Preserved vegetable consumption and gastrointestinal tract cancers: A prospective study.

Background: This study aimed to assess the associations of two common types of preserved vegetables in China, salted and sour pickled vegetables, with the risk of gastrointestinal tract (GI) cancers, including oesophageal cancer, stomach cancer, and colorectal cancer. Methods: The China Kadoorie Biobank collected intake frequency of preserved vegetables among 510 143 adults without self-reported cancer during 2004-2008, and followed up till 31 December 2018. The second resurvey further collected intake frequencies of salted and sour pickled vegetables, which classified the 10 study areas into three types of regions, including the regions never/rarely consuming preserved vegetables (number of participants at baseline = 201 844), mainly consuming salted vegetables (n = 202 927), and mainly consuming sour pickled vegetables (n = 105 372). Cox proportional models were respectively performed to calculate hazard ratios (HRs) for GI cancers with preserved vegetables in the latter two types of regions among baseline participants. Results: In the regions mainly consuming salted vegetables, preserved vegetable consumption was positively associated with stomach cancer (HR = 1.17; 95% confidence interval = 1.00-1.37; P for trend = 0.039). In the regions mainly consuming sour pickled vegetables, a dose-response positive relationship was observed between preserved vegetable consumption and the risk of oesophageal cancer (P for trend = 0.013), with adjusted HR of 1.35 (95% CI 1.02-1.80) for those who daily consumed compared with never consumed. Conclusions: Our findings suggest that different types of preserved vegetables might have different effects on GI cancers, and limiting preserved vegetable consumption might be protective against developing GI cancers.