD) to define cognitive decline. The pooled incidence of POCD utilizing a binary cognitive outcome was summarized. Fifteen studies involving 2103 participants were included. Marked heterogeneity was evident in the cognitive outcome metrics, assessment timeframes, limiting a quantitative synthesis. Of the 9 studies using binarized cognitive outcomes, the incidence of POCD was 23.4% (95% confidence interval [CI], 6.6-46.2) at <3 months, 11.4% (95% CI, 8.1-15.0) at 3 to <12 months, and 6.9% (95% CI, 1.9-14.5) at ≥12 months postoperatively. Of the 15 studies, 9 described blood-based biomarkers, 4 described cerebrospinal fluid (CSF) biomarkers, and 2 measured both blood and CSF markers. The biomarkers evaluated reflected the pathogenic indicators neuronal injury (9 studies), inflammation (5 studies) and of amyloid (5 studies), and Tau (1 study). The studies included were of medium to high quality. Evidence was the most promising for amyloid biomarkers, with 4 of 5 included studies demonstrating associations of lower preoperative biofluid amyloid biomarker levels with increased risk of POCD. In conclusion, preoperative biofluid amyloid biomarkers may hold potential utility for the prediction of POCD, although current evidence remains limited. Other potential preoperative biomarkers for POCD included p-Tau181 and Neurofilament Light, however small sample sizes, study heterogeneity, and conflicting results limited conclusions drawn. Standardized cognitive outcome metrics and common assessment timeframes are additionally required in future studies to ascertain the prognostic utility of these biomarkers for POCD.

Available reviews have shown potential effects of probiotics on neurobehavioral outcomes through 'gut-brain axis' mechanism in adults. However, reviews on cognitive function in children and adolescents are lacking. Therefore, we conducted a systematic review of randomised controlled trials (RCTs) of the effect of probiotic supplementation on cognitive function in children and adolescents. A search of four databases (Cochrane Central Register of Controlled Trials, PsycARTICLES, Scopus, PubMed) was conducted to identify RCTs published from January 1990 to December 2018. Seven studies met the inclusion criteria and their cognitive outcomes were analysed. Only one study found a positive result with Lactobacillus rhamnosus GG (LGG) 1×1010 cfu supplementation with outcomes on attention deficit hyperactivity disorder (ADHD) or Asperger syndrome (AS) manifestations as diagnosed using the International Classification of Diseases-10 criteria. The supplementations were administered to Finnish mothers for 4 weeks before delivery and continuously given for 6 months after delivery if they breastfed, or to the children. ADHD or AS was diagnosed at the age of 13 years in 17.1% children in the placebo and none in the probiotic group (P=0.008). This study found significant differences in species composition and number of cells belonging to the genus Bifidobacterium between healthy children and children who later developed ADHD or AS at different time points. Six remaining studies with varying strains, durations of intervention, start-time of administration, and outcomes demonstrated no difference in cognition after probiotic supplementation. Metagenomic analyses on gut microbiota composition were not performed in any of these studies. In conclusion, the favourable effect of probiotic supplementation on cognitive function in children and adolescents was observed in one study with LGG supplementation by a risk reduction of developing ADHD or AS (i.e. autism). More long-term and follow-up trials using probiotics identifying the effect on cognition are warranted before routine use.

Two hundred and forty (n=240), day-old broiler chicks of strain ‘cobb400’ were divided equally into 3 groups of 80 chicks each in group to observe the effect of probiotics (Protexin) supplementation on growth performance and economics of feeding in broilers. Different dietary treatments were T1–basal diet without probiotics supplementation (control), T2–T1 + probiotics supplementation (50 g/ton of feed) and T3– T1 + probiotics supplementation (100 g/ton of feed). Average daily body weight gain (BWG) was significantly higher (P≤0.01) in T3 compared to T2 and T1 (41.63 ± 0.25 g vs 39.48 ± 0.15, 39.99 ± 0.10). Feed intake during starter, finisher and overall study period remained statistically (P≥0.05) at par. Feed conversion ratio was significantly (P≤0.01) improved with probiotics supplementation @100 g/ton of feed compared to control. Dressing percentage and organ weights (% Body Weight) remained statistically (P≥0.05) similar. Mortality (%) was lower for group T3 (1.25) compared to T2 (3.75) and T1 (5.00) but differences were non-significant (P≥0.05). The return over feed cost was significantly (P≤0.01) higher in T2 (30.99) compared to T1 ( 27.82) and control ( 26.45). The profit per bird over control in group T2 and T3 was 1.37 and 4.54, respectively. Thus, the dietary supplementation of probiotics at 100 g/ton of feed significantly enhanced body weight gain along with better feed conversion ratio and profit without any adverse effect on feed intake, mortality and carcass characteristics.

Dementia is the fifth leading cause of death in the world. Animal studies indicate that in addition to the aging process, intestinal microbiota may play an important role in the neurodegeneration process through the modulation of the gut-brain axis. A systematic review and meta-analysis was conducted to determine the effectiveness of probiotic and synbiotic supplementation on the cognitive function of individuals with dementia. MEDLINE, BVS, SciELO, CENTRAL, Embase, and grey literature were searched from their inception to January 2019. We included data from randomized clinical trials (RCTs) that addressed dementias and assessed the following outcomes: cognitive function; inflammatory, oxidative stress, and metabolic markers; nutritional status; and intestinal microbiota composition. Data searches, article selection, data extraction, and risk-of-bias assessments were performed according to the Cochrane guidelines. Data were pooled by inverse-variance random-effects meta-analyses. GRADE (Grading of Recommendations Assessment, Development, and Evaluations) was used to assess the quality of evidence. Data from 3 RCTs involving 161 individuals with Alzheimer's disease receiving Lactobacillus and Bifidobacterium strains showed no beneficial effect of probiotic supplementation on cognitive function (standardized mean difference, 0.56; 95%CI: -0.06 to 1.18), with very low certainty of evidence. However, probiotic supplementation improved plasma triglycerides, very-low-density lipoprotein cholesterol, insulin resistance, and plasma malondialdehyde. No RCTs included synbiotic supplementation or assessed microbiota composition. Current evidence regarding the use of probiotics and synbiotics for individuals with dementia is insufficient to support their clinical application. PROSPERO registration no: CRD42018116148.

Limited data is available on the effects of multispecies probiotic supplementation on metabolic status in pregnant women in the first half of pregnancy. The current study was carried out to determine the effects of multispecies probiotic capsule supplementation on metabolic status among pregnant women in the first half of pregnancy. A randomized clinical trial was conducted among 60 pregnant women aged 18-37 years. The participants were randomly divided into two groups: group A (n = 30) received multispecies probiotic supplements containing three probiotic bacteria spices Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium bifidum (2 × 109 CFU/g each) and group B (n = 30) received placebo from 9 weeks of gestation for a duration of 12 weeks. Fasting blood samples were taken at the beginning of the study and after 12 weeks of intervention to determine metabolic profiles, inflammatory cytokines and biomarkers of oxidative stress. After 12 weeks of intervention, compared to the placebo group, the pregnant women who consumed probiotic capsule had significantly decreased serum insulin concentrations (-1.5 ± 4.8 vs. +1.3 ± 5.2 µIU/mL, P = 0.03), the homeostasis model of assessment-estimated insulin resistance (HOMA-IR) (-0.3 ± 0.9 vs. +0.3 ± 1.1, P = 0.04), the homeostasis model of assessment-estimated b cell function (HOMA-B) (-7.2 ± 23.1 vs. +5.3 ± 22.6, P = 0.03) and increased quantitative insulin sensitivity check index (QUICKI) (+0.01 ± 0.05 vs. -0.01 ± 0.02, P = 0.03). In addition, changes in serum triglycerides levels (-14.7 ± 46.5 vs. +37.3 ± 74.2 mg/dL, P = 0.002), high-sensitivity C-reactive protein (hs-CRP) (-1.0 ± 2.6 vs. +1.7 ± 4.3 mg/L, P = 0.004), plasma nitric oxide (NO) (+6.8 ± 9.3 vs. -4.7 ± 7.4 µmol/L, P < 0.001), total antioxidant capacity (TAC) (+171.9 ± 187.6 vs. -51.9 ± 208.8 mmol/L, P < 0.001) and glutathione (GSH) concentrations (+34.3 ± 71.6 vs. -36.9 ± 108.3 µmol/L, P = 0.004) in supplemented women were significantly different from those of the placebo group. However, after controlling for baseline levels, age and BMI at the study baseline, the changes in plasma GSH were not significantly different between the groups. Overall, probiotic supplementation for 12 weeks among pregnant women in the first half of pregnancy had beneficial effects on markers of insulin metabolism, triglycerides, biomarkers of inflammation and oxidative stress.

Depression affects millions globally and often coexists with cognitive deficits. This study explored the potential of probiotics in enhancing cognition and ameliorating depressive symptoms in major depressive disorder patients. Utilizing the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol and the Population, Intervention, Comparator, Outcome, and Study design framework, we systematically reviewed randomized controlled trials examining probiotic effects on cognition and depressive symptoms. Searches spanned 7 databases from January 2010 to May 2022. Risk of bias was assessed using Revised Cochrane Risk of Bias 2.0, and meta-analysis was conducted with RevMan 5.4.1. Publication bias was evaluated via Egger test. In a systematic review on the effects of probiotic supplementation on cognition and depressive symptoms in depression patients, 635 records were initially identified, with 4 studies ultimately included. These randomized controlled trials were conducted across diverse regions, primarily involving females, with assessment periods ranging from 1 to 2 months. Concerning cognitive outcomes, a statistically significant moderate improvement was found with probiotic supplementation, based on the mean difference and its 95% confidence interval. However, for depressive symptoms, the overall effect was negligible and not statistically significant. A heterogeneity test indicated consistent findings across studies for both cognitive and depressive outcomes (I² = 0% for both). The potential for publication bias was evaluated using the Egger linear regression test, suggesting no significant bias, though caution is advised due to the limited number of studies. Probiotics may enhance cognitive domains and mitigate depressive symptoms, emphasizing the gut-brain axis role. However, methodological variations and brief intervention durations call for more standardized, extensive research.

The objective of this study was to study the effect of probiotic supplementation in diet on egg production, egg quality, intestinal morphology, and bacterial population in caecum of laying hens. A total of 768 Lohmann Brown-Classic laying hens, aged 42 - 54 weeks, were used. The laying hens were divided into 3 groups, each with 8 subgroups of 32 birds each. The experiment was planned to use a completely randomized design method. The 3 experimental groups were classified based on their dietary treatment as follows: 1) Basal diet (without probiotic supplementation), 2) Basal diet with probiotic 0.01 and 0.02 % in 3, respectively. Data was collected for 12 weeks. Adding probiotic in the diet was no significant difference on egg production, egg quality, and bacterial population in caecum. However, probiotic supplementation in the diet increased villi height of the duodenum significantly improved (p &lt; 0.02), villi height per depth crypt of the duodenum significantly improved (p &lt; 0.05), villi height per depth crypt of the jejunum significantly improved (p &lt; 0.01), and villi height per depth crypt of the ileum significantly improved (p &lt; 0.02). Therefore, studies have shown that dietary probiotic supplementation can improved small intestinal morphology are the most important indexes for measuring the digestive and absorption function of the small intestine are more efficient. HIGHLIGHTS Probiotic (Bacillus subtilis) is a gram-positive, non-pathogenic bacterium that can inhibit digestive enzymes such as protease, amylase, and lipase. These enzymes help increase the efficiency of digestion and absorption of nutrients. As a result of the working mechanism of Bacillus subtilis, it helps strengthen the intestinal wall, eliminates pathogenic microorganisms, reduces damaged intestinal mucosal cells, and improves intestinal absorption, resulting in increased production. Effect of probiotic (Bacillus subtilis) supplementation in laying hen diets on total bacterial load in appendix. No difference was found in the load of total bacteria and Escherichia coli (P &gt; 0.05). Its beneficial properties stimulate the growth of beneficial bacteria in the intestines, such as Bifidobacteria sp. and Lactobacillus sp., causing the production of lactic acid, which makes the colon more acidic, resulting in inhibition of the growth of pathogenic microorganisms. GRAPHICAL ABSTRACT

Background: Multiple sclerosis (MS) is a chronic autoimmune disease characterized by inflammation and demyelination of the central nervous system. Probiotics, through the gut-brain axis, are suggested to enhance clinical outcomes in patients with MS. This study scrutinizes the effects of probiotic supplementation in relapsing-remitting MS (RRMS) patients. Methods: In this parallel, randomized, double-blind, placebo-controlled trial, 90 RRMS patients, with Expanded Disability Status Scale (EDSS) &lt; 4, received either the probiotic (Lactocare®) or a placebo twice daily for four months. Assessed outcomes included level of disability (based on EDSS), cognitive function (Symbol Digit Modalities Test [SDMT], three-second version of Paced Auditory Serial Addition Test [PASAT-3]), depressive symptoms (Beck Depression Inventory- II [BDI-II]), and manual dexterity (Nine-Hole Peg Test [9HPT]). Blinding was performed for outcome assessors and the patients. All assessments were conducted at baseline and after four months, and the findings compared between the groups of the study. Results: Out of 90 randomized patients, 60 completed the trial (29 in the probiotics group, 31 in the placebo group). Probiotics supplementation was not associated with significant improvement in EDSS, BDI-II, PASAT, SDMT, and non-dominant hand 9HPT (p-values &gt; 0.05). Intragroup improvements in PASAT-3 (change median: 2 [IQR:9.5]) and dominant hand 9HPT (change median: -0.43 [IQR: 2.15]) were observed in the probiotic supplementation group, which was comparable to placebo. Conclusion: Supplementation with a seven-strain probiotics product for four months does not result in a significant improvement in depressive symptoms, cognitive performance, level of disability, and manual dexterity of RRMS patients with EDSS &lt; 4.

Increasing evidence suggests that probiotic supplementation may be efficacious in counteracting age-related shifts in gut microbiota composition and diversity, thereby impacting health outcomes and promoting healthy aging. However, randomized controlled trials (RCTs) with probiotics in healthy older adults have utilized a wide variety of strains and focused on several different outcomes with conflicting results. Therefore, a systematic review was conducted to determine which outcomes have been investigated in randomized controlled trials with probiotic supplementation in healthy older adults and what has been the effect of these interventions. For inclusion, studies reporting on randomized controlled trials with probiotic and synbiotic supplements in healthy older adults (defined as minimum age of 60 years) were considered. Studies reporting clinical trials in specific patient groups or unhealthy participants were excluded. In addition to assessment of eligibility and data extraction, each study was examined for risk of bias and quality assessment was performed by two independent reviewers. Due to the heterogeneity of outcomes, strains, study design, duration, and methodology, we did not perform any meta-analyses and instead provided a narrative overview of the outcomes examined. Of 1997 potentially eligible publications, 17 studies were included in this review. The risk of bias was low, although several studies failed to adequately describe random sequence generation, allocation concealment, and blinding. The overall study quality was high; however, many studies did not include sample calculations, and the majority of studies had a small sample size. The main outcomes examined in the trials included microbiota composition, immune-related measurements, digestive health, general well-being, cognitive function, and lipid and other biomarkers. The most commonly assessed outcome with the most consistent effect was microbiota composition; all but one study with this outcome showed significant effects on gut microbiota composition in healthy older adults. Overall, probiotic supplementation had modest effects on markers of humoral immunity, immune cell population levels and activity, as well as the incidence and duration of the common cold and other infections with some conflicting results. Digestive health, general-well-being, cognitive function, and lipid and other biomarkers were investigated in a very small number of studies; therefore, the impact on these outcomes remains inconclusive. Probiotics appear to be efficacious in modifying gut microbiota composition in healthy older adults and have moderate effects on immune function. However, the effect of probiotic supplementation on other health outcomes remains inconclusive, highlighting the need for more well-designed, sufficiently-powered studies to investigate if and the mechanisms by which probiotics impact healthy aging.

BackgroundEmerging evidence suggests gut microbiota modulation may influence neurocognitive function through the gut-brain axis. Although preliminary studies indicate probiotics’ potential benefits for mild cognitive impairment (MCI), well-designed randomized controlled trials remain limited. This protocol paper describes a rigorously designed, registered clinical trial investigating the effects of targeted probiotic supplementation on cognitive and physiological outcomes in MCI participants.MethodsA total of 110 middle-aged and older participants aged 55–80 years with MCI were scheduled to be included in the study, and randomized in a 1:1 ratio to either a probiotic group receiving supplementation consisting of Lactiplantibacillus plantarum ST-III, Lacticaseibacillus rhamnosus KF7, and Lacticaseibacillus paracasei BD5115, or a placebo group with maltodextrin for 12 months. All the participants, researchers, and analysts will remain blinded to the information regarding group allocation in the study. The primary outcome will be the effect of probiotic supplementation on cognitive function, measured by Montreal Cognitive Assessment (the Chinese Beijing Version). The secondary outcomes will include the impact of probiotic supplementation on digestive health, sleep health, facial aging, fundus conditions, olfactory and auditory function, body composition, bone density, and muscle function. Brain magnetic resonance imaging and wearable device including continuous glucose monitor and smart band will also be employed.DiscussionThis study will provide some new insights on how probiotic supplementation could impact cognitive function and other aging-related physiological functions in MCI adults and explore the potential underlying mechanisms. The findings may inform the development of strategies to delay cognitive decline by modulating the gut-brain axis in this high-risk population.Trial registrationChiCTR2400084594.

This article describes the use of the prophylactic effectiveness of probiotic preparation Bacell-M in obstetric-gynecological diseases and mastitis in cows. Duration of recording of residual amount of antibiotic in milk with combined application of Bacell-M with antibiotics is established. The effect of probiotic supplement on milk quality indicators was studied. This probiotic Bacell-M supplement at a dose of 60 g. per head prevents the incidence of cows of obstetric and gynecological pathology. The number of follow-up detention is reduced by 6.7%, subinvolution of the uterus by 13.3% compared to the control group. Postpartum animals (post-calving follow-up) were not recorded in both trial groups, and 6.6% and 13.3% of cows were diagnosed in control groups, respectively. The incidence of acute endometritis in both the experimental and control groups was diagnosed in one percent, but in the experimental groups it was 6.6% lower. The incidence of mastitis in the control groups ranged from 26.6 to 33.3%. However, the use of the probiotic supplement Bacell-M reduced the incidence by 13.3 and 26.7%, respectively. The use of an antibacterial preparation against the background of the use of probiotic agents reduces the time of antibiotic registration in milk by 19,6 hours. Based on the obtained data, the positive effect is confirmed by the use of a fodder probiotic supplement as an agent for the prevention of gynecological diseases and mastitis in cows. Reduced time of antibiotic presence in cow milk and beneficial effect on milk quality are proved.

Objectives Probiotic supplementation has been linked to changes in cognitive function via the gut-brain axis (GBA). However, the current literature lacks a comprehensive review regarding this matter in the elderly population. Method Electronic databases including Medline (PubMed), Scopus, Embase, Web of Science, and Google Scholar were comprehensively searched for identifying studies that assessed the effects of probiotics on the cognitive function of the elderly published until July 2020. Articles were critically reviewed and if met the inclusion criteria, entered the study Results Among a total of 1374 studies, 10 were eligible for meta-analysis. No significant alteration was found in the cognition of the elderly (SMD=-0.04; 95% CI [- 1.07,0.98]; P = 0.93). There was a nonsignificant increase in the level of brain-derived neurotrophic factor (SMD = 0.58; 95% CI [-1.40,2.56]; P = 0.56) and a nonsignificant reduction in malondialdehyde levels (SMD=-0.44; 95% CI [-1.07,0.19]; P = 0.17). Levels of total antioxidant capacity (SMD = 39.93; 95% CI [2.92,76.95]; P = 0.03) and total glutathione (SMD = 61.51; 95% CI [12.39,110.62]; P = 0.01) significantly increased. A significant reduction was also noted in total cholesterol levels (SMD=-4.23; 95% CI [-8.32, −0.14]; P = 0.04). Conclusion Our study did not support the hypothesis of the positive effect of probiotics on cognitive function in the elderly population; which might be due to the heterogeneity across the studies.