Every serious athlete learns to question what’s in their supplement stack. You compare protein quality, check creatine purity, and pay attention to caffeine dose, because small differences can affect performance. Ashwagandha rarely gets the same scrutiny. If the label says “ashwagandha,” it’s easy to assume every product delivers the same ingredient and the same results. It doesn’t.
Over the past decade, ashwagandha has evolved from a traditional Ayurvedic herb into a mainstream dietary supplement ingredient, backed by a rapidly expanding body of clinical research and now found in products ranging from sports recovery formulas to sleep supplements. That popularity is exactly why the question is worth asking: does the evidence back up its effectiveness and its safety?
For KSM-66®, the answer starts with a distinction most labels never make clear.
To most consumers, “ashwagandha” sounds like a single ingredient. Commercially available extracts can differ substantially in the plant parts used, extraction methods, phytochemical profiles, and the depth of clinical evidence supporting them. Because of these differences, the efficacy and safety findings reported for one extract should not automatically be assumed to apply to another.
One of the most important distinctions is whether an extract comes exclusively from the root or includes leaf material too. Both come from the same plant, but they’re chemically different.
Ashwagandha belongs to the nightshade family, and its different plant tissues carry different phytochemical profiles. Leaves generally contain substantially higher concentrations of compounds like Withaferin A and Withanone than roots do. Withaferin A has shown cytotoxic activity in various studies, and both have come up in investigations into reports of herb-associated liver injury.[1]
That means safety and efficacy findings from one extract can’t be generalized to every product marketed simply as “ashwagandha.”
KSM-66® is manufactured exclusively from ashwagandha roots, so the clinical evidence behind it reflects a standardized root-only extract, not a blend of multiple plant parts.
That root-versus-leaf distinction isn’t just scientific anymore. It’s showing up in regulatory policy too.
In April 2026, India’s Ministry of AYUSH directed manufacturers of Ayurvedic products to formulate ashwagandha preparations exclusively from the root.[2] Then the Food Safety and Standards Authority of India (FSSAI) issued a corresponding advisory restricting the use of ashwagandha leaves in foods and nutraceuticals.[3]
Poland, Hungary, and several other European countries have adopted similar root-only positions.
This direction matches both traditional use and modern pharmacopeial standards. Classical Ayurvedic texts, the Ayurvedic Pharmacopoeia of India, the World Health Organization monograph, the British Pharmacopoeia, and the United States Pharmacopeia all name the root as the plant’s principal medicinal part.
That distinction matters here because the safety evidence below applies specifically to KSM-66®, a standardized root-only extract.
Sample size plays an important role in evaluating supplement safety. Smaller trials can identify potential benefits, but larger studies give more confidence that results hold up across different populations, and they’re better positioned to catch rare adverse events.
A multicenter, randomized, double-blind, placebo-controlled trial studied 1,002 adults taking 600 mg of KSM-66® daily for eight weeks.[4] Their liver, kidney, and hematological markers stayed normal throughout, with adverse events occurring at rates comparable to placebo.[4]
An independent 12-week prospective study, published in Frontiers in Nutrition in 2026, monitored liver, kidney, and thyroid function alongside adverse events.[5] Researchers reported no serious adverse events, with lab markers staying within clinically acceptable ranges throughout supplementation.[5]
Together, these two studies form one of the largest published safety datasets for a clinically studied ashwagandha extract. Across different designs and participant populations, KSM-66® showed a favorable safety profile during routine daily use, with no clinically meaningful effects on liver, kidney, or thyroid function.[4][5]
When you’re building a high-performance supplement stack, ingredient quality matters just as much as ingredient quantity.
The word “ashwagandha” on a label tells you surprisingly little on its own.
KSM-66® is manufactured exclusively from ashwagandha roots and standardized to more than 5% total withanolides by HPLC, with Withaferin A and Withanone below detection limits. It’s produced using an aqueous extraction process built on green-chemistry principles.
Before choosing an ashwagandha supplement, ask four simple questions:
A withanolide percentage, by itself, is only part of the story. The ingredients worth trusting are the ones whose composition, manufacturing process, and clinical evidence all point back to the same standardized extract. For athletes who already scrutinize everything else in their stack, ashwagandha deserves the same level of attention.