Welcome to the July 2025 issue of Research Extracts. “The Extracts” is designed to keep busy practitioners and savvy consumers up to date on the latest research on diet, nutrients, botanicals, the microbiome, the environment, and lifestyle approaches to good health and wellness. Our medical team, including NDs, RDs, MS biology, MS chemistry, an LAc, and a Certified Specialist in Sports Dietetics (CSSD), summarizes the essence of several interesting recent studies. 

In this issue: (1) Korean red ginseng and stress/cognitive support, (2) Rhodiola for strength training, (3) dark chocolate and (4) kefir – these last two illustrating the power of specific foods to support female athletic performance.


Korean Red Ginseng Supports Stress Management with Added Cognitive Support*

Everyone experiences stress; it’s an inescapable part of life. Mostly, we muddle through with tried-and-true strategies and techniques like breath control, meditation, or yoga (or chocolate) to get past the toughest times. Occasionally, we want a little extra help keeping our mood balanced, but it can be difficult to know which options are worthwhile. This is where science can lend a hand. 

A clinical trial published in February 2025 studied a specific Panax ginseng (Korean red ginseng) root powder for effects on stress and cognition. The ginseng used in this study was derived from hydroponically grown plants and produced in a way that concentrated its functional components; especially the rare ginsenosides. In this randomized, placebo-controlled study of healthy adults experiencing moderate stress, 70 participants (average age 29; 41% male) took 200 mg of ginseng (with 22.4 mg ginsenosides) daily, while 72 participants (average age 31; 47% male) took a matched placebo. Participants and researchers did not know which they had received during the study and data was collected at the beginning and end of the three-week study. 

Perceived stress levels were measured with the validated Perceived Stress Scale (PSS) questionnaire. Although both groups experienced a decrease in stress over the three weeks of the study, the group using ginseng reported significantly less perceived stress at the end of the study than the placebo group. 

Positive and negative affect (emotional experiences) were measured with the Positive and Negative Affect Schedule (PANAS), which found significantly less negative emotion with ginseng than with placebo. The ginseng group but not the placebo group also experienced significant mood improvement between the beginning and end of the study, while the placebo group did not. 

Cognitive abilities were measured with two subtests of the Cambridge Neuropsychological Test Automated Battery (CANTAB) – the Paired Associate Learning (PAL) test for visual memory and new learning, and the One Touch Stockings of Cambridge (OTSC) test for spatial planning and working memory. Participants taking ginseng made fewer errors in the PAL after three weeks than at the beginning, while the placebo group experienced no significant change. Ginseng users also responded faster in the OTSC test for spatial planning compared to the placebo group and also compared to how well they did at the start of the study. 

Overall, this trial adds to the list of studies demonstrating that Korean red ginseng may be effective at supporting a balanced stress response in healthy people and may have beneficial effects on some aspects of cognition as well.* 

Note: Thorne’s Ginseng Plus contains 420 mg of this unique Korean red ginseng extract in each two-capsule serving for stress resilience, mood, and cognitive support.* You can read more about this unique ginseng and the company Botalys that has pioneered sustainable, biomimetic indoor-farming techniques here.

Contributed by Sheena Smith, MS, MA 

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Rhodiola rosea Extract on Strength Performance in Resistance Training

Rhodiola rosea, a powerful adaptogenic herb long used in traditional medicine, is gaining recognition for its potential to support strength and physical performance. Its active compounds, including rosavin and salidroside, are believed to support muscular endurance, reduce fatigue, and improve recovery – critical elements for strength-focused athletes. By helping the body adapt to physical stress and sustain energy levels during intense training, Rhodiola rosea extract may contribute to greater power output and improved resistance to exhaustion. This positions it as a promising natural aid for those aiming to build strength and maximize athletic performance.*    

The featured study examined the impact of four days of Rhodiola rosea supplementation on upper-body strength performance – specifically bench-press and bench-pull exercises – under both resting and mentally fatigued conditions in healthy young adults. Eighteen participants (including seven women) completed four randomized, counterbalanced experimental sessions, each involving either Rhodiola or a placebo combined with a mental fatigue task (Stroop test) or a control video. The primary outcomes assessed included physical performance (repetitions and velocity), perceived exertion, and cognitive processing. 

The findings revealed that Rhodiola supplementation had minimal effects on mental fatigue, visuo-cognitive function, or subjective exertion levels. However, Rhodiola did show a performance advantage under rested (control video) conditions, significantly improving strength metrics in certain sets, such as increasing the number of repetitions in the bench press and enhancing peak velocity in the bench pull. Among 52 performance comparisons, 17 showed small effect sizes, with 14 favoring Rhodiola. These results suggest that short-term Rhodiola supplementation is safe and may provide modest but meaningful benefits for strength performance, particularly in the absence of mental fatigue.

Note: Thorne’s Rhodiola and Daily Greens Plus each provide 100 mg of Rhodiola extract per serving either as a stand-alone or in synergy with several key ingredients, offering adaptogenic support to enhance mood and benefit physical performance.*

Contributed by Mario Roxas, ND

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Dark Chocolate Enhances Performance and Recovery in Menstruating Female Athletes

Exercise performance and recovery are impacted by hormonal changes across the female menstrual cycle. Gradually increasing estrogen in the follicular phase is associated with anaerobic capacity and muscle strength, while increased progesterone during the luteal phase can lead to reduced coordination and increased fatigue. With more women participating in sports, weightlifting, and other physical activities across their menstruating years, strategies to support both performance and recovery are in demand. 

Fifteen women with regular menstrual cycles and who were trained CrossFit® athletes were given either 35 g of 85% dark chocolate, placebo, or nothing daily for three consecutive days followed by a day of fitness testing. This protocol was repeated at four time points across a single menstrual cycle. In a randomized, crossover design, participants completed each of the three experimental conditions with a two-month washout period between each. 

Dark chocolate supplementation was associated with improvements in both physical and cognitive performance. Participants experienced improved high-intensity exercise performance across all phases of the menstrual cycle after dark chocolate supplementation. Cognitive performance, including faster reaction times, was significantly improved by dark chocolate supplementation during the late luteal phase. There were modest improvements in delayed onset muscle soreness during the luteal phase with dark chocolate consumption. The authors concluded dark chocolate consumption is a promising strategy for supporting exercise performance and recovery in menstruating female athletes.

Note: Try Thorne’s RecoveryPro® mixed in your beverage of choice as a nighttime chocolate treat – hot or cold – to support exercise recovery with whey protein, magnesium bisglycinate, and additional nutrients to promote restful sleep and muscle repair.*

Contributed by Jennifer L. Greer, ND, MEd

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Kefir Consumption for Athletic Performance

Kefir, a fermented dairy beverage, offers gut health support with the presence of probiotics. These probiotics contribute to the production of beneficial metabolites including short-chain fatty acids (SCFAs) as postbiotics. This randomized, controlled trial aimed to identify effects of kefir consumption on the gut microbiota as well as athletic performance, providing additional insights into the use of probiotic foods in athletes’ diets.

Participants were 21 professional female soccer players between the ages of 18 and 29 who were divided into kefir or control groups. The kefir group consumed 200 mL/day of kefir for 28 days while the control group continued their typical diet. To assess the effects of kefir consumption, all participants completed the 30-15 Intermittent Fitness Test (IFT) measuring maximal aerobic speed and oxygen consumption (as VO2 max). Stool samples were also taken for DNA analysis of gut microbiome diversity and composition.

At the end of the study period, the kefir group had the highest microbial diversity and richness, which was moderately positively correlated with VO2 max and aerobic speed. There were also significant compositional differences comparing kefir to control group microbial communities. The kefir group saw increases in beneficial bacterium types such as Akkermansia and Bifidobacterium and decreases in potentially pathogenic Proteobacteria and Faecalibacterium compared to control.

Participants were also categorized into low-, medium-, and high-performance groups based on their IFT results. Overall, the high-performance group had a higher abundance of bacteria that reduces inflammation and facilitates efficient energy metabolism. The medium-performance group saw a high abundance of microbiota related to gut mucosa integrity and energy metabolism, while the low-performance group had a high abundance of bacteria not often associated with efficient energy metabolism. 

While this study only included a sample of female athletes, these results show a potential positive relationship between gut microbiomes and athletic performance metrics. Further research is needed to help inform probiotic consumption recommendations via kefir or other fermented foods as a possible modifiable factor for athletic performance and recovery.

Note: Thorne’s Complete Biotic, provides pre-, pro-, and postbiotics for 360-degree gut health and immune system support, promoting optimal microbial balance and the production of beneficial microbial metabolites in a unique, fast-melt powder.* 

Contributed by Carly Duffy, MPH, RD

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