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Background:
Study Protocol

Bicarbonate Natural Mineral Water from Source “F2 Păltiniș” Facilitates Digestion—A Pilot Study

by
Fabio Pace
1,*,
Antonio Maria Morselli-Labate
2,*,
Aladin Abu Issa
1,* and
Alessandro Zanasi
3,*
1
Gastrointestinal Unit, Bolognini Hospital, 24068 Seriate, Italy
2
Biostatistic, via Battibecco 1, 40123 Bologna, Italy
3
Water Resource Association, 40121 Bologna, Italy
*
Authors to whom correspondence should be addressed.
Gastrointest. Disord. 2025, 7(3), 47; https://doi.org/10.3390/gidisord7030047
Submission received: 15 April 2025 / Revised: 7 July 2025 / Accepted: 8 July 2025 / Published: 11 July 2025
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Abstract

Background: Dyspeptic symptoms are very common in the general population, with an estimated prevalence of 14% to 41%, and the majority of patients experience symptoms without an organic cause for them (so-called functional dyspepsia). While the pathophysiology of functional dyspepsia remains elusive, the impact of functional dyspepsia on quality of life is detrimental. The treatment involves a change in lifestyle—a healthy diet and physical activity—in combination with pharmacological treatments. However, currently, there is no standard therapy for this condition, although a nutritional approach appears to be feasible and well accepted by patients. In this context, the intake of some mineral water types might be able to play an important role. Objective: The aim of the present study was to evaluate whether the regular intake of bicarbonate natural mineral water (Aqua Carpatica from source “F2 Păltiniș”) is able to positively influence the symptomatic process of dyspepsia, promoting digestion and improving the quality of life of patients. Methods: The patients enrolled in this open-label study had diagnosis of functional dyspepsia formulated in accordance with the Rome III criteria. During the 4-week study, patients had to ingest tap water at 1.5 L/day (wash-out period: 2 weeks), and in the 2-week subsequent period, they had to ingest alkaline natural mineral water at 1.5 L/day. The primary efficacy endpoint of this study includes a statistically significant improvement (p < 0.05) in the “heartburn”, “regurgitation”, and “dyspepsia” subscales and the total Reflux Disease Questionnaire’s (RDQ) score with respect to the effects of alkaline natural mineral water. As secondary endpoints, we considered statistically significant improvements (p < 0.05) in quality-of-life scores (Psychological General Well-Being Index—Short form; PGWB-S), the patient’s self-assessment of the state of efficiency of their digestion, and their sense of post-prandial fullness, as well as the use of antacids. Results: Forty-five patients were enrolled: all were Caucasian and mostly women (25, 55.6% vs. 20 men, 44.4%), and they were aged between 25 and 75 years (50.6 ± 13.5 years; mean ± SD). The results of this preliminary study show a significant improvement in functional dyspepsia symptoms—as assessed via the RDQ—and an improvement in quality of life—as assessed using the PGWB-S score—after the intake of alkaline natural mineral water. Conclusions: This preliminary study provides clinical evidence for a recommendation of alkaline natural mineral water as a symptomatic treatment of dyspepsia.

1. Introduction

Dyspeptic symptoms are very common in the general population, with an estimated prevalence of 14% to 41%, and in approximately 80% of cases, there is no structural explanation for them [1,2,3]. The term dyspepsia means “poor digestion”; this syndrome is characterized by a wide and varied range of symptoms: epigastric burning/pain, feeling of early satiety, heaviness, bloating, excessive belching, and dilated stomach cavity. Functional dyspepsia (FD) requires a differential diagnosis with the “organic” form, in which an objective pathology is present, for example, through endoscopic investigation. The causes or risk factors of organic dyspepsia are mainly duodenal or gastric ulcers, erosive gastritis, duodenitis, gastritis, and malignant processes. FD, which belongs to the group of functional gastrointestinal disorders—recently redefined as disorders of gut–brain interaction—is defined as dyspepsia in the absence of structural disease following imaging and endoscopic investigations. FD probably has a multifactorial pathogenesis, which has so far not been precisely established. The data collected suggest that previous acute gastroenteritis and a Western diet can play an important role in its genesis, and it is likely associated with psychological factors [4]. The other risk factors are as follows: female sex, smoking, and, possibly, the use of non-steroidal anti-inflammatory drugs. The association with Helicobacter pylori infection is controversial, since the latter is still an objective endoscopic/histological lesion and therefore indicative of organic dyspepsia. Furthermore, the eradication of this infection does not always lead to an improvement in symptoms and sometimes even results in a worsening of reflux-like symptoms [5].
The pathophysiological factors underlying FD remain partly unknown: its clinical picture is correlated with slowed emptying and an alteration of gastroduodenal motor activity, which is probably attributable to the disordered communication between the intestine and the brain, resulting in motility disorders; visceral hypersensitivity; and alterations of the gastrointestinal microbiota, mucosal and immune function, and central nervous system processing [3,4]. Interestingly, microbiota changes (e.g., dysbiosis) may be a cause or consequence of FD. Often, dyspeptic symptoms overlap with symptoms of gastroesophageal reflux disease, which mainly include heartburn and regurgitation, and vice versa.
It is widely documented that subjects suffering from FD have a significantly compromised quality of life (QoL), and many studies have shown a clear correlation between symptom severity and reduced QoL [6], affecting not only physical but also psychological well-being [7,8], in addition to occupational functioning [9].
Finally, the economic aspect is not negligible: the direct and indirect costs of FD are substantial. In 2009, data on patients with FD in the US population indicated a total expenditure of USD 18.4 billion [10], and other studies concur with these large figures [11].
The treatment of FD involves a change in lifestyle that is based on a healthy diet and physical activity, in combination with pharmacological treatments (acid suppressants, prokinetics, neuromodulators, etc.) [12]. Dietary recommendations include smaller and more frequent meals, avoiding trigger foods. Acidity suppressants are used as first-line treatment. Prokinetics and neuromodulators aim to improve gastric motility and central pain processing, respectively. Overall, the results of pharmacological and diet therapy are often unsatisfactory [13,14]. This is linked with multiple causes. The fact is that this disorder is multifactorial, and therapies generally target a single factor; secondly, there is often an overlap between various functional disorders: For example, FD is often associated with irritable bowel syndrome or gastroesophageal reflux symptoms. Regarding nutritional therapy, however, various scientific evidence shows how the intake of some types of mineral water might be able to play an important role in this context [15]. In particular, natural mineral water that is rich in bicarbonate has attracted interest due to its positive effect on various gastrointestinal disorders, including dyspepsia. It is known that the biological action of mineral water could be a result of its undissociated salts, cations, anions, and trace elements. Moreover, physical factors—such as pH, elements capable of acting on the so-called autonomous intestinal neuropeptides, motility, and endocrine and exocrine digestive secretions—could also affect the biological action. Although there is a lack of scientific research on the effectiveness of natural mineral water that supports their physiological rationality and proves their long-term effects [16], there is nevertheless sufficient evidence that supports the use of mineral water and its potential benefits [17,18,19,20,21,22,23,24,25,26].
Water is essential for our well-being, and it is involved in almost all bodily functions. Even mild chronic dehydration—which is capable of inducing a minimal electrolyte imbalance—can result in the increased risk of disorders in multiple organs and systems, including the gastrointestinal system [27,28]. Adequate hydration is therefore essential for proper digestion. In fact, water is essential for the production of digestive juices, gastric emptying, and the lubrication of the gastrointestinal tract. Dehydration, on the other hand, can hinder digestion, making the process less efficient, increasing the risk of digestive problems [29], and favoring the appearance of dyspeptic symptoms [30].
The main objective of our preliminary study was to evaluate whether the regular intake of bicarbonate natural mineral water is able to positively influence the symptomatic process of dyspepsia, promote digestion, and improve the QoL of patients. If these effects occur, there is a need to schedule a further blinded and controlled study that compares the effect of bicarbonate water with that of mineral water with low mineral contents. The second objective of this study is to collect data and information for the programming of this successive crossover study.

2. Results

2.1. Patients

Forty-five patients suffering from FD were enrolled in this open-label study: all were Caucasian and mostly women (25, 55.6%, vs. 20 men, 44.4%), and they were aged between 25 and 75 years (50.6 ± 13.5 years; mean ± SD). The prevalent symptom declared by the patients was heartburn (22, 48.9%), followed by regurgitation (17, 37.8%), pain behind the breastbone (4, 8.9%), and epigastric pain (2, 4.4%). The baseline clinical characteristics of the study population are shown in Table 1.
Out of the 45 patients admitted to the study, there were 4 drop-outs (8.9%) (two men and two women). Three of the drop-outs did not complete the questionnaires correctly, while one did not show up for the first baseline check. Therefore, forty-one subjects (91.1%) completed the study. The drop-out patients were significantly older (66.5 ± 3.7 vs. 49.0 ± 13.1; p = 0.009) than those who completed the study, and they had higher scores with respect to pain behind the breastbone (6.0 ± 1.4 vs. 3.0 ± 2.4; p = 0.018), pain in the upper stomach (5.5 ± 1.3 vs. 3.0 ± 2.4; p = 0.035), and heartburn (13.3 ± 2.2 vs. 8.2 ± 4.1; p = 0.013). No significant differences were observed with respect to other patient characteristics and baseline values (gender, prevalent symptom declared by the patients, RDQ scores, subjective assessment of post-prandial fullness and digestion, use of antacids, and PGWB-S questionnaire: p values ranging between 0.055 and 1.000).
During the study, all 41 participants respected the quantities of water indicated at the time of enrollment, in addition to the intake times. No handling of missing data was necessary, as all 41 participants completed every item of the RDQ and PGWB-S questionnaire.

2.2. RDQ

The frequencies of symptoms are shown in Table 2. At baseline, acidic taste in the mouth was the most frequent symptom, and it was present in all patients but two (95.1%), followed by feelings of burning in the upper stomach (90.2%) and behind the breastbone during the movement of materials (87.8%); in contrast, less frequent symptoms comprised pain behind the breastbone and pain in the upper stomach (68.3%). During the wash-out period, no significant differences were found, while the intake of alkaline natural mineral water significantly reduced the frequency of all symptoms (p ranging between <0.001 and 0.004), except the feeling of burning behind the breastbone (p = 0.625).
The comparison between the administration of alkaline natural mineral water and the wash-out period was not statistically significant only for the sensation of burning behind the breastbone (p = 1.000) and for pain behind breastbone, which approached statistical significance (p = 0.058); in contrast, statistical significance was observed for the other four symptoms (p ranging between <0.001 and 0.020). A similar pattern was observed when analyzing symptom domains: Heartburn did not exhibit significant changes during either the wash-out period or alkaline mineral water administration, while dyspepsia and regurgitation did not change significantly during the wash-out period but exhibited significant reductions after alkaline natural mineral water intake (p = 0.031 and p = 0.016, respectively), with significant differences between the two water administrations (p = 0.014 and p = 0.008, respectively).
Table 3 shows the results of the RDQ scores. After the wash-out period, scores with respect to the burning sensation behind the breastbone (p = 0.043), burning sensation in the upper stomach (p = 0.001), and acidic taste in the mouth (p = 0.002) showed significant decreases. A similar trend was also observed with respect to the regurgitation (p = 0.004) domain and the total score (p = 0.005). On the other hand, highly significant reductions in all items, domains, and total score were observed after alkaline natural mineral water intake (p < 0.001); all of these reductions were significantly higher than those observed during the wash-out period (p = 0.003 for burning sensation behind the breastbone and p < 0.001 for all other scores).

2.3. Subjective Assessment of Post-Prandial Fullness and the Digestion and Use of Antacids

The results of the scales assessing digestive efficiency and post-prandial fullness are shown in Table 4. Both scales increased during the wash-out period: Digestive efficiency was significant (p = 0.008), but the sense of post-prandial fullness failed to reach a significant value (p = 0.067). The consumption of alkaline natural mineral water significantly increased scores on both scales (p < 0.001), and these improvements were significantly greater than those observed during the wash-out period (p < 0.001).
Antacid use decreased progressively from baseline (29 patients, 70.7%) to the end of the wash-out period (24 patients, 58.5%), and it further declined by the final visit after alkaline mineral water intake (8 patients, 19.5%). The decrease after the wash-out period was not significant (p = 0.125), while the decrease after alkaline natural mineral water consumption was significant (p < 0.001); moreover, it was also significantly different from that observed during the wash-out period (p = 0.028).

2.4. HRQoL (PGWB-S Questionnaire)

Data regarding the quality-of-life questionnaire (PGWB-S) are shown in Table 5. After two weeks of the wash-out period, only anxiety showed a significant increase (p = 0.019); in contrast, after two weeks of alkaline natural mineral water intake, quality of life showed significant improvements when compared to starting values. This was observed in the total score (p < 0.001) and in all examined items (p value ranging from <0.001 to 0.045), except for the self-control item (p = 0.772). The comparison between alkaline natural mineral water and the wash-out period did not show a significant difference, even if it should be pointed out that the total score (p = 0.079)—as well as anxiety (p = 0.092), depressed mood (p = 0.069), and tiredness (p = 0.068) items—had values near the significant level.
Finally, 38 patients (92.7%) had a positive opinion of the treatment (“very good”: 27 cases, 65.9%; “good”: 11 cases, 26.8%), while 2 patients (4.9%) rated it as “moderate”, and only 1 patient (2.4%) rate it as “poor”. The water was well tolerated, and no patients declared any adverse effects.

3. Discussion

Water is an essential nutrient for life; it is the most abundant component in the human body and ensures our well-being. Good hydration, as previously reported, also plays a major role in maintaining good digestive function; however, some mineral water types—in particular, thanks to their mineralization—seem to improve the symptomatic picture of some morbid conditions of the digestive system. For this reason, before testing bicarbonate mineral water, we implemented a wash-out period with normal tap water to provide equal hydration for all studied subjects. The currently available data suggest that crenotherapy is a useful complement to the medical treatment of digestive symptoms, even if solid scientific evidence on the mechanisms that document their real effectiveness is still lacking [16,31].
Despite considerable advancements in the knowledge of several postulated pathophysiological mechanisms and in the symptom-based classification of functional disorders due to the new Rome diagnostic criteria—particularly those dealing with functional dyspepsia [2]—no satisfactory therapeutic approach is currently available for this disorder. In fact, the vast majority—if not all—of the medical therapies currently used to treat FD are off-label and generally target the most prominent symptoms rather than the underlying causes or mechanisms [32]. It is not surprising, therefore, that many treatments are offered to patients—mainly to those with milder FD. One of these choices is the administration of bicarbonate mineral water. In patients with heartburn from FD, the consumption of mineral water may help, as shown in a systematic review of clinical studies [16]. This review only comprised three randomized controlled trials (RCTs), with the other six being pre–post-studies with a single treatment group but no comparison group. Two of the three RCTs reported using mineral water as an add-on to ordinary pharmacological therapies [17,19], whereas the third study reported a reduction in dyspepsia symptoms in the intervention group (mineral water containing only moderate hydrogen carbonate concentrations) compared to the tap water group, where symptoms did not improve after 2 weeks [33]. More recently, another RCT—which included 148 randomized patients with GERD treated with bicarbonate-rich mineral water (verum: n = 73, placebo: n = 75)—reported a complete response rate of 84.72% in the verum and 63.51% in the placebo group (p = 0.0035, number needed for treatment equal to 5) [20].
The advantages of using bicarbonate alkaline mineral water on gastric function and the symptoms of FD were reported by other authors [18].
The mechanisms through which these water types confer therapeutic effects on the digestive tract are complex and still under study. However, the currently available scientific evidence allows us to attribute the biological effects of mineral water to its physico-chemical characteristics [22]. The effects of bicarbonate water on the digestive tract stem both from the role of the hydrogen carbonate anion, which binds protons from gastric acid and buffers them similarly to antacid drugs—thus reducing gastric secretion (H+ + HCO3− → H2O + CO2)—and from its stimulation of gastric motility and the biliary tract. This type of water strengthens the protective mechanisms of the stomach walls, as it improves the secretion of gastric mucosa and blood flow [34]. The stimulating effects of mineral water on both gastric emptying and the cyclic interdigestive motor activity of the gastroduodenal tract were studied using scintigraphic methods and compared to tap water. The results showed that gastric emptying after the intake of bicarbonate mineral water was significantly faster than after tap water intake in both dyspeptic patients and healthy subjects [24]. An increase in oro-cecal transit speed and gastric emptying time after supplementation with bicarbonate water was also confirmed in another study on 30 dyspeptic patients using a breath test with 13C octanoic acid [21]. These data had already emerged from a preclinical study on rats, which showed an increase in gastric-emptying speeds compared to the control after four weeks of regular bicarbonate mineral water intake [18].
Furthermore, the specific favorable effect of a bicarbonate alkaline mineral water was demonstrated with respect to the gastric function and symptoms of FD [18].
In our study, we selected patients with mild-to-moderate symptoms of FD lasting more than 6 months and a significant burden of GERD symptoms. The diagnosis of FD was made according to the Rome III criteria [2] and all patients had a pathological RDQ score in order to be recruited. After 2 weeks of drinking alkaline natural mineral water, the global RDQ score was more than halved. All three subscales of the RDQ showed a similar trend, with the most impressive reduction observed in the regurgitation domain. Consequently, the HRQoL showed a significant improvement in the global score of the used scale (PGWB-S) and the individual items, with only one single parameter (self-control) not significantly normalized at the study’s end.
A slight improvement in the RDQ was also found in the wash-out period with a constant intake of at least 1.5 L of tap water. This can be explained by greater water intake, which consequently results in greater dilution of gastric juices. The improvement in the quality of life is also attributable to better hydration; in fact, this can positively influence mood. When an individual is dehydrated, the brain’s ability to synthesize serotonin—the happiness hormone—is reduced while cortisol—the stress hormone—increases [35,36].
Water was well tolerated, and no adverse effects were observed.
“Lifestyle changes” are often recommended as part of the overall treatment concept, e.g., small low-fat meals that should not be eaten before going to bed, weight reduction, an elevated upper-body position at night, and abstinence from “triggers” such as coffee, chocolate, nicotine, and alcohol [37]. However, natural mineral water is rarely mentioned as part of this concept, even though natural remedies are implemented by an increasing number of patients. The positive influence of hydrogen-carbonate-rich water on heartburn and gastrointestinal symptoms in general has already been demonstrated several times. As an example, an Italian group administered 250 mL of calcium-and-hydrogen-carbonate-rich mineral water (Ca2+ 486.6 mg/L; HCO3− 1750.7 mg/L) to patients with GERD, as demonstrated using pH-metry. In the treated group, a clear and lasting pH increase in the esophagus and stomach was observed, with levels differing significantly from those in the control subjects who had been given tap water. The patients also reported a subjective improvement in their heartburn following the administration of water containing calcium hydrogen carbonates [38].
Interestingly, recent studies conducted on animal models of gut inflammation have proven that bicarbonate-rich mineral water may decrease intestinal inflammation, with significant reductions in disease activity scores, fecal lipocalin-2 levels, pro-inflammatory cytokine release, and intestinal epithelial lesion sizes; these occur through mechanisms involving the modulation of the mucosa-associated microbiota [39].
In our study, bicarbonate-rich mineral water achieved the primary endpoint by qualitatively and quantitatively reducing dyspeptic symptoms—as well as heartburn and regurgitation symptoms—in affected adult patients with FD. The reduction in symptom complaints was paralleled by a relevant improvement in HRQoL and a reduction in the intake of rescue medication. The improvements in digestion, the sense of post-prandial fullness, and the effectiveness of the treatment—experienced by 92.7% of the participants—support possible alkaline natural mineral water supplementation in the treatment of the symptoms related to FD. Moreover, this study confirms our hypothesis that water can have a positive influence on digestion (at least in a Caucasian population); therefore, it is worth undertaking a more complex RCT study to acquire further information on its effects.
It should be pointed out that, because this is a pilot study, some obvious shortcomings may be present. In particular, the open-label design may have increased the likelihood of expectation and observer bias. Additionally, relying solely on subjective endpoints (RDQ and PGWB-S) further amplifies susceptibility to placebo effects, thus supporting the need for a successive blind RCT that also tests objective physiological and biochemical measures.
In the present study, we had four drop-outs, and this decreased the power of the study. However, as we have obtained significant results, the loss of power is not a major concern. It allowed us to estimate the expected drop-out rate in this type of study (approximately 10%), giving us a value that will be taken into account with respect to the size of the following RCT study.
Although our study did not select subjects based on ethnicity, all participants were Caucasian, reflecting the ethnicity distribution of the Italian population, where other ethnicities are rare. This lack of diversity raises questions about applicability to broader populations, and we have no data to assess potential biases or to plan for external validation in multi-ethnic cohorts.

4. Materials and Methods

4.1. Inclusion Criteria

Patients were included in the study if they had dyspeptic symptoms lasting more than 6 months with diagnosis of FD formulated in accordance with the Rome III criteria [2] on the basis of the symptoms and the absence of organic alterations that were documentable upon physical examination and excluded by upper gastrointestinal endoscopy. Functional dyspepsia was diagnosed if the dominant complaint was persistent or recurrent upper abdominal pain or discomfort. Pain consisted of epigastric pain or burning; discomfort was characterized by the presence of one or more symptoms that included post-prandial fullness, early satiety, gastric distension, belching, nausea, or vomiting. All patients had a pathological RDQ score in order to be recruited.
Other inclusion criteria were the following: adults ≥18 years; the ability to fulfill a health-related QoL-validated questionnaire (Psychological General Well-Being Index—Short form, PGWB-S; see below); and the provision of informed consent to participate in the study.

4.2. Exclusion Criteria

To be enrolled in the study, subjects had to have had no esophageal or gastroduodenal lesions on gastrointestinal endoscopy performed in the last 12 months, had to have not been undergoing treatment with antacids or proton pump inhibitors (unless they have completed a wash-out period of at least 2 weeks), and had to not have had other significant chronic pathologies. Finally, they had to not have undergone any pharmacological therapies that could potentially have interfered with symptomatology. The presence of organic gastrointestinal pathologies; previous abdominal surgery; metabolic diseases; and the intake of drugs, such as non-steroidal anti-inflammatory drugs, steroids, and pump inhibitors or membrane protectors, also comprised exclusion criteria. Individuals who either had reverse osmosis systems or other water purification systems in their homes were not admitted to the study.

4.3. Study Design

This is an open-label, uncontrolled pilot study carried out in order to reveal the possible positive effect of alkaline mineral water in influencing the symptomatic process of dyspepsia; if successful, a successive crossover blinded and controlled study will be scheduled, comparing the effects of bicarbonate water with those of mineral water with low mineral contents. This study started with a wash-out period comprising the administration of Aqueduct tap water (2 weeks), followed by a 2-week treatment period with alkaline mineral water (Aqua Carpatica natural mineral water from source “F2 Păltiniș”). The wash-out was carried out such that all participants received sufficient hydration prior to the administration of alkaline water (thus excluding hydration as a possible bias for its effect).
During the first baseline visit, the compilation of medical history forms, administration of a questionnaire for the evaluation of dyspepsia and reflux symptoms (RDQ) [40,41], and the administration of a questionnaire for the evaluation of quality of life (PGWB-S) were carried out [42,43]. The patient was instructed to drink only tap water (Table 6), at a minimum of 1.5 L per day. The patient was seen again after 2 weeks; on this occasion, the two questionnaires were administered a second time to evaluate symptoms (RDQ) and quality of life (PGWB-S). The patient was also provided with the quantity of alkaline mineral water (Table 1) necessary for a supplement of 1.5 L/day in the following two weeks, at the end of which the patient was invited to return for an end-of-study visit and to complete the two questionnaires (RDQ and PGWB-S).
Ingesting the tap or alkaline mineral water supplement involved drinking 250 mL in the morning upon waking, and the remaining amount was spread over the course of a day. All patients were instructed to maintain normal eating habits and lifestyle, and their daily water intake was limited to only the mineral water used in this study.
Adherence to proper hydration was assessed during the check-ups through a detailed anamnestic investigation aimed at assessing whether the enrolled subjects consumed the expected amount of water. Those who did not consume mineral water were required to return the remaining bottles.
To ensure accurate compilation, the questionnaires were filled out in the presence of a doctor.
For the entire duration of this study, the participants were prohibited from using multivitamins or probiotics.

4.4. Reflux Disease Questionnaire (RDQ)

The RDQ is a self-administered questionnaire in which subjects are asked to report the frequency and severity of their six upper gastrointestinal symptoms. Three domains (heartburn, dyspepsia, and regurgitation) were calculated on the basis of the frequency and severity of the six symptoms [41]. The heartburn and regurgitation subscales can be combined into a GERD dimension. In the published survey, the time referent is symptoms that have occurred over the last four weeks. In this study, the time referent was the last two weeks at baseline, as well as the two weeks of the two post-treatment visits.
Each item pertained to the following: (1) four items pertained to the frequency and severity of acidic tastes in the mouth and the upward movement of materials from the stomach (regurgitation scale); (2) four items measured the frequency and severity of pain or burning behind the breastbone (heartburn scale); (3) four items pertained to the frequency and severity of pain or burning in the upper stomach (dyspepsia scale). Response options were of the Likert type, with scores ranging from 0 to 5 for frequency (ranging from not present to daily) and severity (ranging from not present to severe). Each subject’s score was calculated as the mean of the item responses, with higher scores indicating more severe or frequent symptoms. The psychometric properties of the RDQ are described in more detail by Shaw and colleagues [41].

4.5. Psychological General Well-Being Index—Short Form (PGWB-S)

The PGWB-S [42] is a validated 6-item questionnaire with respect to health-related quality of life (HRQoL) derived from the PGWB questionnaire, a 22-item questionnaire widely used in clinical trials and epidemiological research to provide a general evaluation of self-perceived psychological health and well-being [43]. This new questionnaire is constructed on the basis of six items, which are reported in Figure 1. Each item is rated on a 6-point scale (0–5), which assesses the psychological and general well-being of respondents relative to the six HRQoL domains: anxiety, vitality, depressed mood, self-control, positive well-being, and tiredness. The scores for the six domains can be summarized to provide a summary score, which reaches a maximum of 30 points, representing the best achievable “well-being”. For comparability purposes, when using the longer version, a score transformation was applied to convert the lowest and highest possible scores to 0 (worst possible level of well-being) and 110 (maximum level of well-being), respectively, i.e., by multiplying each score by 3.66.

4.6. Other Investigations

In addition to the RDQ, two 1-to-10 scales were used to assess digestive efficiency and post-prandial fullness, and these were also recorded at both visits—after the wash-out period and following supplementation with alkaline natural mineral water.
During the study, in the case of pain/burning that is not tolerated by the patient, the use of antacids was permitted, and the number of tablets taken was considered as one of the secondary end points; relative data were recorded at the bottom of the questionnaire.
Finally, at the end of the study, patients were asked to express an opinion on their satisfaction with the treatment using a 4-point Likert rating scale: “poor”, “moderate”, “good”, and “very good”.

4.7. Endpoints

The primary efficacy endpoint of this study was a statistically significant improvement (p < 0.05) in the “heartburn”, “regurgitation”, and “dyspepsia” subscales and/or in the total RDQ score. This was used to determine whether the alkaline mineral water had a positive effect, thus supporting the rationale for planning a subsequent comparative study capable of quantifying its true effect.
In addition, we also evaluated the difference between the effect of alkaline mineral water compared to the wash-out period in order to rule out any bias from hydration.
As secondary endpoints, we considered statistically significant improvements with alkaline mineral water in QoL scores (PGWB-S), patients’ self-assessment of digestive efficiency, feelings of post-prandial fullness, and antacid use.

4.8. Statistical Methods

4.8.1. Sample-Size Calculation

We aimed to evaluate the sample size of the present crossover pilot study; however, no existing literature data were available regarding differences in the therapeutic effects of various mineral water types on upper gastrointestinal tract symptoms. On the other hand, in another crossover study, which tested the effects of hydrogen-carbonate-rich water on upper gastrointestinal tract symptoms and used the RDQ to evaluate the effects, Beer AM et al. [19] found that the within-patient differences in the heartburn, regurgitation, and dyspepsia scores of the RDQ (i.e., the primary end-point of the present study) had average mean and DS values of about 4 points; thus, we hypothesized that we would be able to detect a difference between the effects of alkaline mineral water and tap water of at least half of these changes (i.e., 2 points). By considering a mean difference of 2 and a standard deviation (SD) equal to 4, the PS Power and Sample Size Calculations package (Version 3.1.2; Department of Statistics, Vanderbilt University, Nashville, TN, USA [44,45]) a sample size of 44 pairs is needed to be able to reject the null hypothesis, with a probability (power) equal to 90% and a type I error of 5%. Thus, we rounded this value and enrolled 45 subjects.

4.8.2. Statistical Analysis

The mean and standard deviation, as well as absolute and relative frequencies, were used as descriptive statistics for ordinal and discrete variables, respectively, and non-parametric statistics were used to analyze the data. Mann–Whitney U, Fisher’s exact, and Pearson chi-square tests were used to compare drop-out patients with participant patients according to ordinal, dichotomous, and nominal variables, respectively. In the evaluation of the effect of both the wash-out period and alkaline natural mineral water administration, as well as their comparison, Wilcoxon matched-pairs test was used to analyze ordinal variables, while McNemar and marginal homogeneity tests were used to analyze dichotomous responses. All data were managed and analyzed via the IBM SPSS Statistics (Ver. 23 for Windows, IBM Co., Armonk, NY, USA) package. Two-tailed p values of less than 0.05 were considered statistically significant.

4.9. Ethics

This protocol study was approved by the Institutional Review Board of the “Water Resource Association” (Bologna, Italy). Because treatment consisted of the simple administration of tap and mineral water only and there were no medical drugs or similar treatments, approval from an official Ethics Committee was not required.
This protocol study conforms to the “World Medical Association Declaration of Helsinki: Ethical principles for medical research involving human participants”, adopted by the 18th WMA General Assembly, Helsinki, Finland, June 1964, and amended by the 64th WMA General Assembly, Fortaleza, Brazil, October 2013.
Only subjects who voluntarily signed an informed consent were included, and subjects were allowed to discontinue participation at any time during the trial.

5. Conclusions

The results of this preliminary study provide clinical evidence for a recommendation of alkaline natural mineral water as a symptomatic treatment of dyspepsia/GERD. On the one hand, this treatment facilitates digestion and is effective and safe in alleviating the symptoms of functional dyspepsia and gastroesophageal symptoms. On the other hand, in contrast to chemically defined drugs with their associated long-term side effects, the repeated administration of the tested water may result in a continuing and predictable therapeutic effect, along with excellent tolerability. The recommendation to prescribe mineral water as an “add-on” treatment during the initial phase of therapy—or even as a sole agent for maintenance therapy—should be considered for patients with FD and/or GERD.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/gidisord7030047/s1. This supplementary file contains: (1) the original raw data in Microsoft Excel format (RowData.xlsx); (2) the complete final database in both IBM SPSS Statistics and Microsoft Excel formats (Database.sav and Database.xlsx, respectively); (3) the syntax files (text files) used to create the final database (CreateDataset.sps) and to analyze the data (DataAnalysis.sps) by means of the IBM SPSS Statistics package are provided in order to allow the replication of the procedure; (4) the output report in Microsoft Excel format (OutputReport.xlsx) of the statistical analysis made by means of the IBM SPSS Statistics package is provided in order to allow the verification of all the results reported in the paper; (5) a text file (ReadMe.txt) with the instructions for activating the procedure.

Author Contributions

Conceptualization, A.Z. and F.P.; methodology, A.Z. and F.P.; formal analysis, A.M.M.-L.; investigation, A.Z., F.P. and A.A.I.; data curation, A.M.M.-L.; writing original draft preparation, A.Z., F.P. and A.M.M.-L.; writing review and editing, A.Z., F.P. and A.M.M.-L. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

This study was conducted in accordance with the Declaration of Helsinki. The protocol study was approved by the Institutional Review Board of the “Water Resource Association” (Bologna, Italy; Code DS-1a/2024).

Informed Consent Statement

Informed consent was obtained from all subjects involved in the study.

Data Availability Statement

The original contributions presented in this study are included in the article/Supplementary Materials.

Acknowledgments

The authors thank Carpathian Springs S.A. (Vatra Dornei, Romania) for providing the water necessary for conducting this study.

Conflicts of Interest

The authors declare no conflicts of interest.

Abbreviations

FD: functional dyspepsia; GERD: gastroesophageal reflux disease; HRQoL: health-related quality of life; PGWB-S: Psychological General Well-Being Index—Short form; QoL: quality of life; RDQ: Reflux Disease Questionnaire; SD: standard deviation

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Gastrointestdisord 07 00047 g001
Figure 1. Psychological General Well-Being Index—Short form (PGWB-S). From: Grossi G. et al., Development and validation of the short version of the Psychological General Well-Being Index (PGWB-S). Health and Quality of Life Outcomes 2006; 4:88 [42].
Figure 1. Psychological General Well-Being Index—Short form (PGWB-S). From: Grossi G. et al., Development and validation of the short version of the Psychological General Well-Being Index (PGWB-S). Health and Quality of Life Outcomes 2006; 4:88 [42].
Gastrointestdisord 07 00047 g001
Table 1. Baseline clinical characteristics of the study population (45 cases).
Table 1. Baseline clinical characteristics of the study population (45 cases).
Basal
Gender
- Males20 (44.4%)
- Females25 (55.6%)
Age (years)
- Mean ± SD50.6 ± 13.5
- Range25–75
Prevalent symptom declared by the patients
- Heartburn22 (48.9%)
- Regurgitation17 (37.8%)
- Pain behind breastbone4 (8.9%)
- Epigastric pain2 (4.4%)
State of efficiency of their digestion (1–10; n = 44)
- Mean ± SD5.9 ± 1.3
- Range3–9
Sense of post-prandial fullness (110; n = 44)
- Mean ± SD5.7 ± 1.2
- Range2–8
Use of antacid drugs33 (73.3%)
Table 2. Patients who declared presence of symptoms and domains reported in the RDQ questionnaire.
Table 2. Patients who declared presence of symptoms and domains reported in the RDQ questionnaire.
BasalAfter Wash-OutAfter Alkaline
Mineral Water		Alkaline Mineral
Water vs. Wash-Out
No. (%)No. (%)p Value aNo. (%)p Value ap Value b
Burning feeling behind breastbone36 (87.8%)34 (82.9%)0.50032 (78.0%)0.6251.000
Pain behind breastbone28 (68.3%)26 (63.4%)0.50018 (43.9%)0.0080.058
Burning feeling in the upper stomach37 (90.2%)37 (90.2%)1.00029 (70.7%)0.0080.005
Pain in the upper stomach28 (68.3%)27 (65.9%)1.00019 (46.3%)0.0080.020
Acid taste in mouth39 (95.1%)39 (95.1%)1.00028 (68.3%)<0.001<0.001
Movement of materials36 (87.8%)36 (87.8%)1.00027 (65.9%)0.0040.003
Heartburn38 (92.7%)36 (87.8%)0.50033 (80.5%)0.3750.739
Dyspepsia38 (92.7%)38 (92.7%)1.00032 (78.0%)0.0310.014
Regurgitation40 (97.6%)40 (97.6%)1.00033 (80.5%)0.0160.008
a McNemar test; b Marginal homogeneity test.
Table 3. Scores of symptoms and domains reported in the RDQ questionnaire.
Table 3. Scores of symptoms and domains reported in the RDQ questionnaire.
BasalAfter Wash-OutAfter Alkaline Mineral WaterAlkaline Mineral
Water vs. Wash-Out
Mean ± SDMean ± SDChange vs. Basalp Value aMean ± SDChange vs. End of Wash-Outp Value aDifferencep Value a
Burning feeling behind breastbone5.2 ± 2.54.8 ± 2.6−0.4 ± 1.30.0433.0 ± 2.0−1.8 ± 1.7<0.001−1.4 ± 2.80.003
Pain behind breastbone3.0 ± 2.42.9 ± 2.5−0.1 ± 1.10.4761.3 ± 1.7−1.6 ± 1.8<0.001−1.5 ± 2.5<0.001
Burning feeling in the upper stomach5.4 ± 2.44.8 ± 2.2−0.6 ± 1.10.0012.3 ± 1.8−2.5 ± 1.7<0.001−1.9 ± 2.2<0.001
Pain in the upper stomach3.0 ± 2.43.1 ± 2.50.1 ± 0.90.4171.2 ± 1.4−1.9 ± 2.1<0.001−2.0 ± 2.7<0.001
Acid taste in mouth6.5 ± 2.45.7 ± 2.1−0.8 ± 1.50.0022.6 ± 2.1−3.1 ± 2.3<0.001−2.3 ± 3.3<0.001
Movement of materials4.9 ± 2.74.6 ± 2.6−0.3 ± 1.20.1362.2 ± 1.9−2.4 ± 2.0<0.001−2.1 ± 2.8<0.001
Heartburn8.2 ± 4.17.7 ± 4.4−0.5 ± 2.10.1254.3 ± 3.3−3.4 ± −3.0<0.001−2.9 ± 4.6<0.001
Dyspepsia8.4 ± 3.87.9 ± 3.8−0.5 ± 1.80.0663.5 ± 2.7−4.3 ± 3.0<0.001−3.8 ± 4.1<0.001
Regurgitation11.4 ± 4.310.3 ± 4.3−1.1 ± 2.30.0044.8 ± 3.4−5.5 ± 3.6<0.001−4.4 ± 5.2<0.001
Total score27.9 ± 9.925.8 ± 10.1−2.1 ± 5.60.00512.6 ± 7.8−13.2 ± 7.9<0.001−11.1 ± 11.9<0.001
a Wilcoxon matched-pair test.
Table 4. Subjective assessment of post-prandial fullness and digestion.
Table 4. Subjective assessment of post-prandial fullness and digestion.
BasalAfter Wash-OutAfter Alkaline Mineral WaterAlkaline Mineral
Water vs. Wash-Out
Mean ± SDMean ± SDChange vs. Basalp Value aMean ± SDChange vs. End of Wash-Outp Value aDifferencep Value a
State of efficiency of their digestion6.0 ± 1.36.2 ± 1.30.2 ± 0.50.0088.0 ± 1.01.9 ± 1.2<0.0011.6 ± 1.5<0.001
Sense of post-prandial fullness5.8 ± 1.26.0 ± 1.30.2 ± 0.70.0677.8 ± 1.11.8 ± 1.5<0.0011.6 ± 1.9<0.001
a Wilcoxon matched-pair test.
Table 5. Health-related quality of life derived from the PGWB-S questionnaire.
Table 5. Health-related quality of life derived from the PGWB-S questionnaire.
BasalAfter Wash-OutAfter Alkaline Mineral WaterAlkaline Mineral Water vs. Wash-Out
Mean ± SDMean ± SDChange vs. Basalp Value aMean ± SDChange vs. End of Wash-Outp Value aDifferencep Value a
Item 05 Anxiety11.2 ± 4.812.1 ± 4.40.9 ± 2.30.01914.1 ± 3.02.1 ± 3.50.0011.2 ± 4.50.092
Item 06 Vitality11.5 ± 2.712.2 ± 2.50.6 ± 2.20.07113.4 ± 2.31.3 ± 2.40.0030.6 ± 4.10.412
Item 07 Depressed mood12.1 ± 3.311.7 ± 3.2−0.4 ± 3.40.66713.1 ± 3.01.4 ± 4.10.0051.8 ± 6.70.069
Item 18 Self-control8.7 ± 4.28.9 ± 3.60.2 ± 2.30.6278.7 ± 4.2-0.2 ± 4.10.772−0.4 ± 5.50.656
Item 20 Positive well-being8.8 ± 4.19.2 ± 4.00.4 ± 1.50.05910.3 ± 3.41.1 ± 2.70.0190.6 ± 3.70.318
Item 21 Tiredness11.4 ± 3.611.4 ± 3.60.0 ± 1.61.00012.4 ± 4.21.0 ± 3.30.0451.0 ± 4.30.068
Total score63.7 ± 16.065.5 ± 13.91.8 ± 9.20.21072.1 ± 11.36.6 ± 10.7<0.0014.8 ± 16.80.079
a Wilcoxon matched-pair test.
Table 6. Main chemical–physical characteristics of tap water and alkaline mineral water (Aqua Carpatica natural mineral water from source “F2 Păltiniș”).
Table 6. Main chemical–physical characteristics of tap water and alkaline mineral water (Aqua Carpatica natural mineral water from source “F2 Păltiniș”).
Aqueduct
Tap Water
(Wash-Out)		Alkaline
Mineral
Water
Dissolved solid residual at 180 °C218.0 mg/L1.130 mg/L
pH at source8.0 UpH6.30 UpH
CO2 Free at sourceN/a972 mg/L
Bicarbonates (HCO3)222.0 mg/L1310 mg/L
Sulfate20.0 mg/L27.7 mg/L
Potassium0.8 mg/L2.66 mg/L
Sodium6.53mg/L7.59 mg/L
Calcium50.0mg/L288.0 mg/L
Magnesium14.0 mg/L87.1 mg/L
Fluoride0.06 mg/L0.3 mg/L
Chlorides3.0 mg/L<5 mg/L
SelenioN/a<20.0 µm/L
SulfideN/a<0.05 mg/L
Nitrate (NO3)5.0 mg/L<0.1 mg/L
Nitrite (NO2)N/a<0.01 mg/L
ZincN/a<10.0 µm/L
N/a: Not available.
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Pace, F.; Morselli-Labate, A.M.; Abu Issa, A.; Zanasi, A. Bicarbonate Natural Mineral Water from Source “F2 Păltiniș” Facilitates Digestion—A Pilot Study. Gastrointest. Disord. 2025, 7, 47. https://doi.org/10.3390/gidisord7030047

AMA Style

Pace F, Morselli-Labate AM, Abu Issa A, Zanasi A. Bicarbonate Natural Mineral Water from Source “F2 Păltiniș” Facilitates Digestion—A Pilot Study. Gastrointestinal Disorders. 2025; 7(3):47. https://doi.org/10.3390/gidisord7030047

Chicago/Turabian Style

Pace, Fabio, Antonio Maria Morselli-Labate, Aladin Abu Issa, and Alessandro Zanasi. 2025. "Bicarbonate Natural Mineral Water from Source “F2 Păltiniș” Facilitates Digestion—A Pilot Study" Gastrointestinal Disorders 7, no. 3: 47. https://doi.org/10.3390/gidisord7030047

APA Style

Pace, F., Morselli-Labate, A. M., Abu Issa, A., & Zanasi, A. (2025). Bicarbonate Natural Mineral Water from Source “F2 Păltiniș” Facilitates Digestion—A Pilot Study. Gastrointestinal Disorders, 7(3), 47. https://doi.org/10.3390/gidisord7030047

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