Probiotic drink kefir shows promise in preventing Alzheimer’s

By Priyanjana Pramanik, MSc.Reviewed by Susha Cheriyedath, M.Sc.Mar 17 2025

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

Image Credit: etorres / Shutterstock

In a recent review article published in the journal Brain Behavior and Immunity Integrative, researchers examined studies on human participants and animal models to evaluate 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, offering neuroprotective benefits due to its anti-inflammatory and antioxidant properties. However, standardized formulations and large-scale clinical studies are needed to validate its therapeutic potential for human patients.

Monitoring and Treatment of Alzheimer’s Disease

Alzheimer’s disease is a leading contributor to the global burden of dementia, accounting for approximately 60% of cases, leading to cognitive decline and memory loss. By 2050, its prevalence is projected to rise to 150 million as populations continue to age. Symptoms of this disease include confusion, language difficulties, and memory loss, which eventually severely 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 contribute to the disease by facilitating the atrophy and damage of brain cells through chronic inflammation linked to microglial overactivation. Additionally, dysregulation in insulin signaling and oxidative stress has been implicated in the disease’s progression, reinforcing the need for multi-targeted 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 Modifications and Alzheimer’s Risk

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

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

Among probiotics, kefir stands out as it has a rich composition of microbes and nutrients, containing minerals, vitamins, and proteins in addition to probiotics. However, its microbial composition can vary significantly depending on production methods, complicating comparisons across studies. Standardizing these formulations will be crucial for ensuring reproducibility in future clinical applications. Recent research suggests that kefir may support brain health by decreasing 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 illustrates the role of intestinal dysbiosis in neuroinflammation and the pathophysiology of Alzheimer's disease. Dysbiotic gut microbiota activates inflammatory pathways, leading to increased oxidative stress. This, in turn, triggers microglial activation in the central nervous system. Activated microglia then stimulate astrocytes, resulting in the disruption of the blood-brain barrier (BBB), which further perpetuates 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

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

GALT= Gut-associated lymphoid tissue. The figure illustrates 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 affects the gut-brain axis through bidirectional nerve communication and bloodstream transport of bacterial metabolites, toxins, and fragments, influencing brain function and inflammation. It aids in 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, preventing harmful bacterial byproducts translocation to the bloodstream and protecting systemic and neurological health (LeBlanc et al., 2013).

Lessons from Rodent and Fly Models

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. One 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, hippocampal neuron preservation, 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 medication, and kefir showed reduced neuronal damage and memory decline, while simvastatin (a lipid-lowering medication) and kefir jointly decreased 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 decreasing amyloid accumulation, while the other showed that kefir reduced brain damage while improving motor skills and survival. Additionally, biochemical analyses in these models confirmed reductions in oxidative stress markers and enhancements in neuronal survival.

Conclusions

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

Integrating lifestyle and dietary interventions with pharmacological treatments is necessary, particularly as Alzheimer’s is a complex condition affected by several factors. While kefir shows promise in animal models and a single study involving human participants, its effects may depend on microbial strain composition and dosage. Clinical trials and longitudinal studies are necessary to assess the long-term impacts of this and other probiotics, generating evidence on its interactions with other measures to prevent cognitive declines.

A comprehensive understanding of its efficacy and safety, including optimal doses and standardized formulations, is also needed to gauge its utility in therapeutic and clinical contexts. Moreover, researchers emphasize that kefir’s therapeutic potential is influenced by variations in microbial content and fermentation conditions, necessitating further standardization efforts before clinical implementation. While a cure for Alzheimer’s disease remains unavailable, emerging research offers promising strategies for improved screening, monitoring, prevention, and management.