Rabu, 3 Oktober 2012
Withania somnifera (Ashwagandha) has historically been used as a strengthening herb. One of the common names for W. somnifera is Indian ginseng. This hints at its restorative properties. In fact, ashwagandha has historically been used in individuals who are debilitated and who suffer from nervous exhaustion, emaciation and anemia. In these individuals, ashwagandha is helpful in convalescence after acute illness or stress, impotence, chronic disease with inflammation and bony degeneration, as a general tonic, for hypertension and high cholesterol.
Ashwagandha has been shown to have immunostimulatory, anticarcinogenic, and radiosensitizing effects in preclinical studies. Immunostimulatory effects in chemotherapy induced immunosuppression in mice were seen at a dose that corresponds to 4-6 g per day in humans. When ashwagandha was combined with cyclophosphamide, it prevented myelosuppression, resulted in a significant increase in hemoglobin concentration, red blood cell count, white blood cell count, platelet count and body weight as compared with untreated (cyclophosphamide only) mice.
Withaferin A, a constituent of ashwagandha, has been shown to have anti-angiogenesis effect in-vitro in human umbilical vein endothelial cells (HUVEC). It also appears to have antineoplastic effect on animal models and human cell lines.
Perhaps the most interesting indication for ashwagandha is its radiosensitizing properties. At least five in-vivo animal studies have confirmed a radiosensitizing effect of ashwagandha in mice. The mice that received the ashwagandha experienced increased tumor cure, growth delay of partially responding tumors and prolonged survival over radiation.
In lab studies, ashwagandha has been shown to be safe in doses up to 100 mg per kg of body weight in a single dosage. This is equivalent to 21 gm per day in an average adult man. The therapeutic dosage recommended by naturopathic physicians in most cases is under 10 gm per day.
Despite promising pre-clinical studies there is insufficient clinical oncology trial data of ashwagandha to recommend its use during chemotherapy or radiation. Naturopathic physicians, Ayurvedic physicians, and integrative oncologists sometimes prescribe ashwagandha in the post-chemotherapy setting.