Allium vegetables and garlic supplements do not reduce risk of colorectal cancer, based on meta-analysis of prospective studies

source extracted confidence: high 2026-04-09
#adult #aged #allium #colon #colorectal-neoplasms

Allium vegetables and garlic supplements do not reduce risk of colorectal cancer, based on meta-analysis of prospective studies

Zhu et al., 2014 | Clin Gastroenterol Hepatol | Meta Analysis

Citation

Zhu Beibei, Zou Li, ... Miao Xiaoping. Allium vegetables and garlic supplements do not reduce risk of colorectal cancer, based on meta-analysis of prospective studies. Clin Gastroenterol Hepatol. 2014-Dec;12(12):1991-2001.e1-4; quiz e121. doi:10.1016/j.cgh.2014.03.019

Abstract

BACKGROUND & AIMS: Laboratory studies have provided evidence that allium vegetables and garlic supplements might protect against colorectal cancer (CRC), but epidemiologic studies have produced inconsistent findings. METHODS: We conducted a meta-analysis of prospective studies evaluating the associations between allium vegetables, garlic supplements, and CRC risk. We pooled effect measures using fixed- or random-effect models, assessing the highest vs the lowest intakes. We used a dose-response regression model to evaluate the relationship between allium vegetable intake and CRC risk. RESULTS: Our analysis included 8 studies with 20 reports of the effects of allium vegetables (5458 patients with CRC including 7,125,067 person-years) and 5 studies with 11 reports of the effects of garlic supplements (2685 patients with CRC including 2,304,439 person-years). We found no association between higher intake of allium vegetables and CRC risk (relative risk [RR], 1.06; 95% confidence interval [CI], 0.96-1.17; P = .26). Intake of allium vegetables did not correspond to CRC risk (P for nonlinear = .24, P for linear = .20). In subgroup analysis, a higher consumption of allium vegetables was associated marginally with increased risk of colon cancer among women (RR, 1.23; 95% CI, 1.01-1.50; P = .05). Use of garlic supplements was associated significantly with an increased risk of CRC (RR, 1.18; 95% CI, 1.02-1.36; P = .03). CONCLUSIONS: In a meta-analysis, we found no evidence that higher intake of allium vegetables reduced the risk for CRC. We observed that garlic supplements increased the risk for CRC, but this finding requires external validation.

Key Findings

Our analysis included 8 studies with 20 reports of the effects of allium vegetables (5458 patients with CRC including 7,125,067 person-years) and 5 studies with 11 reports of the effects of garlic supplements (2685 patients with CRC including 2,304,439 person-years). We found no association between higher intake of allium vegetables and CRC risk (relative risk [RR], 1.06; 95% confidence interval [CI], 0.96-1.17; P = .26). Intake of allium vegetables did not correspond to CRC risk (P for nonlinea

Outcomes Measured

  • Requires manual extraction

Population

Field Value
Population crc including 7
Sample Size 5458
Age Range See abstract
Condition See abstract

MeSH Terms

  • Adult
  • Aged
  • Allium
  • Colon
  • Colorectal Neoplasms
  • Diet
  • Female
  • Garlic
  • Humans
  • Male
  • Middle Aged
  • Prospective Studies
  • Risk Assessment
  • Vegetables

Evidence Classification

  • Level: Meta Analysis
  • Publication Types: Journal Article, Meta-Analysis, Research Support, Non-U.S. Gov't
  • Vertical: garlic

Provenance

Source extracted via PubMed E-utilities API on 2026-04-09