Ashwagandha is made from the root of Withania somnifera, a small shrub in the nightshade family (Solanaceae), the same plant family as tomatoes and peppers. The root contains a group of naturally occurring compounds called withanolides, which are responsible for most of the herb’s biological effects. It also contains alkaloids, saponins, iron, and a base of carbohydrates and fiber that make up the bulk of the raw root material.
The Plant Itself
Withania somnifera is a short, woody shrub that grows across India, the Middle East, and parts of Africa. The roots, which are the primary part used in supplements, typically reach about 10 cm long and 2 cm thick. They’re woody and bright in color. While both the roots and leaves contain bioactive compounds, traditional preparations and most modern supplements focus on the root.
The leaves actually have a very different chemical profile than the roots. They contain over 100 times more withaferin A, one of the more potent and potentially harsh compounds in the plant. This matters because some manufacturers use leaf material (sometimes without disclosing it) to cheaply boost the total withanolide count on the label, according to the American Botanical Council.
Withanolides: The Key Active Compounds
Withanolides are steroidal lactones, a class of compounds with a structure that allows them to interact with various systems in the body, including stress-hormone pathways and inflammatory signaling. When researchers extract ashwagandha root using ethanol or water, they consistently find the same core group of withanolides: withaferin A, withanolide A, withanolide B, withanone, withastramonolide, and several withanosides (IV and V). These are the compounds that clinical trials typically measure and that supplement labels refer to when they list a “withanolide percentage.”
Most commercial root extracts are standardized to contain somewhere between 2.5% and 10% total withanolides, though some concentrated formulas push higher. The standardization process ensures a consistent dose of these active compounds from batch to batch, since the raw plant material can vary depending on where and how it was grown.
Other Bioactive Compounds
Beyond withanolides, ashwagandha root contains two notable alkaloids: isopelletierine and anaferine. Alkaloids are nitrogen-containing compounds that can affect the nervous system, and they likely contribute to ashwagandha’s calming reputation, though the withanolides get most of the research attention. The root also contains saponins, compounds that can influence immune function and help the body absorb other nutrients.
Mineral and Nutritional Makeup
The raw root is surprisingly rich in iron. Lab analyses of ashwagandha roots from different growing regions in India found iron concentrations ranging from about 350 to 945 parts per million, making it one of the more mineral-dense herbal roots. The root also contains meaningful amounts of potassium (1.4% to 2.2% of dry weight), along with smaller quantities of calcium, magnesium, phosphorus, zinc, copper, and manganese.
In terms of basic nutrition, fresh ashwagandha root is mostly water (around 70%) and carbohydrates, with very little protein or fat. Dried root powder is roughly 63% carbohydrate and 4% to 5% fiber. None of this nutritional content is why people take it, but it does mean ashwagandha powder isn’t nutritionally empty the way some herbal extracts can be.
Roots vs. Leaves: Why It Matters
This distinction is worth understanding if you’re shopping for a supplement. Root-based extracts have a broader, more balanced withanolide profile and much lower levels of withaferin A. Leaf-based material is heavily skewed toward withaferin A, which at high concentrations can be cytotoxic, meaning it can damage cells. In animal safety studies, root extracts standardized for withaferin A showed no adverse effects at doses up to 2,000 mg per kilogram of body weight, but those studies used carefully controlled concentrations.
The American Botanical Council has flagged undisclosed use of leaves and stems in ashwagandha products as a form of adulteration. If a supplement label says “root extract,” it should contain only root material. Products that list unusually high withanolide percentages without specifying the plant part may be using leaf material to inflate those numbers.
How Supplements Extract the Active Compounds
Manufacturers use solvents to pull the withanolides and other bioactive compounds out of the dried root material. The most common solvents are ethanol (alcohol) and water, which each dissolve slightly different sets of compounds. Ethanol extracts tend to capture a wider range of withanolides, while water extracts pull more of the withanosides, which are sugar-bound forms of withanolides.
Newer extraction methods use subcritical water, which involves heating water under pressure to between 100°C and 200°C. This approach avoids chemical solvents entirely and has shown the highest extraction yields at 200°C for 30 minutes. Some brands also use supercritical fluid extraction with carbon dioxide. These “green” methods are gaining traction as manufacturers try to avoid residual solvent contamination, though conventional ethanol and water extraction remain the industry standard.
After extraction, the liquid is dried into a concentrated powder and tested to confirm the withanolide percentage before being encapsulated or packaged. The final product you buy in a capsule or powder is this concentrated extract, not simply ground-up root, which is why extract-based supplements deliver a more consistent and potent dose than raw ashwagandha powder.