Ashwagandha is one of the most popular herbal supplements, and for good reason. There’s extensive clinical research backing its efficacy for stress reduction, and some data suggesting it may be effective for improving testosterone levels and semen parameters in men. A search for “ashwagandha” on the medical research database PubMed returns over 1,400 results.
There are thousands of brands selling ashwagandha in various forms, doses and potencies, and it can be hard for consumers to determine what the best ashwagandha product is.
In this article we’ll explain what form and dosage of ashwagandha we recommend based on a review of medical research, as well as which brand we recommend.
Ashwagandha Form and Dosage
One of the most important things when choosing an herbal supplement is that it contains a dosage that’s been proven effective in medical research. Just because an herb is effective in some studies doesn’t mean it’s effective at all doses.
Ashwagandha is available in many forms, but most of the medical studies use either ashwagandha extract, which is a more concentrated form of the herb, or ashwagandha root powder which is the basic powderized form of the herb.
Both forms have been shown to be effective for reducing anxiety, but we tend to recommend ashwagandha extract as it’s more potent and is used more frequently in medical studies.
A medical review of ashwagandha for anxiety published in the Journal of Alternative and Complementary Medicine highlighted three studies where ashwagandha extract was used. In all three studies, it was found to be effective at reducing anxiety.
The doses used in the studies were 600, 600 and 1,000 milligrams (mg) per day. We tend to recommend a minimum dose of 600 mg because this seems to be the standard from medical research.
Many ashwagandha supplements are also standardized for the active compounds in ashwagandha called withanolides. This means the manufacturer will ensure that a minimum amount of withanolides exists in the formulation, effectively ensuring its potency.
We don’t have a preference between generic (not standardized) ashwagandha extract and standardized ashwagandha. There are many studies proving both to be effective.
In summary, we recommend looking for an ashwagandha extract supplement at a dosage of 600 mg per day or above.
One of the best resources for evaluating different brands of supplements is ConsumerLab. This is an independent laboratory that tests supplements to ensure they’re accurately labeled and pure.
For whatever reason, they failed to test any of their ashwagandha extract supplements for heavy metals, so we can use their data to assess label accuracy and potency but not safety.
Only three brands of ashwagandha met our category of recommendation standard of an extract product providing at or above 600 mg per day.
Nature’s Answer sells a liquid ashwagandha extract that’s available on their site and on Amazon. The per-dose serving is only 400 mg, but since it’s a liquid dropper it’s very easy to just use more drops to increase the serving 50% to 600 mg.
Vitamin World sells a capsule ashwagandha extract at 500 mg per serving, with instructions to take two capsules daily for a total serving of 1,000 mg.
We can’t actively recommend either product because neither publishes independent testing proving their products are low in heavy metals. And as we referenced earlier, for whatever reason ConsumerLab doesn’t publish the contaminant testing for ashwagandha extract supplements as they typically do for other supplement categories.
ConsumerLab did publish contaminant testing for ashwagandha root powders, and they found that Organic India ashwagandha root powder, which is available in capsule form, contains safe levels of heavy metals.
The Organic India product seems to be the safest option of those reviewed since it was the only one tested for not only efficacy but toxicity.
We also manufacture and sell an ashwagandha extract product that is batch-tested for label accuracy and purity by an independent lab, but unfortunately we’ve been out of stock of this product for a while due to supply chain issues.
Ashwagandha Safety Risks
The reason we’re very cautious about recommending third-party ashwagandha supplements without extensive safety testing is because this is a root which uptakes heavy metals at a relatively high level compared with other medicinal plants.
A medical review of heavy metal accumulation in various medicinal plants found ashwagandha to show “very high metal bioaccumulation.” The levels of heavy metals absorbed by ashwagandha were significantly higher than all other plants examined.
Unsurprisingly, only 56% of ashwagandha brands pass ConsumerLab tests.
We believe that avoidance of risk is important for long-term health, so we recommend that consumers only purchase ashwagandha from suppliers with proof of independent purity tests.
Organic India at least passed ConsumerLab testing, but unfortunately ConsumerLab doesn’t publish the actual levels of heavy metals found, so we can’t independently assess whether we believe their product to be safe.
What is KSM 66 Ashwagandha
If you’ve reviewed ashwagandha products recently, you may notice many brands featuring something called “KSM-66” ashwagandha on their ingredients list.
This is a patented extract which is “full-spectrum”, meaning it maintains the ratio of active chemicals as in the dry herb. The company which manufactures it also claims they use no leaves in the formulation; only ashwagandha root.
We haven’t come across any clinical data suggesting that KSM-66 is more effective than non-patented ashwagandha extract. If they believe so, we recommend that they prove it in a medical trial comparing the effects. Until then, we will continue to show no preference in our ashwagandha recommendations between KSM-66 and other versions of ashwagandha.