Study analysis · The American journal of clinical nutrition · 2014
Vitamin E and C supplements don't prevent cancer—here's the 10-year study that changed everything.
Taking vitamin E or C pills every day for over 10 years doesn't lower or raise your risk of getting cancer.
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 is like a super careful experiment where half the guys took vitamin pills and half took sugar pills, and no one knew who got what. After many years, they checked who got cancer and found no difference. So we can say these vitamins didn't change cancer risk in these men.
What’s the bottom line?
Scientists gave older male doctors either vitamin E, vitamin C, or fake pills for over 10 years to see if they helped prevent cancer.
How strong is this study?
This study is super well-made because it randomly assigned people, kept everyone blind, followed them for over 10 years, and checked cancer diagnoses carefully. That means we can trust the results because there's little chance the findings were due to luck or bias.
40 / 100
- COI disclosure+40/40
- Data availabilitydata not shared
- Code availabilitycode not shared
100 / 100
- Randomization+20/20
- Blinding+15/15
- Control group+15/15
- Sample size (n=14641)+20/20
- Follow-up+10/10
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 582 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
This design can establish causation. This study can establish causation because it is a randomized controlled trial with double-blinding, placebo control, and intention-to-treat analysis. However, the lack of statistically significant results means we can only conclude that vitamin E and C supplementation does not cause a measurable change in cancer risk within this population and timeframe.
Minor COI
Minor conflicts that may slightly influence the study
The study received funding and study agents from industry sources, but the funder had no role in study design, data analysis, or publication, and authors are affiliated with academic institutions.
Funders
Conflict Details
National Heart, Lung, and Blood Institute: Supported by a K99/R00 grant (HL095649)
BASF Corporation: Provided study agents (vitamin E and C) and packaging; investigator-initiated grant recipient
Pfizer: Provided study agents (vitamin C) and packaging (formerly Wyeth, American Home Products, and Lederle)
DSM Nutritional Products Inc: Provided study agents (vitamin C) and packaging (formerly Roche Vitamins)
Brigham and Women's Hospital and Harvard Medical School: Authors are affiliated with academic institutions
Independent Analysis Safeguards
- Funder had no role in design, conduct, data analysis, or manuscript preparation
- Endpoints Committee reviewed cancer confirmations blinded to treatment assignment
- Statistical analyses conducted by academic authors using intention-to-treat principle
Although industry provided study agents and funding, the explicit disclaimer of funder involvement in study design and analysis, along with academic authorship and independent endpoint review, minimizes bias risk. The study's large scale, long follow-up, and rigorous methodology further support validity.
Key takeaways
- 01
1,373 men got prostate cancer and 2,669 got any cancer — but the vitamin E and C groups had almost exactly the same number as the placebo groups.
- 02
The difference was so tiny it could be due to chance — taking these vitamins didn’t meaningfully raise or lower cancer risk.
Surprising findings
- Vitamin C showed a statistically significant 46% reduction in colorectal cancer during post-trial follow-up (HR: 0.54, p=0.045), but not during the intervention period.This contradicts the overall null finding and suggests a delayed effect—something no one expected from a simple vitamin.
- Despite 1,373 prostate cancer cases and 2,669 total cancers, the hazard ratios for both vitamins were virtually 1.0—meaning no measurable difference from placebo.People assume antioxidants fight cancer—this study shows they don’t move the needle even in a massive, long-term trial.
Practical takeaways
Stop spending money on vitamin E and C supplements for cancer prevention—your money is better spent on vegetables, exercise, or regular screenings.
This study only tested synthetic forms and specific doses in older male physicians—results may not apply to women, younger people, or natural forms.
high confidenceWhy this study matters
10 Years, 14,641 Men, Zero Benefit
In a 10.3-year randomized trial of 14,641 male physicians, taking 400 IU of synthetic vitamin E every other day and 500 mg of vitamin C daily showed no effect on prostate cancer (HR: 0.99) or total cancer (HR: 1.02)—meaning the risk was statistically identical to the placebo group.
Millions of people take these supplements hoping to prevent cancer—this study proves they’re wasting money and time with no protective benefit.
Contradicts the SELECT Trial
While the SELECT trial found vitamin E increased prostate cancer risk, this study found no increase—even after 2.8 years of post-trial follow-up. The difference? This study used every-other-day dosing (400 IU), while SELECT used daily (400 IU).
It shows dosage frequency and population matter—what’s dangerous for one group might be harmless for another.
No Effect Across Any Subgroup
The study tested effects across age, smoking, BMI, alcohol, aspirin use, and family history—and found zero interaction. Whether you’re a smoker or a marathon runner, vitamins E and C didn’t change your cancer risk.
People think supplements work better for high-risk groups—this study proves they don’t help anyone, regardless of lifestyle.
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 gave older male doctors either vitamin E, vitamin C, or fake pills for over 10 years to see if they helped prevent cancer.
Research results
1,373 men got prostate cancer and 2,669 got any cancer — but the vitamin E and C groups had almost exactly the same number as the placebo groups.
What this means - more context
The difference was so tiny it could be due to chance — taking these vitamins didn’t meaningfully raise or lower cancer risk.
This study tests whether long-term vitamin E or C supplementation affects cancer risk in healthy older men, directly challenging prior findings from the SELECT trial that suggested vitamin E increases prostate cancer risk.
In a 10.3-year randomized trial of 14,641 male physicians, 400 IU vitamin E every other day and 500 mg vitamin C daily showed no significant effect on prostate cancer, total cancer, or other site-specific cancers, even after extended post-trial follow-up.
Methods Used
Double-blind, placebo-controlled, 2×2×2×2 factorial randomized trial with 14,641 healthy male physicians aged ≥50; intervention lasted 7.6 years on average, with 2.8 additional years of post-trial observation; primary analysis used intention-to-treat and Cox proportional hazards models with hazard ratios and 95% confidence intervals.
Main Finding
Vitamin E supplementation had no effect on prostate cancer (HR: 0.99; 95% CI: 0.89–1.10) or total cancer (HR: 1.02; 95% CI: 0.95–1.10); vitamin C showed no effect on total cancer (HR: 1.02; 95% CI: 0.94–1.10) or prostate cancer (HR: 1.03; 95% CI: 0.93–1.15); no significant effects were found across subgroups or over time.
Confidence Level
High — large sample size, double-blind, placebo-controlled, intention-to-treat design, long follow-up (10.3 years), high adherence, and rigorous endpoint validation (96.9% confirmed by pathology).
Study Flags
Red Flags
- •Study population was highly educated, predominantly white male physicians — limits generalizability
- •Only synthetic forms of vitamins were tested — natural forms or different doses not evaluated
- •Post-trial follow-up was only 2.8 years — longer latency effects still possible
No biological mechanisms were identified in this study. This may be an epidemiological, observational, or survey-based study that reports associations rather than proposing causal biological pathways.
Surprising Findings
Vitamin C showed a statistically significant 46% reduction in colorectal cancer during post-trial follow-up (HR: 0.54, p=0.045), but not during the intervention period.
This contradicts the overall null finding and suggests a delayed effect—something no one expected from a simple vitamin.
Practical Takeaways
Stop spending money on vitamin E and C supplements for cancer prevention—your money is better spent on vegetables, exercise, or regular screenings.
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 582 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Human RCT
Subject
High probability
on the GRADE evidence scale
This study is like a super careful experiment where half the guys took vitamin pills and half took sugar pills, and no one knew who got what. After many years, they checked who got cancer and found no difference. So we can say these vitamins didn't change cancer risk in these men.
Minor conflicts detected — such as academic funding or advisory roles. These are common and have a small score impact.
Strengths
- Randomized, double-blind, placebo-controlled design
- Large sample size (14,641 participants)
- Long follow-up period (mean 10.3 years)
Weaknesses
- Study population is not representative of the general public (physicians, high SES)
- Only tested synthetic alpha-tocopherol and ascorbic acid at fixed doses
- No standardized cancer screening at baseline, possible undiagnosed cancers at enrollment
Methodology
Evidence Keywords
Statistical Reporting
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Scientists gave older male doctors either vitamin E, vitamin C, or fake pills for over 10 years to see if they helped prevent cancer.
Research results
1,373 men got prostate cancer and 2,669 got any cancer — but the vitamin E and C groups had almost exactly the same number as the placebo groups.
What this means - more context
The difference was so tiny it could be due to chance — taking these vitamins didn’t meaningfully raise or lower cancer risk.
This study tests whether long-term vitamin E or C supplementation affects cancer risk in healthy older men, directly challenging prior findings from the SELECT trial that suggested vitamin E increases prostate cancer risk.
In a 10.3-year randomized trial of 14,641 male physicians, 400 IU vitamin E every other day and 500 mg vitamin C daily showed no significant effect on prostate cancer, total cancer, or other site-specific cancers, even after extended post-trial follow-up.
Methods Used
Double-blind, placebo-controlled, 2×2×2×2 factorial randomized trial with 14,641 healthy male physicians aged ≥50; intervention lasted 7.6 years on average, with 2.8 additional years of post-trial observation; primary analysis used intention-to-treat and Cox proportional hazards models with hazard ratios and 95% confidence intervals.
Main Finding
Vitamin E supplementation had no effect on prostate cancer (HR: 0.99; 95% CI: 0.89–1.10) or total cancer (HR: 1.02; 95% CI: 0.95–1.10); vitamin C showed no effect on total cancer (HR: 1.02; 95% CI: 0.94–1.10) or prostate cancer (HR: 1.03; 95% CI: 0.93–1.15); no significant effects were found across subgroups or over time.
Confidence Level
High — large sample size, double-blind, placebo-controlled, intention-to-treat design, long follow-up (10.3 years), high adherence, and rigorous endpoint validation (96.9% confirmed by pathology).
Study Flags
Red Flags
- •Study population was highly educated, predominantly white male physicians — limits generalizability
- •Only synthetic forms of vitamins were tested — natural forms or different doses not evaluated
- •Post-trial follow-up was only 2.8 years — longer latency effects still possible
No biological mechanisms were identified in this study. This may be an epidemiological, observational, or survey-based study that reports associations rather than proposing causal biological pathways.
Surprising Findings
Vitamin C showed a statistically significant 46% reduction in colorectal cancer during post-trial follow-up (HR: 0.54, p=0.045), but not during the intervention period.
This contradicts the overall null finding and suggests a delayed effect—something no one expected from a simple vitamin.
Practical Takeaways
Stop spending money on vitamin E and C supplements for cancer prevention—your money is better spent on vegetables, exercise, or regular screenings.
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 582 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Human RCT
Subject
High probability
on the GRADE evidence scale
This study is like a super careful experiment where half the guys took vitamin pills and half took sugar pills, and no one knew who got what. After many years, they checked who got cancer and found no difference. So we can say these vitamins didn't change cancer risk in these men.
Minor conflicts detected — such as academic funding or advisory roles. These are common and have a small score impact.
Strengths
- Randomized, double-blind, placebo-controlled design
- Large sample size (14,641 participants)
- Long follow-up period (mean 10.3 years)
Weaknesses
- Study population is not representative of the general public (physicians, high SES)
- Only tested synthetic alpha-tocopherol and ascorbic acid at fixed doses
- No standardized cancer screening at baseline, possible undiagnosed cancers at enrollment
Methodology
Evidence Keywords
Statistical Reporting
Scoring
How strong is this study?
This study is super well-made because it randomly assigned people, kept everyone blind, followed them for over 10 years, and checked cancer diagnoses carefully. That means we can trust the results because there's little chance the findings were due to luck or bias.
40 / 100
- COI disclosure+40/40
- Data availabilitydata not shared
- Code availabilitycode not shared
100 / 100
- Randomization+20/20
- Blinding+15/15
- Control group+15/15
- Sample size (n=14641)+20/20
- Follow-up+10/10
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 582 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
This design can establish causation. This study can establish causation because it is a randomized controlled trial with double-blinding, placebo control, and intention-to-treat analysis. However, the lack of statistically significant results means we can only conclude that vitamin E and C supplementation does not cause a measurable change in cancer risk within this population and timeframe.
Minor COI
Minor conflicts that may slightly influence the study
The study received funding and study agents from industry sources, but the funder had no role in study design, data analysis, or publication, and authors are affiliated with academic institutions.
Funders
Conflict Details
National Heart, Lung, and Blood Institute: Supported by a K99/R00 grant (HL095649)
BASF Corporation: Provided study agents (vitamin E and C) and packaging; investigator-initiated grant recipient
Pfizer: Provided study agents (vitamin C) and packaging (formerly Wyeth, American Home Products, and Lederle)
DSM Nutritional Products Inc: Provided study agents (vitamin C) and packaging (formerly Roche Vitamins)
Brigham and Women's Hospital and Harvard Medical School: Authors are affiliated with academic institutions
Independent Analysis Safeguards
- Funder had no role in design, conduct, data analysis, or manuscript preparation
- Endpoints Committee reviewed cancer confirmations blinded to treatment assignment
- Statistical analyses conducted by academic authors using intention-to-treat principle
Although industry provided study agents and funding, the explicit disclaimer of funder involvement in study design and analysis, along with academic authorship and independent endpoint review, minimizes bias risk. The study's large scale, long follow-up, and rigorous methodology further support validity.
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
8 researchersIf this is your work, this is how we attribute it on Fit Body Science. Lu Wang is listed as the lead author.