Dietary intake of essential minor and trace elements from Asian diets

In view of the limited data available from the Asian region on the daily intake of nutritionally essential trace elements, a study was taken up, as part of a coordinated research project of the International Atomic Energy Agency, to estimate the daily dietary intake and organ content of some selected trace elements of importance in radiation protection, and also in nutrition. Nine Asian countries--Bangladesh, China, India, Indonesia, Japan, South Korea, Pakistan, Philippines, and Vietnam--which represented more than 50% of the world's population, participated in this study. Analysis of about 700 diet samples was carried out for four minor (calcium, potassium, magnesium, and sodium) and eight trace (chromium, cobalt, copper, iron, iodine, manganese, selenium, and zinc) elements using nuclear and other sensitive analytical methods employing neutron activation analysis (NAA), inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma atomic emission spectrometry (ICP-AES), and atomic absorption spectrometry (AAS) techniques. These samples consisted of the total cooked diet, market basket, duplicate diets, and 225 staple foods. Emphasis was placed on the quality assurance and harmonization of the sampling techniques to ensure quality data. Significant inter- and intra-country variations in daily dietary intake of various trace elements were observed. The maximum inter-country variation was observed for iodine intake (factor of more than 45), being highest for Japan and lowest for Pakistan. For iron, an important trace element, the variation between the intakes was by a factor of four being lowest for Vietnam and highest for Pakistan.