Potentially false Overinterpreted Certainty of evidence: moderate provisional C-SUP-06

Multivitamins, iron, folic acid, B6, magnesium, zinc and copper supplements increase mortality, and folic acid (with B12) increases cancer.

In short: This claim is probably false: randomised trials show no increase in deaths from multivitamins and no significant increase in cancer from folic acid; the cited harm comes from an observational survey that cannot show cause and effect.

Conclusion: Probably false: randomised trials do not show that multivitamins or folic acid increase mortality or cancer.

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

وفي دراسة Iowa Women's Health ارتبط استعمال المتعددات والحديد والنحاس وحمض الفوليك بزيادة الوفيات على مدى 22 سنة.

not verbatim – paraphrase. Translation by the project; the Arabic wording is authoritative.

Translation

Multivitamins, iron, folic acid, B6, magnesium, zinc and copper supplements increase mortality, and folic acid (with B12) increases cancer.

Origin

Source status: Archive editors
Attribution: Archive editors (eltayebat.com); not verified as Elawady's own words
Origin: https://eltayebat.com/rule/oral-supplements/
Attribution uncertainty: Written by the archive operators; study selection is the archive's, not necessarily Elawady's.

Claimed mechanism: Not specified.
Claimed health effect: Higher total mortality; cancer.
Population concerned: Older women (Iowa); patients with heart disease (Norway).
Geographic restriction by Elawady: none found

Scientific assessment

Potentially false – The available evidence tends to speak against the statement, but is not conclusive.

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

1. What was claimed?

Common vitamin/mineral pills increase death and cancer.

2. What is demonstrably correct?

Iowa (A-SUP-06): multivitamins HR 1.06 (1.02–1.10), iron HR 1.10, folic acid HR 1.15 (1.00–1.32), copper HR 1.45 – associations in older women. This is weak, hypothesis-generating support: several associations (B6, folic acid, magnesium, zinc) would not meet the authors' own Bonferroni threshold (P=0.0033), some changed direction with lifestyle adjustment, the authors caution against causal interpretation, and the most robust signal is for iron; no folic acid/B12-cancer analysis is reported. Ebbing 2009: folic acid + B12 associated with more cancer (HR 1.21) in Norwegian heart patients.

3. What is wrong or exaggerated?

Associations from self-reported cohort data cannot show harm; supplement users differ from non-users (e.g. taking supplements because of illness). RCT meta-analyses show no mortality effect of multivitamins and no significant cancer effect of folic acid. The archive omits that calcium was inversely associated with mortality in the same cohort.

4. What remains unclear?

Long-term (>10 years) effects of high-dose folic acid are less studied.

5. Which studies support it?

A-SUP-06, A-SUP-17, A-SUP-18.

6. Which studies contradict it?

A-SUP-26 (RCT meta-analysis, RR 0.98), Vollset 2013 (I-SUP-07), O'Connor 2022 (I-SUP-08), A-SUP-25 (PHS II, total mortality HR 0.94, n.s.), COSMOS (I-SUP-106; mortality HR 0.93, 0.81-1.08). Loftfield 2024 (I-SUP-107) found a small positive association (HR 1.04) in an observational analysis, consistent with confounding rather than harm.

7. What applies to Germany and Europe?

Applies equally.

8. What is known about Egypt?

Applies equally.

9. What practical conclusion is appropriate?

Routine supplements are not needed for well-nourished people, but there is no good evidence that standard-dose multivitamins or folic acid shorten life.

Assessment details

Rationale for certainty of evidence: The mortality claim rests on an observational cohort with self-reported supplement use (Iowa; HR 1.06–1.15, copper 1.45). Meta-analysis of 21 RCTs (91,074 people) found no effect of multivitamin-multimineral supplements on mortality (RR 0.98); an individual-participant meta-analysis of 13 folic acid RCTs (49,621 people) found no significant effect on cancer incidence (RR 1.06, 0.99–1.13). The Norwegian signal (Ebbing 2009) was not confirmed in the pooled analysis.
Source quality: Observational cohort presented as evidence of harm; RCT evidence points to no effect.
Regional transferability: High.
Individual exceptions: Iron overload disorders (haemochromatosis) are a real reason to avoid iron supplements.
Regional scope of the claim: general (biological/medical)
Last reviewed: 26 October 2026 provisional

Scientific evidence in detail

Overinterpreted – A real finding exists, but the claim draws more from it than the data allow (e.g. association taken as cause, animal data applied to humans, small effect presented as large).

Research question: In adults, do multivitamin, iron, folic acid, B6, magnesium, zinc and copper supplements increase mortality, and does folic acid (with B12) increase cancer?

Research question in detail (PICO)

Population

Adults (older women in Iowa; heart patients in Norway)

Intervention or exposure

Multivitamin and mineral supplements; folic acid +/- B12

Comparison

No supplement/placebo

Geographic scope

universal biology

Outcomes

All-cause mortality
Cancer incidence

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

What speaks for the claim?

Supplements and mortality in older women

Mursu J et al.. Arch Intern Med 2011 · PMID 21987192 · DOI 10.1001/archinternmed.2011.445 Cohort studyfull text, structured risk-of-bias assessment

Iowa Women's Health Study: several supplements associated with higher mortality.

Actual result
Multivitamins HR 1.06 (1.02-1.10); iron 1.10; copper 1.45.
Methodological quality
low (observational, self-report)
Relevance
direct but confounded
Limitations
Healthy-user and sick-user bias.

Original publication
Folic acid + B12 and cancer in Norway

Ebbing M et al.. JAMA 2009 · PMID 19920236 · DOI 10.1001/jama.2009.1622 Randomised controlled trialabstract checked

Norwegian trials: folic acid + B12 associated with more cancer.

Actual result
Cancer HR 1.21 (1.03-1.41).
Methodological quality
moderate (RCT pooled post-hoc)
Relevance
direct
Limitations
Not confirmed in larger pooled analysis.

Original publication

What speaks against the claim?

Multivitamins and death – trials

Macpherson H et al.. Am J Clin Nutr 2013 · PMID 23255568 · DOI 10.3945/ajcn.112.049304 Meta-analysisabstract checked

Meta-analysis of 21 RCTs: multivitamins had no effect on mortality.

Actual result
RR 0.98 (0.94-1.02).
Methodological quality
high
Relevance
direct

Original publication
Folic acid and cancer – 50,000 trial participants

Vollset SE et al.. Lancet 2013 · PMID 23352552 · DOI 10.1016/S0140-6736(12)62001-7 Meta-analysisfull text, structured risk-of-bias assessment

Individual-data meta-analysis of 13 folic acid RCTs: no significant cancer increase.

Actual result
RR 1.06 (0.99-1.13).
Methodological quality
high
Relevance
direct
Limitations
Upper bound 1.13.

Original publication
Daily multivitamin in older adults (COSMOS trial)

Sesso HD et al.. Am J Clin Nutr 2022 · PMID 35294969 · DOI 10.1093/ajcn/nqac056 Randomised controlled trialabstract checkednewly added

COSMOS: no mortality increase with daily multivitamin.

Actual result
HR 0.93 (0.81-1.08).
Methodological quality
high (RCT)
Relevance
direct
Limitations
3.6 years.

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?

Randomised evidence does not show that multivitamins increase mortality or that folic acid increases cancer.

Why some studies weigh more

RCTs and IPD meta-analyses outweigh cohort associations; Loftfield's HR 1.04 is small and likely confounded.

Is a causal relationship established? Not established Associations come from observational data; RCTs are null.

Remaining uncertainty

Single minerals (iron, copper, zinc) lack large RCTs on mortality.

Justified conclusion

The claim overinterprets cohort associations as harm.

Why do studies seem to disagree?

Iowa/Loftfield (observational) vs COSMOS/Macpherson (randomised): observational associations likely reflect reverse causation and confounding.

Does this depend on the country?

General biological effects: Same human physiology everywhere.
Eating habits: Supplement use patterns differ by country; not region-specific for this question.
Origin of the food: Not relevant.
Contaminants: Product quality and contamination vary by market (not assessed here).
National production conditions: Not relevant.
Legal rules: Supplements are regulated as foods in the EU; Egyptian rules not verified.
Actual monitoring data: No monitoring data reviewed.

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

Statistical re-check

Crude cancer risks and P for mortality – Crude RR about 0.97; P about 0.32 for mortality HR 0.93. recalculated
CI symmetry HR 1.04 (1.02-1.07) – Asymmetry from rounding; small effect. recalculated

Certainty of the overall evidence (GRADE, simplified)

Main outcome

Mortality with multivitamins

Starting level

high (randomised trials)

Reasons for downgrading

imprecision for single minerals

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
Europe PMC	26 October 2026	`TITLE:multivitamin AND (TITLE:mortality OR TITLE:cancer OR TITLE:"cardiovascular") AND PUB_YEAR:[2019 TO 2026]`	both directions	28
Europe PMC	26 October 2026	`TITLE:"folic acid" AND TITLE:cancer AND (PUB_TYPE:"Meta-Analysis") AND PUB_YEAR:[2014 TO 2026]`	both directions	5
Europe PMC	26 October 2026	`(TITLE:"iron supplement" OR TITLE:"zinc supplement" OR TITLE:"magnesium supplement" OR TITLE:"copper supplement") AND TITLE:mortality AND (PUB_TYPE:"Meta-Analysis" OR PUB_TYPE:"Randomized Controlled Trial")`	supporting evidence	0

How deeply was this checked?

9 linked studies: 2 checked in full text (2 of them with a structured risk-of-bias assessment), 7 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: Potentially false (moderate)
26 October 2026 · Phase 4 (systematic evidence review) · Re-examined with extended evidence; verdict unchanged: Potentially false (moderate)
COSMOS strengthens the multivitamin part, but single minerals remain untested in RCTs; verdict kept.
New sources: I-SUP-106 I-SUP-107

In plain language

One large survey of older American women found that those who took some vitamin and mineral pills died slightly more often. But such surveys cannot show cause and effect. When the pills were tested in randomised trials, they did not increase deaths, and folic acid did not increase cancer.

Studies on this claim

Studies supporting the claim (2)

Supplements and mortality in older women

Mursu J et al.. Arch Intern Med 2011 · PMID 21987192 · DOI 10.1001/archinternmed.2011.445

Cohort studycited by the Tayebat archivefull text, structured risk-of-bias assessment★ key study

Several supplements were linked to slightly more deaths; calcium to fewer.

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?
Mortality with supplements.
How was the study done?
Cohort.
How many people, animals or samples were studied?
38,772 women.
What was actually found?
Small associations both ways.
How large was the observed effect?
HR 1.06 (MV), 0.91 (Ca).
What do the results mean in everyday life?
Not proof of harm.
What are the study's limitations?
Confounding.
What does it say about Elawady's specific claim?
Partly supports; contradicts calcium claim.
Do the results apply to Germany and Europe?
Moderate.
What can explicitly not be concluded from this study?
Causation.
Scientific details →
Folic acid + B12 and cancer in Norway

Ebbing M et al.. JAMA 2009 · PMID 19920236 · DOI 10.1001/jama.2009.1622

Randomised controlled trialcited by the Tayebat archiveabstract checked

More cancer and deaths with folic acid plus B12 in heart patients.

Does the study support the specific claim? Partly · 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?
Cancer with B vitamins.
How was the study done?
Pooled RCTs.
How many people, animals or samples were studied?
6,837.
What was actually found?
More cancer.
How large was the observed effect?
HR 1.21.
What do the results mean in everyday life?
Uncertain signal.
What are the study's limitations?
Secondary.
What does it say about Elawady's specific claim?
Partly supports.
Do the results apply to Germany and Europe?
Norway.
What can explicitly not be concluded from this study?
General harm.
Scientific details →

Studies contradicting or limiting the claim (5)

Multivitamins and death – trials

Macpherson H et al.. Am J Clin Nutr 2013 · PMID 23255568 · DOI 10.3945/ajcn.112.049304

Meta-analysiscited by the Tayebat archiveabstract checked

No effect on mortality.

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?
Mortality.
How was the study done?
Meta-analysis.
How many people, animals or samples were studied?
91,074.
What was actually found?
No effect.
How large was the observed effect?
RR 0.98.
What do the results mean in everyday life?
Neither harm nor benefit.
What does it say about Elawady's specific claim?
Contradicts mortality claim.
Do the results apply to Germany and Europe?
Applicable.
Scientific details →
Folic acid and cancer – 50,000 trial participants

Vollset SE et al.. Lancet 2013 · PMID 23352552 · DOI 10.1016/S0140-6736(12)62001-7

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

No significant effect of folic acid on cancer over about 5 years.

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?
Folic acid and cancer.
How was the study done?
IPD meta-analysis.
How many people, animals or samples were studied?
49,621.
What was actually found?
No significant effect.
How large was the observed effect?
RR 1.06 (0.99–1.13).
What do the results mean in everyday life?
Folic acid does not cause cancer in the short term.
What are the study's limitations?
5 years.
What does it say about Elawady's specific claim?
Contradicts C-SUP-06.
Do the results apply to Germany and Europe?
Applicable.
What can explicitly not be concluded from this study?
Very long-term effects.
Scientific details →
USPSTF evidence review 2022

O'Connor EA et al.. JAMA 2022 · PMID 35727272 · DOI 10.1001/jama.2021.15650

Systematic reviewindependent cross-checkabstract checked★ key study

Supplements gave little or no protection; beta-carotene harmful; multivitamins slightly fewer cancers.

Does the study support the specific claim? Partly · 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?
Supplement benefits/harms.
How was the study done?
SR.
How many people, animals or samples were studied?
739,803.
What was actually found?
Little benefit; some harms.
How large was the observed effect?
OR 0.93 MV cancer; 1.20 beta-carotene lung cancer.
What do the results mean in everyday life?
Supplements are not a prevention strategy.
What are the study's limitations?
Not for deficiency.
What does it say about Elawady's specific claim?
Mixed.
Do the results apply to Germany and Europe?
Applicable.
What can explicitly not be concluded from this study?
Effects in deficient people.
Scientific details →
PHS II: multivitamins and heart disease

Sesso HD et al.. JAMA 2012 · PMID 23117775 · DOI 10.1001/jama.2012.14805

Randomised controlled trialcited by the Tayebat archiveabstract checked

No reduction in heart attacks or strokes; no increase in deaths.

Does the study support the specific claim? Yes · 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?
CV prevention.
How was the study done?
RCT.
How many people, animals or samples were studied?
14,641.
What was actually found?
Null.
How large was the observed effect?
HR 1.01.
What do the results mean in everyday life?
Not needed for heart.
What are the study's limitations?
Physicians.
What does it say about Elawady's specific claim?
Supports C-SUP-01; contradicts C-SUP-06.
Do the results apply to Germany and Europe?
Applicable.
Scientific details →
Daily multivitamin in older adults (COSMOS trial)

Sesso HD et al.. Am J Clin Nutr 2022 · PMID 35294969 · DOI 10.1093/ajcn/nqac056

Randomised controlled trialindependent cross-checkabstract checked★ key study

Over 3.6 years a daily multivitamin neither reduced nor increased cancer, heart disease or deaths.

No increase in all-cause mortality (HR 0.93, 0.81-1.08) in a randomised trial.

Does the study support the specific claim? Partly · 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?
To test whether a daily multivitamin prevents cancer and heart disease.
How was the study done?
Randomised placebo-controlled trial.
How many people, animals or samples were studied?
21,442 older US adults.
What was actually found?
No effect on total cancer, CVD or deaths; possible fewer lung cancers (secondary).
How large was the observed effect?
Cancer HR 0.97 (0.86-1.09); death HR 0.93 (0.81-1.08).
What do the results mean in everyday life?
Multivitamins do not prevent major diseases in well-fed older people, and did not cause harm.
What are the study's limitations?
Short follow-up.
What does it say about Elawady's specific claim?
Supports C-SUP-01; contradicts C-SUP-06.
Do the results apply to Germany and Europe?
Applicable.
What can explicitly not be concluded from this study?
Cannot exclude small long-term effects.
Scientific details →

Studies with mixed or unclear results (2)

Folic acid and bowel polyps

Cole BF et al.. JAMA 2007 · PMID 17551129 · DOI 10.1001/jama.297.21.2351

Randomised controlled trialcited by the Tayebat archiveabstract checked

No prevention of polyps; possible increase in advanced lesions (borderline).

Does the study support the specific claim? Partly · 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?
Adenoma prevention.
How was the study done?
RCT.
How many people, animals or samples were studied?
1,021.
What was actually found?
No benefit.
How large was the observed effect?
RR 1.04; 1.67 advanced.
What do the results mean in everyday life?
Not useful for polyps.
What are the study's limitations?
Attrition.
What does it say about Elawady's specific claim?
Mixed.
Do the results apply to Germany and Europe?
Applicable.
What can explicitly not be concluded from this study?
Harm at fortification doses.
Scientific details →
Multivitamins and death in 390,000 Americans

Loftfield E et al.. JAMA Netw Open 2024 · PMID 38922615 · DOI 10.1001/jamanetworkopen.2024.18729

Cohort studyindependent cross-checkabstract checked

People who took multivitamins did not live longer; their risk of death was about 4% higher, which may reflect who takes supplements rather than the pills.

Small positive association (HR 1.04) in an observational analysis; not causal evidence.

Does the study support the specific claim? Partly · 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?
To see whether multivitamin users live longer.
How was the study done?
Three large cohort studies combined.
How many people, animals or samples were studied?
390,124 adults.
What was actually found?
No survival benefit; slight 4% higher death risk.
How large was the observed effect?
HR 1.04 (1.02-1.07).
What do the results mean in everyday life?
Multivitamins do not help healthy people live longer.
What are the study's limitations?
Observational; self-report.
What does it say about Elawady's specific claim?
Supports C-SUP-01; only weakly relevant to the harm claim in C-SUP-06.
Do the results apply to Germany and Europe?
Applicable.
What can explicitly not be concluded from this study?
Cannot prove that multivitamins cause harm.
Scientific details →

Regional context

Germany / EU

Applies equally.

Egypt

Applies equally.

What applies in my country?

General scientific assessment

Potentially false Probably false: randomised trials do not show that multivitamins or folic acid increase mortality or cancer.

This statement concerns biological or medical relationships. The scientific assessment above applies regardless of the country; country-specific food data do not change it.

References

Dietary supplements and mortality rate in older women: the Iowa Women's Health Study.. Mursu J et al.. Arch Intern Med 2011 · PMID 21987192 · DOI 10.1001/archinternmed.2011.445
Cancer incidence and mortality after treatment with folic acid and vitamin B12.. Ebbing M et al.. JAMA 2009 · PMID 19920236 · DOI 10.1001/jama.2009.1622
Multivitamin-multimineral supplementation and mortality: a meta-analysis of randomized controlled trials.. Macpherson H et al.. Am J Clin Nutr 2013 · PMID 23255568 · DOI 10.3945/ajcn.112.049304
Effects of folic acid supplementation on overall and site-specific cancer incidence during the randomised trials: meta-analyses of data on 50,000 individuals.. Vollset SE et al.. Lancet 2013 · PMID 23352552 · DOI 10.1016/S0140-6736(12)62001-7
Vitamin and Mineral Supplements for the Primary Prevention of Cardiovascular Disease and Cancer: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force.. O'Connor EA et al.. JAMA 2022 · PMID 35727272 · DOI 10.1001/jama.2021.15650
Multivitamins in the prevention of cardiovascular disease in men: the Physicians' Health Study II randomized controlled trial.. Sesso HD et al.. JAMA 2012 · PMID 23117775 · DOI 10.1001/jama.2012.14805
Multivitamins in the prevention of cancer and cardiovascular disease: the COcoa Supplement and Multivitamin Outcomes Study (COSMOS) randomized clinical trial.. Sesso HD et al.. Am J Clin Nutr 2022 · PMID 35294969 · DOI 10.1093/ajcn/nqac056
Folic acid for the prevention of colorectal adenomas: a randomized clinical trial.. Cole BF et al.. JAMA 2007 · PMID 17551129 · DOI 10.1001/jama.297.21.2351
Multivitamin Use and Mortality Risk in 3 Prospective US Cohorts.. Loftfield E et al.. JAMA Netw Open 2024 · PMID 38922615 · DOI 10.1001/jamanetworkopen.2024.18729

← Back to overview

Multivitamins, iron, folic acid, B6, magnesium, zinc and copper supplements increase mortality, and folic acid (with B12) increases cancer.

Original statement

Translation

Origin

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?

Supplements and mortality in older women

Folic acid + B12 and cancer in Norway

What speaks against the claim?

Multivitamins and death – trials

Folic acid and cancer – 50,000 trial participants

Daily multivitamin in older adults (COSMOS trial)

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 (2)

Supplements and mortality in older women

Folic acid + B12 and cancer in Norway

Studies contradicting or limiting the claim (5)

Multivitamins and death – trials

Folic acid and cancer – 50,000 trial participants

USPSTF evidence review 2022

PHS II: multivitamins and heart disease

Daily multivitamin in older adults (COSMOS trial)

Studies with mixed or unclear results (2)

Folic acid and bowel polyps

Multivitamins and death in 390,000 Americans

Regional context

Germany / EU

Egypt

What applies in my country?

General scientific assessment

References