Flavonoid consumption and esophageal cancer among black and white men in the United States
Flavonoids and proanthocyanidins are bioactive polyphenolic components of fruits and vegetables that may account for part of the protective effect of raw fruit and vegetable consumption in esophageal cancer. We studied the relationship between esophageal cancer and dietary proanthocyanidins, flavonoids and flavonoid subclasses (anthocyanidins, flavan-3-ols, flavanones, flavones, flavonols and isoflavonoids) using recently developed USDA and Tufts flavonoid and proanthocyanidin databases. The study was a population-based, case-control analysis of 161 white men with esophageal adenocarcinoma (EAC), 114 white and 218 black men with esophageal squamous cell carcinoma (ESCC) and 678 white and 557 black male controls who lived in 3 areas of the United States. Neither total flavonoid nor proanthocyanidin intake was associated with EAC and ESCC in either white or black men. In white men, inverse associations were observed between anthocyanidin intake and EAC (4th vs. 1st quartile odds ratio [OR], 0.47, 95% confidence interval [CI], 0.24-0.91; ptrend = 0.04) and between isoflavonoid intake and ESCC (4th vs. 1st quartile OR, 0.43, 95% CI, 0.20-0.93; ptrend = 0.01). None of the associations remained significant after adjusting for dietary fiber, which is strongly correlated with flavonoid consumption. We conclude that total flavonoids and proanthocyanidins do not have strong protective effects in either EAC or ESCC. Some protective effects were evident in flavonoid subclasses and population subgroups. In white men, foods rich in anthocyanidins may have chemopreventive effects in EAC and those rich in isoflavonoids may do so in ESCC.