Effects of Coffee on the Gastro-Intestinal Tract: A Narrative Review and Literature Update.

The objective of the present research was to review the state of the art on the consequences of drinking coffee at the different levels of the gastrointestinal tract. At some steps of the digestive process, the effects of coffee consumption seem rather clear. This is the case for the stimulation of gastric acid secretion, the stimulation of biliary and pancreatic secretion, the reduction of gallstone risk, the stimulation of colic motility, and changes in the composition of gut microbiota. Other aspects are still controversial, such as the possibility for coffee to affect gastro-esophageal reflux, peptic ulcers, and intestinal inflammatory diseases. This review also includes a brief summary on the lack of association between coffee consumption and cancer of the different digestive organs, and points to the powerful protective effect of coffee against the risk of hepatocellular carcinoma. This review reports the available evidence on different topics and identifies the areas that would most benefit from additional studies.

Proton Pump Inhibitors are Risk Factors for Viral Infections: Even for COVID-19?

During the ongoing pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), more attention should be paid to the balance of risks and benefits associated with proton pump inhibitors for the following reasons. One of the main functions of gastric juice is to inactivate swallowed microorganisms, thereby inhibiting infectious agents from reaching the intestine. Studies have documented that proton pump inhibitors are a risk factor for rotavirus, influenza virus, norovirus, and Middle East respiratory syndrome coronavirus infections, and are associated with an increased risk of acute gastroenteritis during periods of highest circulation of enteric viruses. In light of the evidence for gastrointestinal infection implying a fecal-oral transmission of SARS-CoV-2 and given the magnitude of the SARS-CoV-2/coronavirus disease 2019 pandemic, associated with the widespread misuse of proton pump inhibitors, this suggests that we should not rule out the hypothesis that patients treated with proton pump inhibitors may be more at risk of being infected by SARS-CoV-2.

Use of Point-of-Care Gastric pH Testing to Assess the Efficacy of Acid Suppression Therapy in the Neonatal Intensive Care Unit.

OBJECTIVE: The use of acid suppression therapies in newborns lacks efficacy and is associated with adverse effects. Point-of-care (POC) assessment of gastric aspirate pH may provide an objective, noninvasive measure of gastric acidity in tube fed infants. We conducted the present study to characterize the POC gastric pH levels in gastric tube fed infants before and after initiation of enteral omeprazole or ranitidine. STUDY DESIGN: Retrospective cohort study of infants with gastric aspirate pH levels determined by POC pH strips. Gastric pH levels recorded during 7 days before and 14 days after medication initiation were compared using Wilcoxon's sign-rank tests. RESULTS: Among 307 evaluated infants, 284 (92%) had a median gastric pH level ≥4 in 7 days prior to ranitidine or omeprazole. In 14 days after medication initiation, the median gastric pH of infants with pretreatment median gastric pH < 4 increased to 4.5 and 5 (p < 0.01) in the ranitidine and omeprazole groups, respectively. There was no change in infants with pretreatment median gastric pH ≥4. CONCLUSION: Among infants receiving gastric tube feedings and enteral omeprazole or ranitidine, only those with a pretreatment gastric pH level <4 demonstrated a significant increase in gastric pH. Validation of our findings against esophageal pH multichannel intraluminal impedance testing is needed.

Gastric Acid and Pepsin Work Together in Simulated Gastric Acid Inhalation Leading to Pulmonary Fibrosis in Rats.

BACKGROUND The clinical association between gastroesophageal reflux disease (GERD) and idiopathic pulmonary fibrosis (IPF) has been known for many years, but it is still unclear. The present study investigated the association between experimentally simulated aspiration and pulmonary fibrosis. MATERIAL AND METHODS A total of 120 male Sprague-Dawley rats were randomly divided into a negative control group, a bleomycin group, and 3 simulated aspiration groups. The bleomycin group was administered a one-time intratracheal injection of bleomycin, whereas the 3 simulated aspiration groups were treated either with an intratracheal instillation of gastric fluid combined with pepsin, with pepsin alone, or with hydrochloric acid, all twice a week, and the negative control group was administered normal saline twice a week. Lung tissues were collected to evaluate pathological changes and the mRNA expression levels of connective tissue growth factor (CTGF), type I collagen, and transforming growth factor. RESULTS The results demonstrated that the degree of fibrosis in the early stage was low in each of the 3 simulated aspiration groups, but gradually increased over time. The expression levels of the downstream factor of fibrosis, CTGF, and type I collagen also reflected this trend. CONCLUSIONS The study demonstrates that aspiration of gastric contents can cause pulmonary fibrosis, and mixed aspiration of pepsin and gastric fluid can accelerate this process. This study provides strong evidence in support of a potential association between human GERD and IPF.

Sleep and Nocturnal Gastroesophageal Reflux: An Update.

Nocturnal gastroesophageal reflux has been associated with poor sleep quality. Normal physiological adaptations of the aerodigestive system to sleep prolong and intensify nocturnal reflux events. This occurrence leads to sleep disruption, as well as to esophageal, laryngeal, and laryngopharyngeal reflux. Controversy exists on whether OSA and nocturnal reflux are causally linked or merely associated because of shared risk factors. Advances in diagnostic technology have provided new insights into gastroesophageal reflux and the mechanisms of nocturnal reflux during sleep. This update reviews new data on causal links between sleep and gastroesophageal reflux disease.

Gastric acid suppression promotes alcoholic liver disease by inducing overgrowth of intestinal Enterococcus.

Chronic liver disease is rising in western countries and liver cirrhosis is the 12th leading cause of death worldwide. Simultaneously, use of gastric acid suppressive medications is increasing. Here, we show that proton pump inhibitors promote progression of alcoholic liver disease, non-alcoholic fatty liver disease, and non-alcoholic steatohepatitis in mice by increasing numbers of intestinal Enterococcus spp. Translocating enterococci lead to hepatic inflammation and hepatocyte death. Expansion of intestinal Enterococcus faecalis is sufficient to exacerbate ethanol-induced liver disease in mice. Proton pump inhibitor use increases the risk of developing alcoholic liver disease among alcohol-dependent patients. Reduction of gastric acid secretion therefore appears to promote overgrowth of intestinal Enterococcus, which promotes liver disease, based on data from mouse models and humans. Recent increases in the use of gastric acid-suppressive medications might contribute to the increasing incidence of chronic liver disease.Proton pump inhibitors (PPIs) reduce gastric acid secretion and modulate gut microbiota composition. Here Llorente et al. show that PPIs induce bacterial overgrowth of enterococci, which, in turn, exacerbate ethanol-induced liver disease both in mice and humans.

Physiologic, pathophysiologic, and pharmacologic regulation of gastric acid secretion.

PURPOSE OF REVIEW: The present review summarizes the past year's literature, both clinical and basic science, regarding physiologic and pharmacologic regulation of gastric acid secretion in health and disease. RECENT FINDINGS: Gastric acid kills microorganisms, assists digestion, and facilitates absorption of iron, calcium, and vitamin B12. The main stimulants of acid secretion are the hormone gastrin, released from antral G cells; paracrine agent histamine, released from oxyntic enterochromaffin-like cells; and neuropeptide acetylcholine, released from antral and oxyntic intramural neurons. Gastrin is also a trophic hormone that participates in carcinogenesis. Helicobacter pylori may increase or decrease acid secretion depending upon the acuity and predominant anatomic focus of infection; most patients manifest hypochlorhydria. Despite the fact that proton pump inhibitors (PPIs) are amongst the most widely prescribed drugs, they are underutilized in patients at high risk for UGI bleeding. Although generally considered well tolerated, concerns have been raised regarding associations between PPI use and dementia, kidney disease, myocardial infarction, pneumonia, osteoporosis, dysbiosis, small bowel injury, micronutrient deficiency, and fundic gland polyps. SUMMARY: Our understanding of the physiologic, pathophysiologic, and pharmacologic regulation of gastric secretion continues to advance. Such knowledge is crucial for improved and safe management of acid-peptic disorders.

The Susceptibility to Dental Erosion Differs among Individuals.

Studies of wine tasters and patients with self-induced vomiting have revealed that 30-50% of individuals at high risk do not develop erosive lesions. The aim was to investigate this apparent individual susceptibility to enamel erosion. Two enamel specimens were made from each of 3 premolars from 8 persons (donors). Six acrylic mouth appliances were worn by 6 volunteers (carriers). One specimen from each donor was mounted on each appliance. The carriers wore the appliances for 9 days. The appliances were immersed in 0.01 M HCl for 3 min twice per day to imitate a vomiting/reflux situation. The enamel specimens were analysed by a white-light interferometer to measure enamel loss (in micrometres). The enamel loss varied significantly both between the donor teeth (p = 0.009) and the carriers (p = 0.004). The lesion in the specimen with the largest amount of enamel loss was 4 times as deep as in the specimen with the lowest. In 1 carrier, all specimens displayed enamel loss above the mean, including the specimen from the donor with the most resistant enamel. The variation in susceptibility to erosion among individuals appears to be influenced both by the sustainability of the enamel and by factors in the oral environment. This could explain the variation in prevalence and severity of dental erosions among patients exposed to similar acidic challenges. The results suggest that for certain individuals, only minimal acidic challenges may be sufficient to cause damage to the teeth, while others may never develop dental erosions despite extensive exposure to acid.

Effect of baclofen on gastric acid pocket in subjects with gastroesophageal reflux disease symptoms.

Postprandial gastroesophageal reflux (PGER) in the distal esophagus (DE) is associated with a gastric juice 'acid pocket' (AP). Baclofen reduces AP extension into the DE in healthy volunteers, in part through increased lower esophageal sphincter (LES) pressure. We aimed to verify whether baclofen also affects postprandial AP location and extent in gastroesophageal reflux disease (GERD) patients. Thirteen treatment-naive heartburn-prevalent GERD patients underwent two AP studies, after pretreatment with baclofen 40 mg or placebo 30 minutes preprandially. We performed pH-probe stepwise pull-throughs (PT) (1 cm/min, LES -10 to +5 cm) before and every 30 minutes from 30 minutes before up to 150 minutes after a test meal. After the meal, both after placebo and baclofen, gastric pH significantly dropped at 30, 60, 90 minutes postprandially (P: nadir pHs of 3.9 ± 0.6, 2.3 ± 0.6, 2.1 ± 0.4; B: nadir pHs of 2.5 ± 0.4, 2.8 ± 0.4, 2.5 ± 0.3; all P < 0.05). After placebo, LES pressure decreased at 60, 90 and 120 minutes postprandially (32.7 ± 6.1 vs. 24.5 ± 3.1, 27.3 ± 5.9, 27.3 ± 6.0 mmHg; analysis of variance [ANOVA], P = 0.037), but this was prevented by baclofen (25.4 ± 3.4 vs. 29.4 ± 2, 32.2 ± 1.4, 35.5 ± 1.7 mmHg, ANOVA, P = not significant (NS)). Baclofen did not significantly decrease the postprandial AP extent above the LES but prevented the postprandial increase in transient lower esophageal sphincter relaxations (TLESRs) (preprandial vs. postprandial, placebo: 1.1 ± 0.3 vs. 3.7 ± 0.7, P < 0.05; baclofen: 1.4 ± 0.4 vs. 2 ± 0.5, P = NS). In GERD patients, baclofen significantly increases postprandial LES pressure, prevents the increase TLESRs but, unlike in healthy volunteers, does not affect AP extension into the DE.

Gastric acid induces mucosal H2S release in rats by upregulating mRNA and protein expression of cystathionine gamma lyase.

It is well known that hydrogen sulfide (H2S) protects the gastric mucosa against gastric acid and other noxious stimulants by several mechanisms but until now the effect of gastric acid on H2S production has not been evaluated. This study was performed to determine the effect of basal and stimulated gastric acid secretion on mRNA and protein expression of cystathionine gamma lyase (CSE) and cystathionine beta synthase (CBS), and on mucosal release of H2S in rats. Seventy-two male rats were randomly assigned into 9 groups (8 in each)-control, distention, and pentagastrin-induced gastric acid secretion groups. The effects of 15% alcohol solution, propargylglycine (PAG), L-NAME, and pantoprazole were also investigated. Under anesthesia, animals underwent tracheostomy and midline laparotomy. A catheter was inserted into the stomach through the duodenum for gastric washout. At the end of the experiments, the animals were killed and the gastric mucosa was collected to measure H2S concentration and to quantify mRNA expression of CSE and CBS by quantitative real-time PCR, and expression of their proteins by western blot. Basal and stimulated gastric acid secretion increased mucosal levels of H2S, and mRNA and protein expression of CSE. Pantoprazole and L-NAME reversed H2S release and restored protein expression of CSE to the control level. Pantoprazole, but not propargylglycine, pretreatment inhibited the elevated level of protein expression of eNOS in response to distention-induced gastric acid secretion. Our findings indicated that NO mediated the stimulatory effect of gastric acid on H2S release and protein expression of CSE.

The Evolution of Stomach Acidity and Its Relevance to the Human Microbiome.

Gastric acidity is likely a key factor shaping the diversity and composition of microbial communities found in the vertebrate gut. We conducted a systematic review to test the hypothesis that a key role of the vertebrate stomach is to maintain the gut microbial community by filtering out novel microbial taxa before they pass into the intestines. We propose that species feeding either on carrion or on organisms that are close phylogenetic relatives should require the most restrictive filter (measured as high stomach acidity) as protection from foreign microbes. Conversely, species feeding on a lower trophic level or on food that is distantly related to them (e.g. herbivores) should require the least restrictive filter, as the risk of pathogen exposure is lower. Comparisons of stomach acidity across trophic groups in mammal and bird taxa show that scavengers and carnivores have significantly higher stomach acidities compared to herbivores or carnivores feeding on phylogenetically distant prey such as insects or fish. In addition, we find when stomach acidity varies within species either naturally (with age) or in treatments such as bariatric surgery, the effects on gut bacterial pathogens and communities are in line with our hypothesis that the stomach acts as an ecological filter. Together these results highlight the importance of including measurements of gastric pH when investigating gut microbial dynamics within and across species.

H. pylori and its modulation of gastrointestinal microbiota.

The discovery of Helicobacter pylori (H. pylori) changed the dogma of the stomach as a sterile organ. H. pylori is an obligate pathogen in the human stomach and recognized as a definite carcinogen. Extensive research on the interaction of this bacterium with the gastric mucosa has been performed over the past three decades. The development of new nucleotide sequencing techniques and new biocomputational tools has opened the field for studying the diversity and complexity of the microbiome in the gastrointestinal tract independently of cultural methods. These techniques allow to better characterize further gastric bacteria. However, the differentiation of alive resident and transient microbes requires an analysis beyond the pure detection of bacterial genomic material applying a combination with metabolomic analyses. Currently, the interaction of gastric microbiota with each other, with H. pylori and with the host is addressed by extensive research. This review gives a concise overview on current knowledge on this topic.

Relationship between multiple water swallows and gastroesophageal reflux in patients with normal esophageal motility.

Multiple water swallows (MWS) stimulates neural inhibition, resulting in abolition of contractions in the esophageal body and complete lower esophageal sphincter relaxation, which is followed by peristalsis and the lower esophageal sphincter contraction. We assessed the relationship between MWS and gastroesophageal reflux in patients with esophageal symptoms and with normal findings by high-resolution manometry (HRM). We retrospectively reviewed the clinical records of patients who underwent HRM and a 24-hour ambulatory impedance-pH study. Correlation between the findings of the impedance-pH study and abnormal MWS responses without motility disorders was evaluated. Independent t-tests were used for statistical analysis. Of 28 patients, 20 (71%) had abnormal MWS responses: four (20%) had abnormal responses during MWS, six (30%) had abnormal responses after MWS, and 10 (50%) had abnormal responses both during and after MWS. Total acid exposure times were significantly longer in patients with abnormal MWS responses than in patients with normal MWS responses. In particular, upright acid exposure time and all reflux percent times were significantly longer in patients with abnormal MWS responses. However, bolus clearance time and longest reflux episode were not different between the two groups. Abnormal MWS responses predicted increased acid exposure times in patients with normal findings of HRM by the Chicago classification.

Role of gastric acid inhibition, prostaglandins and endogenous-free thiol groups on the gastroprotective effect of a proteolytic fraction from Vasconcellea cundinamarcensis latex.

OBJECTIVES: The aim of this study was to extend our knowledge about the mechanism involved in the gastroprotective effect of P1G10, a proteolytic fraction rich in cysteine proteinases from Vasconcellea cundinamarcensis (syn. Carica candamarcensis) latex, which demonstrated gastric healing and protection activities in rats. METHODS: Wistar rats were submitted to gastric lesions by indomethacin and treated with P1G10 (10 mg/kg). Free thiol groups and prostaglandin E2 content were measured in gastric mucosal and gastrin levels in blood samples. To evaluate the participation of nitric oxide (NO) or proteolytic activity of P1G10 on its gastroprotective effect, animals were treated with an inhibitor of NO production (L-NAME) or the fraction inhibited by iodoacetamide, respectively. Gastric secretion study (acidity and pepsin activity) was also performed. KEY FINDINGS: P1G10 (10 mg/kg) inhibited the occurrence of gastric lesions by indomethacin, restored the free thiol groups content on gastric mucosa and increased moderately prostaglandin E2 levels (34%). Furthermore, the treatment decreased the gastrin levels (95%), suggesting a possible modulation of secretory activity. This effect was accordant with attenuation of gastric acidity (42%) and pepsin activity (69%) seen in animals subjected to pyloric ligation. The inhibition of NO production or the proteolytic activity of P1G10 does not affect the gastroprotective effect. CONCLUSIONS: These results can explain the gastroprotective activity of P1G10 and serve a basis for further studies of this active principle.

Prostaglandin pathways in duodenal chemosensing.

Acid-sensing pathways, which trigger mucosal defense mechanisms in response to luminal acid, involve the rapid afferent-mediated "capsaicin pathway" and the sustained "prostaglandin (PG) pathway." Luminal acid quickly increases protective PG synthesis and release from epithelia, although the mechanism by which luminal acid induces PG synthesis is still mostly unknown. Acid exposure augments purinergic ATP-P2Y signaling by inhibition of intestinal alkaline phosphatase activity. Since P2Y activation increases intracellular Ca2+, we further hypothesized that ATP-P2Y signals increase the generation of H2O2 derived from dual oxidase, a member of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase family activated by Ca2+. Our recent studies suggest that acid exposure increases H2O2 output, followed by phospholipase A2 and cyclooxygenase activation, increasing PG synthesis. Released prostaglandin E2 augments protective HCO3- and mucus secretion via EP4 receptor activation. Thus, the PG pathway as a component of duodenal acid sensing consists of acid-related intestinal alkaline phosphatase inhibition, ATP-P2Y signals, dual oxidase 2-derived H2O2 production, phospholipase A2 activation, prostaglandin E2 synthesis, and EP4 receptor activation. The PG pathway is also involved in luminal bacterial sensing in the duodenum via activation of pattern recognition receptors, including Toll-like receptors and nucleotide-binding oligomerization domain 2. The presence of acute mucosal responses to luminal bacteria suggests that the duodenum is important for host defenses and may reduce bacterial loading to the hindgut using H2O2, complementing gastric acidity and anti-bacterial bile acids.

Does a relationship still exist between gastroesophageal reflux and Helicobacter pylori in patients with reflux symptoms?

BACKGROUND: The nature of the relationship between Helicobacter pylori and reflux esophagitis (RE) is not fully understood. In addition, the effect of H. pylori eradication on RE and gastroesophageal reflux disease (GERD) is unclear. This study was designed to investigate the relationship between H. pylori infection and the grade of GERD in patients with reflux symptoms. METHODS: Between January 2010 and July 2013, 184 consecutive patients with daily reflux symptoms for at least one year were evaluated at the ambulatory for functional esophageal disease, Tor Vergata University Hospital, Rome, Italy. All patients underwent a pretreatment evaluation, which included anamnesis, clinical examination, Esophagogastroduodenoscopy (EGDS) with biopsy, esophageal manometry and 24-hour pH-metry. All statistical elaborations were obtained using Statigraphies 5 plus for Window XP. RESULTS: There was no statistical difference regarding Lower Esophageal Sphincter (LES) pressure between patients who were H. pylori-positive and H. Pylori-negative (19.2 ± 9.5 (range: 3.7 to 46.2) and 19.7 ± 11.0 (range: 2.6 to 61), respectively). Further, no significant difference was evidenced in esophageal wave length (mean value: 3.1 seconds in H. pylori-negative patients versus 3.2 seconds in H. pylori-positive patients) or in esophageal wave height (mean value: 72.2 ± 39.3 in H. pylori-negative patients versus 67.7 ± 28.4 in H. pylori-positive patients). We observed that hiatal hernia (P = 0.01), LES opening (P = 0.05), esophageal wave length (P = 0.01) and pathological reflux number (P = 0.05) were significantly related to the presence of esophagitis. However, H. pylori infection was not significantly related to the presence of reflux esophagitis. CONCLUSIONS: Our clinical, endoscopic, manometric and pH-metric data shows no significant role of H. pylori infection in the development of GERD or in the pathogenesis of reflux esophagitis. However, current data do not provide sufficient evidence to define this relationship and further prospective large studies are needed.

Intrinsic causes of erosion.

Gastric juice entering the mouth causes dental erosion. Common causes for the migration of gastric juice through the lower and upper oesophageal sphincters are reflux disease, laryngopharyngeal reflux, eating disorders, chronic alcoholism and pregnancy. Gastroesophageal reflux is a common condition affecting up to 65% of the Western population at some point in their lifetime. A typical clinical sign of acidic gastric juice entering the mouth is palatal dental erosion. As the condition becomes more chronic it becomes more widespread. There have been relatively few randomised studies investigating the aetiology of acids causing erosion. Of the few that have reported their findings, it appears that gastric acids have the potential to induce moderate-to-severe erosion. This literature review reports the conditions associated with the movement of gastric juice and dental erosion using medical and dental sources.

Natural defense by saliva and mucosa against oral infection by Leptospira.

Leptospirosis caused by drinking water has not been as frequently reported as percutaneous infection. Resistance to oral infection by pathogenic Leptospira was examined in an experimental hamster infection model. The results suggested some natural defenses against oral infection by Leptospira. First, we found that characteristic linear agglutination of Leptospira rapidly occurs when mixed with human saliva. That human saliva attenuated the infectivity of the treated leptospires by its agglutination activity suggested saliva to be the first line of defense against oral infection by leptospires. Second, only 10(1) Leptospira organisms caused death after submucosal injection into oral mucosa in hamsters, but oral infection with drinking water containing 10(5) organisms/mL did not cause death. This result showed that the mucosa plays the role of a physical barrier. Third, hamsters intragastrically infected by leptospires, with doses lethal to hamsters in oral infection, showed no signs of illness, which suggested that gastric acid plays an important role in preventing oral infection. Based on these results, saliva, mucosa, and gastric acid make up a natural defense, which confers high resistance to hosts against oral infection by leptospires.