Probiotics—good bacteria from the pharmacy or expensive placebo?

Aim of the study: Irritable bowel syndrome (IBS) is a common gastrointestinal disorder in which an imbalance in the gut microbiota plays a significant role. A growing number of studies are exploring treatment options involving probiotics, prebiotics, synbiotics, and fecal microbiota transplantation (FMT), but it is still unclear which option is best.

Results: Prebiotics and synbiotics did not show significant improvement. Network meta-analysis indicated beneficial effects of probiotics (OR = 0.53, 95% CI, 0.48 to 0.59) and FMT (OR = 0.46, 95% CI, 0.33 to 0.64) on IBS, with no serious adverse events reported. In short, probiotics and FMT are effective for managing IBS, with Bifidobacterium and Lactobacillus as the dominant strains. However, the most effective probiotic combination or strain remains unclear, while prebiotics and synbiotics did not show significant improvement.

Aim of the study: This systematic review and meta-analysis aimed to consolidate evidence on dietary interventions for atopic eczema/dermatitis (AD) skin symptoms in children without food allergies, following PRISMA 2020 guidelines. The systematic review was updated in May 2022 and June 2023, focusing on randomized placebo-controlled trials (RCTs) involving children with AD but no food allergies.

Results: The effect on clinical signs of AD was assessed using SCORAD scores, and a meta-analysis of SCORAD outcomes was conducted using random-effects models (CRD42022328702). The review included 27 RCTs examining prebiotics, Vitamin D, evening primrose oil, and replacing cow’s milk formula with partially hydrolyzed whey milk formula. A meta-analysis of 20 RCTs assessing probiotics, alone or combined with prebiotics, found a significant reduction in SCORAD scores, suggesting a consistent trend toward alleviating AD symptoms in children without food allergies. However, evidence for other dietary interventions remains limited, highlighting the need for well-designed intervention studies that target multiple factors to understand interactions between causes and propose reliable strategies for modifying them.

Aim of the study: Over 60 percent of the human population has a reduced ability to digest lactose because of low lactase enzyme activity. Probiotics are live bacteria or yeasts that supplement the gastrointestinal flora.

Results: Growing evidence shows that probiotic bacteria in fermented and unfermented milk products can be used to relieve the clinical symptoms of lactose intolerance (LI). In this systematic review, the effectiveness of probiotics in treating LI was assessed using 15 randomized double-blind studies. Eight probiotic strains with the most proven benefits were studied. Results showed varying levels of effectiveness but an overall positive relationship between probiotics and lactose intolerance.

Aim of the study: The pharmacology, uses, dosages, safety, drug interactions, and contraindications of probiotics are reviewed.

Results: Probiotics have been shown to be effective in preventing and treating various medical conditions, particularly those involving the gastrointestinal tract. Evidence supporting their role in other conditions is often conflicting.

Aim of the study: To date, no adequate treatment is available for irritable bowel syndrome with predominant constipation (IBS-C). Fibers with prebiotic properties and probiotic products have shown promise in relieving IBS-C-related complaints.

Results: Stool frequency improved significantly in the AF and Probiotic BLa80 groups compared with placebo (P < 0.001 and P = 0.02, respectively). Probiotic BLa80 significantly reduced IBS symptom severity (P = 0.03), while AF showed a trend toward reducing constipation symptoms (PAC-SYM, P = 0.10). No significant changes in stool consistency, stool mass, or QoL measures were observed for AF or Probiotic BLa80 compared with placebo. Daily dietary supplementation with Acacia fiber and probiotics may help IBS-C patients by relieving IBS-related complaints compared with a placebo supplement.

Aim of the study: Probiotic supplements have been shown to improve cognitive function in patients with Alzheimer’s disease (AD). However, it is still unclear whether this also applies to older people with mild cognitive impairment (MCI).

Results: Forty-two MCI patients (age > 60 years) were randomly divided into two groups and took either probiotics (n=21) or placebo (n=21) for 12 weeks. Various scale scores, gut microbiota measures, and blood markers were recorded before and after treatment. After 12 weeks, cognitive function and sleep quality improved in the probiotic group compared with the control group, and the underlying mechanisms were associated with changes in the intestinal microbiota. In conclusion, our study showed that probiotic treatment improved cognitive function and sleep quality in older MCI patients, providing important insights into the clinical prevention and treatment of MCI.

Aim of the study: This review aims to provide a comprehensive overview of in vitro, animal, and clinical studies of the bacterial strain Lactiplantibacillus plantarum 299v (L. plantarum 299v; formerly called Lactobacillus plantarum 299v) published up to June 30, 2020.

Results: L. plantarum 299v is used in many different food products and dietary supplements. In freeze-dried form, L. plantarum 299v is robust and stable at room temperature, allowing consumer health products such as capsules, tablets, or powder sachets to have a long shelf life. The strain is protected by patents for a wide range of indications and applications worldwide and is also trademarked as LP299V®.

Aim of the study: Infertility is a widespread global issue affecting approximately 15% of sexually active couples and accounting for about 50% of cases. It remains common and is often inadequately treated.

Results: Four randomized clinical studies met the inclusion criteria, focusing on men diagnosed with idiopathic male infertility (oligozoospermia, teratozoospermia, and asthenozoospermia). The findings showed that probiotic use had promising antioxidant properties, combating reactive oxygen species (ROS) and thereby protecting sperm DNA from damage associated with declining sperm quality. Significant improvements were observed in all sperm parameters, particularly motility. Consequently, probiotic supplements may be a treatment option for men diagnosed with idiopathic infertility, with positive effects on sperm quality.

Aim of the study: Background/Objectives: Obesity is often associated with chronic low-grade inflammation, which contributes to metabolic dysfunction. However, the comparative effects of nutritional supplements on inflammatory biomarkers in adults who are overweight or obese remain unclear.

Results: Exploratory meta-regression suggested that age, exercise co-interventions, and the proportion of male participants may partly explain differences in selected outcomes. Conclusions: Nutritional supplements had effects on specific biomarkers. Probiotics combined with omega-3 fatty acids, synbiotics, green tea extract, and curcumin may improve selected inflammatory biomarkers. However, differences in supplement dose, intervention duration, and participant characteristics call for cautious interpretation and further high-quality trials.

Aim of the study: Exposure to air pollution has been linked to elevated malondialdehyde (MDA) levels, a marker of oxidative stress, while synbiotics—by modulating the intestinal microbiota—may reduce inflammation and oxidative stress. Despite these possibilities, evidence on the effect of synbiotic supplements in reducing oxidative stress caused by air pollution in children remains limited.

Results: A significant reduction in MDA levels was observed within the synbiotic group (from 148.80 ± 80.72 to 51.54 ± 82.94, P< 0.001), although no significant difference was found between the synbiotic and omega-3 groups (P = 0.75). However, after adjusting for confounding variables, synbiotic supplementation was significantly associated with a reduction in MDA. These findings suggest that synbiotics may help counteract air-pollution-induced oxidative stress in children and adolescents, highlighting the need for further large-scale studies to explore their potential protective role in children’s environmental health.