Cohort studyindependent cross-checkabstract checked I-SOD-123 standard review
Soda linked to more hip fractures, cola or not
Soda consumption and risk of hip fractures in postmenopausal women in the Nurses' Health Study.
Overview
Fung TT et al.. Am J Clin Nutr 2014 · PMID 25099544 · DOI 10.3945/ajcn.114.083352
In 73,572 US nurses, each daily soda was linked to 14% more hip fractures; colas were not worse than other sodas.
Does the study support the specific claim? Partly · Methodological quality: high
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Examine soda and hip fractures.
- How was the study done?
Prospective cohort over up to 30 years.
- How many people, animals or samples were studied?
73,572 women; 1873 fractures.
- What was actually found?
More soda, more fractures; regular and diet alike; cola not special.
- How large was the observed effect?
RR 1.14 per serving/day.
- What do the results mean in everyday life?
Soda may be a marker of risk; phosphoric acid not shown to be the cause.
- What are the study's limitations?
Observational.
- What does it say about Elawady's specific claim?
Weakens the phosphoric-acid explanation.
- 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
- Fung TT et al.
- Journal
- Am J Clin Nutr
- Year
- 2014
- Identifier
- PMID 25099544 DOI 10.3945/ajcn.114.083352
- Verification
- verified – PubMed efetch 2026-10-26 + Crossref 2026-10-26
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
NIH grants (PubMed record)
2. Research question
Is soda consumption associated with hip fracture in postmenopausal women?
3. Study design and population
- Study design
- Cohort study – Prospective cohort with repeated FFQs, up to 30 years
- Population
Postmenopausal US women (Nurses' Health Study)
- Country
USA
- Period
Up to 30 years of follow-up
- Sample size
73,572; 1873 hip fractures
- Inclusion and exclusion criteria
Postmenopausal women in NHS
4. Methods and endpoints
- Exposure / intervention
Total, regular, diet, cola and non-cola soda
- Comparator
Lower intake
- Endpoints
Incident hip fracture
- Statistical methods
Cox models with confounder adjustment
5. Actual results
- Results
Each additional serving/day of total soda: RR 1.14 (1.06-1.23). Regular soda RR 1.19 (1.02-1.38); diet soda RR 1.12 (1.03-1.21). Associations did not differ significantly between colas and non-colas, or caffeinated and caffeine-free sodas. Attributable risk 12.5%.
- Absolute risks
Crude cumulative proportion 2.5% (1873/73,572) over up to 30 years (recalculated)
- Authors' conclusion
Increased soda consumption of all types may be associated with increased hip fracture risk; a clear mechanism was not apparent.
6. Strengths
- Large prospective cohort
- Repeated diet measures
- Hard outcome
7. Weaknesses
- Observational
- Women only
- Mechanism unclear
8. Risk of bias
- Orienting tool
- ROBINS-E
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- some concerns
- Rationale
Residual confounding (milk displacement, lifestyle).
9. Assessment of the statistical interpretation
No cola-specific signal, which argues against a phosphoric-acid-specific mechanism.
10. Relevance to the specific claim
Mixed for C-SOD-08: soda is associated with more hip fractures, but cola and non-cola sodas were similar, so phosphoric acid is not supported as the explanation.
11. Independent contrary findings
Heaney 2001 (I-SOD-124).
12. Transferability to Germany and Europe
Applicable.
13. Overall methodological judgement
Association with a hard outcome; mechanism not identified.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | high |
| Risk of bias | some concerns |
| Precision of results | high |
| Directness | direct |
| Reproducibility | partly replicated |
| Consistency with the overall evidence | mixed |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Role of milk displacement and caffeine.
15. Linked fact checks
- Phosphoric acid in cola drains the bones; women who drink cola daily (sugary or diet) have 3.7% lower hip bone density. – Studies with mixed or unclear results