Meta-analysisindependent cross-checkabstract only checked★ key study I-VEG-09 in-depth review
Dietary nitrate and blood pressure
Inorganic nitrate and beetroot juice supplementation reduces blood pressure in adults: a systematic review and meta-analysis.
Overview
Siervo M et al.. J Nutr 2013 · PMID 23596162 · DOI 10.3945/jn.112.170233
Nitrate from beetroot juice lowered systolic blood pressure by about 4 mm Hg in short trials.
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?
Nitrate and BP
- How was the study done?
Meta-analysis of RCTs
- How many people, animals or samples were studied?
254
- What was actually found?
Lower systolic BP
- How large was the observed effect?
-4.4 mm Hg
- What do the results mean in everyday life?
Vegetable nitrate may benefit BP.
- What are the study's limitations?
Short
- What does it say about Elawady's specific claim?
Contradicts harm claim
- Do the results apply to Germany and Europe?
High
- What can explicitly not be concluded from this study?
Cannot show long-term outcomes.
Scientific in-depth review
1. Full reference
- Authors
- Siervo M et al.
- Journal
- J Nutr
- Year
- 2013
- Identifier
- PMID 23596162 DOI 10.3945/jn.112.170233
- Verification
- verified – PubMed efetch 2026-10-25
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
not stated in abstract
2. Research question
Effect of inorganic nitrate/beetroot on BP.
3. Study design and population
- Study design
- Meta-analysis – Systematic review and meta-analysis of RCTs (crossover)
- Population
Adults
- Country
Multiple
- Period
2006-2012 trials
- Sample size
16 trials; 254 participants
- Inclusion and exclusion criteria
RCTs vs placebo
4. Methods and endpoints
- Exposure / intervention
Inorganic nitrate or beetroot juice
- Comparator
Placebo
- Endpoints
Systolic and diastolic BP
- Statistical methods
Random effects; meta-regression
5. Actual results
- Results
Systolic BP -4.4 mm Hg (95% CI -5.9 to -2.8; P<0.001); diastolic -1.1 mm Hg (-2.2 to 0.1; P=0.06); dose-response with nitrate dose.
- Absolute risks
not reported
- Authors' conclusion
Nitrate supplementation reduces systolic BP; long-term trials needed.
6. Strengths
- RCT-based
7. Weaknesses
- Small, short (2 h - 15 d)
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
Short trials.
9. Assessment of the statistical interpretation
Clinically relevant short-term effect.
10. Relevance to the specific claim
Contradicts general nitrate harm (C-VEG-08).
11. Independent contrary findings
None.
12. Transferability to Germany and Europe
High.
13. Overall methodological judgement
Evidence of benefit.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | some concerns |
| Precision of results | moderate |
| Directness | indirect |
| 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 outcomes.
15. Linked fact checks
- Nitrate from fertilisers (together with pesticides) in lettuce, rocket and other leaves harms the people who eat them. – Studies contradicting or limiting the claim