Onion Consumption Linked to Lower Colorectal Cancer Mortality in Japan, New Study Finds
Tokyo, Japan – A nationwide ecological study in Japan suggests a correlation between increased onion shipment volume and decreased colorectal cancer mortality rates across the country’s prefectures. Researchers analyzing data from a nationwide health insurance claims database and agricultural statistics found that prefectures with higher per capita onion consumption exhibited lower age-adjusted colorectal cancer mortality rates.The study, published in Nutrition, adds to a growing body of evidence suggesting dietary factors play a significant role in colorectal cancer prevention.
the research, conducted by a team at Keio university School of Medicine, utilized data from 47 prefectures in japan spanning a 14-year period (2000-2014). Analyzing onion shipment volume per capita alongside age-adjusted colorectal cancer mortality rates, the study revealed a statistically significant negative correlation (r = -0.36,*P* < 0.01). This indicates that as onion shipment volume increased in a prefecture, the corresponding colorectal cancer mortality rate tended to decrease. The study controlled for potential confounding factors including red meat consumption, smoking rates, and socioeconomic status.
“Our findings suggest that increased onion consumption may be associated with a reduced risk of colorectal cancer mortality in japan,” stated dr. Kazuhiro Yoshida, lead author of the study and Professor of Gastroenterology at Keio University. “Onions are rich in quercetin, a flavonoid with known antioxidant and anti-inflammatory properties, and previous laboratory studies have demonstrated its potential to inhibit the growth of colorectal cancer cells.”
Colorectal cancer is a leading cause of cancer-related deaths worldwide, and Japan has experienced a rising incidence of the disease in recent decades, mirroring dietary shifts towards more Westernized eating patterns. The study’s findings are particularly relevant given Japan’s traditionally high onion consumption, and the potential for public health interventions promoting increased intake of this readily available vegetable.
Researchers caution that this is an ecological study, meaning it examines population-level data and cannot establish a direct causal link between onion consumption and reduced cancer mortality. Further research, including individual-level studies and clinical trials, is needed to confirm these findings and elucidate the underlying mechanisms. Though, the study provides compelling evidence to support the inclusion of onions as part of a dietary strategy for colorectal cancer prevention.
