Welcome to the April 2020 edition 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. Our medical team, which includes NDs, MDs, PhDs, RDs, an MS, and an LAc, has summarized the essence of several of the most interesting studies.

Research summaries in this month’s issue include: (1) ashwagandha for stress and sleep, (2) spending time in nature for stress reduction, (3) timing of meals for best metabolic effects, and (4) effects of salt on immune function.

We are all feeling it a little more these days – stress, difficulty sleeping, irritability, moodiness – so we need all the resources we can get to help make us feel better and support our resistance to stress. The first two studies show two different approaches to dealing with stress during these uncertain times – one a botanical, the other an activity.

Stressed out? Having trouble sleeping? Ashwagandha’s help is supported by a recent double-blind study.

Ashwagandha (Withania somnifera) is one of the most revered botanicals in India’s ancient Ayurvedic medical system. This adaptogenic botanical has a broad range of therapeutic benefits. Numerous studies support its use for cognitive function, stress, muscle strength, endurance and recovery, glucose metabolism, hormone balance, sexual function, and thyroid health.*

In this double-blind, placebo-controlled trial, 60 stressed but otherwise healthy adults (ages 18-55) were given one of three protocols for eight weeks: (1) 125 mg ashwagandha root extract twice daily, (2) 300 mg ashwagandha root extract twice daily, or (3) placebo twice daily.

Changes in the Perceived Stress Scale (PSS; participants had a PSS score of 20 or higher to be included in the study) were assessed at baseline and at four and eight weeks. Other assessments were the Hamilton Anxiety Rating Scale (HAM-A), a 7-point sleep scale, and serum cortisol, these latter assessed at baseline and the end of the study. The ashwagandha was a concentrated, broad-spectrum extract – KSM-66®.

Fifty-eight participants (average age 31) completed the study. At the study’s end, participants in both ashwagandha groups had significantly lower stress scores on the PSS compared to the placebo group – with the 600-mg daily group experiencing the most significant decrease.

Serum cortisol levels decreased significantly in both ashwagandha groups, while individuals taking placebo had no significant decrease in cortisol; the most significant decrease was in the 600-mg ashwagandha group. Scores on the HAM-A were significantly lower only in the 600-mg ashwagandha group. Sleep quality improved in both ashwagandha groups compared to placebo.

In this study, participants taking ashwagandha experienced improved resistance to stress, better sleep quality, and lower cortisol.*

See Thorne products containing KSM-66

Contributed by Kathi Head, ND


  • Salve J, Pate S, Debnath K, Langade D. Adaptogenic and anxiolytic effects of ashwagandha root extract in healthy adults: a double-blind, randomized, placebo-controlled clinical study. Cureus 2019 Dec 25;11(12):e6466. doi: 10.7759/cureus.6466.

Study shows spending time in nature decreases stress and anxiety.

High numbers of stress, anxiety, and depression complaints are common at U.S. colleges and universities. Although conventional treatments consisting of counseling and medication are utilized when appropriate, increasing evidence demonstrates that time in nature can provide benefit to mental health and well-being. What has not been thoroughly studied is the minimum time needed to produce the desired effect.

The objective of this study was to determine the “dose” of time that could be prescribed to U.S. college students as a prevention strategy for mental health issues such as stress and anxiety, and the type of engagement needed to elicit prevention.

A scoping review approach guided this study, allowing the researchers to identify and review available literature and identify themes and gaps in it, as a step toward more focused research efforts. Subjects for the review included individuals of average college age, and interventions for the review included engaging in a defined activity while in nature for a specific and measured period of time.

A total of 10,917 pieces of literature were screened for inclusion. A total of 155 studies were considered for review, and 14 were selected that met all defined criteria, such as being published after 2000 and including a minimum of 12 participants.

A review of the 14 studies revealed that as few as 10-20 minutes and up to 50 minutes in natural settings had a significant and positive impact on psychological and physiological markers for stress and anxiety

As little as 10 minutes in a natural setting had significant impact on mental health measures.

Contributed by Amanda Frick, ND, LAc


  • Meredith G, Rakow D, Eldermire E, et al. Minimum time dose in nature to positively impact the mental health of college-aged students, and how to measure it: A scoping review. Front Psychol 2020;10. doi:10.3389/fpsyg.2019.02942

A heavier breakfast to get lighter?  

A single-blind, randomized, cross-over study of diet-induced thermogenesis (DIT; the energy required to process and store food after a meal) found that breakfast generates 2.5-times higher DIT than dinner regardless of calorie content.

In this study, 16 young and healthy male subjects spent three days under laboratory conditions with regulated activity, controlled calorie intake, and monitored sleep. The first day allowed the subjects to acclimate to the environment and control their diet prior to investigational meals.

On the second day, the men received either a low calorie (11% total energy expenditure; TEE) breakfast and high calorie (69% TEE) dinner or the reverse, with all receiving a moderate lunch (20% TEE).  On the third day, the groups were reversed. During the study, indirect calorimetry, serum glucose, insulin, cortisol, and ACTH were measured, and participants were surveyed for hunger and appetite for sweets several times a day both before and after meals.

The authors conclude that timing of the major caloric meal of the day is likely to have an impact on post-prandial energy expenditure, that a higher-calorie breakfast curbs appetite and cravings later in the day to help reduce snacking, and that glucose metabolism is favorable when breakfast is the major caloric meal of the day.

The researchers suggest that shifting calories to breakfast and away from dinner assists in weight management efforts, even with calorie restriction, and might also have a positive impact on metabolic health.

Contributed by Sheena Smith, MS MA 


  • Richter J, Herzog N, Janka S, et al. Twice as high diet-induced thermogenesis after breakfast versus dinner on high-calorie as well as low-calorie meals. J Clin Endocrinol Metab 2020.105(3). doi: 10.1210/clinem/dgz311.

Does a High-Salt Diet Affect Immune Function?

Most Americans eat a so-called standard Western diet; i.e., a diet that tends to be high in salt and sugar content, saturated fats, and simple carbohydrates, and which plays a negative role in many chronic health conditions.

Although a high-salt diet is a factor in inflammation in the body, some research has shown that it might also affect immunity. Researchers set out to understand more about the ways dietary salt might affect the immune system.

The researchers investigated specifically how a high-salt diet affects bacterial kidney infections. Kidney infections were chosen because bacterial infections of the bladder and kidneys are common infections, and the kidneys maintain the balance of salt (as sodium) and water in the body.

In animals fed a high-salt diet, infected kidneys contained up to six times more bacteria than infected kidneys of animals fed a no-salt or low-salt diet. This led the researchers to investigate why the bacterial burden might be higher in those consuming a high-salt diet.

The antibacterial immune response in the kidney involves three types of immune cells – neutrophils that remove bacteria by ingesting them, and monocytes and dendritic cells that identify harmful bacteria and attract neutrophils to the infection. 

Although the research did not show a difference in the number of immune cells present in the infected kidneys, it was discovered that neutrophils were not as effective at killing the infection in the animals on a high-salt diet.

The immune-suppressive effect of a high-salt diet was found to be a result of the normal process of eliminating excess sodium from the body.

Contributed by Jennifer L. Greer, ND, MEd


  • Jobin K, Stumpf N, Schwab S, et al. A high-salt diet compromises antibacterial neutrophil responses through hormonal perturbation. Sci Transl Med 2020;12(536).