Randomised controlled trialindependent cross-checkfull text checked★ key study I-DRY-105 in-depth review
Extra milk, yogurt and cheese cut hip fractures in nursing-home residents
Effect of dietary sources of calcium and protein on hip fractures and falls in older adults in residential care: cluster randomised controlled trial.
Overview
Iuliano S et al.. BMJ 2021 · PMID 34670754 · DOI 10.1136/bmj.n2364
Hip fractures 42 v 93 (HR 0.54) over two years; deaths not different.
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 more dairy prevents fractures in older people.
- How was the study done?
Cluster randomised trial, 2 years.
- How many people, animals or samples were studied?
7195 residents in 56 Australian care homes.
- What was actually found?
Fewer fractures, hip fractures and falls; no effect on deaths.
- How large was the observed effect?
Hip fracture HR 0.54 (0.35-0.83).
- What do the results mean in everyday life?
In frail older people with low intake, adding dairy prevents about 1 hip fracture per ~90 residents.
- What are the study's limitations?
Dairy-industry funding; special population.
- What does it say about Elawady's specific claim?
Contradicts the claim that dairy increases hip fractures.
- Do the results apply to Germany and Europe?
Applies to care homes in Europe; less to healthy adults.
- What can explicitly not be concluded from this study?
Cannot show the same effect in young, well-fed adults.
Scientific in-depth review
1. Full reference
- Authors
- Iuliano S et al.
- Journal
- BMJ
- Year
- 2021
- Identifier
- PMID 34670754 DOI 10.1136/bmj.n2364
- Verification
- verified – PubMed efetch 2026-10-26
- Retracted
- no
- Corrections
- none
- Extent checked
- full text
- Conflicts of interest and funding
Funded by Dairy Australia, several national dairy organisations and Fonterra (in-kind foods), plus university/hospital foundations; authors report lecture/research fees from pharmaceutical companies.
2. Research question
Does increasing calcium and protein intake with dairy foods reduce fractures and falls in institutionalised older adults?
3. Study design and population
- Study design
- Randomised controlled trial – Two-year cluster randomised controlled trial in 60 aged-care facilities (56 analysed); fracture adjudication blinded
- Population
Permanent residents of Australian aged-care facilities, mean age 86, 68% women, vitamin D replete, low calcium/protein intake
- Country
Australia
- Period
2-year trial (registered ACTRN12613000228785)
- Sample size
7195 residents (3301 intervention, 3894 control); 27 v 29 facilities
- Inclusion and exclusion criteria
Facilities serving no more than two dairy servings/day
4. Methods and endpoints
- Exposure / intervention
Additional milk (incl. milk-powder fortification), yogurt and cheese: dairy 2.0 -> 3.5 servings/day; +562 mg calcium, +12 g protein/day
- Comparator
Usual menus (700 mg calcium, 58 g protein/day)
- Endpoints
Fractures, hip fractures, falls, all-cause mortality
- Statistical methods
Mixed-effects Cox models with facility as random effect
5. Actual results
- Results
All fractures 121 v 203, HR 0.67 (0.48-0.93); hip fractures 42 v 93, HR 0.54 (0.35-0.83); falls 1879 v 2423, HR 0.89 (0.78-0.98); deaths 900 v 1074, HR 1.01 (0.43-3.08). Hip-fracture reduction significant from month 5. No adverse gastrointestinal events attributed to the intervention.
- Absolute risks
Not reported in the abstract; crude cumulative proportions (ignoring clustering and follow-up): hip fracture 1.27% v 2.39% (crude ARR about 1.1 percentage points, crude NNT about 90) (stats/I-DRY-105_iuliano_fractures.py).
- Authors' conclusion
Improving calcium and protein intakes by using dairy foods is a readily accessible intervention that reduces the risk of falls and fractures in aged-care residents.
6. Strengths
- Randomised design with hard outcomes
- Large sample
- Blinded fracture verification
- Food-based intervention
7. Weaknesses
- Dairy-industry funding
- Cluster design with few clusters per arm
- Less than half followed >15 months
- Compliance measured in about 10% of residents
- Population with low baseline intake; not generalisable to well-nourished adults
- Mortality CI implausibly wide
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
Randomisation at facility level; outcome assessment blinded; funding by dairy industry.
9. Assessment of the statistical interpretation
Relative effects are large; crude absolute effect about 1 hip fracture prevented per ~90 residents over the trial. CI log-symmetry OK for fracture HRs; mortality CI asymmetric and wide (uninformative).
10. Relevance to the specific claim
First large RCT with fracture endpoints: more dairy (milk, yogurt, cheese) reduced hip fractures, the opposite of 'increases rather than prevents hip fractures' in this population.
11. Independent contrary findings
Cohort dose-response signals for milk and hip fracture (I-DRY-03, A-DRY-01) in well-nourished populations.
12. Transferability to Germany and Europe
Older adults with low intake in institutions; relevance to younger, well-nourished adults uncertain.
13. Overall methodological judgement
Moderate-quality RCT evidence against the claim that dairy increases fractures, limited to older adults with low intakes.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | some concerns |
| Precision of results | moderate |
| Directness | direct |
| Reproducibility | not replicated |
| Consistency with the overall evidence | mixed |
| Regional transferability | moderate |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Replication; effects in community-dwelling adults; milk versus fermented dairy.
15. Linked fact checks
- High milk consumption raises mortality (women drinking 3+ glasses/day had 93% higher mortality) and increases rather than prevents hip fractures. – Studies contradicting or limiting the claim