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Ingredient review

Withania somnifera

Description

What is it?

Withania somnifera (WS) is also commonly known as ashwagandha, “Indian Winter cherry” or “Indian Ginseng”. Its root, leaves, and seeds have been historically used as a tonic to assist with stress, neuroprotection, arthritis, pain, and inflammation. It is one of the most highly regarded ayurvedic medicines. (20) Withania somnifera extract contains numerous phytochemicals, such as alkaloids, flavonoids, steroidal lactones, saponins, neurotransmitters, essential and nonessential fatty acids, ergostane, and gamma amino butyric acid, which contribute to its many therapeutic effects. (3)

Not be confused with: Withania coagulans 

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Main uses

Anxiety and stress
Cognition in neurological disorders
Fertility
Joint pain and muscular performance

Formulations

Form
Bioavailability and safety
Non-proprietary standardized extracts
Withanolides absorbed rapidly, withaferin A had 1.5x higher bioavailability than withanolide A in mice (17)
High dose of 2000mg/kg of body weight of a standardized extract containing <3% of Withaferin A did not produce adverse effects or toxicity in rats (16)
KSM-66® (root extract containing a 5% concentration of withanolides)
No data on bioavailability currently available
Has been shown to be safe for 12 weeks (1)
Sensoril® (root and leaf extract containing a minimum of 8% concentration of withanolides) (5)
No data on bioavailability currently available
Has been shown to be safe for 12 weeks (18)(23)
Shoden® (root and leaf extract standardized to 35% withanolide glycosides) (14)
No data on bioavailability currently available
Has been shown to be safe for 8 weeks (14)

Dosing & administration

Adverse effects

Ashwagandha is generally reported to be safe, with only minor adverse effects of gastrointestinal distress, diarrhea, nausea, and vomiting associated with large doses. Rare cases of hepatotoxicity have been reported. (15)

Pharmacokinetics

Absorption

  • Withaferin-A and withanolide A have been shown to be rapidly absorbed in mice. (10)
  • Oral bioavailability of witherfarin A has shown to be ~32% in rats but can easily pass through epithelial cells as shown in vitro. (9)

Distribution

  • From highest to lowest concentrations, withaferin A has been shown to have tissue distribution in the stomach, heart, lung, kidney, small intestine, and spleen in rats. (21)

Metabolism

  • Intestinal and liver first-pass metabolism may contribute to low bioavailability of witherfarin A as shown in rats and in vitro. (9)

Excretion

  • No data currently available

References