Horsetail is rich in silicic acid and silicates, which provide approximately 2–3% elemental silicon. Potassium, aluminum, and manganese, along with fifteen different types of flavonoids, are also found in this herb. The presence of these flavonoids, as well as saponins, is believed to cause the diuretic effect, while the silicon content is thought to exert a connective tissue-strengthening and anti-arthritic action. Some experts have suggested the element silicon in horsetail is also a vital component for bone and cartilage formation. Anecdotal reports suggest that horsetail may be of some use in the treatment of brittle nails.