Background: Quarantine with social distancing has reduced transmission of COVID-19; however, fear of the disease and these remedial measures cause anxiety and stress. It is not known whether these events have impacted the prevalence of gastrointestinal (GI) symptoms and disorders of brain-gut interaction (DGBI).Methods: An online platform evaluated the prevalence of GI symptoms during the COVID-19 pandemic. Data collection utilized validated questionnaires and was fully anonymized. Findings were compared with identical data acquired in 2019. The association of results with stress and anxiety was analyzed.Results: Data were collected from 1896 subjects May -August 2019 to 980 nonidentical subjects May -June 2020. GI symptoms were reported by 68.9% during the COVID-19 lockdown compared with 56.0% the previous year (p < 0.001). The prevalence of irritable bowel syndrome (26.3% vs. 20.0%; p < 0.001), functional dyspepsia (18.3% vs. 12.7%; p < 0.001), heartburn (31.7% vs. 26.2%, p = 0.002), and self-reported milk intolerance (43.5% vs. 37.8% p = 0.004) was higher during the pandemic. Many individuals reported multiple symptoms. Anxiety was associated with presence of all GI symptoms. High levels of stress impacted functional dyspepsia (p = 0.045) and abdominal pain (p = 0.013). The presence of DGBI (p < 0.001; OR 22.99), self-reported milk intolerance (p < 0.001; OR 2.50), and anxiety (p < 0.001; OR 2.18) was independently associated with increased GI symptoms during COVID-19 pandemic. Conclusions:The prevalence of GI symptoms was significantly higher during the COVID-19 lockdown than under normal circumstances the previous year. This increase was attributable to increased numbers of patients with DGBI, an effect that was associated with anxiety.

As the gastrointestinal tract may also be a crucial entry or interaction site of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the role of the gut mucosal immune system as a first-line physical and immunological defense is critical. Furthermore, gastrointestinal involvement and symptoms in coronavirus disease 2019 (COVID-19) patients have been linked to worse clinical outcomes. This review discusses recent data on the interactions between the virus and the immune cells and molecules in the mucosa during the infection. By carrying out appropriate investigations, the mucosal immune system role in SARS-CoV-2 infection in therapy and prevention can be established. In line with this, COVID-19 vaccines that stimulate mucosal immunity against the virus may have more advantages than the others.

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Vitamin D is a secosteroid hormone with known beneficial effects on several body systems other than the musculoskeletal system.&nbsp;Both 25 dihydroxy vitamin D [25(OH)2D] and its active hormonal form, 1,25-dihydroxyvitamin D [1,25(OH)2D] are essential for hu-man physiological functions, including damping down inflammation and the excessive intracellular oxidative stresses. In the present study we set out to review all available literature on vitamin D and the role it plays in epigenetics and gene regulation. We searched the PubMed/Medline electronic database for studies published in the English language up to January 2020. The Medical Subject Headings (MeSH) database was searched with the keywords &lsquo;vitamin D&rsquo;, &lsquo;DNA methylation&rsquo;, &lsquo;nutritional supplements&rsquo;, &lsquo;epigenome&rsquo; and &lsquo;pregnancy&rsquo;. Observational studies, supplementation studies, and meta-analyses dealing with the effect of vitamin D on epigenetics and gene regula-tion were included in the review. The obtained information from the databases such as PubMed, Google Scholar, and ResearchGate was analysed and summarized.&nbsp;We found that hypovitaminosis D increases the incidence and severity of several age-related common diseases such as the oxidative stress-associated metabolic disorders. These include obesity, insulin resistance, type 2 diabetes, hypertension, pregnancy complications, memory disorders, osteoporosis, autoimmune diseases, certain cancers, and systemic inflammatory diseases. New understandings of vitamin D-related advances in metabolomics, transcriptomics, epigenetics, in relation to its ability to control oxidative stress in conjunc-tion with micronutrients, vitamins, and antioxidants, following normalization of serum 25(OH)D and tissue 1,25(OH)2D concentra-tions, are likely to promise better cost-effective clinical outcomes in humans.&nbsp;There is a strong reciprocity between the vitamin D system and epigenetic mechanisms. The vitamin D system is, on the one hand regu-lated by epigenetic mechanisms and, on the other hand, is involved in regulating epigenetic events.

Aims: We aimed to evaluate the prevalence of irritable bowel syndrome (IBS), functional dyspepsia (FD), and their overlap syndrome (OS) in the Bulgarian population and to assess the risk factors associated with these disorders. Methods: We sent an internet-based survey to Bulgarian adults. The survey collected data on socio- demographic, behavioral and lifestyle characteristics, and diagnostic questions following the Rome IV criteria to assess IBS, FD and their overlap occurrence. Results: Data was collected from 1,896 individuals (mean age = 35.5 years, 18-65, SD=11.7), 73.1% females. The prevalence of IBS was 20% (14% were with predominant constipation, 32% with predominant diarrhea, 52% had IBS with mixed bowel habits, and 2% unclassified IBS). Gender (p=0.005), age (p<0.001), marital status (p=0.009), occupation (p=0.001), alcohol consumption (p=0.013), sexual problems (p<0.001), FD (p<0.001), and milk intolerance (p<0.001) were significantly associated with IBS. Females (p=0.032; OR: 1.50), patients with FD (p<0.001; OR: 104.98), sexual problems (p= 0.001; ОR: 1.55 ), and milk intolerance (p<0.001; OR: 2.22) are at a higher risk of having IBS. The prevalence of FD was 12.7% (39% had postprandial distress syndrome, 33% epigastric pain syndrome, and 28% had the overlapping variant). Patients with IBS (p<0.001; OR: 127.88) and milk intolerance (p<0.001) were significantly associated with FD prevalence. The prevalence of OS was 11.7%. Gender (p=0.013), milk intolerance (p<0.001, OR: 1.65), urinary (p=0.035) and sexual problems (p<0.001, ОR: 1.80) were associated with OS prevalence. Conclusion: This is the first study to estimate the prevalence of IBS, FD, and their OS and assess the behavioral and demographic risk factors associated with these disorders in the Bulgarian population. Our results are valuable in filling in the epidemiological data gap regarding IBS, FD, and OS in Eastern Europe.