Table 3:
Potentially protective biological activity of kefir in neurodegenerative diseases.
| Study type | Model | Treatment | Main findings | Reference |
|---|---|---|---|---|
| Animal | Aged (10-month-old) Swiss albino mice | Daily oral administration of PFT (2 mg/kg) for 6 weeks | Reverses age-associated oxidative changes as demonstrated by inhibited oxygen radical formation | Ghoneum et al. (2020) |
| Reduces NO and MDA levels | ||||
| Increases GSH, total antioxidant capacity, and antihydroxyl radical content | ||||
| Eight-week-old spontaneously hypertensive rats | Daily oral administration of kefir (0.3 ml/100 g) made from kefir grains for 9 weeks | Decreases mean arterial pressure | de Almeida Silva et al. (2020) | |
| Improves intestinal barrier morphology | ||||
| Reduces TNF-α and IL-6 levels in hypothalamic paraventricular nucleus and rostral ventrolateral medulla | ||||
| Drosophila melanogaster model of AD | Kefir mixed with food | Improves neurodegenerative phenotype as demonstrated by enhanced survival rate and climbing ability of flies as well as reduced severity of vacuolar lesions in the brain | Batista et al. (2021) | |
| Eight-week-old C57BL/6J mice | Daily oral administration of kefir (0.2 ml) containing L. lactis, L. kefiranofaciens, P. spp., and B. breve for 3 weeks | Improves repetitive and reward-seeking behavior as well as enhances contextual learning and memory | van de Wouw et al. (2020) | |
| Decreases peripheral inflammation as measured by reduced circulating levels of neutrophils, lower concentration of CXCL1, higher concentration of IL-10, and increased circulating regulatory T cells | ||||
| Increases prevalence of L. reuteri, E. plexicaudatum, B. pseudolongum, P. goldsteinii, B. intestinalis, Anaerotruncus unclassified, and Alistipes unclassified in the gut | ||||
| Decreases prevalence of L. bacterium 3_1_46FAA, C. acnes, B. amyloliquefaciens, and Ca. Arthromitus in the gut | ||||
| Human clinical trials | Humans with suspected AD | Daily oral administration of kefir (2 ml/kg) containing A. aceti, A. sp., L. delbrueckii, L. fermentum, L. fructivorans, E. faecium, Leuconostoc spp., L. kefiranofaciens, Ca. famata, and Ca. krusei for 90 days | Improves memory, visual-spatial, abstraction, executive, language, constructive, and attentive abilities | Ton et al. (2020) |
| Reduces serum levels of TNF-α, IL-12p70, and IL-8 | ||||
| Enhances mitochondrial function as measured by increased mitochondrial membrane potential and reduced intracellular ROS in erythrocytes | ||||
| Humans with suspected AD | Daily oral administration of probiotic milk (200 ml) containing L. acidophilus, L. casei, B. bifidum, and L. fermentum for 12 weeks | Increases cognitive function as demonstrated by improved MMSE scores, which contrasts the decline of such scores in the control group | Akbari et al. (2016) | |
| Enhances energy metabolism as demonstrated by improved insulin metabolism and serum levels of triglycerides | ||||
| Decreases oxidative stress and inflammation as measured by lowered MDA and CRP levels |
AD, Alzheimer’s disease; CRP, C-reactive protein; CXCL, CXC motif ligand; GSH, glutathione; IL, interleukin; MDA, malondialdehyde; MMSE, Mini-Mental State Examination; NO, nitric oxide; PFT, probiotics fermentation technology; ROS, reactive oxygen species; and TNF-α, tumor necrosis factor α.