Comparison of magnesium amount in black, green, fruit, and herbal teas

The diet is the main source of minerals and trace elements, thus exposure to dietary essential elements has a direct impact on human health. Magnesium is a major component of the bones, but furthermore it influences the nervous system and muscle activity. Therefore its needs must be met via nutrition. There is a non-negligible discrepancy between intake and requirements. So magnesium is often uptaken in form of nutrition supplements. Thus there is an interest in the amount of magnesium in natural products, where it is supposed to vary. In this study, various commercially available tea bags of different kinds of tea (black tea, green tea, fruit tea and herbal tea) were analysed for their magnesium content. After a microwave assisted digestion with nitric acid and water at temperatures up to 220°C, the element concentration was measured with ICP-OES (inductively coupled plasma-optical emission spectroscopy) as it is a simultaneous, fast and reliable method with low detection limits. All samples were prepared in duplicate. In all samples high amounts of magnesium (approx. 1 g kg-1) could be found. No statistically significant differences were registered between the different classes of teas.