In a new study, researchers have confirmed what many kratom users have experienced for themselves: that the plant's effects can vary depending on the product in question.
Kratom naturally contains over 40 alkaloids — a class of organic compounds that are responsible for the plant's effects. (Brown et al., 2017, pg 305) But the balance of these kratom alkaloids can vary from product to product. The study's authors set out to explore what these alkaloid differences might mean for kratom users.
After analyzing over 50 commercial kratom products, the researchers confirmed that alkaloid content "... is highly variable in genetically similar kratom plant material." (Todd et al., 2020, pg 8) They also noted that "... individuals who self-administer kratom tea to treat pain, addiction, or depression might achieve very different results depending on the alkaloid profile of the product that they use." (pg 8)
As expected, the kratom samples they tested contained varying levels of mitragynine and 7-hydroxymitragynine, which are often considered kratom's primary alkaloids. (pg 3) But the researchers also found that the test samples contained wildly varying levels of another alkaloid, speciofoline.
While the mitragynine content of the samples varied by fourfold, "the speciofoline content varied by more than 90-fold." (pg 3) The alkaloid disparity was so high that the researchers grouped the samples into two categories: those with high levels of speciofoline and those with low levels.
However, the researchers were unsure what role, if any, speciofoline plays in kratom's effects. In their tests, speciofoline "did not exhibit appreciable affinity for any of the opioid receptors." (pg 5) In contrast, both mitragynine and 7-hydroxymitragynine are known to interact with opioid receptors. As a result, the researchers emphasized that future studies should explore speciofoline's properties more thoroughly. (pg 6)
After noting the samples' alkaloid differences, the researchers suspected that they contained non-kratom plant matter. After all, the kratom plant (mitragyna speciosa) has many close relatives with similar alkaloids, such as Mitragyna diversifolia, Mitragyna hirsuta, and Mitragyna rotundifolia. The researchers theorized that plant matter from these trees could've been added to their products during production and potentially skewed their results. (pg 3-5)
To test this theory, the researchers analyzed the genetic makeup of their samples, including three commercial kratom products and a young cultivated kratom plant. (pg 5, Table 1) But their test results revealed that the samples "... had ≥99% sequence similarity with M. speciosa" (pg 5), confirming that the majority of the tested products were, in fact, kratom.
As a result, the researchers noted that kratom's varying alkaloid content "... is not due to misidentification of species or substitution." Instead, the phenomenon could be explained by "... a number of other factors including plant age, growing conditions, and processing methods." (pg 5)
The study's conclusions are at odds with the experiences of some kratom users, who have commented that all kratom is alike and that there are no discernable differences between kratom products. The study is freely available to read in its entirety and can be viewed online here.