Mushroom consumption and risk of gastric cancer: a pooled analysis within the stomach cancer pooling project and a combined meta-analysis with other observational studies.

Edible mushrooms have high concentrations of vitamins and minerals. They are considered 'functional foods' for their disease-prevention properties. Mushroom consumption may reduce the risk of gastric cancer, the fifth most common cancer worldwide. We investigated the association between mushroom consumption and gastric cancer risk in a pooled analysis within the Stomach Cancer Pooling (StoP) Project and in a meta-analysis that also included previously published studies. A total of 3900 gastric cancer cases and 7792 controls from 11 studies were included in the StoP analysis. Mushroom consumption was measured using food frequency questionnaires. Higher mushroom consumption was associated with a lower risk of gastric cancer [relative risk (RR) for the highest vs. lowest consumption categories, 0.82; 95% confidence interval (CI), 0.71-0.95]. The corresponding RRs were 0.59 (95% CI, 0.26-1.33) in a meta-analysis of four previously published studies and 0.77 for all studies combined (95% CI, 0.63-0.95; n = 15 studies). In geographic subgroup analysis, the pooled risk in Western Pacific countries was (RR, 0.59; 95% CI, 0.40-0.87; n = 6). The stronger effect in Asian countries may reflect high level of antioxidants in mushroom species consumed in Asia.