Iron intake does not significantly correlate with iron deficiency among young Japanese women: A cross-sectional study

Objectives: We evaluated the association of nutrient intake with Fe deficiency with regard to lifestyle factors and health condition in young Japanese women. Uniquely among developed countries, dietary habits render Japanese populations vulnerable to Fe deficiency, owing to their relatively low intake of Fe and high intake of Fe absorption inhibitors, such as green tea and soyabeans. Design: A cross-sectional study. Setting and subjects: The subjects were 1019 female Japanese dietetic students aged 18-25 years. Dietary habits during the preceding month were assessed using a previously validated, self-administered, diet history questionnaire. Blood analysis was performed to assess body Fe status. Subjects were categorized with Fe deficiency when their serum ferritin levels were <12 ng/ml. Twenty-nine dietary variables, i.e. intakes of energy, sixteen nutrients including Fe and twelve food groups, were analysed using multivariate logistic regression models adjusted for possible confounders. Results: Of the subjects, 24.5 % were categorized with Fe deficiency. However, no dietary factors assessed were significantly associated with Fe deficiency. The risk of Fe deficiency was significantly lower in women with infrequent or no menstrual cycles than in those with regular cycles (OR = 0.58; 95 % CI 0.34, 1.00) and significantly higher in women with heavy menstrual flow than in women with average flow, albeit that these were self-reported (OR = 1.83; 95 % CI 1.35, 2.48). Conclusions: These results suggest that dietary habits, including Fe intake, do not significantly correlate with Fe deficiency among young Japanese women.