Randomised controlled trialcited by the Tayebat archiveabstract only checked★ key study A-SUP-04 in-depth review

CARET: beta-carotene and vitamin A raised lung cancer in smokers

Effects of a combination of beta carotene and vitamin A on lung cancer and cardiovascular disease.

Overview

Omenn GS et al.. N Engl J Med 1996 · PMID 8602180 · DOI 10.1056/NEJM199605023341802

Lung cancer was 28% more frequent with the supplements; the trial was stopped early.

Does the study support the specific claim? Yes · Methodological quality: high

Study explained simply

What did the researchers want to find out?: Prevent lung cancer?
How was the study done?: RCT.
How many people, animals or samples were studied?: 18,314 high-risk adults.
What was actually found?: More lung cancer, more deaths.
How large was the observed effect?: RR 1.28; 1.17.
What do the results mean in everyday life?: Smokers should avoid beta-carotene pills.
What are the study's limitations?: Early stopping.
What does it say about Elawady's specific claim?: Supports.
Do the results apply to Germany and Europe?: Applicable.
What can explicitly not be concluded from this study?: Effect in non-smokers.

Authors: Omenn GS, Goodman GE, Thornquist MD, Balmes J, Cullen MR, Glass A, Keogh JP, Meyskens FL, Valanis B, Williams JH, Barnhart S, Hammar S
Journal: N Engl J Med
Year: 1996
Identifier: PMID 8602180 DOI 10.1056/NEJM199605023341802
Verification: verified – PubMed E-utilities efetch, 2026-10-25
Retracted: no
Corrections: none
Extent checked: abstract only
Conflicts of interest and funding: not stated in abstract; grants: NCI NIH HHS

Do beta-carotene and retinol prevent lung cancer and CVD?

Study design: Randomised controlled trial – Multicentre, randomised, double-blind, placebo-controlled primary prevention trial (CARET)
Population: Smokers, former smokers, asbestos-exposed workers
Country: USA
Period: mean 4.0 years; stopped 21 months early
Sample size: 18,314
Inclusion and exclusion criteria: see abstract

Exposure / intervention: 30 mg beta-carotene + 25,000 IU retinyl palmitate daily
Comparator: Placebo
Endpoints: Lung cancer incidence; mortality
Statistical methods: RR with 95% CI

Results: Lung cancer RR 1.28 (1.04–1.57), P=0.02; death any cause RR 1.17 (1.03–1.33); lung cancer death RR 1.46 (1.07–2.00); CVD death RR 1.26 (0.99–1.61).
Absolute risks: not reported in abstract
Authors' conclusion: No benefit; may have had an adverse effect on lung cancer and on death from lung cancer, CVD and any cause.

See results.

None contradicting.

High: biology and trial populations comparable to European adults.

Strong evidence of harm in high-risk smokers.

Multidimensional assessment
Multidimensional assessment
Authenticity of the source	verified
Methodological quality	high
Risk of bias	low
Precision of results	moderate
Directness	direct
Reproducibility	replicated
Consistency with the overall evidence	consistent
Regional transferability	high
Adequacy of the interpretation (by the archive)	correctly reported

Note: according to the archive, the studies were compiled by the archive operators. Whether Dr. Elawady himself cited this study is not established.

What the archive says about the study: CARET stopped early after beta carotene plus vitamin A raised lung cancer (RR 1.28) and lung-cancer death (RR 1.46) in smokers.
A. What was actually studied?: Beta-carotene + retinol vs placebo.
B. What did the authors find?: RR 1.28 lung cancer; RR 1.17 all-cause death.
C. What conclusions do the authors themselves draw?: No benefit; possible harm.
D. What does the archive derive from it?: Used as evidence of harm.
E. Is this derivation scientifically justified?: Yes; correct.
Adequacy of the interpretation (by the archive): correctly reported