TABLE 2.
Review of selected studies on the psychoprotective effects of substances contained in food.
| Source | Sample | Preparation (Bacterial strain) | Results or conclusions |
| Healthy persons | |||
| Diop et al. (106) | Healthy adults. Blinded, randomized study. Duration – 12 weeks | Lactobacillus acidophilus Rosell-52, Bifidobacterium longum Rosell-175 (3 × 109 CFU/day) | Probiotic therapy has been shown for the first time to reduce gastrointestinal complaints in people under stress: • Significant reduction in gastrointestinal symptoms compared to the placebo group; • Significant reduction in the severity of stress-induced nausea and abdominal pain. |
| Messaoudi et al. (37) | Healthy adults. Double-blind, randomized study. N = 55, duration – 30 days | Lactobacillus helveticus R0052, Bifidobacterium longum R0175 (3 × 109 CFU/day) | The first study to show that administration of a psychobiotic alleviates stress-induced psychiatric symptoms: • Reduction in anxiety symptoms on the HSCL-90 scale; • Significant reduction in anxiety and depressive symptoms; • Confirmed reduction of the stress hormone cortisol in urine; • In the group of people with lower cortisol levels (less stressed), improvements in depression and anxiety scores on the PSS, HADS, and HSCL-90 scales. |
| Depression | |||
| Wallace et al. (107) | Depressed patients who were not taking antidepressants. Blinded, randomized study. N = 108, duration – 16 weeks | Lactobacillus helveticus R0052, Bifidobacterium longum R0175 (6 × 109 CFU/day) | After 4 weeks of taking the psychobiotic, there was a reduction in scores on the assessment scales: • Poor mood (MADRS – Montgomery-Asberg Depression Scale, QUIDS-SR16 – Quick List of Depressive Symptoms); • Stress intensity (PSQI – Sleep Quality Questionnaire); • Anhedonia (SHAPS – Scale of Perceived Pleasure); Level of anxiety (GAD-7 – Generalized Anxiety Questionnaire, STAI – State and Trait Anxiety Inventory). |
| Kazemi et al. (108) | Depressed patients who were taking antidepressants (sertaline, escitalopram, fluixetine, or amitriptyline). RCT study. N = 81, duration – 8 weeks | Lactobacillus helveticus, Bifidobacterium longum | • Decreased scores on the Beck Depression Scale (compared to the group taking placebo or the prebiotic galactooligosaccharide). • Increase serotonin production from tryptophan (decrease in kynurenine/tryptophan ratio) |
| Rudzki et al. (109) | Patients with depression. Double-blind RCT study. N = 60, duration – 8 weeks | SSRI + Lactobacillus plantarum 299v (10 × 109 CFU/day) | Augmenting SSRI treatment with probiotic bacteria Lactobacillus Plantarum 299v improved cognitive performance and reduced KYN levels in MDD patients. Reduced KYN levels may have contributed to cognitive improvement in the LP299v group compared to the placebo group |
| Wallace et al. (107) | Patients with depression. Double-blind RCT study. N = 10, duration – 8 weeks | Lactobacillus helveticus Rosell-52, Bifidobacterium Longum Rosell-175 (3 × 109 CFU) | Probiotics have a role in alleviating symptoms of depression |
| Heidarzadeh-Rad et al. (110) | Patients with depression. RCT post hoc analysis. N = 78, duration – 8 weeks | Lactobacillus helveticus Rosell-52, Bifidobacterium Longum Rosell-175 (≥ 10 × 109 CFU) | Eight-week supplementation in depressed patients improved depressive symptoms, likely by increasing BDNF levels |
| Alzheimer’s disease | |||
| Agahi et al. (111) | Alzheimer’s patients. Double-blind RCT study. N = 48, duration – 12 weeks | Lactobacillus fermentum, Lactobacillus plantarum, Bifidobacterium lactis, Lactobacillus acidophilus, Bifidobacterium bifidum, Bifidobacterium longum (3 × 109 CFU/day) | Cognitive and biochemical indications in patients with severe AD are insensitive to probiotic supplementation. Therefore, in addition to the composition and dose of probiotic bacteria, the severity of the disease and the timing of administration profoundly affect treatment outcomes. |
| Akbari et al. (112) | Alzheimer’s patients. Double-blind RCT study. N = 52, duration – 12 weeks | 200 mL/day of milk product containing Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium bifidum, Lactobacillus fermentum (2 × 109 CFU/day) | Probiotic treatment had no significant effect on biomarkers of oxidative stress and inflammation, fasting glucose and other lipid profiles. The study showed that probiotic consumption for 12 weeks had a positive effect on cognitive function and some metabolic statuses in AD patients |
| Tamtaji et al. (113) | Alzheimer’s patients. Double-blind RCT study. N = 79, duration – 12 weeks | Lactobacillus acidophilus, Bifidobacterium bifidum, Bifidobacterium longum (6 × 109 CFU/day) + 200 mcg selenium | Co-supplementation of probiotics and selenium for 12 weeks in AD patients improved cognitive function and some metabolic profiles |
| Chronic fatigue syndrome | |||
| Wallis et al. (114) | Patients with Chronic Fatigue Syndrome. Open-label study. N = 44, duration – 6 weeks | Alternating antibiotic and probiotic therapy: Erythromycin + Lactobacillus rhamnosus (2.5 × 1010 CFU/day), Bifidobacterium lactis (1.5 × 1010CFU/day), Bifidobacterium breve (5 × 106 CFU/day), Bifidobacterium longum (5 × 106 CFU/day) | Specific microorganisms interact with some ME/CFS symptoms and offer the promise of therapeutic potential targeting intestinal dysbiosis in this population |
| Cognitive dysfunction | |||
| Hwang et al. (115) | Patients with mild cognitive impairment. Double-blind RCT study. N = 92, duration – 12 weeks | Lactobacillus plantarum C29 (1.25 × 1010 CFU/day) + powdered fermented soybeans (DW2009) | DW2009 can be safely administered to improve cognitive function in people with MCI |
| Kobayashi et al. (116) | Patients with mild cognitive impairment. Open-label study. N = 27, duration – 6 months | Bifidobacterium breve A1 (2 × 1010 CFU/day) | Oral supplementation of B. breve A1 in participants with MCI improved cognitive function, thus suggesting the potential of B. breve A1 for improving cognitive function and maintaining quality of life in the elderly |
| Kobayashi et al. (117) | Patients with mild cognitive impairment. Double-blind RCT study. N = 117, duration – 12 weeks | Bifidobacterium breve A1 (2 × 1010 CFU/day) | The results of the present study suggest the safety of B. breve A1 supplementation and its potential in maintaining cognitive function in elderly people with memory impairment |
Source: Own compilation based on literature review.