The Effect of Probiotic Supplementation on the Mental Status, Inflammation, and Intestinal Barrier in Major Depressive Disorder Patients Using Gluten-free or Gluten-containing Diet (SANGUT)

The Effect of Probiotic Supplementation on the Mental Status, Inflammation, and Intestinal Barrier in Major Depressive Disorder Patients Using Gluten-free or Gluten-containing Diet

A 12-week, Randomized, Double-blind, and Placebo-controlled Study Evaluating the Effect of Probiotic Supplementation on the Mental Status, Inflammation, And Intestinal Barrier in Major Depressive Disorder Patients Using Gluten-free or Gluten-containing Diet

More and more evidence confirms the relationship between the gut-brain-microbiota axis and the symptoms of mood disorders. A potential pathway connecting the intestines and the brain in depression is inflammation. Interventions for reducing inflammation and restoring the integrity of the intestinal mucosa are promising approaches in patients with major depressive disorder (MDD). Gut dysbiosis and the diet containing gluten are potential factors may be factors that negatively affect the communication between intestinal and brain. Gluten has a high immunogenic potential and affinity for the intestinal mucosa layer. In patients with an abnormal reaction to gluten, the elimination diet led to improved mood symptoms. However, the relationship between gluten and depression is still poorly understood. Intestinal microbiota can affect the digestion of gluten and reduce its immunogenic potential. Studies have shown that probiotic supplementation has an anti-inflammatory effect, can lead to changes in intestinal permeability and alleviate the symptoms of depression. This evidence supports the need for co-therapy, including the elimination of gluten and the restoration of intestinal eubiosis to reduce inflammation and modulate the gut-brain-microbiota axis. The objective of the SANGUT study is to determine the impact of interventions concerning the gut-brain-microbiota axis (probiotic supplementation, gluten-free diet and their combination) on the mental state, markers of inflammation and markers of intestinal permeability in adult patients with MDD. The study will last 12 weeks and consist of four visits (V): V0 - Screening (Day 0), V1 - Baseline (up to 1 week after Screening), V2 (six weeks after Baseline), V3 - End of the study (12 weeks after Baseline). The main hypothesis is that probiotic supplementation and/or a gluten-free diet will reduce the symptoms of depression, lower the level of inflammatory markers and favourably affect the integrity of the intestinal mucosal barrier.

Probiotics; dietary supplements, Diet, Gluten-Free, Inflammation, Gastrointestinal Microbiome, Intestinal mucosal permeability, Gut-brain axis, Gut permeability, EEG functional connectivity, Cortisol, Hypothalamic-pituitary-adrenal axis, Cognitive function

The probiotic and gluten-free diet group (PRO-GFD) will receive one capsule containing the probiotic mixture powder (Sanprobi Stress; Sanprobi sp. z o.o., sp.k., Szczecin, Poland) in the amount of 3 × 10^9 colony forming units (CFU) per day divided in two equal doses, comprising two bacteria strains: Lactobacillus helveticusRosell®-52, Bifidobacterium longumRosell®-175, and excipients: potato starch, magnesium stearate, and the capsule shell of hydroxypropyl methylcellulose. The participants will be asked to consume supplements before breakfast. The group will follow the elimination diet containing no gluten.

The placebo and gluten-free diet group (PLA-GFD) will receive one capsule containing only the excipients, i.e. maize starch, maltodextrins, and the capsule shell. The participants will be asked to consume supplements before breakfast. The group will follow the elimination diet containing no gluten.

The probiotic and gluten-containing diet group (PRO-GD) will receive one capsule containing the probiotic mixture powder (Sanprobi Stress; Sanprobi sp. z o.o., sp.k., Szczecin, Poland) in the amount of 3 × 10^9 colony forming units (CFU) per day divided in two equal doses comprising two bacteria strains: Lactobacillus helveticusRosell®-52, Bifidobacterium longumRosell®-175 and excipients: potato starch, magnesium stearate, and the capsule shell of hydroxypropyl methylcellulose. The participants will be asked to consume supplements before breakfast. The group will stay with their current diet.

The placebo and gluten-containing diet group (PLA-GD) will receive one capsule containing only the excipients, i.e. maize starch, maltodextrins, and the capsule shell. The participants will be asked to consume supplements before breakfast. The group will stay with their current diet.

The changes in Montgomery-Åsberg Depression Rating Scale(MADRS) total score to measure the severity of depression symptoms

A 10-item questionnaire to measure the severity of depressive symptoms in individuals with mood disorders. The assessment is performed by an experienced clinical psychiatrist. Each item yields a score of 0 to 6 (overall score ranges from 0 to 60). The higher score indicates a higher severity of the depressive episode. MADRS cut-off points include: 0 to 6: symptom absent 7 to 19: mild depression 20 to 34: moderate depression more than 34: severe depression

The changes in Beck Depression Inventory (BDI) total score to measure the severity of depression symptoms

A 21-item multiple-choice self-report inventory to measure the severity of depression. Each item yields a score of 0 to 3 (overall score ranges from 0 to 63). The higher score indicates more severe depression symptoms. BDI cut-off points include: 0 to 9: no/minimal depression 10 to 18: mild depression 19 to 29: moderate depression 30 to 63: severe depression

The changes in Symptom Checklist-90 (SCL-90) total score to measure the severity of psychopathological impairment

A 90-item self-reported inventory to evaluate a broad range of psychological problems and symptoms of psychopathology. The SCL-90 measure symptom intensity on nine different subscales: somatization, obsessive-compulsive, interpersonal sensitivity, depression, anxiety, hostility, phobic anxiety, paranoid ideation, psychoticism. Each item yields a score of 0 to 4 (overall score ranges from 0 to 364). The higher score indicates more severity of symptoms.

A 36-item self-reported survey to evaluate a health status including vitality, physical functioning, bodily pain, general health perceptions, physical role functioning, emotional role functioning, social role functioning, and mental health. Raw scores are transforming to 0-100 scale. The higher score indicates a better health state.

A 10-item self-reported questionnaire to measure the perception of stress. Each item yields a score of 0 to 4 (overall score ranges from 0 to 40). The higher score indicates higher perceived stress.

FC will be assessed, based on resting-state EEG-recordings, with the application of a Phase Lag Index (PLI), measuring connectivity strength between a given pair of cortical areas. The global neural network organization will be analyzed with Minimum Spanning Tree algorithm.

Changes in Gastrointestinal Symptom Rating Scale (GSRS) total score to measure intensity of experienced gastrointestinal symptoms

A 15-item self-reported questionnaire to measure gastrointestinal symptoms in five clusters: reflux, abdominal pain, indigestion, diarrhoea and constipation. Each item yields a score of 0 to 3 (overall score ranges from 0 to 45). The higher score indicates a higher intensity of experienced symptoms.

Inclusion Criteria: Outpatients aged 18-60 years old; Signed written Informed Consent Form; Meet the DSM-5 criteria for MDD; Body mass index (BMI) ≥18.5 kg/m2 and ≤30 kg/m2; MADRS (Montgomery-Asberg Depression Scale) total score at screening (V0) and at baseline (V1) of 20 points or more (moderate or severe depression); A willingness and motivation to follow the study protocol. Exclusion Criteria: Diagnosis of autoimmune, neurological, immunocompromised, thyroid, inflammatory bowel diseases, diabetes, cancers, and/or IgE-dependent allergy; Psychiatric comorbidities (except specific personality disorder) including mental retardation, organic brain dysfunction, or addiction (except nicotine and caffeine); High risk of suicide in the investigator's opinion; An infection one month before the study baseline visit (V1); The use of antibiotics and/or probiotics three months prior to the study; Glucocorticosteroids and/or metformin treatment; Intake of any other drugs which in the investigator' opinion may affect the results of study; Intake of any dietary supplementation (except for vitamin D according to the "Vitamin D supplementation guidelines, 2018") which in the investigator' opinion may affect the results of the study; Changes in a pharmacotherapy and/or psychotherapy of MDD 2 weeks before the trial entry; Electroconvulsive therapy (ECT) 12 months before the trial entry; No specific diet (e.g., elimination, vegan, reduction) and changes in physical activity 4 weeks before the trial entry; Pregnancy or lactation.

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