New ashwagandha research: strength, thyroid function, healthy testosterone, brain health

Improved Strength and Enhanced Recovery

One of ashwagandha’s well-known benefits is its revitalizing property. A recent double-blind placebo-controlled study was conducted to explore whether an ashwagandha extract can improve strength training and recovery.

In the study³ led by Tim Ziegenfuss from the Center for Applied Health Sciences (Stow, OH), young, recreationally active men were asked to consume 500 mg of an ashwagandha extract-Sensoril from Natreon Inc. (New Brunswick, NJ)-or a placebo daily for 12 weeks.  Baseline measures included body composition, muscular strength, power, endurance, and a 7.5-km cycling time trial. These were repeated after 12 weeks of supplementation and an upper and lower body resistance training program.

At the end of the study, significantly greater gains were seen in the ashwagandha group compared to placebo in average squat power and bench press performance. Further significant improvements were evident in 7.5-km cycling times and perceived recovery scores, indicating that this extract improved both upper and lower body strength and has potential benefits for exercise recovery.

Reference
3. Ziegenfuss TN et al. “Effects of an aqueous extract of Withania somnifera on strength training adaptations and recovery: the STAR trial.” Nutrients. Published online November 20, 2018.

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Healthy Thyroid Function

Ashwagandha has traditionally been used in the Ayurvedic system of medicine for supporting thyroid function. Subclinical hypothyroidism, a condition in which thyroid stimulating hormone (TSH) levels are elevated, is estimated to occur in 3%-8% of the general population and is often devoid of obvious thyroid deficiency symptoms.

To evaluate the effects of ashwagandha supplementation on individuals with subclinical hypothyroidism, researchers in India conducted a double-blind placebo-controlled trial⁴ in 50 individuals between the ages of 18 and 50 with elevated TSH levels between 4.5 and 10 micro IU/L.  Participants supplemented with 600 mg of ashwagandha root extract-KSM-66 from Ixoreal Biomed (Los Angeles, CA)-daily or a placebo for eight weeks.

Serum levels of the thyroid hormones TSH, T3, and T4 were assessed at baseline and at the end of the study. Levels of all three hormones were significantly improved in those supplementing with ashwagandha compared with placebo. Ashwagandha extract was able to normalize thyroid function in individuals with subclinical hypothyroidism.

Reference
4. Sharma AK et al. “Efficacy and safety of ashwagandha root extract in subclinical hypothyroid patients: a double-blind, randomized placebo-controlled trial.” Journal of Alternative and Complementary Medicine, vol. 24, no. 3 (March 2018): 243-248

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Enhanced Testosterone and DHEA Levels

A further Ayurvedic indication for ashwagandha includes supporting vigor and vitality. In a recent double-blind placebo-controlled crossover study⁵, Adrian Lopresti and colleagues from Murdoch University (Perth, Western Australia, Australia) aimed to assess ashwagandha’s effects on fatigue, vigor, and hormone levels in aging men.

Fifty-seven overweight males aged 40-70 with mild fatigue were asked to supplement with ashwagandha-as Shoden beads from Arjuna Natural Ltd. providing 21 mg of withanolide glycosides per day-or a placebo for eight weeks. Treatments were then crossed over for an additional eight weeks. 

Improvements in fatigue, vigor, and sexual as well as psychological well-being were reported over the supplementation period in the ashwagandha group; however, the difference in these changes versus placebo did not reach statistical significance.

Ashwagandha supplementation led to a statistically significant increase in testosterone versus placebo (14.7%) as well as in salivary levels of DHEA sulfate (18%). Low testosterone levels occur in those with mood disorders, obesity, cardiovascular disease, and type 2 diabetes and are associated with reduced quality of life, while some studies indicate that DHEA levels are a predictor of longevity in men. Higher DHEA levels are also associated with enhanced mood and reduced fatigue. Thus, ashwagandha’s beneficial effects on these hormones may lead to improvements in quality of life in aging men.

Reference
5. Lopresti AL et al. “A randomized, double-blind, placebo-controlled, crossover study examining the hormonal and vitality effects of ashwagandha (Withania somnifera) in aging, overweight males.” American Journal of Men’s Health, vol. 13, no. 2 (March-April 2019). Published online March 10, 2019.

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Improved Cognitive Health

An additional traditional use of ashwagandha is for supporting memory and cognitive function. To explore whether ashwagandha supplementation can improve cognitive health in individuals with mild cognitive impairment, Dnyanraj Choudhary from the Indian Red Cross Society (Pune, India) led a double-blind placebo-controlled study⁶ in which 50 adults were asked to supplement with 300 mg of an ashwagandha root extract twice daily-KSM-66 from Ixoreal Biomed-or a placebo for eight weeks. 

A battery of cognitive tests was used to assess changes in cognitive function, including memory, executive function, and attention. These measures included the Wechsler Memory Scale III, a validated tool assessing several types of memory; the Wisconsin Card Sorting Test and the Eriksen Flanker Task to assess executive function; and the Trail Making Test and Mackworth Clock Test to assess attention and information processing speed.

At the end of the study, significant improvements were evident with ashwagandha supplementation in immediate and general memory, executive function, sustained attention, and information processing speed. These results indicate that ashwagandha may be an effective intervention for enhancing cognitive function in adults with mild cognitive impairment.

Reference
6. Choudhary D et al. “Efficacy and safety of ashwagandha (Withania somnifera (L.) Dunal) root extract in improving memory and cognitive functions.” Journal of Dietary Supplements, vol. 14, no. 6 (November 2, 2017): 599-612

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