Probiotic drink kefir shows promise for preventing Alzheimer's disease

Probiotic drink kefir shows promise for preventing Alzheimer's disease

Could a simple probiotic drink help fight Alzheimer's? A new study examines how kefir reduces neuroinflammation and supports brain health, offering hope for future nutritional interventions.

Article published in a recent article in the JournalBrain behavior and immunity integrativeResearchers examined studies involving human participants and animal models to examine the effects of kefir, a fermented food rich in probiotics, on cognitive function, neurodegeneration and oxidative stress. They concluded that kefir shows promise as a potential complementary treatment for Alzheimer's disease and offers neuroprotective benefits due to its anti-inflammatory and antioxidant properties. However, standardized formulations and large-scale clinical trials are required to validate its therapeutic potential for human patients.

Monitoring and treating Alzheimer's disease

Kefir's potential brain-boosting effects may extend beyond Alzheimer's disease, with emerging research suggesting it may regulate mood and stress by affecting the gut-brain axis. Some studies have linked probiotic-rich diets to reductions in anxiety and depressive symptoms.

Alzheimer's disease is a leading contributor to the global burden of dementia, accounting for approximately 60% of cases, resulting in cognitive decline and memory loss. By 2050, the prevalence is expected to rise to 150 million as the population continues to age. Symptoms of this disease include confusion, speech difficulties and memory loss, which eventually greatly affect behavior and condition, leading to loss of independence.

There is currently no cure for this condition, and current treatments focus primarily on managing symptoms. However, emerging approaches aim to reduce the accumulation of tau proteins and beta-amyloid plaques, which researchers have shown facilitates atrophy and damage to brain cells through chronic inflammation associated with microglial overactivation. Furthermore, dysregulation of insulin signaling and oxidative stress have been implicated in disease progression, reinforcing the need for multiple treatment strategies. Diagnostic advances have also allowed doctors to detect early risk factors by monitoring biomarkers in cerebrospinal fluid and blood, shifting the focus to prevention.

Lifestyle changes and Alzheimer's risk

While some cases are inherited, most cases of Alzheimer's are sporadic and influenced by aging, lifestyle and medical conditions such as obesity, diabetes and high blood pressure. Research suggests that treating these risk factors could prevent over 30% of cases. Gut health also plays a role, as an imbalance in gut bacteria can trigger inflammation and worsen cognitive decline through pathways such as the TLR4/MYD88/NLRP3 signaling cascade.

Lifestyle changes, particularly diet, have been identified as a helpful way to reduce risk factors. Fermented foods are rich in probiotics, which are being studied to boost cognitive function in people with Alzheimer's. Such foods contain beneficial compounds that may reduce neuroinflammation and oxidative stress, both key factors in disease progression.

Among probiotics, kefir stands out because, in addition to probiotics, it contains a comprehensive composition of microbes and nutrients that include minerals, vitamins and proteins. However, microbial composition can vary significantly depending on production methods, complicating comparisons across studies. Standardization of these formulations is critical to ensure reproducibility in future clinical applications. Recent research suggests that kefir may support brain health by reducing oxidative damage and inflammation and modulating insulin signaling pathways such as the PI3K/AKT/GSK-3β/MTOR axis, which plays a key role in neuronal survival and synaptic plasticity. In this review, researchers systematically identified and assessed studies on the effects of kefir on Alzheimer's disease.

This figure demonstrates the role of gut dysbiosis in the neuroinflammation and pathophysiology of Alzheimer's disease. Dysbiotic gut microbiota activates inflammatory pathways, leading to increased oxidative stress. This in turn triggers the activation of microglia in the central nervous system. Active microglia then stimulate astrocytes, leading to disruption of the blood-brain barrier (BBB), which further progresses microglial activation in a vicious cycle. Both BBB compromise and microglial activation contribute to the formation and deposition of beta-amyloid plaques and neurofibrillary tangles through hyperphosphorylation of tau protein, which promote neuronal apoptosis, synaptic dysfunction, and disease progression.

Limited evidence from human studies

The researchers identified seven relevant studies from five medical databases, only one of which included human participants. In this study, 13 patients with Alzheimer's disease received kefir supplementation; The analysis found that their oxidative stress and inflammatory markers decreased while their motor skills, cognitive function and memory improved. Specifically, patients showed a 28% improvement on Mini-Mental State Examination (MMSE) scores and approximately 66% and 62% on immediate and late memory tests, respectively. However, another study cited in the review (Agahi et al., 2018) found no cognitive benefits in severe Alzheimer's patients, highlighting the need for further investigation into the dosage, microbial composition, and stage-specific effects of kefir supplementation.

Galt = gut-associated lymphoid tissue. The figure shows the central role of the gut microbiota in human health through interconnected functions. It regulates the immune system by promoting tolerance to non-pathogenic stimuli and competing with pathogens. The microbiota influences the gut-brain axis through bidirectional nerve communication and bloodstream transport of bacterial metabolites, toxins and fragments that influence brain function and inflammation. It supports metabolism by producing short-chain fatty acids, converting bile acids and synthesizing digestive enzymes while contributing to vitamin production. A healthy microbiota maintains the intestinal barrier that prevents harmful bacterial byproducts from translocation into the bloodstream and protects systemic and neurological health (LeBlanc et al., 2013).

Lessons from rodent and fly models

Unlike many dairy products, kefir contains significantly reduced levels of lactose, making it more digestible for people with lactos intolerance. Some studies suggest that kefir may help improve lactose digestion over time by increasing the presence of beneficial gut bacteria.

Of the remaining studies, four included rodent participants, namely mice, albino rats and Wistar rats. These studies focused on brain tissue change, neuroinflammation and cognitive function. A research article found that kefir modified the gut microbiome, reducing brain inflammation via TLR4 pathway modulation and improving cognitive function. Additionally, kefir supplementation was associated with reduced beta-amyloid accumulation, preservation of hippocampal neurons, and improved learning ability in rodent models.

Another study showed that combining stem cell therapy with kefir effectively protects against oxidative stress and neuroinflammation. Rodents treated with pioglitazone, an anti-diabetic drug, and kefir showed reduced neuronal damage and memory decline, while simvastatin (a lipid-lowering drug) and kefir together reduced neuroinflammation and oxidative stress.

Two studies examined the effects of kefir on amyloid buildup and neurodegeneration using fly models. One found that kefir increased motor function and antioxidant activity while reducing amyloid accumulation, while the other showed that kefir reduced brain damage while improving motor skills and survival. Furthermore, biochemical analyzes confirmed reductions in oxidative stress markers and improvements in neuronal survival in these models.

Conclusions

While symptom management is the primary approach in current Alzheimer's treatment, commonly used medications do not stop disease progression despite improving cognitive outcomes. Dietary approaches are increasingly being considered as the risk of developing the disease, with kefir in focus due to its richness in bioactive compounds.

Integrating lifestyle and nutritional interventions with pharmacological treatments is necessary, especially since Alzheimer's disease is a complex disease influenced by multiple factors. While kefir shows promise in animal models and a single study with human participants, its effects may depend on the composition and dosage of the microbial strain. Clinical trials and longitudinal studies are necessary to evaluate the long-term effects of this and other probiotics, thereby generating evidence of its interactions with other interventions to prevent cognitive decline.

A comprehensive understanding of its efficacy and safety, including optimal doses and standardized formulations, is also required to measure its utility in therapeutic and clinical contexts. In addition, the researchers emphasize that the therapeutic potential of kefir is influenced by variations in microbial content and fermentation conditions, which requires further standardization efforts before clinical implementation. While a cure for Alzheimer's disease is not available, emerging research offers promising strategies for improved screening, monitoring, prevention and treatment.

Sources: