Overall, Withania somnifera has not undergone significant scientific investigation in humans, therefore much of its use is based on pharmacological effects demonstrated in experimental models or traditional usage. In practice, it is often used in herbal combination treatments.
The pharmacological effects of the herb, which have been well established in animal studies, provide a theoretical basis for its use in situations characterised by stress.
More specifically, oral administration of an aqueous, standardised extract of Withania somnifera (in a dose extrapolated from the human dose) has been found to offer protection against experimentally induced biological, physical and chemical stressors.
In one in-vivo study, plasma cortisol levels and adrenal weight were significantly lower, while liver weight increased.
To date, controlled studies are unavailable to determine and clarify whether these effects are also significant in humans.
(For more information see ‘Clinical note — Allostasisand adaptation to stress’ in the Siberian ginseng monograph.)
Although controlled studies are lacking, the herb’s pharmacological effects, such as its GABA-mimetic activity and ability to lower cortisol levels, provide a theoretical basis for its use in anxiety states. One study used a herbal combination treatment known as Geriforte, which contains primarily W. somnifera. The product was taken by 34 subjects with anxiety neurosis, and after 12 weeks significant reductions in the frequency, duration and intensity of symptoms were observed.
ANABOLIC AND WEIGHT GAIN PROMOTION
Both animal and human studies have shown significant improvements in weight gain during the growth phase with the use of withania. It is suspected that an anabolic effect is responsible.
Withania-fortified milk (2 g/day for 60 days) has been investigated in children and found to induce weight gain, increase total plasma proteins and haemoglobin levels.
The herb is used in the treatment of iron deficiency anaemia due to its effects on haemopoeisis and natural iron content. This use has been supported by studies showing increased haemoglobin levels in children, induced by withania.
Prevention of bone marrow depression Animal studies suggest a potential role for withania as an adjunctive treatment during chemotherapy for the prevention of drug-induced bone marrow depression.
The ability to stimulate stem cell proliferation has led to concerns that Withania somnifera could reduce cyclophosphamide-induced toxicity and therefore reduce its usefulness in cancer therapy. However, preliminary animal studies indicate that withania could prove to be a potent and relatively safe radiosensitiser and chemotherapeutic agent.
In animal studies, repeated administration of withania (100 mg/kg) inhibited morphine tolerance and dependence. Based on this observation, and its ability to modulate stress responses in general, withania is used in herbal combination therapy during opiate withdrawal.
Withania is traditionally incorporated into herbal combination formulations for symptom relief in osteoarthritis and rheumatoid arthritis. Its documented anti-inflammatory and antioxidant activities provide some support for this use, although controlled studies have not established efficacy.
Withania: Other Uses
Traditionally used in convalescence for people who are stressed and both physically and emotionally exhausted. It is considered a non-stimulating tonic allowing for the restoration of vitality.
As the alkaloids are considered to be sedative and able to reduce blood pressure and heart rate, it is also used in practice for insomnia, although controlled trials are lacking in this area.
- Fluid extract (1:2): 5-13 ml/day.
- Dried root: 3-6 g/day in capsule or tea form.
Large doses can cause gastrointestinal upset, diarrhoea and vomiting.
Central nervous system and respiratory depression, decreased body temperature, gastrointestinal upset and kidney and liver abnormalities have been noted.
Acute toxicity studies in animals show a good margin of safety with a high therapeutic index.