Safety assessment of a Mitragyna speciosa leaf extract by a 90-day feeding study in rats
- 1Natural Health and Food Products Research Group, Centre for Applied Research and Innovation, BC Institute of Technology
- 2Pharmacognosy Institute and Department of Pharmaceutical Sciences, Retzky College of Pharmacy, University of Illinois Chicago
Abstract
Background: Mitragyna speciosa is a deciduous evergreen tree belonging to the coffee (Rubiaceae) family. Traditionally used as a restorative, the extensive historical use data shows kratom has a low risk profile with respect to acute and chronic use. These conclusions cannot be unilaterally extended to all kratom products in the marketplace, of which there is a wide variety, with many far removed from traditional kratom preparations.
Methods: A 90-day toxicity study was conducted for the purpose of identifying a no observed adverse effect level (NOAEL) for a proprietary extract prepared from M. speciosa leaf, standardized to a target mitragynine concentration. Sprague Dawley Crl:CD (SD) rats (80 male and 80 female) were grouped as 20 male and 20 female and dosed daily by gavage (10 mL/kg body weight) with SpecioTea™ supplying mitragynine at 0, 15, 30, or 60 mg/kg/day for 90 days. The following parameters and end points were evaluated in this study: clinical signs, body weights, body weight gains, food consumption, ophthalmology, clinical pathology parameters (hematology, coagulation, clinical chemistry, and urinalysis), gross necropsy findings, organ weights, and histopathologic examinations.
Results: Daily oral administration of SpecioTea™ resulted in dose-related reductions in food consumption and lower body weights at ≥15 mg/kg/day. Functional observation battery findings were generally consistent with the known pharmacology of the test article at ≥30 mg/kg/day and non-adverse clinical pathology findings at ≥15 mg/kg/day. Adverse changes were observed in the ovary, testis, and epididymis at 60 mg/kg/day. Thus 30 mg/kg b.w./day of SpecioTea™ was designated as NOAEL.
Conclusion: Due to findings at all SpecioTea™ dose levels, a no-observed effect level (NOEL) could not be established. Based on the observed adverse changes in the ovary, testis, and epididymis at 60 mg/kg/day, the no observed adverse effect level (NOAEL) for SpecioTea™ is 30 mg/kg/day for males and females. The results from this study provides evidence in support of the low toxicity associated with a proprietary kratom leaf extract. Scientifically relevant data from studies such as this should form the basis through which further research on the benefits and safety of kratom products are conducted.
Related
- Associations Between Kratom (Mitragyna Speciosa) Use and Real-Time Anxiety and Sadness: A 15-Day Ecological Momentary Assessment Study
- Phytochemical Screening and Protective Effects of Hancornia speciosa Leaf Extract Against Fatty Acid-Induced Lipotoxicity in HepG2 Cells
- Efficacy and Safety of Vitex Extract on Menopausal Symptoms and Quality of Life in Postmenopausal Women: A Randomized Placebo-Controlled Trial
- Ethnopharmacological evaluation of Irvingia gabonensis (Aubry-Lecomte ex O'Rorke) Baill. seed extract: integrated computational and in vitro assessment of antioxidant, antidiabetic, and anticancer activities with in vivo validation of antidiabetic activity
- Assessment of antibacterial and antioxidant potentials of Aspergillus fumigatus crude extract, the isolated endophyte from Centella asiatica (L.) urban supported by molecular docking
BibTeX
@article{brown2026safety,
title = {{Safety assessment of a Mitragyna speciosa leaf extract by a 90-day feeding study in rats}},
author = {Paula N. Brown and Michael Chan},
journal = {Frontiers in Pharmacology},
year = {2026},
month = oct,
doi = {10.3389/fphar.2026.1922596},
url = {https://www.frontiersin.org/articles/10.3389/fphar.2026.1922596/full},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Safety assessment of a Mitragyna speciosa leaf extract by a 90-day feeding study in rats
AU - Paula N. Brown
AU - Michael Chan
PY - 2026
DA - 2026/10/21
JO - Frontiers in Pharmacology
DO - 10.3389/fphar.2026.1922596
UR - https://www.frontiersin.org/articles/10.3389/fphar.2026.1922596/full
AB - Background: Mitragyna speciosa is a deciduous evergreen tree belonging to the coffee (Rubiaceae) family. Traditionally used as a restorative, the extensive historical use data shows kratom has a low risk profile with respect to acute and chronic use. These conclusions cannot be unilaterally extended to all kratom products in the marketplace, of which there is a wide variety, with many far removed from traditional kratom preparations. Methods: A 90-day toxicity study was conducted for the purpose of identifying a no observed adverse effect level (NOAEL) for a proprietary extract prepared from M. speciosa leaf, standardized to a target mitragynine concentration. Sprague Dawley Crl:CD (SD) rats (80 male and 80 female) were grouped as 20 male and 20 female and dosed daily by gavage (10 mL/kg body weight) with SpecioTea™ supplying mitragynine at 0, 15, 30, or 60 mg/kg/day for 90 days. The following parameters and end points were evaluated in this study: clinical signs, body weights, body weight gains, food consumption, ophthalmology, clinical pathology parameters (hematology, coagulation, clinical chemistry, and urinalysis), gross necropsy findings, organ weights, and histopathologic examinations. Results: Daily oral administration of SpecioTea™ resulted in dose-related reductions in food consumption and lower body weights at ≥15 mg/kg/day. Functional observation battery findings were generally consistent with the known pharmacology of the test article at ≥30 mg/kg/day and non-adverse clinical pathology findings at ≥15 mg/kg/day. Adverse changes were observed in the ovary, testis, and epididymis at 60 mg/kg/day. Thus 30 mg/kg b.w./day of SpecioTea™ was designated as NOAEL. Conclusion: Due to findings at all SpecioTea™ dose levels, a no-observed effect level (NOEL) could not be established. Based on the observed adverse changes in the ovary, testis, and epididymis at 60 mg/kg/day, the no observed adverse effect level (NOAEL) for SpecioTea™ is 30 mg/kg/day for males and females. The results from this study provides evidence in support of the low toxicity associated with a proprietary kratom leaf extract. Scientifically relevant data from studies such as this should form the basis through which further research on the benefits and safety of kratom products are conducted.
SN - 1663-9812
ER -