Dietary vitamin A intake and incidence of gastric cancer in a general Japanese population: the Hisayama Study.

Background: The results of prospective studies examining the association between dietary vitamin A intake and the risk of gastric cancer have often been conflicting. The objective of this study was to investigate this issue in a general Japanese population. Methods: A total of 2,467 community-dwelling Japanese subjects aged 40 years or older were followed up prospectively for 14 years. Dietary vitamin A intake was estimated using a semiquantitative food frequency method. Results: During the follow-up period, gastric cancer developed in 93 subjects. The age- and sex-adjusted incidence of gastric cancer rose progressively with increasing levels of dietary vitamin A intake: at 2.2, 3.0, 3.8, and 4.5 per 1,000 person-years for quartile groups defined by dietary vitamin A intake levels of <639, 639-837, 838-1,061, and >1,061 μg retinol equivalents (RE)/day, respectively ( P for trend <0.01). The risk of gastric cancer was significantly higher in the fourth quartile than in the first one even after multivariate adjustment [hazard ratio (HR) = 1.47, 95% confidence interval (CI) = 0.70-3.09, P = 0.30 for the second quartile; HR = 1.85, 95% CI = 0.82-4.18, P = 0.14 for the third quartile; HR = 2.96, 95% CI = 1.12-7.80, P = 0.03 for the fourth quartile]. Comparable effects of vitamin A intake were observed irrespective of the location or histological type of gastric cancer. The HR for gastric cancer increased significantly only in subjects with a combination of high vitamin A intake (>1,061 μg RE/day) and Helicobacter pylori infection. Conclusions: Our findings suggest that dietary vitamin A intake is clearly associated with the risk of gastric cancer in the general Japanese population. [ABSTRACT FROM AUTHOR]