Estimation of iron requirements for women by numerical analysis of population-based data from the National Health and Nutrition Surveys of Japan 2003-2007.
Iron requirements were estimated from the results of the National Health and Nutrition Surveys of Japan 2003-2007 using the numerical analysis of requirements based on an integral equation. The numerical analysis used population-based data on iron nutriture, the prevalence of inadequate iron status, and the distribution of iron intakes. The cutoff value for inadequate iron status was defined as a serum ferritin concentration <30ng/mL. Iron intakes and menstrual blood losses followed a log-normal distribution and published values were corrected accordingly to calculate usual values. For women aged 18-29 years old, the median of the estimated median iron requirement (corresponding to the estimated average requirement by using the terminology of the dietary reference intakes) was 7.59mg (range, 6.86-8.11). The median of the estimated usual iron intake covering the needs of women with 80mL per cycle of menstrual blood loss was 11.27mg (range, 10.16-12.00), and the median of the usual iron intake covering the needs of 97.7% of women was 13.93mg (range, 12.55-14.81). For women aged 30-49 years old, the corresponding figures were 8.13mg (range, 7.96-8.69), 11.95mg (range, 11.72-12.77), and 14.71mg (range, 14.44-15.72).