Randomised controlled trialindependent cross-checkabstract checked★ key study I-SOD-111 in-depth review
Sparkling water for 12 weeks caused no harm
Randomized trial of carbonated water consumption on snacking behavior, alcohol intake, and health indices in healthy Japanese adults.
Overview
Hashimoto H et al.. Sci Rep 2026 · PMID 42106408 · DOI 10.1038/s41598-026-51479-x
In a 12-week trial in 45 Japanese adults, drinking 500 mL of sparkling water daily caused no adverse effects and was linked to less snacking.
Does the study support the specific claim? No · Methodological quality: moderate
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Test the effect of daily sparkling water on eating and health markers.
- How was the study done?
Randomised trial: sparkling vs still water for 12 weeks.
- How many people, animals or samples were studied?
45 healthy adults.
- What was actually found?
Less snacking and alcohol, slightly lower weight and liver enzymes; no side effects.
- How large was the observed effect?
Weight -0.72 kg (-1.37 to -0.07).
- What do the results mean in everyday life?
Plain sparkling water appears safe for healthy adults.
- What are the study's limitations?
Small, open-label, many outcomes.
- What does it say about Elawady's specific claim?
Contradicts the claim that all sparkling water must be avoided.
- Do the results apply to Germany and Europe?
Applicable.
- What can explicitly not be concluded from this study?
Cannot show benefits are real; exploratory.
Scientific in-depth review
1. Full reference
- Authors
- Hashimoto H et al.
- Journal
- Sci Rep
- Year
- 2026
- Identifier
- PMID 42106408 DOI 10.1038/s41598-026-51479-x
- Verification
- verified – PubMed efetch 2026-10-26 + Crossref 2026-10-26
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
Authors declare no competing interests (PubMed record); funding not stated in abstract
2. Research question
Does daily carbonated water change snacking, alcohol intake and health indices compared with still water?
3. Study design and population
- Study design
- Randomised controlled trial – Randomised, open-label, placebo-controlled, parallel-group trial, 12 weeks
- Population
Healthy Japanese adults aged 20-64, BMI 23.0-<30.0
- Country
Japan
- Period
2025-2026
- Sample size
46 randomised; 45 completed (22 carbonated, 23 still water)
- Inclusion and exclusion criteria
Healthy adults with BMI 23-<30
4. Methods and endpoints
- Exposure / intervention
Carbonated water 500 g/day containing 4.3 +- 0.1 g CO2
- Comparator
Non-carbonated water
- Endpoints
Snacking frequency, alcohol intake, anthropometry, blood biochemistry, adverse events
- Statistical methods
Between-group differences in change from baseline; no multiplicity adjustment
5. Actual results
- Results
Snacking frequency lower with carbonated water at week 4 (MD -1.39 times/week; 95% CI -2.82 to -0.28) and week 12 (-1.49; -2.93 to -0.05); alcohol intake -24.44 g/week (-44.02 to -4.86); body weight -0.72 kg (-1.37 to -0.07); BMI -0.26; AST -4.05 U/L; ALT -9.47 U/L. No study beverage-related adverse events.
- Absolute risks
not applicable
- Authors' conclusion
Daily carbonated water may be associated with favourable changes in snacking and alcohol behaviour and modest improvements in anthropometric and liver indices; exploratory, interpret cautiously.
6. Strengths
- Randomised, placebo (still water) controlled
- 12 weeks
- Adverse events recorded
7. Weaknesses
- Small
- Open-label
- Many outcomes without multiplicity adjustment
- Week-4 CI asymmetric around the estimate (-2.82 to -0.28 around -1.39), suggesting a non-normal or adjusted method
8. Risk of bias
- Orienting tool
- RoB 2
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- some concerns
- Rationale
Open-label; multiple outcomes.
9. Assessment of the statistical interpretation
Benefits are exploratory; the relevant finding for C-SOD-14 is the absence of beverage-related adverse events over 12 weeks at 500 mL/day.
10. Relevance to the specific claim
Contradicts the claim that all carbonated water is harmful: 12 weeks of daily carbonated water produced no adverse events and, if anything, small favourable changes. Also quantifies typical carbonation (4.3 g CO2 per 500 g) for C-SOD-13.
11. Independent contrary findings
None found showing harm from plain carbonated water in healthy people.
12. Transferability to Germany and Europe
Plain carbonated water is common in Europe; transferable.
13. Overall methodological judgement
Small but direct randomised evidence of safety of plain carbonated water in healthy adults.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | some concerns |
| Precision of results | low |
| Directness | direct |
| Reproducibility | not replicated |
| Consistency with the overall evidence | consistent |
| Regional transferability | moderate |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Effects in people with reflux disease or irritable bowel.
15. Linked fact checks
- All carbonated waters of every kind (including unsweetened sparkling water) are harmful and must be avoided. – Studies contradicting or limiting the claim