Duplicate portion sampling gives the most accurate iron intake estimate: Implications for iron status of female students

Abstract. Iron deficiency (ID) is one of the most common nutritional problems in the developing world, affecting primarily women of childbearing age. Poor dietary iron intake is a major reason of ID. Accurate measurement of iron intake is of crucial importance to combat the problem. The daily dietary iron intake of 67 female students aged between 20-30 years (a mean BMI of 21.8±3.4 kg/m2) was evaluated using three assessment methods: atomic absorption spectrometry of 3-day food duplicate samples, and food composition tables (FCTs) in combination with either food frequency questionnaire (FFQ) or dietary records. Iron status was examined using hematological and biochemical tests. The dietary iron intake determined by duplicate portion sampling (DPS; 4.12±1.84 mg/day) was significantly lower than the FCT-based estimates ( P<0.001), and it was less than ¼ of the recommended dietary allowance of 18 mg/day. No significant correlation was found between DPS technique and FCT-based assessment methods. Fifty percent of the participants had small or depleted iron stores (serum ferritin< 30 ng/mL), but only 4.5% had ID anemia (serum ferritin< 12 ng/mL and hemoglobin<12 g/dL). Dietary iron intakes and FFQ-based intakes of vitamin C were not significantly correlated with all the investigated hematological parameters. In order to take some steps toward more practical approaches to combat this health problem, development of an accurate iron intake assessment seems to be the first priority. In this regard, improvement and validation of national FCTs would be a promising solution.