Comparison of lithium levels between Japanese and foreign mineral waters

Abstract

Purpose: To measure the lithium levels of mineral waters and compare those of Japanese mineral waters to foreign ones. Methods: The lithium levels of Japanese mineral waters, foreign mineral waters, and Japanese tap waters were compared using the Kruskal-Wallis test due to a skewed distribution. Results: As a whole, there was a significant difference between the 3 groups. Post hoc comparison by Bonferroni correction revealed that the lithium levels of foreign mineral waters were significantly higher than Japanese mineral waters and tap waters, though there was no significant difference between Japanese mineral waters and tap waters. Discussion: The present findings indicate that foreign mineral waters may have higher lithium levels than Japanese mineral waters and tap waters. In future studies, it is desirable to consider which type of mineral waters (Japanese or foreign) the residents drink, for adjustment of the analytic data of any potential lithium effect on suicide rates and other mental states.