Randomised controlled trialindependent cross-checkabstract checked I-SOD-117 standard review
Fizz does not change the blood-sugar effect of a sweet drink
No influence of carbonation on glycemic response, gastric emptying, and satiety of sweetened drinks.
Overview
Lau ERL, Henry CJ. Nutrition 2017 · PMID 28606564 · DOI 10.1016/j.nut.2017.02.001
Adding carbonation to a sugary drink did not change blood sugar, stomach emptying or fullness in 15 healthy adults.
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 whether carbonation changes how a sugary drink is handled.
- How was the study done?
Same drink with different carbonation levels on different days.
- How many people, animals or samples were studied?
15 healthy adults.
- What was actually found?
No difference in blood sugar or stomach emptying.
- How large was the observed effect?
No significant differences.
- What do the results mean in everyday life?
The sugar, not the bubbles, drives the blood-sugar response.
- What are the study's limitations?
Very small, single tests.
- What does it say about Elawady's specific claim?
Contradicts 'the gas, not the sugar, is the problem'.
- Do the results apply to Germany and Europe?
Applicable.
- What can explicitly not be concluded from this study?
Cannot exclude subtle long-term effects.
Scientific in-depth review
1. Full reference
- Authors
- Lau ERL, Henry CJ
- Journal
- Nutrition
- Year
- 2017
- Identifier
- PMID 28606564 DOI 10.1016/j.nut.2017.02.001
- 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
Does carbonation of a sweetened beverage change glycaemic response, gastric emptying and satiety?
3. Study design and population
- Study design
- Randomised controlled trial – Within-subject crossover comparison of non-, low- and high-carbonated 50 g glucose drinks
- Population
Healthy adults
- Country
Singapore
- Period
2017
- Sample size
15 (6 women, 9 men)
- Inclusion and exclusion criteria
Healthy volunteers after overnight fast
4. Methods and endpoints
- Exposure / intervention
Low- or high-carbonated 500 mL drink with 50 g glucose
- Comparator
Non-carbonated identical drink
- Endpoints
Blood glucose; antral area and gastric emptying (ultrasound); satiety and thirst
- Statistical methods
Within-subject comparisons
5. Actual results
- Results
No significant differences in glycaemic response between drinks. Higher carbonation increased antral cross-sectional area during the first 20 min (P<0.010) without significant differences in gastric volume or emptying rate. No effect on satiety; thirst AUC lower with high carbonation (P=0.009).
- Absolute risks
not applicable
- Authors' conclusion
Carbonation of a glucose solution did not increase glycaemic response nor alter gastric emptying and satiety.
6. Strengths
- Isolates carbonation as the only difference
- Objective gastric measures
7. Weaknesses
- Very small
- Single exposure
- Randomisation not stated in abstract
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
Small acute study.
9. Assessment of the statistical interpretation
Underpowered for small differences; consistent with sugar, not CO2, driving metabolic effects.
10. Relevance to the specific claim
Contradicts the claim that the harm of soda lies in the carbonation rather than the sugar: carbonation did not change the glucose response to a sugary drink.
11. Independent contrary findings
A rat study (not added) proposed CO2-induced ghrelin release; human evidence lacking.
12. Transferability to Germany and Europe
Applicable.
13. Overall methodological judgement
Small but direct test of carbonation's metabolic effect.
| 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 | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Long-term studies.
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