Verdict No. 3060 · Search date 2026-09-08 · Methodology v1.0
Long-term factorial supplementation with garlic extract plus steam-distilled garlic oil,
does it really help with Reduction of gastric-cancer incidence?
30-Second Summary
D
Evidence Grade D · 34 · Safety caution
This is a null verdict for incidence only; gastric-cancer mortality belongs on a separate page.
Caution. This was years of concentrated garlic extract plus oil; bleeding, gastrointestinal effects, and interactions should not be equated with ordinary food intake.
What the
research showsGrade D with 34 points. After 7.3 years of supplementation and follow-up to 22.3 years, the randomized factorial estimate for gastric-cancer incidence was OR 0.81 (95% CI 0.57-1.13), a null result. Gastric-cancer mortality HR 0.66 (0.43-1.00) is a separate endpoint.
research showsGrade D with 34 points. After 7.3 years of supplementation and follow-up to 22.3 years, the randomized factorial estimate for gastric-cancer incidence was OR 0.81 (95% CI 0.57-1.13), a null result. Gastric-cancer mortality HR 0.66 (0.43-1.00) is a separate endpoint.
What the
ads claimIt should not be claimed to prevent gastric cancer or credited with the H. pylori-treatment effect.
ads claimIt should not be claimed to prevent gastric cancer or credited with the H. pylori-treatment effect.
Useful facts when choosing a product
- This verdict applies only to the displayed formulation, route, dose, duration, population, endpoint, and comparator.
- Raw garlic, powder, garlic oil, stabilized-allicin products, aged garlic extract, black garlic, fermented garlic, and isolated S-allylcysteine are not interchangeable.
- Caution. This was years of concentrated garlic extract plus oil; bleeding, gastrointestinal effects, and interactions should not be equated with ordinary food intake.
Chamgap Semantic Classification Code
Permanent code issued
S.garlic-extract-oil.oral.gastric-cancer-incidence.reduce.factorialSupplements and nutraceuticals > Garlic extract plus oil > Oral > Gastric-cancer incidence > Reduction claim > Randomized factorial placebo
Issued so the null incidence result remains retrievable; gastric-cancer mortality and H. pylori eradication are separate. The code identifies the intervention and claim; it never contains the evidence grade, score, or safety result.
Exact Claim Classification
These independent facets prevent evidence from different forms, routes, populations, effects, and comparators from being mixed.
| Intervention class | S · Supplement or nutraceutical |
|---|---|
| Canonical ingredient or intervention | Garlic extract plus garlic oil |
| Source or part used | Clove-derived extract and essential oil from Allium sativum L. |
| Formulation or processing | Combined garlic extract and steam-distilled garlic oil supplementation |
| Route | Oral |
| Dose | Trial-specified garlic extract and oil; exact daily milligrams require full-text confirmation |
| Duration | 7.3 years of treatment in 1995-2003; follow-up through 2017 (22.3 years) |
| Population | 3,365 residents of Linqu, Shandong, a high-risk region for gastric cancer |
| Effect or condition | Lower gastric-cancer incidence |
| Primary endpoint | Cumulative gastric-cancer incidence during follow-up |
| Comparator | Garlic-factor placebo under the factorial contract adjusting for H. pylori and vitamin assignments |
| Duplicate-detection key | Garlic extract plus garlic oil|Combined garlic extract and steam-distilled garlic oil supplementation|Oral|3,365 residents of Linqu, Shandong, a high-risk region for gastric cancer|Lower gastric-cancer incidence|7.3 years of treatment in 1995-2003; follow-up through 2017 (22.3 years) |
Gap Measurement · Verdict 3060 · D 34
What the research actually shows
The Shandong trial's 2×2×2/2×2 structure, 151 incident cancers, and 94 gastric-cancer deaths were checked separately.
Why this is classified as D (34)
A large, long, independently funded hard-endpoint trial with low structural bias is strong, but E0 governs and yields D/34.
Counterpoint. The mortality signal leaves a long-term hypothesis but cannot replace the distinct incidence endpoint and analysis.
Rejudgment record. Independent Codex cross-check — One formulation, route, population, claim, principal endpoint, and comparator
Scoring profile behind this grade
| Endpoint | H | Hard endpoint - actual events such as death |
| Replication | R1 | Single confirmatory trial |
| Independence | I2 | Decisive evidence is publicly or non-profit funded |
| Effect size | E0 | Null |
| Precision | C0 | The confidence interval leaves room for benefit |
The scoring table and the verdict agree (D).
Cross-check — AI research and Codex final gate
AI was used for research and drafting. Blind grading, adversarial audit, and the methodology boundary rules were then reapplied before Codex performed the final evidence, grade, copy, and build checks. If a grade cannot be narrowed, both evidence positions and their reasons are published.
Evidence Table
| Study | Design | Sample | Funding | Endpoint | Result | Weight |
|---|---|---|---|---|---|---|
| Effects of Helicobacter pylori treatment and vitamin and garlic supplementation on gastric cancer incidence and mortality: follow-up of a randomized intervention trial | The cited design, allocation, masking, endpoint hierarchy, and analysis limitations were independently checked. | 151 | Funding, product support, employee authorship, and declared conflicts were assessed separately. | The principal endpoint contract is preserved; secondary outcomes remain separate. | Verified estimates are preserved; missing confidence intervals or event counts were not invented. | Evidence weight reflects directness, formulation match, endpoint hierarchy, and reporting limitations. |
Receipt — 1 References
All 1 cited sources were verified for existence at the original page (as of 2026-09-08).
Li WQ et al. BMJ. 2019;366:l5016. PMID: 31511230. PMCID: PMC6737461. DOI: 10.1136/bmj.l5016. NCT00339768.
checkedResearch and draft: AI used · Cross-check: blind grading and adversarial audit
Final verification and publication gate: Codex · Verification cutoff: 2026-09-08 · Corrections: none
Final verification and publication gate: Codex · Verification cutoff: 2026-09-08 · Corrections: none
Cite this verdict
[Chamgap] Garlic Supplementation for Gastric-Cancer Incidence—No Significant Reduction in 3,365 Randomized Participants With Long Follow-Up — Evidence Grade D·34. 1 cited sources checked. Source: https://chamgap.com/en/verdicts/gut/garlic-supplementation-gastric-cancer-incidence-shandong/ · CC BY 4.0CC BY 4.0 — free to use with attribution; do not distort grades, numbers, or verdict meaning.
What this document does and does not do
Chamgap is an information source. It reports what research has and has not confirmed; it does not tell readers what to take or buy. That decision belongs to readers and, when needed, medical or legal professionals. This verdict reflects literature available up to the search date and may change as new research appears. Nothing here is medical advice.