農作物中の元素の濃度分布に関する検討 [in Japanese] Distribution of elements in agricultural products [in Japanese]
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Agricultural products are major dietary sources of minerals, or trace elements. In this study, we measured the levels of inorganic elements in agricultural products available in Kanagawa prefecture, Japan, from home-grown and store-bought vegetables to locally-harvested shiitake mushrooms, using instrumental neutron activation analysis. The present measurements focused on eight nutritionally essential elements (Mg, Ca, Cr, Mn, Fe, Zn, Na, and K), for which recommended intake levels have been established in Japan, and nine other elements (Al, Sc, Co, Rb, Sr, Cs, Ba, Cl, and Br). The data are summarized in Tables 6-8 by the type of vegetable. With regard to the nutrient elements, the measured values for each vegetable were compared to the reference values listed in the Japanese food composition tables (Standard Tables of Food Composition in Japan, 5<sup>th</sup> revised and enlarged edition, 2009; Kagawa Nutrition University Publishing Division). The measured values for several elements (e.g., Mg and Ca) were comparable to their reference values, and those for other nutrient elements were also approximated to the reference values. The Mn contents in the sampled green leaf vegetables were slightly lower than the reference values, while the Fe contents in certain types of vegetable differed markedly from the reference values over a range from less than 30%- to more than 3-fold. For most inorganic elements, including Fe, their levels in the produce varied quite widely both within and between the varieties of vegetable, with Maximum/Minimum value became 100 times or more for non-nutrient elements (e.g., Sc and Cs) that were usually found at an extremely low concentration (10<sup>-3</sup>mgkg<sup>-1</sup>). When examined in terms of food groups, leafy vegetables in the "green and yellow vegetables" group, particularly spinach, shungiku (Garland chrysanthemum), and mulukhiya, contained a larger amount of the nutrient and non-nutrient elements compared to the produce categorized in the "other vegetables" group such as daikon radish, burdock root, and fuki (Japanese butterbur). The Br content tended to be low in home-grown vegetables. Considering that the restriction of methyl bromide use was introduced shortly before the time of sample collection, the commercial vegetables analyzed in this study might contain a higher amount of Br residue compared to their home-grown, pesticide-free counterparts. The Fe content of spinach showed a strong positive correlation with the Sc and Al contents, suggesting that the three elements were transferred from soil, which abundantly contains them, and that a considerable variation in the levels of Fe, Sc, and other elements in produce could be attributed to the difference in the composition of soil in which the produce was grown. In shiitake mushrooms, which are known to accumulate an increased concentration of radioactive Cs (such as <sup>137</sup>Cs), the Cs level was specifically and markedly higher compared to other produce. similar results were obtained for Rb, and a strong positive correlation was noted between the Cs and Rb contents of shiitake mushrooms, suggesting that these elements may go through a similar process when they are transferred to the mushrooms. Contribution to the daily intake elements that depended in agricultural products was calculated from the result of the analytical value of agricultural products in this work and amount of farm products that Japanese woman takes in a day (2007). Potassium is the highest intake from agricultural products for Japanese amount of the dietary reference intakes. Hereafter, it was the order of Mg, Fe, Zn and Ca.
- Japanese Journal of Food Chemistry and Safety
Japanese Journal of Food Chemistry and Safety 16(3), 123-136, 2009
Japanese Society of Food Chemistry