Meta-analysisindependent cross-checkfull text checked★ key study I-DRY-103 in-depth review
Extra dairy helps children build bone
The Effects of Dairy Product Supplementation on Bone Health Indices in Children Aged 3 to 18 Years: A Meta-Analysis of Randomized Controlled Trials.
Overview
Hidayat K et al.. Adv Nutr 2023 · PMID 37414219 · DOI 10.1016/j.advnut.2023.06.010
In 21 trials, children given extra dairy gained about 2-4% more bone mineral and grew slightly taller.
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 extra dairy improves children's bones.
- How was the study done?
Meta-analysis of randomised trials.
- How many people, animals or samples were studied?
21 trials, children 3-18 years.
- What was actually found?
More bone mineral (about 2-4%), slightly more height, higher IGF-I.
- How large was the observed effect?
Whole-body BMC +25 g (+3%).
- What do the results mean in everyday life?
Milk and other dairy help growing bones; removing them needs a calcium plan.
- What are the study's limitations?
Bone density is a surrogate; some authors work for a dairy company.
- What does it say about Elawady's specific claim?
Contradicts the idea that milk is harmful for children; confirms that dairy raises IGF-I.
- Do the results apply to Germany and Europe?
Applies everywhere.
- What can explicitly not be concluded from this study?
Cannot show fewer fractures later in life.
Scientific in-depth review
1. Full reference
- Authors
- Hidayat K et al.
- Journal
- Adv Nutr
- Year
- 2023
- Identifier
- PMID 37414219 DOI 10.1016/j.advnut.2023.06.010
- Verification
- verified – PubMed efetch 2026-10-26
- Retracted
- no
- Corrections
none (PubMed and Crossref checked)
- Extent checked
- full text
- Conflicts of interest and funding
Funded by National Natural Science Foundation of China; three authors employed by Yili Group (a dairy producer).
2. Research question
Does dairy supplementation improve bone mass and growth in children and adolescents?
3. Study design and population
- Study design
- Meta-analysis – Systematic review and random-effects meta-analysis of RCTs (PubMed, Web of Science); RoB by Cochrane tool; certainty by NutriGrade
- Population
Children and adolescents 3-18 y
- Country
Multinational (Western and Asian trials)
- Period
Searches to 2023
- Sample size
21 publications (RCTs)
- Inclusion and exclusion criteria
Parallel or crossover RCTs, dairy (milk 15 RCTs, mixed dairy 4, cheese 1, yogurt 1) added to habitual diet vs control/placebo
4. Methods and endpoints
- Exposure / intervention
Dairy supplementation (150-1723 mg calcium/day where reported)
- Comparator
Habitual diet, juice or placebo
- Endpoints
BMC, aBMD, height, bone turnover markers, PTH, 25(OH)D, IGF-I
- Statistical methods
Random-effects WMD; subgroup and meta-regression; Begg/Egger
5. Actual results
- Results
Whole-body BMC +25.37 g (+3.0%), whole-body aBMD +0.016 g/cm2 (+1.8%), total hip BMC +0.49 g, femoral neck aBMD +0.030 g/cm2, lumbar spine BMC +0.85 g (+4.1%), height +0.21 cm; serum IGF-I +19.89 (units given as nmol/L), urinary deoxypyridinoline -1.78 nmol/mmol creatinine, PTH -10.46 pg/mL; 25(OH)D +4.98 ng/mL with vitamin D-fortified dairy. Effects consistent across sex, region, baseline calcium, duration and Tanner stage. Certainty (NutriGrade): high for height and whole-body BMC/aBMD; moderate for IGF-I and several others.
- Absolute risks
not applicable (continuous outcomes; no fracture endpoints)
- Authors' conclusion
Dairy supplementation during growth leads to a small but significant increase in bone mineral mass parameters.
6. Strengths
- Only RCTs
- Many bone sites; consistent subgroups
- Certainty grading
7. Weaknesses
- Dairy-industry-employed co-authors
- Surrogate outcomes (BMC), not fractures
- Small absolute effects
- Reported IGF-I increase implausibly large (possible unit error; see stats/C-DRY-06_igf1.py)
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
Two-database search; industry COI; otherwise reasonable methods.
9. Assessment of the statistical interpretation
Mean differences are modest (1-4% bone mineral); clinical fracture benefit not shown. The IGF-I magnitude is not used.
10. Relevance to the specific claim
Directly relevant to the safety question: randomised trials show that adding dairy (mostly milk) increases bone mineral and slightly increases height in children; removing milk and yogurt without substitutes removes this source. It also shows that dairy raises circulating IGF-I in children, consistent with the mechanism part of C-DRY-06.
11. Independent contrary findings
Effects are small; fracture benefit in children not shown; calcium from other sources may give similar bone effects (not assessed here).
12. Transferability to Germany and Europe
Biological; applies to Egypt and Europe.
13. Overall methodological judgement
Moderate-to-high certainty that dairy modestly helps bone accrual in children; supports the existing safety note.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| 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
Long-term fracture outcomes; comparison with fortified non-dairy alternatives.
15. Linked fact checks
- Milk is a 'substitute for blood' and carries every hormone, pesticide and antibiotic the animal received; therefore milk must be avoided. – Studies contradicting or limiting the claim
- Fresh milk, yogurt (incl. laban rayeb, ayran, labneh) and white/cottage cheese are harmful and must be avoided, whereas aged cheeses (cheddar, mozzarella, romi), processed cheese triangles, cream (qeshta), butter and ghee are allowed. – Studies contradicting or limiting the claim
- Milk intake raises circulating IGF-1, and higher IGF-1 increases prostate cancer risk; this is the mechanism behind the dairy-prostate cancer link ('the same hormone that makes a calf grow'). – Studies supporting the claim