Riboflavin deficiency and esophageal cancer: A case control-household study in the Caspian Littoral of Iran

Background: In a case-household-control-household study in two very high and low esophageal cancer (EC) risk regions of the Caspian Littoral of Iran, a total of 21 cases (12 subjects from the high risk and 9 subjects from the low-risk region) with a total of 91 household members (57 subjects from the high risk and 34 subjects from the low-risk region) were investigated. Cases were matched for sex and age (±5 years) with non-blood relative controls. Methods: A standard 24-h dietary recall questionnaire was used to estimate riboflavin intake. The erythrocyte glutathione reductase activity coefficient (EGR-AC) was measured to assess riboflavin status. The Student t-test was used to test differences, and χ2 analysis was applied to test associations. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were also calculated. Results: Results indicated that in both regions, the mean daily intake of riboflavin for cases was less than that of the controls (0.66 ± 0.43 mg/day versus 0.82 ± 0.37 mg/day) whereas for their households, it was virtually the same. Both cases and control households showed riboflavin deficiency in two regions, with higher deficiency in the high risk area. Statistical analysis revealed significant differences between the two regions for EGR-AC (P < 0.001). Odd ratios indicated that the risk of developing EC for persons living in riboflavin-deficient households was more than twice of non-deficient households. Conclusion: Therefore, this study suggests that riboflavin deficiency may play an important role in the etiology of esophageal cancer in the Caspian Littoral of Iran.