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

Abstract

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 5 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 5 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.

Dietary Determinants of and Possible Solutions to Iron Deficiency for Young Women Living in Industrialized Countries: A Review

“…[76] found dietary calcium intake to be inversely associated with serum ferritin concentration, regardless of whether calcium was consumed with iron. Other studies, however, have found no association between iron status and calcium [47,48,49,50,54,56,57] or dairy product or milk intake [45,49,50,59,66]. It has been suggested that in some cases, the negative associations between iron status and calcium or dairy product intake may be due to the displacement of other foods from the diet (e.g., meat), rather than the inhibitory effect of calcium itself [48].…”

“…The majority of cross-sectional studies in young women have not found an association between total dietary iron intake and iron status [45,46,47,48,49,50,51,52,53,54,55,56,57,58,59]. Those studies showing a positive relationship included women aged 35 to 60 years [60], and a study which showed a positive relationship between iron intake and serum ferritin concentrations in smokers only [61].…”

“…Only a few studies have found no association between meat or heme iron intake and iron status [50,55,61]. These have included a study in Japanese women [50], a study in 80 university students from the United States [61], and data from women in the UK National Diet and Nutrition Survey [55]. …”

“…Although ascorbic acid is recognized as a powerful enhancer of iron absorption, the majority of studies in young women have not found any association between iron status and total daily ascorbic acid intake [45,46,47,48,49,50,53,56,57,60,61,67,72,73], or fruit and vegetable intake [50,54,59,60,74]. A study in females aged 35 to 69 years found a negative association between intake of fruit juice and iron status, but a positive association between ascorbic acid intake and iron status [54].…”

“…Despite the emergence of a potential role for β-Carotene and vitamin A in iron absorption [75], only one cross-sectional study has considered vitamin A intake and found no association with iron status [50]. …”