Horsetail (Equisetum spp,) as a source of silicon supplement in human nutrition—a myth?

Horsetail (Equisetum arvense L.) has long been attributed to have relatively high contents of water-soluble silicon that could be of benefit for humans. Yet, no specific studies have investigated the silicon content of horsetail to determine silicon levels and availability. Our goal was to determine the silicon content of tea made from horsetail and the extractable silicon from the plants using the solvents hexane, dichloromethane, ethanol, methanol, water, and potassium hydroxide for comparison with the silicon levels in the whole plant. The results demonstrated that the level of silicon in the whole plant is approximately 5% whereas the maximum water-extractable silicon was only 0.3% of the plant. Indeed, the amount of extractable silicon from normal usage of horsetail tea is less than the silicon content present in one slice of bread. The conclusion from these studies is that the silicon from horsetail is not responsible for the health benefits attributed to the plant. [ABSTRACT FROM AUTHOR]