Copyright ©The Author(s) 2019. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Oct 21, 2019; 25(39): 6025-6040
Published online Oct 21, 2019. doi: 10.3748/wjg.v25.i39.6025
Allicin as add-on therapy for Helicobacter pylori infection: A systematic review and meta-analysis
Xiao-Bei Si, Xu-Min Zhang, Shuai Wang, Yu Lan, Shuo Zhang, Lin-Yu Huo
Xiao-Bei Si, Xu-Min Zhang, Shuai Wang, Yu Lan, Department of Gastroenterology, Beijing Jishuitan Hospital, Beijing 100035, China
Shuo Zhang, Department of Cardiology, Fu Wai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences, Beijing 100037, China
Lin-Yu Huo, Department of Neurology, Beijing Haidian Hospital, Beijing 100080, China
Author contributions: Si XB, Lan Y, and Zhang S performed study design; Si XB and Zhang S performed study selection; Si XB and Wang S performed data collection; Si XB, Zhang XM, and Huo LY performed data analysis; Si XB performed manuscript drafting; Lan Y performed critical review of the manuscript. All authors revised the manuscript and approved the final version.
Supported by BeiJing JiShuiTan Hospital Foundation for Young Scholars, No. QN-201906.
Conflict-of-interest statement: There is no conflict of interest associated with any of the senior author or other co-authors who contributed their efforts in this manuscript.
PRISMA 2009 Checklist statement: The authors have read the PRISMA 2009 Checklist, and the manuscript was prepared and revised according to the PRISMA 2009 Checklist.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Corresponding author: Yu Lan, MA, Professor of Internal Medicine, Chief, Department of Gastroenterology, Beijing Jishuitan Hospital, No. 31, Xinjiekou East Street, Beijing 100035, China.
Telephone: +86-10-58398289
Received: August 1, 2019
Peer-review started: August 1, 2019
First decision: August 27, 2019
Revised: September 16, 2019
Accepted: September 27, 2019
Article in press: September 27, 2019
Published online: October 21, 2019

Allicin (2-propene-1-sulfinothioic acid S-2-propenyl ester, diallyl thiosulfinate) extracted from garlic, has proven activity against Helicobacter pylori (H. Pylori) infection. In recent years, clinical trials have explored its utility as an add-on therapy with variable outcomes reported.


To perform a systemic review of allicin as an add-on treatment for H. Pylori infection and assess its efficacy in randomized controlled trials (RCTs).


Electronic databases including MEDLINE, EMBASE, the Web of Science, the Cochrane Database, the China National Knowledge Infrastructure Database, Chinese VIP Information Databases, Chinese Medical Databases, and the Wan-Fang Database were searched for keywords including “allicin”, “Helicobacter pylori”, “randomized clinical trials”, and their synonyms. A meta-analysis was performed using the fixed-effects model for low heterogeneity and the random-effects model for high heterogeneity with sensitivity analysis. Bias was evaluated using Egger’s tests. Trial sequential analysis (TSA) was used to evaluate information size and treatment benefits. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) was used to assess the level of quality, and studies were classed as “high quality”, “moderate quality”, “low quality”, and “very low quality”.


A total of eight RCTs consisting of 867 participants (435 from the allicin group and 432 from the control group) were included. Eradication rate in the allicin group (93.33%, 406/435) was significantly higher than that of the control group (83.56%, 361/432) [I2 = 0%, odds ratio (OR) = 2.75, 95% confidence interval (CI): 1.74-4.35, P < 0.001]. The healing rate of ulcers following H. pylori therapy in the allicin group (86.17%, 349/405) was significantly higher than that of the control group (75.87%, 305/402) [I2 = 0%, OR = 2.05, 95%CI: 1.39-3.03, P < 0.001]. The total remission rate of peptic ulcers across all allicin groups was 95.99%, which was significantly higher than that of controls [95.99% (359/374) vs 89.25% (332/372), I2 = 0, heterogeneity P = 0.84, OR = 3.13, 95%CI: 1.51-6.51, P =0.002]. No significant differences in side effects were observed. TSA suggested that the trials were of sufficient standard to draw reliable conclusions. The quality of outcomes including eradication rates and side effects was graded as “very low” due to downgrades for “risk of bias” and “indirectness”. Other outcomes such as ulcer healing rates and total ulcer remission rates were graded as "low" due to downgrades for “risk of bias”.


Allicin as an add-on therapy improves H. pylori eradication, healing of ulcers, and remission of symptoms. These results are suggested to be treated with caution due to limited quality.

Keywords: Allicin, Helicobacter pylori, Randomized controlled trials, Add-on therapy, Systematic review, Meta-analysis

Core tip: The present systematic review assessed the efficacy and safety of allicin as an add-on treatment to PPI triple therapy and bismuth containing quadruple therapy for Helicobacter pylori infection. As a result, allicin was confirmed to increase the eradication rate, healing rate of ulcers, and remission rate of digestive symptoms but not rate of side effects.