Mostly false Not supported by high-quality evidence Certainty of evidence: moderate provisional C-VEG-08

Nitrate from fertilisers (together with pesticides) in lettuce, rocket and other leaves harms the people who eat them.

In short: This claim is mostly false for adults: large cohort studies link nitrate from vegetables with lower blood pressure, less cardiovascular disease and lower mortality, while harmful associations concern nitrate from processed meat and drinking water; only infants are a special risk group (C-VEG-07).

Conclusion: For adults, vegetable nitrate is not shown to be harmful; it is linked to lower blood pressure and mortality, unlike nitrate from processed meat or contaminated water.

Original statement
Scientific assessment
Scientific evidence in detail
In plain language
Studies on this claim
Regional context
What applies in my country?
References

Original statement

شويه نترات في اسمده شويه مبيدات حضرتك بيخشوا لك مع الخص والجرجير مع الكونروف مع الورق مع البتاع

verbatim according to source. Translation by the project; the Arabic wording is authoritative.

Translation

Nitrate from fertilisers (together with pesticides) in lettuce, rocket and other leaves harms the people who eat them.

Origin

Source status: Video transcript (own words)
Attribution: Elawady (machine transcript)
Video: Dr Diaa Al Awady د ضياء العوضي is live! شريحة في الدماغ (Open source)
Published: 1 February 2026
Timestamp: 0:58:14 (location in the original video’s automatic YouTube caption track; confirms where the words occur, not who speaks)
Attribution uncertainty: Archive transcript (YouTube captions or AI-generated); wording may contain transcription errors; no timestamps available.

Claimed mechanism: Fertiliser nitrate accumulates in leaves.
Claimed health effect: Toxic effects, methaemoglobinaemia ('green man').
Population concerned: Everyone
Geographic restriction by Elawady: none found

Diverging source versions

Source status: Archive editors
Attribution: Archive editors
Origin: https://eltayebat.com/rule/leafy-greens-cucurbits/
Attribution uncertainty: Archive editorial text and study selection written by the archive operators, not necessarily by Elawady.

Scientific assessment

Mostly false – Essential parts of the statement are not supported by the evidence or are strongly exaggerated.

Certainty of evidence: moderate – Further research may still affect the assessment.

1. What was claimed?

Fertiliser nitrate in greens harms consumers.

2. What is demonstrably correct?

Leafy greens such as rocket, lettuce and spinach accumulate nitrate, influenced by fertilisation and light; nitrite/nitrate poisoning causing methaemoglobinaemia exists (mainly from contaminated water or infant feeding).

3. What is wrong or exaggerated?

For adults, vegetable nitrate is converted to nitric oxide and lowers blood pressure in trials (Siervo 2013). The EU regulates maximum levels; exceeding a limit is not the same as harm.

4. What remains unclear?

Long-term effects of very high vegetable nitrate intakes and on thyroid disease are not established in RCTs.

5. Which studies support it?

Weak: Ward 2010 (I-VEG-126), an imprecise association of dietary nitrate with thyroid cancer in one cohort of older women.

6. Which studies contradict it?

Siervo 2013 (RCTs, blood pressure); Bondonno 2021 (I-VEG-123) and Bondonno 2024 (I-VEG-124): vegetable nitrate associated with lower CVD and mortality; Erichsen 2025 (I-VEG-125): no association of plant nitrate with colorectal cancer; Aune 2017.

7. What applies to Germany and Europe?

Regulated by EU Reg. 2023/915.

8. What is known about Egypt?

Egyptian nitrate monitoring data were not found.

9. What practical conclusion is appropriate?

Normal consumption of leafy greens is not a nitrate risk for adults; infants are a special case.

Assessment details

Rationale for certainty of evidence: RCTs show that dietary nitrate lowers systolic blood pressure (-4.4 mm Hg, Siervo 2013). Large source-specific cohort analyses now separate vegetable nitrate from other sources: plant-sourced nitrate was associated with lower all-cause mortality (HR 0.83, 0.80-0.87; Bondonno 2024, I-VEG-124) and lower CVD (HR 0.85; Bondonno 2021, I-VEG-123) and was not associated with colorectal cancer (Erichsen 2025, I-VEG-125), whereas nitrate from processed meat and tap water was associated with higher mortality. The only harm signal for dietary nitrate found (thyroid cancer, Ward 2010, I-VEG-126) is imprecise (RR 2.9, 1.0-8.1) and not replicated.
Source quality: Machine transcript; mixes fertiliser nitrate, pesticides and a clinical case of nitrite poisoning.
Regional transferability: EU maximum levels exist (e.g. fresh spinach 3,500 mg/kg; rocket 6,000-7,000 mg/kg; lettuce 2,000-5,000 mg/kg depending on type and season). Egyptian levels were not reviewed.
Individual exceptions: Young infants (see C-VEG-07).
Regional scope of the claim: general (biological/medical)
Last reviewed: 26 October 2026 provisional

Scientific evidence in detail

Not supported by high-quality evidence – There is no good evidence for the claim; this alone does not prove it wrong.

Research question: In adults, does nitrate from fertilised leafy vegetables (lettuce, rocket) harm health?

Research question in detail (PECO)

Population

Adults

Intervention or exposure

Vegetable nitrate

Comparison

Low vegetable nitrate

Geographic scope

universal biology; nitrate content production-dependent

Outcomes

blood pressure
CVD
mortality
cancer
thyroid disease

Study results as reported by the authors. Our assessment follows below.

What speaks for the claim?

Possible thyroid signal for nitrate in one cohort

Ward MH et al.. Epidemiology 2010 · PMID 20335813 · DOI 10.1097/EDE.0b013e3181d6201d Cohort studyabstract checkednewly added

Ward 2010 Iowa Women's Health Study.

Actual result
Dietary nitrate Q4 vs Q1: thyroid cancer RR 2.9 (1.0-8.1); hypothyroidism OR 1.2.
Methodological quality
low (imprecise, single cohort)
Relevance
indirect
Limitations
Few cases; not replicated.

Original publication

What speaks against the claim?

Nitrate source matters

Bondonno NP et al.. Eur J Epidemiol 2024 · PMID 38802612 · DOI 10.1007/s10654-024-01133-5 Cohort studyabstract checkednewly added

Bondonno 2024 source-specific nitrate (52,247; 27 y).

Actual result
Plant nitrate HR 0.83 (0.80-0.87) all-cause mortality; meat-additive nitrate 1.19 (1.14-1.25).
Methodological quality
moderate
Relevance
direct
Limitations
Observational.

Original publication
Nitrate from vegetables linked to less heart disease

Bondonno CP et al.. Eur J Epidemiol 2021 · PMID 33884541 · DOI 10.1007/s10654-021-00747-3 Cohort studyabstract checkednewly added

Bondonno 2021 (53,150; 23 y).

Actual result
Moderate vegetable nitrate CVD HR 0.85 (0.82-0.89); SBP -2.58 mmHg.
Methodological quality
moderate
Relevance
direct
Limitations
Observational.

Original publication
Dietary nitrate and blood pressure

Siervo M et al.. J Nutr 2013 · PMID 23596162 · DOI 10.3945/jn.112.170233 Meta-analysisabstract checked

Siervo 2013 meta-analysis of RCTs.

Actual result
Inorganic nitrate/beetroot juice lowers SBP by 4.4 mmHg.
Methodological quality
moderate-high (RCT MA, short-term)
Relevance
direct (surrogate)
Limitations
Short trials.

Original publication

What does the overall evidence say?

Editorial assessment based on the studies above – not itself a study result.

Which position is better supported?

For adults, nitrate from vegetables is associated with lower blood pressure, CVD and mortality; harm signals concern nitrate from processed meat and drinking water, not vegetables.

Why some studies weigh more

Source-specific cohorts plus RCTs on BP outweigh one imprecise thyroid finding.

Is a causal relationship established? Possible, not established BP lowering is causal in RCTs; hard outcomes observational.

Remaining uncertainty

Thyroid signal; very high intakes.

Justified conclusion

No evidence that vegetable nitrate harms adults; benefit is plausible.

Why do studies seem to disagree?

Ward 2010 (thyroid cancer) vs Danish cohorts (no harm, lower mortality): different outcomes, small vs large case numbers; the thyroid signal is imprecise and not replicated.

Does this depend on the country?

General biological effects: Universal.
Eating habits: Rocket (jarjir) and lettuce are common in Egypt.
Origin of the food: Nitrate depends on fertiliser, season and light.
Contaminants: Nitrate is natural, not a contaminant in the usual sense.
National production conditions: Egyptian nitrate data not reviewed.
Legal rules: EU Reg. 2023/915 maximum levels.
Actual monitoring data: not reviewed

A regional difference that changes the conclusion is not supported by robust data.

Statistical re-check

CI symmetry – Consistent within rounding. recalculated
Precision of thyroid finding – RR 2.9 (1.0-8.1), p ~0.046: imprecise. recalculated

Certainty of the overall evidence (GRADE, simplified)

Main outcome

CVD and mortality with higher vegetable nitrate in adults

Starting level

low (observational studies)

Reasons for upgrading

dose-response
consistent with RCT mechanism (BP)

Result

moderate

Simplified assessment by a single reviewer, following the GRADE approach; not a formal GRADE panel. GRADE rates the body of evidence for one outcome, not individual studies.

Search strategy

Documented literature searches for this review (search strings in the original database syntax).

Database	Date	Search	Looking for	Hits
PubMed	26 October 2026	`(dietary nitrate OR "nitrate intake") AND (vegetable*) AND (cancer OR mortality OR thyroid) AND (meta-analysis[pt] OR cohort)`	supporting evidence	20
PubMed	26 October 2026	`("vegetable nitrate" OR "plant-derived nitrate") AND (cardiovascular OR "blood pressure" OR mortality) AND (cohort OR prospective)`	contradicting evidence	6
PubMed	26 October 2026	`(nitrate) AND (source OR plant-sourced OR "animal-sourced") AND (mortality OR cancer) AND ("Danish Diet, Cancer, and Health")`	both directions	13

How deeply was this checked?

8 linked studies: 2 checked in full text (1 of them with a structured risk-of-bias assessment), 6 on the basis of the abstract, 0 bibliographically only. No formal assessment with two independent reviewers and no independent human expert review has taken place yet.

Last scientific review: 26 October 2026

History of the verdict

25 October 2026 · Phase 1 · Initial assessment: Mostly false (low)
26 October 2026 · Phase 4 (systematic evidence review) · Verdict changed: Mostly false (low) → Mostly false (moderate)
Source-specific cohort analyses (Bondonno 2021, 2024; Erichsen 2025) now separate vegetable nitrate (inverse association) from processed-meat and water nitrate (positive association), resolving the main uncertainty cited in the previous rationale. Certainty raised from low to moderate; verdict unchanged.
New sources: I-VEG-123 I-VEG-124 I-VEG-125 I-VEG-126

In plain language

Elawady said that fertiliser nitrates and pesticides enter the body with lettuce and rocket. Leafy vegetables do contain nitrate, and the EU sets limits for it. In adults, nitrate from vegetables is turned into a substance that relaxes blood vessels, and trials show a small drop in blood pressure. The real risk applies to very young babies.

Studies on this claim

Studies supporting the claim (1)

Possible thyroid signal for nitrate in one cohort

Ward MH et al.. Epidemiology 2010 · PMID 20335813 · DOI 10.1097/EDE.0b013e3181d6201d

Cohort studyindependent cross-checkabstract checked

In Iowa women, the highest dietary nitrate intake was linked to more thyroid cancer, but the estimate was very imprecise.

Imprecise association of dietary nitrate with thyroid cancer in one cohort.

Does the study support the specific claim? Partly · Methodological quality: low · Certainty of evidence: see overall assessment of the claim

Original publication · Scientific details

Study explained simply
What did the researchers want to find out?
Relate nitrate to thyroid outcomes.
How was the study done?
Cohort.
How many people, animals or samples were studied?
21,977 women.
What was actually found?
Weak positive association.
How large was the observed effect?
RR 2.9 (1.0-8.1).
What do the results mean in everyday life?
A possible signal needing confirmation, not proof of harm.
What are the study's limitations?
Few cases.
What does it say about Elawady's specific claim?
Weak support.
Do the results apply to Germany and Europe?
Moderate.
What can explicitly not be concluded from this study?
Cannot show that vegetables harm the thyroid.
Scientific details →

Studies contradicting or limiting the claim (6)

Dietary nitrate and blood pressure

Siervo M et al.. J Nutr 2013 · PMID 23596162 · DOI 10.3945/jn.112.170233

Meta-analysisindependent cross-checkabstract checked★ key study

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 · Certainty of evidence: see overall assessment of the claim

Original publication · Scientific details

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 details →
EU nitrate limits for leafy vegetables

European Commission. Official document 2023

Guideline / position statementindependent cross-checkfull text checked★ key study

The EU caps nitrate in spinach, lettuce and rocket and sets a much lower limit for baby food.

Does the study support the specific claim? No · Methodological quality: moderate · Certainty of evidence: see overall assessment of the claim

Original publication · Scientific details

Study explained simply
What did the researchers want to find out?
Set limits
How was the study done?
Regulation
How many people, animals or samples were studied?
Not applicable
What was actually found?
Limits per product
How large was the observed effect?
Not applicable
What do the results mean in everyday life?
Nitrate in EU greens is controlled.
What are the study's limitations?
Limits are not health thresholds per se
What does it say about Elawady's specific claim?
Regulatory context
Do the results apply to Germany and Europe?
High
What can explicitly not be concluded from this study?
Cannot show harm or safety at individual level.
Scientific details →
Fruit, vegetables and death rates

Aune D et al.. Int J Epidemiol 2017 · PMID 28338764 · DOI 10.1093/ije/dyw319

Meta-analysisindependent cross-checkfull text, structured risk-of-bias assessment★ key study

Each extra 200 g of fruit and vegetables a day was linked to 10% lower death risk; green leafy vegetables and salads were also protective.

Does the study support the specific claim? No · Methodological quality: high · Certainty of evidence: see overall assessment of the claim

Original publication · Scientific details

Study explained simply
What did the researchers want to find out?
F&V and outcomes
How was the study done?
Meta-analysis
How many people, animals or samples were studied?
95 studies
What was actually found?
Lower CVD, cancer, mortality
How large was the observed effect?
RR 0.90 per 200 g
What do the results mean in everyday life?
Eat plenty of vegetables.
What are the study's limitations?
Observational
What does it say about Elawady's specific claim?
Contradicts avoidance
Do the results apply to Germany and Europe?
High
What can explicitly not be concluded from this study?
Cannot prove causation.
Scientific details →
Nitrate from vegetables linked to less heart disease

Bondonno CP et al.. Eur J Epidemiol 2021 · PMID 33884541 · DOI 10.1007/s10654-021-00747-3

Cohort studyindependent cross-checkabstract checked★ key study

Danes eating about a cup of leafy greens' worth of nitrate daily had 15% less cardiovascular disease than those eating the least.

Vegetable nitrate associated with lower BP and CVD.

Does the study support the specific claim? No · Methodological quality: moderate · Certainty of evidence: see overall assessment of the claim

Original publication · Scientific details

Study explained simply
What did the researchers want to find out?
Relate vegetable nitrate to BP and CVD.
How was the study done?
Cohort, 23 years.
How many people, animals or samples were studied?
53,150 adults.
What was actually found?
Lower BP and CVD with moderate intake.
How large was the observed effect?
HR 0.85 (0.82-0.89).
What do the results mean in everyday life?
Nitrate from greens does not appear harmful for adults; it may be protective.
What are the study's limitations?
Observational.
What does it say about Elawady's specific claim?
Contradicts the claim.
Do the results apply to Germany and Europe?
European.
What can explicitly not be concluded from this study?
Cannot prove causation.
Scientific details →
Nitrate source matters

Bondonno NP et al.. Eur J Epidemiol 2024 · PMID 38802612 · DOI 10.1007/s10654-024-01133-5

Cohort studyindependent cross-checkabstract checked★ key study

Nitrate from plants was linked to 17% lower mortality, whereas nitrate from processed meat and tap water was linked to higher mortality.

Plant-sourced nitrate inversely associated with mortality; harm signals from meat/water nitrate.

Does the study support the specific claim? No · Methodological quality: moderate · Certainty of evidence: see overall assessment of the claim

Original publication · Scientific details

Study explained simply
What did the researchers want to find out?
Compare nitrate sources and mortality.
How was the study done?
Cohort, 27 years.
How many people, animals or samples were studied?
52,247 adults.
What was actually found?
Plant nitrate inverse; meat/water nitrate positive.
How large was the observed effect?
HR 0.83 (0.80-0.87) plant.
What do the results mean in everyday life?
Nitrate in vegetables is not the nitrate to worry about.
What are the study's limitations?
Observational.
What does it say about Elawady's specific claim?
Contradicts the claim.
Do the results apply to Germany and Europe?
European.
What can explicitly not be concluded from this study?
Cannot prove causation.
Scientific details →
Vegetable nitrate not linked to bowel cancer

Erichsen DW et al.. Environ Int 2025 · PMID 40628182 · DOI 10.1016/j.envint.2025.109658

Cohort studyindependent cross-checkabstract checked

In 54,610 Danes, nitrate from vegetables was not linked to colorectal cancer; high nitrate in tap water was linked to distal colon cancer.

No association of plant-sourced nitrate with colorectal cancer.

Does the study support the specific claim? No · Methodological quality: moderate · Certainty of evidence: see overall assessment of the claim

Original publication · Scientific details

Study explained simply
What did the researchers want to find out?
Relate nitrate sources to bowel cancer.
How was the study done?
Cohort.
How many people, animals or samples were studied?
54,610 adults.
What was actually found?
Food nitrate null; tap water positive.
How large was the observed effect?
HR 1.48 tap water.
What do the results mean in everyday life?
Vegetable nitrate is not a bowel-cancer risk in this cohort.
What are the study's limitations?
Observational; subgroups.
What does it say about Elawady's specific claim?
Contradicts the claim.
Do the results apply to Germany and Europe?
European.
What can explicitly not be concluded from this study?
Cannot exclude small effects.
Scientific details →

Studies with mixed or unclear results (1)

Courgette soup poisoning in two babies

Savino F et al.. Ann Nutr Metab 2006 · PMID 16809905 · DOI 10.1159/000094301

Case series / case reportcited by the Tayebat archiveabstract checked

Two infants under 3 months developed methaemoglobinaemia from concentrated courgette soup.

Does the study support the specific claim? Partly · Methodological quality: low · Certainty of evidence: see overall assessment of the claim

Original publication · Scientific details

Study explained simply
What did the researchers want to find out?
Report cases
How was the study done?
Case report
How many people, animals or samples were studied?
2 infants
What was actually found?
Methaemoglobinaemia
How large was the observed effect?
30.4% and 27%
What do the results mean in everyday life?
Don't give vegetable broths to young infants.
What are the study's limitations?
Two cases
What does it say about Elawady's specific claim?
Infant-specific
Do the results apply to Germany and Europe?
High
What can explicitly not be concluded from this study?
Cannot show harm in adults.
Scientific details →

Regional context

Germany / EU

Regulated by EU Reg. 2023/915.

Egypt

Egyptian nitrate monitoring data were not found.

What applies in my country?

General scientific assessment

Mostly false For adults, vegetable nitrate is not shown to be harmful; it is linked to lower blood pressure and mortality, unlike nitrate from processed meat or contaminated water.

The following areas of food safety are relevant to this statement:

Pesticides and pesticide residues
Veterinary medicines and antibiotics
Hormonal growth promoters
Contaminants (heavy metals, PFAS, PCBs, dioxins, nitrate)
Pathogens (Salmonella, Campylobacter, etc.)

Eggs · Poultry · Dairy · Fish and seafood · Red meat · Fruit and vegetables

Choose a country to see the checked information for it.

Limits: legal rules describe what is allowed, not what every single food contains. Measurement data come from samples and are meaningful only together with their method details.

Country of residence or purchase Compare with another country

References

Nitrate intake and the risk of thyroid cancer and thyroid disease.. Ward MH et al.. Epidemiology 2010 · PMID 20335813 · DOI 10.1097/EDE.0b013e3181d6201d
Inorganic nitrate and beetroot juice supplementation reduces blood pressure in adults: a systematic review and meta-analysis.. Siervo M et al.. J Nutr 2013 · PMID 23596162 · DOI 10.3945/jn.112.170233
Commission Regulation (EU) 2023/915 on maximum levels for certain contaminants in food (Annex I, section 6.1 Nitrates). European Commission. Official document 2023
Fruit and vegetable intake and the risk of cardiovascular disease, total cancer and all-cause mortality-a systematic review and dose-response meta-analysis of prospective studies.. Aune D et al.. Int J Epidemiol 2017 · PMID 28338764 · DOI 10.1093/ije/dyw319
Vegetable nitrate intake, blood pressure and incident cardiovascular disease: Danish Diet, Cancer, and Health Study.. Bondonno CP et al.. Eur J Epidemiol 2021 · PMID 33884541 · DOI 10.1007/s10654-021-00747-3
Source-specific nitrate intake and all-cause mortality in the Danish Diet, Cancer, and Health Study.. Bondonno NP et al.. Eur J Epidemiol 2024 · PMID 38802612 · DOI 10.1007/s10654-024-01133-5
Source-specific nitrate and nitrite intake and association with colorectal cancer in the Danish Diet, Cancer and Health Cohort.. Erichsen DW et al.. Environ Int 2025 · PMID 40628182 · DOI 10.1016/j.envint.2025.109658
Methemoglobinemia caused by the ingestion of courgette soup given in order to resolve constipation in two formula-fed infants.. Savino F et al.. Ann Nutr Metab 2006 · PMID 16809905 · DOI 10.1159/000094301

← Back to overview

Nitrate from fertilisers (together with pesticides) in lettuce, rocket and other leaves harms the people who eat them.

Original statement

Translation

Origin

Diverging source versions

Scientific assessment

1. What was claimed?

2. What is demonstrably correct?

3. What is wrong or exaggerated?

4. What remains unclear?

5. Which studies support it?

6. Which studies contradict it?

7. What applies to Germany and Europe?

8. What is known about Egypt?

9. What practical conclusion is appropriate?

Assessment details

Scientific evidence in detail

What speaks for the claim?

Possible thyroid signal for nitrate in one cohort

What speaks against the claim?

Nitrate source matters

Nitrate from vegetables linked to less heart disease

Dietary nitrate and blood pressure

What does the overall evidence say?

Which position is better supported?

Why some studies weigh more

Remaining uncertainty

Justified conclusion

How deeply was this checked?

In plain language

Studies on this claim

Studies supporting the claim (1)

Possible thyroid signal for nitrate in one cohort

Studies contradicting or limiting the claim (6)

Dietary nitrate and blood pressure

EU nitrate limits for leafy vegetables

Fruit, vegetables and death rates

Nitrate from vegetables linked to less heart disease

Nitrate source matters

Vegetable nitrate not linked to bowel cancer

Studies with mixed or unclear results (1)

Courgette soup poisoning in two babies

Regional context

Germany / EU

Egypt

What applies in my country?

General scientific assessment

References