Ashwagandha (Withania somnifera)
Ashwagandha is a popular Ayuvedic herb. Studies show that it has anti-inflammatory effects. Ashwagandha also relaxes the central nervous system in animals. Laboratory studies found that ashwagandha kills some cancer cells and enhances some immune cells possibly by damaging the cancer cells’ ability to generate the energy it needs to reproduce. Ashwagandha also reduces the level of an important antioxidant in tumor cells, which may enhance the ability of radiation therapy to kill those cells. However, this herb may induce abortion, so pregnant women should not use it.
Uses
- To treat cancer
Ashwagandha has shown promise in animal and laboratory experiments, but further studies in humans are needed to support its use in cancer treatment. Ashwagandha reduced the growth of breast, central nervous system, colon, and lung cancer cells without affecting normal cells. Ashwagandha was also shown to prevent chemotherapy-induced neutropenia in mice In a small study of breast cancer patients, it alleviated chemotherapy-induced fatigue and improved quality of life. Larger trials are needed to confirm these observations. - To treat diabetes
Studies in laboratory animals suggest that ashwagandha may improve type 2 diabetes. - To reduce fatigue
Ashwagandha has been shown to increase blood cell counts in the lab; however, it is unclear if this will reduce fatigue in humans. - To reduce pain
A clinical trial suggests that a standardized water extract of ashwagandha may produce benefit in patients with knee joint pain. Mild side effects like nausea and gastritis were observed in a few patients. - To treat rheumatoid arthritis
A clinical trial showed that a compound of herbs and minerals containing ashwagandha reduced the pain of rheumatoid arthritis. Because the formula contained multiple herbs and minerals, whether ashwagandha played a role in the reduction in pain severity and disability is unclear. - As a sedative
Ashwagandha has been shown to have a tranquilizing effect in animal studies.
Mechanism of Action
Alkaloids, steroidal lactones, saponins, and withanolides are thought to be the biologically active components of ashwagandha. Studies have pointed to cyclooxygenase (COX) inhibition as the mechanism for the herb’s anti-arthritic effects. In animal studies, ashwagandha’s anti-inflammatory activity was comparable to hydrocortisone. It exhibits antioxidant effects in the brain, and tranquilizing effects on the central nervous system in animals possibly by influencing GABA receptor function. Withanolides in the roots and leaves are considered similar to steroids in their biological activities. Triethylene glycol, a compound isolated from the leaves, was identified an active sleep-inducing component in a murine model, and may potentially be used to relieve insomnia.
Ashwagandha may inhibit tumor growth and increases cytotoxic T lymphocyte production. In vitro studies have shown that root extracts have cytotoxic properties against lung, colon, central nervous system, and breast cancer cell lines. Withaferin A induces reactive oxygen species (ROS) generation and disruption of mitochondrial function in a human leukemia cell line, thereby inducing apoptosis. In estrogen receptor-positive (ER+) and negative (ER-) breast cancer cells, withaferin A induces apoptosis (cell death) and decreased tumor size. Withianone also exerts anticancer activity by binding to the TPX2-Aurora A Complex. Other studies show ashwagandha’s cytotoxicity is related to its structure; it enhances ATPase and inhibits succinate dehydrogenase activities, impairing oxidative phosphorylation.
In animal studies, ashwagandha enhanced the effects of radiation therapy by reducing tumor GSH levels. It was also shown to reverse paclitaxel-induced neutropenia in mice.
No significant interactions have been reported between ashwagandha and either CYP3A4 or CYP2D6 enzymes in human liver microsomes.
Dosage
The lowest effective dose for acute usage of ashwagandha, and perhaps the most cost-effective dose, is 300-500 mg. The optimal dose is 6,000 mg a day usually divided into three doses (2,000 mg) and while 300-500 mg is effective for most situations a lower dose of 50-100mg can be seen as effective in few instances such as reducing the immunosuppression seen with stress and augmenting anxiolytic (anxiety reducing agents). Ashwagandha root extract is the preferred form of ashwagandha, for the purposes of supplementation.
Ashwagandha should be taken with meals. If taken once a day, it should be taken with breakfast.
Safety
While the root extract of ashwagandha appears to be virtually nontoxic at this point in time, high doses of isolated Withaferin A (the anticancer molecule) do possess a toxicity; in worst scenarios, it is about 4-fold higher than the therapeutic dose and difficult to reach via the root extract