If your skin, hair and nails need a boost, this formula from Nature’s Sunshine is your go-to. The unique ingredient of horsetail plant, also known as shavegrass, contains the highest amount of silica of all known herbs. Silica is found in connective tissues throughout the body and is important in the building and normal repair of healthy connective tissue. In addition to silicon, horsetail contains large amounts of flavonoids, quercetin, sterols and saponins.