Potential benefits of kefir and its compounds on Alzheimer's disease: A systematic review

Alzheimer's disease, characterized by the progressive loss of cognitive functions of the brain, is still an incurable pathology. Current treatments primarily aim to alleviate symptoms, acting mainly on behavioral changes, having a modest impact in the disease course. Recently, potential role of probiotics in managing Alzheimer's has been explored. Kefir, a fermented food teeming with live microorganisms, is thought to influence the gut microbiota, potentially reducing inflammation and the accumulation of toxic proteins in the brain. Additionally, kefir contains bioactive compounds, such as B vitamins, choline, and folic acid, which are essential for neuronal health and cognitive function. Thus, kefir could emerge as a promising complementary treatment for Alzheimer's disease. This systematic review, conducted in January 2024, examined the effects of kefir in both in vivo animal models and human patients with neurodegenerative conditions. The review was based on studies retrieved from BVS, Embase, PubMed/MEDLINE, Scopus, and Web of Science databases. Seven studies were included, involving invertebrates, murine models, and human participants. In animal models, the primary outcomes were antioxidant effects, reduced beta-amyloid deposition, and attenuation of vascular damage and neurodegeneration. In human studies, kefir supplementation resulted in decreased levels of inflammatory cytokines, reactive oxygen species (ROS), and oxidative proteins, and was associated with improvements in memory. Given its potential benefits, kefir could serve as a valuable adjunct to conventional treatments for Alzheimer's disease, warranting further investigation in clinical settings.