TABLE 1.

Review of selected studies on the psychoprotective effect of probiotics.

Source	Sample	Bioactive ingredient	Results or conclusions
Gazerani (96)	Review article – group struggling with migraine headaches	Folate in the form of folic acid – B9	Addition of a methyl group to DNA methyltransferase during the DNA methylation process and adequate serum homocysteine secretion levels prevent migraine headaches
Cater et al. (97); Parikh et al. (98)	Review article – neurotherapeutic properties among healthy human populations and newborns	Docosahexaenoic acid – omega-3	Stimulates neurotransmission and development of the cerebral cortex and visual organ through the blood-brain barrier. Increased neuro-efficiency of non-verbal and verbal communication processes
Parikh et al. (98)	Review article – among a population of people with nervous system conditions – depression and newborns with encephalopathy	Alpha-lipoic acid, lignans, soluble fiber, phytoestrogen – secoisolariciresinol diglucoside	Development and size of cortical cells in the prenatal and postnatal periods. Neuromodulates cognitive-behavioral behavior. Prevention against depressive symptoms in offspring and hypoxic-ischemic encephalopathy among newborns. Reduced oxidative stress parameters in the oxidation process reducing inflammation within the nervous system
Park et al. (99); Mulati et al. (100)	Depressed patients. Blinded randomized study. N = 40, duration – 8 weeks An obese mouse model of neuronal impairment. Blinded, randomized study. Duration – 14 weeks	Flavonoids	Improving brain-derived neurotrophic parameter (BDNF), reducing symptoms in the pathomechanism of depression. PSD-95 protein expression affects dysfunction within synapses and neurons
Mittal et al. (101)	Review article – reduction in symptoms and progression of Parkinson’s disease	Exogenous amino acid – tryptophan	Metabolic transformations to the starting compound serotonin allow to achieve regulation of the diurnal rhythm, emotional state. Participation in the metabolism of catecholamines regulating processes at the level of the brain-gut axis. Prevention in the pathomechanism of Parkinson’s disease
Fernández et al. (102); Dogan-Sander et al. (103); Godos et al. (104)	Review studies, meta-analysis of studies. Improvement of neuronal and cognitive impairment in patients with Parkinson’s disease, schizophrenia, depression	Magnesium calcium, selenium, zinc, manganese, copper, antioxidants – vitamin D, E, C, carotenoids	Reducing the mechanism of oxidative stress achieving systemic balance consequently the absence of chronic inflammation along with a decrease in CRP, IL-6, WBC indices and somato-psychological symptoms in a depressed state.
Godos et al. (104); Burton-Freeman et al. (105)	Review studies, meta-analysis of studies Improving neuronal and cognitive impairment in patients with Alzheimer’s disease, inflammation within neurons	Complex carbohydrates, eicosapentaenoic acid, amino acid – glycine, polyphenols, anthocyanins	Regulation of neuromodulator and neurotransmitter expression. Reduced activation of the hypothalamic-pituitary-adrenal axis under the influence of lower levels of endogenous stress – lower corticosterone concentrations. Proper insulin secretion and glucose ejection into cells – adequate GLUT receptor functionality. Modulation of the processes of neurogenesis, synaptic plasticity and activation of microglia in the central nervous system. Prevention of inflammation, neurodegenerative changes through inactivation of the process of oxidation of the LDL fraction, lipid peroxidation and activation of the enzymes catalase and superoxide dismutase

Source: Own compilation based on literature review.