Zinc, Selenium and Molybdenum Contents in Rice Grown on Lao PDR

Abstract

Rice is a staple food for East Asian and Southeastern Asian people. In particular, people in Lao PDR consume a large amount (180 kg/year/capita) of rice and are considered to be dependent on this cereal not only for energy intake but also for the intake of protein and several micro-nutrients including trace elements. However, there is no report on the content of trace elements in Laotian rice. In the present study, we determined zinc (Zn), selenium (Se) and molybdenum (Mo) contents in Laotian rice and compared them with other types of Asian rice. Thirteen polished rice samples were collected in 4 prefectures (Vientiane, Luang-Phabang, Xiangkouang and Champsak) of Lao PDR. Their Zn, Se and Mo contents were analyzed by atomic absorption spectrometry, fluorometry and inductively coupled plasma-mass spectrometry, respectively, and compared with those in Japanese (n = 4), Thailand (n = 3), Malaysian (n = 10), Indian (n = 2) and Pakistan (n = 1) rice. Zn content in Laotian rice was 13.2±2.3 μg/g (n = 13) and was higher than that in Japanese rice (10.5±2.0 μg/g) and Malaysian rice (6.2±2.2 μg/g). Se content in Laotian rice was 19±7 ng/g and was similar to that in Japanese (17±7 ng/g) and Malaysian rice (39 ±9 μg/g) but was lower than Thailand rice (39±8 ng/g). In contrast to Zn content, Mo content in Laotian rice (327±177 ng/g) was lower than that in Japanese (613±232 ng/g) and Malaysian (730±285 ng/g) rice. Based on the analytical results and consumption of rice in Lao PDR (500 g/day/capita), daily intakes of Zn, Se and Mo from rice in the Laotian population were estimated to be 6.6 mg/day/capita, 9.5 μg/day/capita and 164 μg/day/capita, respectively. These results indicate that rice is a principal source of Zn and Mo in the Laotian population.