Prebiotics & Probiotics

Prebiotics are a type of dietary fiber that our bodies cannot digest; instead, they serve as nourishment for beneficial gut bacteria. By fermenting these fibers, gut microbes produce short-chain fatty acids (SCFAs) like butyrate, which strengthen the intestinal lining, reduce inflammation, and support overall gut health. A healthy gut-brain axis, facilitated by prebiotics, can enhance cognitive functions such as memory and focus, and may improve mood. Consuming prebiotic-rich foods like leeks, asparagus, chicory, green bananas, garlic, onions, wheat, oats, and beans can support this process.

The PROMOTe study, a placebo-controlled randomized trial, investigated whether a prebiotic supplement could improve cognition in healthy older twins. Over 12 weeks, one twin from each pair received protein supplementation with a prebiotic, while the other received protein with a placebo. Cognitive function, measured by the CANTAB battery, improved significantly in the prebiotic group compared to placebo. Despite more adverse events in the prebiotic group, compliance was high. These findings suggest that prebiotics can positively influence cognitive performance, likely through gut-brain axis mechanisms, in older adults with low protein intake.

This 12-week randomized, double-blind, active-controlled study investigated the effects of multi-strain probiotics on Alzheimer’s patients. The probiotic group showed a 36% increase in serum brain-derived neurotrophic factor (BDNF), reduced inflammatory marker IL-1β, and increased antioxidant enzyme activity (SOD), compared to minimal changes in the control group. These biomarkers are associated with improved neuron function and reduced neurodegeneration. While cognitive function showed a trend toward improvement, changes were not statistically significant. The results suggest that probiotics may enhance neuroprotection in Alzheimer’s disease.

This systematic review and meta-analysis examined the effects of probiotics and prebiotics on neurocognitive function, focusing on aging and neurodegenerative conditions. Human studies showed a modest improvement in cognitive tests like MMSE, with significant heterogeneity in outcomes. Animal studies demonstrated consistent neurocognitive improvements, such as faster escape times in maze tests. Mechanisms included anti-inflammatory effects, increased antioxidant activity, and modulation of the gut-brain axis. However, variability in study quality and funding biases highlight the need for more robust clinical trials to validate these findings.

This systematic review explores the effects of probiotics, prebiotics, and fecal microbiota transplant (FMT) on cognitive function through gut microbiota manipulation. The evidence indicates that probiotics and FMT improve cognition by reducing neuroinflammation and promoting gut-brain axis health. Probiotics enhanced cognitive function in healthy individuals and patients with conditions like Alzheimer’s disease and mild cognitive impairment. Prebiotics showed limited cognitive benefits, possibly due to short treatment durations. The findings highlight gut microbiota's role in brain health but emphasize the need for larger, long-term studies to confirm efficacy.

This randomized controlled trial studied the effects of prebiotics (B-GOS and FOS) on stress and emotional processing in 45 healthy adults over three weeks. Participants taking B-GOS had lower cortisol levels upon waking, indicating reduced stress. They also showed less attentional focus on negative emotions in a task compared to those taking FOS or a placebo. However, no changes in subjective stress or anxiety scores were observed. These findings suggest B-GOS prebiotics may positively influence stress and emotional regulation through gut-brain interactions.

This randomized, double-blind, placebo-controlled trial examined the effects of probiotics on cognitive function and mood in healthy older adults. Over 12 weeks, participants consuming probiotics (Bifidobacterium bifidum and Bifidobacterium longum) showed improved mental flexibility and reduced stress compared to placebo. Probiotics also increased brain-derived neurotrophic factor (BDNF) levels, which are essential for learning and memory. Gut microbiota composition shifted, reducing inflammation-linked bacteria. These findings suggest probiotics may support brain health and stress-management via the gut-brain axis.

This review examines the role of probiotics and prebiotics in brain development and neurological health through the gut-brain axis. The gut microbiota, influenced by diet, affects neurotransmitter production, inflammation, and neurodevelopment, particularly in early life. Probiotics (e.g., Lactobacillus, Bifidobacterium) and prebiotics show potential to improve conditions like depression, anxiety, and neurodevelopmental disorders by enhancing microbiota composition and reducing inflammation. While animal and some human studies highlight promising effects on cognitive function, results vary, and more targeted clinical trials are needed to confirm their benefits.

This systematic review and meta-analysis examined the effects of probiotics on cognitive function in individuals with mild cognitive impairment (MCI) and Alzheimer’s disease (AD). Among the studies, probiotics were found to improve cognitive performance significantly in those with MCI but showed limited benefits in AD patients. The analysis highlighted the role of probiotics in reducing neuroinflammation and enhancing gut-brain axis activity. Heterogeneity among studies was significant, attributed to differences in probiotic strains, dosages, and study durations. These findings suggest probiotics as a promising intervention, particularly for early cognitive decline stages, but further robust trials are needed.

This systematic review analyzed five randomized controlled trials on the effects of probiotics on mild cognitive impairment (MCI). Probiotic interventions using strains like Lactobacillus and Bifidobacterium over 12-16 weeks showed improvements in cognitive domains such as memory, attention, and mental flexibility. Benefits were most pronounced in individuals with MCI and not in those with advanced dementia or normal cognition. Probiotics appear to act through the gut-brain axis, reducing neuroinflammation and increasing brain-derived neurotrophic factor (BDNF). These findings support probiotics as a potential preventive measure for cognitive decline, though further research is needed.

This review highlights the potential of prebiotics in promoting cognitive resilience, defined as the ability to maintain or regain cognitive function under challenging conditions like stress, poor sleep, or unhealthy diets. Prebiotics support beneficial gut bacteria, which produce compounds that reduce inflammation and enhance brain health. The review emphasizes that while preclinical and limited human studies show promising effects, such as improved memory and stress resilience, evidence remains inconclusive. Future research should target vulnerable populations, such as those experiencing chronic stress or aging-related cognitive decline, to better understand prebiotics' role in mitigating cognition-taxing factors.

This review explores the potential of prebiotics, like inulin and fructo-oligosaccharides (FOS), to mitigate Alzheimer’s disease (AD) progression via the gut-brain axis. Prebiotics promote beneficial gut bacteria, such as Bifidobacterium, which produce compounds like butyrate. These compounds reduce neuroinflammation, enhance gut barrier integrity, and may improve brain health. Animal studies show prebiotics can lower inflammation and improve cognition, but human evidence is limited. The review suggests prebiotics may support AD prevention, emphasizing the need for clinical trials to confirm their cognitive benefits and establish effective dosages.

This review explores how probiotics and prebiotics impact the gut-brain axis and support mental health by influencing gut microbiota composition. These compounds may reduce symptoms of depression, anxiety, Alzheimer’s disease, and stress by enhancing neurotransmitter production, reducing neuroinflammation, and improving gut barrier integrity. Mechanisms include short-chain fatty acid production and modulation of the hypothalamic-pituitary-adrenal axis. Although animal and some human studies show promise, evidence remains preliminary, and larger trials are needed to confirm therapeutic effects.