Equisetum arvense is also known as mare’s tail, shave grass, joint grass, and is a plant consisting of leafless tubular rushes. The plant grows in moist soils, and it is known for its concentration of minerals, particularly of silica or silicon dioxide. As it may be expected, the principal ingredient of horsetail is silica, which is present in organic form such as silicic acid, and therefore more bioavailable than the inorganic mineral. Other active ingredients are flavoglucosides, saponins like equisetonin, alkaloids like nicotine and palustrine, tannins, and minerals like manganese, magnesium and potassium.
- Bone fortifier. This has been the traditional use of horsetail, especially to accelerate the healing of broken bones, since silica makes up part of the mucopolysaccharides or glycosaminoglycans with critical structural roles, essential for the integrity of the connective tissue of bone. Degeneration of bone with age, is linked to decreasing levels of silica in tissues. Silica works best when taken together with other bone building minerals like calcium, magnesium, boron and zinc.
- Diuretic. The saponins of silica are the second major group of ingredients of the herb, and they possess a mild diuretic effect. Therefore traditionally horsetail has been widely used for genito-urinary problems including inflammations, kidney stones, lithiasis, involuntary urination, nephritis, gout and prostate problems.
- Hair, skin and nail bolster. Silica is a major critical component not only of bone, but also of skin, hair and nails. Traditionally used for improving the appearance of hair and nails, horsetail was shown in clinical research that it measurably improves skin integrity and appearance.
- Immune booster. Silicic acid appears to stimulate an increase in white blood cells, thus helping to boost the immune system’s resistance to infection. In the past, tea made out of horsetail was given to patients with tuberculosis.
- Styptic. Horsetail also appears to possess styptic properties, and thereby helping to heal bleeding ulcers.
Caution. Although no toxic effects have been reported for normal internal or external use the herb should be avoided when on antihypertensive drugs, such as corticosteroids, digitalis, heparin, and lithium.