Kratom is made from the leaves of a tropical tree called Mitragyna speciosa, native to Southeast Asia. The tree belongs to the same plant family as coffee (Rubiaceae) and grows wild in Thailand, Malaysia, and Myanmar. Its large, dark green leaves contain more than 50 active alkaloids, and these leaves are dried and ground into the powders, capsules, and extracts sold commercially.
The Kratom Tree
In its native tropical environment, a kratom tree can reach up to 80 feet tall and 15 feet wide, with a straight trunk covered in light grayish-green bark. The leaves are the part that matters commercially. Fully mature kratom leaves measure roughly 6 to 8 inches long and 3 to 5 inches wide, each with 12 to 15 pairs of veins running through them. The texture ranges from waxy and glossy to soft and matte, depending on the tree’s growing conditions.
Kratom also produces round clusters of bright yellow flowers, each cluster containing 80 to 100 tiny blossoms with a sweet floral scent. The tree’s seeds are extremely small (1 to 2 millimeters) and have wing-like structures that let them travel long distances by wind or water. But seeds aren’t used in kratom products. It’s the leaves that contain the alkaloids people are after.
What’s Inside the Leaves
The World Health Organization has documented more than 50 alkaloids in kratom leaves. The dominant one, mitragynine, makes up as much as 66% of the total alkaloid content, though concentrations vary widely depending on the tree’s age, location, and growing conditions. Lab analyses of commercial products have found mitragynine levels ranging from 0.7% to 38.7% of the leaf material by weight.
The second most abundant alkaloid is paynantheine, accounting for about 10% of total alkaloid content. A compound called 7-hydroxymitragynine gets a lot of attention because it’s roughly 10 times more potent than mitragynine at activating the brain’s opioid receptors, but it typically makes up less than 2% of the alkaloid content in raw leaves. Research published in ACS Central Science found that the body actually converts mitragynine into 7-hydroxymitragynine during digestion through liver enzymes, which appears to be a key reason kratom produces its effects.
Both mitragynine and 7-hydroxymitragynine are partial agonists at the same brain receptors that prescription opioids target. “Partial” means they activate these receptors less fully than drugs like morphine. They also block two other types of opioid receptors (kappa and delta), which gives kratom a different overall effect profile than conventional opioids.
How Leaves Become Products
The simplest kratom product is plain powder. Leaves are harvested, dried, and ground into a fine powder. That’s it. The whole leaf is used, and nothing is extracted or concentrated. This is the most common form sold.
Extracts go through additional steps. The dried, crushed leaves are boiled in water to pull out the alkaloids, then strained to remove plant solids. The liquid is simmered down until it forms a thick, dark paste, which is then dried and ground into a concentrated powder. Extracts are labeled with potency ratios like “2X” or “10X,” indicating how much stronger they are compared to regular powder. They can range from twice as potent to as much as 50 times stronger than standard leaf powder.
Kratom is also sold as whole crushed leaf (for brewing into tea), in pre-filled capsules, and as liquid tinctures or shots.
What the Vein Colors Mean
Kratom products are often marketed by “vein color,” typically red, green, or white. These labels refer to the color of the veins running through the leaf at the time of harvest, which changes as the leaf matures. White vein leaves come from younger, less mature growth. Green vein leaves sit in the middle of the growth cycle. Red vein leaves come from the most mature leaves, where pigmentation has shifted due to prolonged sunlight exposure, humidity, and soil conditions.
Yellow and gold varieties don’t come from differently colored veins at all. These are created through specific drying or fermentation techniques after harvest, such as extended sun drying or controlled fermentation, which alter the leaf’s color and alkaloid profile.
Contamination Concerns
Because kratom is an unregulated botanical product, quality control varies dramatically between suppliers. The FDA tested 30 different kratom products from various sources and found significant levels of lead and nickel, at concentrations exceeding safe limits for daily oral intake. For heavy users, exposure to these metals could be many times above safe thresholds, potentially leading to nervous system damage, kidney problems, anemia, or high blood pressure over time.
This contamination isn’t inherent to the plant itself. It reflects the lack of standardized manufacturing controls. Kratom is grown in tropical soils, processed in facilities with varying standards, and imported without the testing requirements that apply to regulated supplements or pharmaceuticals.
Legal Status in the U.S.
Kratom occupies a legal gray zone. The FDA does not approve it as a drug, a dietary supplement, or a food additive. As of December 2025, the agency considers kratom-containing dietary supplements to be adulterated, meaning they don’t meet the legal standard for safe use. No prescription or over-the-counter drug products containing kratom or its alkaloids are legally marketed in the United States.
Despite this federal position, kratom remains widely available for purchase in most states. Some states and municipalities have passed their own bans or regulations. In September 2024, the FDA awarded a grant for a human abuse potential study on kratom, signaling continued federal interest in formally classifying the substance.