Causal relationship of garlic or onion with gastric cancer based on a Mendelian randomization study

Area of Science:

• Gastroenterology
• Oncology
• Nutritional Epidemiology

Background:

• Observational studies suggest a link between garlic/onion consumption and reduced gastric cancer (GC) risk.
• Mendelian randomization (MR) offers a robust method to investigate causal relationships, minimizing confounding factors.

Purpose of the Study:

• To investigate the potential causal relationship between garlic/onion intake and gastric cancer (GC) risk using MR analysis.
• To evaluate the specific impact of garlic and onion consumption on GC development.

Main Methods:

• Utilized single nucleotide polymorphisms (SNPs) associated with garlic and onion intake as instrumental variables for MR analysis.
• Employed the inverse variance weighted (IVW) method, supplemented by MR-Egger, weighted median, simple mode, and weighted mode analyses.
• Conducted sensitivity analyses including Cochran's Q test, pleiotropy tests, and leave-one-out methods to ensure result robustness.

Main Results:

• The IVW method indicated a significant inverse association between garlic intake and GC risk (OR = 0.70, 95% CI: 0.49-0.99, P = 0.046).
• No significant causal relationship was observed between onion intake and GC risk.
• Sensitivity analyses confirmed the robustness of the findings regarding garlic's effect on GC.

Conclusions:

• Garlic consumption may play a protective role in reducing the risk of gastric cancer (GC).
• These findings suggest garlic as a potential dietary strategy for GC prevention and management.
• Further research could explore mechanisms underlying garlic's chemopreventive effects against GC.