The investigation initially set out to explore whether kavalactones, derived from the root of the kava plant (Piper methysticum Forst), would elevate mood and wellbeing by producing a feeling of relaxation without cognitive impairment given the lack of sleep and mood support options for populations like military special operators and elite athletes who require uninterrupted optimal performance.
“We report a novel finding that kavalactones may support performance by maintaining or rescuing the desire to expend energy in the context of significant physical and mental strain in well-conditioned individuals, even in a context of already normal cortisol, sleep and mood,” the research team wrote in the Journal of the International Society of Sports Nutrition.
Funded by Thorne, the study was conducted in collaboration with the Human Performance Lab at Sovaris Aerospace, a biomedical intelligence, countermeasures and training company focused on human spaceflight and extreme operating environments on Earth.
An unexpected effect
The placebo-controlled, crossover study investigated the effects of the kava extract on cortisol, sleep and motivation state to expend (move) or conserve (rest) energy in a group of 15 healthy, physically fit young males engaging in a two-a-day intensive preparation class for special operations forces qualification.
Participants took either a single dose of 225 mg kavalactones (typical dosing seen in the U.S. dietary supplement marketplace) or matching placebo (both provided by Thorne) before bedtime for 14 days. After a 10-day washout period, participants switched test groups. Two individuals from the supplemented group dropped out of the study at the end of the first loading period citing morning grogginess.
“Grogginess, or a carryover effect of the nervous system depressant action of kava into the next day, is a known possible effect of kava for some users and, as such, was an anticipated effect in this study and not considered an adverse effect,” the study noted.
The research team measured salivary cortisol at the beginning and end of each two-week loading phase, and participants completed weekly questionnaires during loading to assess the primary endpoints of sleep and mood quality. They also monitored motivation to move (expend energy) and motivation to rest (conserve energy) to detect any adverse carryover of the calming effects from nighttime kava use on performance the next day.
“We did not expect to see the opposite effect, which was the conservation of motivation to move and the positive trends in motivation to move with kavalactones,” Stephen Phipps, ND, PhD, chief innovation officer at Thorne, told NutraIngredients-USA. “That was quite intriguing.”
The study did not identify any changes or clinically significant findings related to the normal, healthy parameters for cortisol, sleep and mood recorded at baseline in this group.
Thorne will continue to explore whether the novel motivation to move finding is repeatable or sustainable over prolonged periods, the potential mechanism of action behind this effect and whether it translates to females, deconditioned individuals and those with comorbidities.
Kava on the DoD Prohibited List
Although the researchers affirm kava as promising candidate for high-performance environments due to its long history of safe use when consumed within therapeutic range, it is also a recent addition to the Department of Defense (DoD) Prohibited Dietary Supplement Ingredient List.
The list—compiled and maintained by DoD’s Operation Supplement Safety (OPSS)—contains over 800 ingredients found in dietary supplements that service members should avoid unless authorized by a DoD health care provider.
“DoDI 1010.04 and Service-specific regulations restrict the use of all substances intended to alter one’s mental state or state of consciousness,” said Andrea Lindsey, MS, director at OPSS and senior nutrition scientist at the Consortium for Health and Military Performance (CHAMP). “Based on the possibility of impairment and subsequent threat to military readiness, kava was added to the DoD Prohibited Dietary Supplement Ingredients List on April 23, 2024.”
She also noted that U.S. Food and Drug Administration (FDA) issued a consumer advisory for kava in 2002 due to its potential but rare associations with severe liver damage as well as a 2020 scientific memorandum that highlighted concerns about kava’s adverse health effects.
Earlier this year, the Kava Coalition announced that it is supporting work towards a monograph and therapeutic compendium for aqueous kava and modern kava extracts to address historical misconceptions and compile contemporary scientific evidence supporting its safety and efficacy when produced and used responsibly.
“In addition to reported adverse events, kava is considered to be a psychoactive substance, and there have been reported cases of kava impairment (similar to alcohol intoxication),” Lindsey said, citing research associating kava consumption with increased risk of car crashes and impairment of motor coordination while driving.
Commenting on the current study design, she added that the researchers did not describe the method used to collect or monitor adverse events that may occur throughout the study and drew attention to the two of 15 total participants that dropped out citing morning grogginess.
“It appears that more work is necessary to understand whether kava as a dietary supplement can be shown as safe without associated impairments, before determining its efficacy for any potential performance benefit,” she told NutraIngredients-USA.
Thorne noted that kava is not on the World Anti-Doping Agency's (WADA) Prohibited List and is therefore not prohibited in athletes. While daytime kava consumption would not be compatible with peak performance due to its calming action on the nervous system, Dr. Phipps explained, kava has a general half-life of roughly 10 hours, so bedtime consumption would not be expected to have notable lasting effects into the following working day.
In addition, he highlighted that the proprietary AB-free form of kava used in the study has had the cytotoxic flavokavains A and B associated with hepatotoxic risk removed while preserving the six major kavalactones known to have calming effects in humans.
Ongoing research
Next in this line of research is a study at the Mayo Clinic, which will focus on the effects of bedtime kava consumption on motivation, performance, cognition, mood and symptoms of burnout in a group of 200 highly stressed medical personnel. It will incorporate additional molecular markers and other assessment instruments to further evaluate the effects of Thorne’s specific kava extract.
“The purpose of our ongoing research is to better answer questions related to kava’s impact on such things as military readiness and human performance,” Dr. Phipps said. “Our carefully designed prospective Mayo Clinic study is one step in this direction, and our follow up research and conversations in military settings is another.
“But if our initial findings can be replicated, it is possible that kava (when used before sleep) may be found to enhance rather than hinder military readiness.”
Source: Journal of the International Society of Sports Nutrition
doi: 10.1080/15502783.2024.2377194
“Kavalactones support motivation to move during intensive training in males preparing for military special operations forces”
Authors: Sheena Y. Smith et al.