Randomised controlled trialindependent cross-checkabstract checked★ key study I-LEG-122 standard review
Phytate lowers iron absorption from beans
Phytic acid concentration influences iron bioavailability from biofortified beans in Rwandese women with low iron status.
Overview
Petry N et al.. J Nutr 2014 · PMID 25332466 · DOI 10.3945/jn.114.192989
Removing phytate from bean meals almost doubled the iron absorbed by women with low iron.
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?
Measure phytate effect on bean iron.
- How was the study done?
Isotope crossover study.
- How many people, animals or samples were studied?
22 women.
- What was actually found?
Phytate reduces absorption.
- How large was the observed effect?
406 -> 746 ug with dephytinisation.
- What do the results mean in everyday life?
Phytate is a real inhibitor; soaking and fermentation help.
- What are the study's limitations?
Small; short-term.
- What does it say about Elawady's specific claim?
Supports C-LEG-08 mechanism.
- Do the results apply to Germany and Europe?
Universal.
- What can explicitly not be concluded from this study?
It does not show that eating beans causes anaemia.
Scientific in-depth review
1. Full reference
- Authors
- Petry N et al.
- Journal
- J Nutr
- Year
- 2014
- Identifier
- PMID 25332466 DOI 10.3945/jn.114.192989
- Verification
- verified – PubMed efetch 2026-10-26 + Crossref works API
- Retracted
- no
- Corrections
ErratumIn J Nutr. 2015 Aug;145(8):1973. doi: 10.3945/jn.115.214254.; Crossref updated-by: erratum
- Extent checked
- abstract only
- Conflicts of interest and funding
Non-US government support (PubMed publication type).
2. Research question
How does phytic acid influence iron bioavailability from iron-biofortified beans?
3. Study design and population
- Study design
- Randomised controlled trial – Randomised crossover stable-isotope absorption study
- Population
22 Rwandese women with low iron status
- Country
Rwanda (study registered NCT01521273)
- Period
Not stated in abstract
- Sample size
22
- Inclusion and exclusion criteria
Women with low iron status.
4. Methods and endpoints
- Exposure / intervention
Bean meals with native, ~50% or >95% dephytinised beans
- Comparator
Control (non-biofortified) beans
- Endpoints
Iron absorption (erythrocyte isotope incorporation)
- Statistical methods
Crossover comparisons
5. Actual results
- Results
Fractional absorption from control-bean meals 9.2%, 30% higher than from biofortified meals; absolute iron absorbed from biofortified meals 406 ug, 19% more than control; after ~50% and >95% dephytinisation 599 and 746 ug.
- Absolute risks
Not applicable
- Authors' conclusion
Phytic acid strongly decreases iron bioavailability from biofortified beans.
6. Strengths
- Gold-standard isotope method
- Randomised crossover
7. Weaknesses
- Small
- Single-meal-series absorption, not iron status
- Abstract only
- An erratum exists (J Nutr 2015;145:1973, PMID 26239777); its content has no abstract and could not be read, so it is unknown whether any reported number was corrected
8. Risk of bias
- Orienting tool
- RoB 2
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- low
- Rationale
Crossover with objective outcome.
9. Assessment of the statistical interpretation
Derived values: ~7.1% vs 9.2% fractional absorption; beans still delivered ~340-406 ug absorbed iron per meal series (stats/C-LEG-08_petry2014_absorption.py).
10. Relevance to the specific claim
Confirms the phytate mechanism of C-LEG-08.
11. Independent contrary findings
I-LEG-123 (iron-rich beans improved iron status).
12. Transferability to Germany and Europe
Mechanism universal.
13. Overall methodological judgement
Strong mechanistic support; does not imply that legumes worsen iron status overall.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | high |
| Risk of bias | low |
| Precision of results | moderate |
| Directness | direct |
| Reproducibility | replicated |
| Consistency with the overall evidence | consistent |
| Regional transferability | moderate |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Effect of Egyptian preparation (ful with lemon/tomato); content of the 2015 erratum.