Ashwagandha: The 5% Withanolide Standard

Most ashwagandha you can buy is sold by its patent name. The patent name is a marketing convenience, not a measure of efficacy. What your body actually responds to is the concentration of withanolides, the family of steroidal lactones that drive ashwagandha's stress-resilience and sleep effects.

What withanolides are, and why the percentage matters

Withanolides are the bioactive steroidal lactones in ashwagandha root that drive its adaptogenic effects. A clinical-grade extract is standardised to at least 5% withanolides, so every 600 mg dose delivers at least 30 mg of active compounds, in every batch. The percentage, not the brand name, is what ties a product to the studied material.

A clinical-grade extract is standardised to at least 5% withanolides. That means every 600 mg dose contains at least 30 mg of the active compounds, every batch, with per-batch testing to verify it. Without a stated percentage, the milligrams on the front of the pack tell you nothing about how much active you are actually taking.

What the research studied

Ashwagandha's stress and strength research clusters on a standardised root extract at 600 mg per day. A 2012 trial in the Indian Journal of Psychological Medicine reported lower stress scores and serum cortisol; an eight-week randomised trial in the Journal of the International Society of Sports Nutrition reported greater muscle strength and faster recovery alongside resistance training.

Both trials used the same 600 mg/day standardised root extract, taken as 300 mg twice daily. The 2012 Indian Journal of Psychological Medicine study measured a significant reduction in stress-scale scores and serum cortisol against placebo. The 2015 Journal of the International Society of Sports Nutrition study, run over eight weeks with resistance training, measured greater gains in strength and muscle recovery. The standardisation guarantee, not the brand on the bottle, is what links your supplement to that studied dose.

The stress finding does not rest on one study. A 2024 meta-analysis in Explore, pooling nine randomised trials, reported a significant reduction in perceived-stress and anxiety scores and in serum cortisol against placebo. A separate 2016 trial in the Journal of Evidence-Based Complementary and Alternative Medicine, also at 600 mg per day over eight weeks, moved perceived stress and cortisol in the same direction. Two independent trials and a meta-analysis, all at the studied dose.

How much, and for how long

The studied dose is 600 mg per day of a standardised root extract, taken as 300 mg twice daily, for about eight weeks. Across the stress and sleep trials, the clearer effects appeared at that dose and over that duration, not from a single dose or a two-week course. Consistency across the eight-week window is the pattern the research rewards.

The trials that reported the strongest signals ran for eight weeks or longer at 600 mg per day. A shorter course, or a lower dose you cannot verify because the label hides the standardisation percentage, is harder to map onto that evidence. The number on the pack and the weeks on the calendar both matter.

Ashwagandha's evidence is not only about stress. Randomised trials and a 2021 meta-analysis have also examined sleep. We cover that in Ashwagandha for sleep: what the evidence shows.

The EX1 take

EX1 Ashwagandha is a 600 mg root extract standardised to 5% withanolides, manufactured at WHO-GMP and AYUSH-GMP certified facilities with per-batch testing. The active dose, the standardised potency, and the per-batch testing to back it.

Related reading: Ashwagandha for sleep: what the evidence shows, and why most multivitamins underperform.