Meta-analysisindependent cross-checkabstract checked★ key study I-SOD-120 in-depth review
Sugary and diet drinks linked to higher death rates
Association of Consumption of Sugar-Sweetened Beverages or Artificially Sweetened Beverages with Mortality: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies.
Overview
Zhang YB et al.. Adv Nutr 2021 · PMID 33786594 · DOI 10.1093/advances/nmaa110
Pooled cohorts: each daily sugary drink was linked to 8% higher overall and cardiovascular mortality; diet drinks were linked at 1.5 or more per day.
Does the study support the specific claim? Yes · Methodological quality: high
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Pool cohort studies on sweetened drinks and death.
- How was the study done?
Dose-response meta-analysis.
- How many people, animals or samples were studied?
About 0.9-1 million participants.
- What was actually found?
Sugary drinks linked to more deaths; diet drinks at higher doses too.
- How large was the observed effect?
SSB HR 1.08 per serving.
- What do the results mean in everyday life?
Fewer sugary drinks is consistent with longer life; diet drinks are not clearly protective.
- What are the study's limitations?
Observational; reverse causation for diet drinks.
- What does it say about Elawady's specific claim?
Supports the direction of both claims.
- Do the results apply to Germany and Europe?
Applicable.
- What can explicitly not be concluded from this study?
Cannot prove causation.
Scientific in-depth review
1. Full reference
- Authors
- Zhang YB et al.
- Journal
- Adv Nutr
- Year
- 2021
- Identifier
- PMID 33786594 DOI 10.1093/advances/nmaa110
- 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 (non-US government support listed)
2. Research question
Are SSB and ASB intakes associated with all-cause, CVD and cancer mortality?
3. Study design and population
- Study design
- Meta-analysis – Systematic review and dose-response meta-analysis of prospective cohorts (7 databases/registries to March 2020); NutriGrade
- Population
General, diseased or occupational populations in cohorts
- Country
International
- Period
to March 2020
- Sample size
15 studies (17 cohorts); all-cause SSB analysis 965,851; CVD 898,005
- Inclusion and exclusion criteria
Prospective cohorts reporting SSB/ASB and mortality
4. Methods and endpoints
- Exposure / intervention
SSB and ASB per 355 mL serving/day
- Comparator
Lower intake
- Endpoints
All-cause, CVD and cancer mortality
- Statistical methods
Dose-response meta-analysis; NutriGrade
5. Actual results
- Results
Per serving/day SSB: all-cause mortality HR 1.08 (1.04-1.12); CVD mortality HR 1.08 (1.04-1.12). ASB J-shaped: all-cause HRs 1.01, 1.04, 1.08, 1.13 at 1, 1.5, 2, 2.5 servings/day; CVD mortality 1.01 (0.96-1.07), 1.07 (1.01-1.13), 1.15 (1.08-1.23), 1.25 (1.14-1.37). No association with cancer mortality. NutriGrade quality high for SSB-all-cause and SSB-CVD mortality; low to moderate for others.
- Absolute risks
not reported
- Authors' conclusion
Higher SSB and ASB intakes were associated with higher all-cause and CVD mortality.
6. Strengths
- Dose-response
- Large pooled population
- Quality grading
7. Weaknesses
- Observational
- Overlap with included single cohorts (e.g. Malik 2019, EPIC)
8. Risk of bias
- Orienting tool
- AMSTAR 2
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- some concerns
- Rationale
Abstract-level judgement.
9. Assessment of the statistical interpretation
Per-serving HR 1.08 implies about 1.17 at 2 servings/day (log-linear), smaller than the single-cohort figures (1.31-1.35) the archive quotes (stats/C-SOD-03_mortality.py). ASB curve may reflect reverse causation.
10. Relevance to the specific claim
Supports C-SOD-03 (SSB and CVD/all-cause mortality, high NutriGrade) with a smaller pooled effect size; supports the association part of C-SOD-10 at higher ASB doses.
11. Independent contrary findings
Causality uncertain; ASB associations prone to reverse causation.
12. Transferability to Germany and Europe
Applicable.
13. Overall methodological judgement
Best pooled mortality estimate; confirms direction, moderates magnitude.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | high |
| Risk of bias | some concerns |
| Precision of results | high |
| Directness | direct |
| Reproducibility | replicated |
| Consistency with the overall evidence | consistent |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Causal contribution of sweeteners.
15. Linked fact checks
- Sugar-sweetened soft drinks raise the risk of coronary heart disease, cardiovascular death and early death (e.g., two or more daily servings: +35% coronary heart disease in women; +31% cardiovascular and +21% total mortality). – Studies supporting the claim
- Diet soda is not a safe alternative to sugary soda: artificially sweetened drinks are linked to higher mortality, especially circulatory deaths. – Studies supporting the claim