Study analysis · Critical Reviews in Food Science and Nutrition · 2018
Beetroot juice won't make you smarter—here's what the science actually says.
Drinking beetroot juice or taking nitrate supplements doesn't improve your memory or brain blood flow, no matter how much you drink.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
In simple terms
This study looked at lots of small experiments where people took beetroot juice or nitrate pills to see if it helped their brain. It found that, overall, it didn’t help. But because each experiment was tiny and didn’t last long, we can’t say for sure if it might help in bigger or longer studies.
What’s the bottom line?
Scientists looked at 13 studies where people took beetroot juice or nitrate pills to see if it helped their brain work better or increased blood flow to the brain.
How strong is this study?
The scientists did a good job collecting and combining all the best studies they could find, which is like checking every report in a school project to see what’s true. But most of the original studies were too small and didn’t last long enough, so even though the method was good, the pieces they used weren’t strong enough to give a clear answer.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
44 / 100
- Randomization+20/20
- Blindingblinding unclear
- Control group+15/15
- Sample sizeno sample size reported
- Follow-upno follow-up reported
100 / 100
77 / 100
- P-values+15/15
- Effect size+20/20
- Confidence intervals+15/15
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 555 / 100
Probability of being correct
The highest quality evidence. Systematic reviews and meta-analyses that pool randomized controlled trials, giving the most reliable summary of experimental evidence.
This design can establish causation. This study can establish causation because it is a systematic review and meta-analysis of randomized controlled trials (RCTs), which are the gold standard for causal inference. However, the individual RCTs included had small sample sizes, short durations, and high risk of type II errors, which limits the strength of the causal conclusion.
No Conflicts
No conflicts of interest identified
No conflicts of interest or funding statements were disclosed in the provided text, and no industry affiliations or financial ties were evident among authors.
The manuscript lacks a formal conflict of interest declaration or funding statement. However, all authors are affiliated with academic institutions (Newcastle University, Leeds Beckett University, etc.), and no industry ties, employment, or financial relationships with commercial entities are disclosed or implied. The study is a systematic review and meta-analysis of existing trials, reducing potential for direct industry influence.
Key takeaways
- 01
13 studies with 297 people: no improvement in thinking skills.
- 02
9 studies with 163 people: no increase in brain blood flow, even during mental tasks.
- 03
Longer use (over days) showed even less effect.
- 04
The changes seen were tiny and not meaningful — like flipping a coin and getting one more head than tails.
- 05
It doesn't help your brain work better in real life.
Surprising findings
- Longer supplementation led to smaller cerebral blood flow effectsMost people assume supplements build up over time—this shows the opposite: prolonged use may cause adaptation or diminishing returns, which contradicts the 'more is better' assumption.
- The only study showing cognitive improvement used nitrite in older adults for 10 weeksOne outlier study (Justice et al., 2015) showed improvement—but it was the only one using nitrite (not nitrate) in older adults over 10 weeks, suggesting the positive effect might be an anomaly, not a trend.
Practical takeaways
Stop spending money on beetroot juice for brain enhancement—save it for other proven brain-healthy foods like berries or fatty fish.
This doesn't mean beetroot is unhealthy—it may still help with exercise performance or blood pressure, just not cognition or brain blood flow.
medium confidenceWhy this study matters
No brain boost from beetroot juice
A meta-analysis of 13 trials with 297 participants found inorganic nitrate/nitrite supplements had no significant effect on cognitive function (SMD +0.06, P=0.32)—meaning the effect was statistically negligible, like flipping a coin and getting one extra head.
Millions buy beetroot juice for 'brain health'—this study shows it's not working for cognition, despite bold marketing claims.
Longer use = less effect on blood flow
Meta-regression revealed that longer supplementation duration was inversely linked to cerebral blood flow changes (β: -0.001, P=0.02)—meaning the more days you take it, the less impact it has.
This flips the script: most supplements are assumed to work better over time, but here, the opposite happens—short-term use shows the only faint hints of effect.
All studies were on young, healthy people
11 of 13 cognitive trials and 8 of 9 blood flow trials involved healthy adults under age 36—meaning we have zero reliable data on whether this works for older adults, those with dementia, or people with cognitive decline.
If you're over 50 and taking beetroot for memory, this study says we simply don't know if it helps—or hurts—your specific situation.
Want the whole report?
Detailed mode opens the full scientific breakdown — every score component, the methodology, conflicts of interest, the evidence analysis behind each claim, and the raw study data.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Scientists looked at 13 studies where people took beetroot juice or nitrate pills to see if it helped their brain work better or increased blood flow to the brain.
Research results
13 studies with 297 people: no improvement in thinking skills. 9 studies with 163 people: no increase in brain blood flow, even during mental tasks. Longer use (over days) showed even less effect.
What this means - more context
The changes seen were tiny and not meaningful — like flipping a coin and getting one more head than tails. It doesn't help your brain work better in real life.
Does inorganic nitrate or nitrite supplementation improve cognitive function or cerebral blood flow in adults?
A meta-analysis of 13 trials (297 participants) found no significant effect of inorganic nitrate/nitrite on cognitive function (SMD +0.06, P=0.32). Nine trials (163 participants) showed no significant effect on resting (SMD +0.14, P=0.31) or stimulated cerebral blood flow (SMD +0.23, P=0.19). Longer supplementation duration was inversely associated with cerebral blood flow changes (P=0.02).
Methods Used
Systematic review and meta-analysis of 13 randomized controlled trials for cognitive function and 9 for cerebral blood flow. Participants were adults aged 18–73, mostly healthy and under 36. Interventions were inorganic nitrate/nitrite supplements (median duration <7 days; median sample size 23 for cognition, 16 for blood flow). Outcomes measured via standardized mean differences using random-effects models.
Main Finding
Inorganic nitrate or nitrite supplementation had no significant effect on cognitive function (SMD +0.06, 95% CI: -0.06 to 0.18, P=0.32) or cerebral blood flow at rest (SMD +0.14, 95% CI: -0.13 to 0.41, P=0.31) or during stimulation (SMD +0.23, 95% CI: -0.11 to 0.56, P=0.19). Longer intervention duration was associated with smaller cerebral blood flow effects (β: -0.001, P=0.02).
Confidence Level
Low. Evidence is limited by small sample sizes (median 16–23 per trial), short intervention durations (10/13 cognition trials <7 days), and lack of power to detect subtle effects. Most trials involved healthy young adults, limiting generalizability.
Study Flags
Red Flags
- •Small sample sizes (median 16–23 participants per trial)
- •Short intervention durations (10 of 13 trials <7 days)
- •All participants were healthy and mostly under age 36, limiting generalizability
Surprising Findings
Longer supplementation led to smaller cerebral blood flow effects
Most people assume supplements build up over time—this shows the opposite: prolonged use may cause adaptation or diminishing returns, which contradicts the 'more is better' assumption.
Practical Takeaways
Stop spending money on beetroot juice for brain enhancement—save it for other proven brain-healthy foods like berries or fatty fish.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 555 / 100
Probability of being correct
The highest quality evidence. Systematic reviews and meta-analyses that pool randomized controlled trials, giving the most reliable summary of experimental evidence.
Systematic Review with Meta-Analysis
Subject
Moderate probability
on the GRADE evidence scale
This study looked at lots of small experiments where people took beetroot juice or nitrate pills to see if it helped their brain. It found that, overall, it didn’t help. But because each experiment was tiny and didn’t last long, we can’t say for sure if it might help in bigger or longer studies.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Systematic review following Cochrane and PRISMA guidelines
- Comprehensive search across two major databases
- Use of random-effects meta-analysis to account for heterogeneity
Weaknesses
- Small total sample size (n=297 for CF, n=163 for CBF)
- Median trial size was very small (23 and 16 participants per trial)
- Most interventions lasted less than 7 days
Methodology
Evidence Keywords
Statistical Reporting
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Scientists looked at 13 studies where people took beetroot juice or nitrate pills to see if it helped their brain work better or increased blood flow to the brain.
Research results
13 studies with 297 people: no improvement in thinking skills. 9 studies with 163 people: no increase in brain blood flow, even during mental tasks. Longer use (over days) showed even less effect.
What this means - more context
The changes seen were tiny and not meaningful — like flipping a coin and getting one more head than tails. It doesn't help your brain work better in real life.
Does inorganic nitrate or nitrite supplementation improve cognitive function or cerebral blood flow in adults?
A meta-analysis of 13 trials (297 participants) found no significant effect of inorganic nitrate/nitrite on cognitive function (SMD +0.06, P=0.32). Nine trials (163 participants) showed no significant effect on resting (SMD +0.14, P=0.31) or stimulated cerebral blood flow (SMD +0.23, P=0.19). Longer supplementation duration was inversely associated with cerebral blood flow changes (P=0.02).
Methods Used
Systematic review and meta-analysis of 13 randomized controlled trials for cognitive function and 9 for cerebral blood flow. Participants were adults aged 18–73, mostly healthy and under 36. Interventions were inorganic nitrate/nitrite supplements (median duration <7 days; median sample size 23 for cognition, 16 for blood flow). Outcomes measured via standardized mean differences using random-effects models.
Main Finding
Inorganic nitrate or nitrite supplementation had no significant effect on cognitive function (SMD +0.06, 95% CI: -0.06 to 0.18, P=0.32) or cerebral blood flow at rest (SMD +0.14, 95% CI: -0.13 to 0.41, P=0.31) or during stimulation (SMD +0.23, 95% CI: -0.11 to 0.56, P=0.19). Longer intervention duration was associated with smaller cerebral blood flow effects (β: -0.001, P=0.02).
Confidence Level
Low. Evidence is limited by small sample sizes (median 16–23 per trial), short intervention durations (10/13 cognition trials <7 days), and lack of power to detect subtle effects. Most trials involved healthy young adults, limiting generalizability.
Study Flags
Red Flags
- •Small sample sizes (median 16–23 participants per trial)
- •Short intervention durations (10 of 13 trials <7 days)
- •All participants were healthy and mostly under age 36, limiting generalizability
Surprising Findings
Longer supplementation led to smaller cerebral blood flow effects
Most people assume supplements build up over time—this shows the opposite: prolonged use may cause adaptation or diminishing returns, which contradicts the 'more is better' assumption.
Practical Takeaways
Stop spending money on beetroot juice for brain enhancement—save it for other proven brain-healthy foods like berries or fatty fish.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 555 / 100
Probability of being correct
The highest quality evidence. Systematic reviews and meta-analyses that pool randomized controlled trials, giving the most reliable summary of experimental evidence.
Systematic Review with Meta-Analysis
Subject
Moderate probability
on the GRADE evidence scale
This study looked at lots of small experiments where people took beetroot juice or nitrate pills to see if it helped their brain. It found that, overall, it didn’t help. But because each experiment was tiny and didn’t last long, we can’t say for sure if it might help in bigger or longer studies.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Systematic review following Cochrane and PRISMA guidelines
- Comprehensive search across two major databases
- Use of random-effects meta-analysis to account for heterogeneity
Weaknesses
- Small total sample size (n=297 for CF, n=163 for CBF)
- Median trial size was very small (23 and 16 participants per trial)
- Most interventions lasted less than 7 days
Methodology
Evidence Keywords
Statistical Reporting
Scoring
How strong is this study?
The scientists did a good job collecting and combining all the best studies they could find, which is like checking every report in a school project to see what’s true. But most of the original studies were too small and didn’t last long enough, so even though the method was good, the pieces they used weren’t strong enough to give a clear answer.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
44 / 100
- Randomization+20/20
- Blindingblinding unclear
- Control group+15/15
- Sample sizeno sample size reported
- Follow-upno follow-up reported
100 / 100
77 / 100
- P-values+15/15
- Effect size+20/20
- Confidence intervals+15/15
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 555 / 100
Probability of being correct
The highest quality evidence. Systematic reviews and meta-analyses that pool randomized controlled trials, giving the most reliable summary of experimental evidence.
This design can establish causation. This study can establish causation because it is a systematic review and meta-analysis of randomized controlled trials (RCTs), which are the gold standard for causal inference. However, the individual RCTs included had small sample sizes, short durations, and high risk of type II errors, which limits the strength of the causal conclusion.
No Conflicts
No conflicts of interest identified
No conflicts of interest or funding statements were disclosed in the provided text, and no industry affiliations or financial ties were evident among authors.
The manuscript lacks a formal conflict of interest declaration or funding statement. However, all authors are affiliated with academic institutions (Newcastle University, Leeds Beckett University, etc.), and no industry ties, employment, or financial relationships with commercial entities are disclosed or implied. The study is a systematic review and meta-analysis of existing trials, reducing potential for direct industry influence.
Standing
Who’s using this study?
The videos and claims on this site that lean on this study, and the researchers who wrote it.
1 video from Dr Brad Stanfield cite this study, drawing 1 claim from it.
- Very strong evidence
Randomized or controlled trials support this claim, alongside consistent supporting evidence.
Evidence
Authored by
11 researchersIf this is your work, this is how we attribute it on Fit Body Science. Tom Clifford is listed as the lead author.