Otherindependent cross-checkabstract checked I-SOD-115 standard review
A soft drink holds about 6 g of CO2 per litre
Ethanol as a Probe for the Mechanism of Bubble Nucleation in the Diet Coke and Mentos Experiment.
Overview
Kuntzleman TS, Kuntzleman JT. Molecules 2021 · PMID 33802982 · DOI 10.3390/molecules26061691
Chemistry research states that carbonated soft drinks generally contain about 6 g of carbon dioxide per litre.
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?
Study how bubbles form in soft drinks.
- How was the study done?
Laboratory experiments.
- How many people, animals or samples were studied?
Not applicable.
- What was actually found?
States typical CO2 content of soft drinks (~6 g/L).
- How large was the observed effect?
Not applicable.
- What do the results mean in everyday life?
A 300 mL drink holds less than 2 g of CO2.
- What are the study's limitations?
Approximate value.
- What does it say about Elawady's specific claim?
Shows the CO2 in a drink is tiny compared with what the body produces.
- Do the results apply to Germany and Europe?
Applicable.
- What can explicitly not be concluded from this study?
Not a health study.
Scientific in-depth review
1. Full reference
- Authors
- Kuntzleman TS, Kuntzleman JT
- Journal
- Molecules
- Year
- 2021
- Identifier
- PMID 33802982 DOI 10.3390/molecules26061691
- Verification
- verified – PubMed efetch 2026-10-26 + Crossref 2026-10-26
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
Not stated in abstract record
2. Research question
How does ethanol affect bubble nucleation and CO2 degassing in carbonated beverages?
3. Study design and population
- Study design
- Other – Physical chemistry experiments on CO2 degassing
- Population
Not applicable
- Country
USA
- Period
2021
- Sample size
Not applicable
- Inclusion and exclusion criteria
Not applicable
4. Methods and endpoints
- Exposure / intervention
Carbonated beverages and carbonated water with ethanol
- Comparator
Without ethanol
- Endpoints
Critical CO2 concentration for degassing
- Statistical methods
Model fitting
5. Actual results
- Results
Full-text passages (PMC8002754, checked 2026-10-26): 'Carbonated sodas contain about ~6.0 g CO2 L-1' and 'carbonated soft drinks generally contain ~6.0 g of CO2' per litre.
- Absolute risks
not applicable
- Authors' conclusion
Mechanistic conclusions on bubble nucleation (not relevant to health).
6. Strengths
- Quantitative CO2 content statement
7. Weaknesses
- CO2 content given as a general approximation, not measured per brand
8. Risk of bias
- Orienting tool
- none applicable
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- not assessable
- Rationale
Used only as a source for typical CO2 content.
9. Assessment of the statistical interpretation
300 mL x 6 g/L = 1.8 g CO2 (stats/C-SOD-13_co2_budget.py).
10. Relevance to the specific claim
Provides the typical CO2 content of soft drinks used to test the claim that a 300 mL Pepsi exceeds daily body CO2 production.
11. Independent contrary findings
None.
12. Transferability to Germany and Europe
Carbonation levels are similar across markets (assumption).
13. Overall methodological judgement
Adequate source for an order-of-magnitude calculation.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | not assessable |
| Precision of results | moderate |
| Directness | indirect |
| Reproducibility | unknown |
| Consistency with the overall evidence | consistent |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Brand-specific measurements.
15. Linked fact checks
- Elawady: the harm of soda is the carbonated water itself, not the sugar or sweetener; one 300 ml Pepsi delivers more carbon dioxide than the body produces in a whole day, and colas contain sodium bicarbonate that neutralises stomach acid and increases reflux. – Studies contradicting or limiting the claim