Ashwagandha: Benefits, Dosage and Does It Actually Work?
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- 12 May, 2026
Ashwagandha has gone from an obscure Ayurvedic herb to one of the UK’s best-selling supplements in just a few years. It’s now stocked in supermarkets, recommended by personal trainers and appearing in everything from sleep aids to testosterone boosters. But does it actually work?
The short answer: yes — and the research is more solid than you might expect.
What Is Ashwagandha?
Ashwagandha (Withania somnifera) is a root extract used in Ayurvedic medicine for centuries. It’s classified as an adaptogen — a herb that helps the body adapt to stress by modulating the stress response system, particularly cortisol. The most researched form is KSM-66, a patented root-only extract standardised to a high concentration of withanolides (the active compounds). Look for KSM-66 or Sensoril on the label rather than generic ashwagandha powder.
What Does the Research Show?
Stress and Cortisol Reduction
This is the most robust area. Multiple double-blind, placebo-controlled trials have found ashwagandha significantly reduces perceived stress, anxiety and cortisol levels. A 2019 study found 240mg of KSM-66 daily produced a 23% reduction in cortisol over 60 days — a meaningful, measurable result.
Testosterone and Male Performance
Several trials have found ashwagandha produces modest but statistically significant increases in testosterone in men — particularly those who are stressed or sleep-deprived. A 2019 study found an average 14.7% increase in testosterone in men taking 600mg KSM-66 daily over 8 weeks. The mechanism is likely indirect: by reducing cortisol (which suppresses testosterone), ashwagandha creates a more favourable hormonal environment.
Sleep Quality
Ashwagandha has been shown to improve sleep quality and sleep onset in multiple trials. High evening cortisol is one of the most common causes of poor sleep — and ashwagandha directly addresses this.
Strength and Recovery
Studies in resistance-trained individuals have found ashwagandha supplementation produces greater improvements in strength, recovery and body composition compared to placebo when combined with a training programme.
Who Benefits Most?
Ashwagandha works best for people who are under significant stress, sleeping poorly, training hard and wanting better recovery, or looking to support natural testosterone levels. If you’re already stress-free and sleeping well, the effects will be subtler.
How to Take It
- Dose: 300–600mg of KSM-66 or Sensoril extract daily
- Timing: Evening is ideal — the cortisol-lowering effect supports sleep quality
- With food: Improves absorption and reduces any mild nausea
- How long: Give it 4–8 weeks before assessing the effect
Is It Safe?
Ashwagandha has a strong safety profile at 300–600mg daily. Rare cases of liver toxicity have been reported at very high doses with low-quality products. Stick to reputable brands using KSM-66 or Sensoril. Not recommended during pregnancy. Consult your GP if you have thyroid conditions or take immunosuppressants.
We stock ashwagandha in our testosterone support and health supplements ranges.
Buffalo Nutrition — 132 Cricklewood Broadway, London NW2 3EE | Mon–Sat 10:30am–7pm | 4.9★ on Google | Free UK delivery over £50
