Ultimate Guide to Adaptogens

First off, What Are Adaptogens and What Are They Supposed To Do?

Adaptogens are a select group of herbs (and some mushrooms) that support the body’s natural ability to deal with stress. They are called adaptogens because of their unique ability to “adapt” their function according to the specific needs of the body. This may be physical, chemical or biological needs. They have been compared to a thermostat, moderating the body’s stress response like a thermostat controls temperature. They have special compounds that can possess opposing qualities, such as being relaxing or stimulating. The correct response is triggered according to the body’s specific needs. They are found today in a growing list of drinks, teas, tinctures and powders. They are often used as a healthy alternative to some prescribed medications and stimulants, anabolic steroids as well as common pick-me-ups like caffeine and sugar. There are dozens of plants, growing in some of the world’s harshest environments, that fall under the adaptogen category. (You can find a list of adaptogens and their benefits here.)

Cartoon drawings of popular adaptogen herbs

Ginseng is one of the most well-known adaptogenic herbs. It is said to increase energy, improve cognitive function, act as an anti-inflammatory, help with erectile dysfunction, prevent flu and lower blood sugar. Another well-known adaptogen, Rhodiola Rosea, is said to enhance mental performance and physical stamina. Others, like reishi, ashwagandha and holy basil soothe stressed adrenals. Astragalus has immune-boosting qualities. Schizandra is used to resist infections, increase skin health, and combat insomnia, coughing, and thirst.

Adaptogenic herbs act in non-specific ways to increase resistance to stress, without disturbing normal biological functions, explains celebrity doctor and alternative medicine champion Andrew Weil. [1]

Each one claims to do something a little different, but on the whole, adaptogens help your body handle stress,” says Dr Brenda Powell, co-medical director of the Center for Integrative and Lifestyle Medicine at the Cleveland Clinic’s Wellness Institute. Adaptogens do for your adrenal glands what exercise does for the muscles, she says. They do this by interacting with the hypothalamic-pituitary-adrenal (HPA) axis and the sympathoadrenal system, tweaking hormone production and physiological responses to ensure the body functions optimally.[2]

Researchers from the Swedish Herbal Institute believe adaptogens work at a cellular level. “Studies on animals and isolated neuronal cells have revealed that adaptogens exhibit neuroprotective, anti-fatigue, antidepressive, anxiolytic, nootropic and CNS stimulating activity.” [3]  Clinical trials have demonstrated they can increases mental work capacity against a background of stress and fatigue, particularly intolerance to mental exhaustion and enhanced attention.

laboratory microscope

“When the body is subjected to stress, adaptogens help the adrenal glands mount an immediate hormonal response by manufacturing and releasing more stress hormones,” says Dr Ben Tabachnik, a former Russian scientist who emigrated to the U.S., bringing with him decades of adaptogenic research once regarded as a state secret.

“When the stress stops, however, the adaptogens help the adrenal glands shut down more quickly. In cases where stress is prolonged and/severe, the adrenals reserve their resources by reducing the amount of hormones they release due to adaptogenic restoration by hypothalamic receptor sensitivity. This conserved energy becomes available to continue the body’s response to stressors, thereby delaying adrenal exhaustion.”  [4]

Dr Teiraona Low Dog, a well-known western doctor who specializes in herbal medicine, said adaptogens “could be the most important class of plants that we are going to find in the 21st century. “On top of daily meditation, healthier eating, and writing daily in a journal, these herbs could be an essential part of helping you manage your stress.”

Adaptogens should not be considered as a ‘miracle cure’, experts caution. They should be considered as part of a whole-body treatment that includes a proper diet, regular exercise and adequate sleep. They will be of little assistance if the people taking them aren’t addressing the root causes of stress in their life such as diet, exercise and adequate amounts of sleep.

Why this (not so) sudden interest?

Herbs that are good sources of antioxidants and anti-inflammatory agents and that also happen to boost energy levels, fight stress, promote health and all without harmful side effects? No wonder there’s interest, especially in North America where stress-related health issues have reached epidemic proportions. A U.S. Department of Health and Human Services’ (HHS) report in 2004 showed almost half of all people are taking at least one prescription medication and one in six taking three or more medications. [5]  In 2012, nearly 360,00 people received treatment for stimulant addiction. [6] People are using prescription stimulants not just to get high, but also to enhance performance, notes the Beach House Centre for Recovery. “Athletes and students have a long history of abusing prescription stimulants to outperform their peers.” [7]

Coloured pill bottles

Another popular and unhealthy antidote for stress has become energy drinks, made up primarily of caffeine and sugar. According to a review published in the journal Frontiers in Public Health, these drinks may be associated with a number of serious health problems, affecting sleep, causing weight gain and even spiking blood pressure. [8] Evidence suggests they may lead to substance abuse, mental health problems, a higher diabetes risk, tooth decay, and kidney damage.  “The wide range of conditions that energy drinks can negatively impact was quite astounding,” said study author Josiemer Mattei, Ph.D., assistant professor of nutrition at Harvard T.H. Chan School of Public Health. [8] In 2017 the Canadian Paediatric society warned that children, under 18, a huge and growing market for energy drink manufacturers, should avoid sports and energy drinks.

“Our bodies evolved during a period when the primary stressors were physical and were tied to the fight for survival. If you couldn’t adapt, you died,” points out, Dr Tabachnik, who gained worldwide recognition for his work implementing scientific discoveries in physiology, biochemistry, pharmacology and nutrition into the training programs of elite athletes, including members of the Soviet National Olympic Team.  Stressors today are chronic such as pollution, unhealthy food, noise, jobs, personal relationships and information most of which don’t demand a physical response, he says.

“In some ways stress can be very positive, because it can mobilize our body to cope with changes, with challenges. In other ways, though, our systems overreact, which can be damaging to our health. If the stress is prolonged, or if it’s too strong or too damaging, if too much of the stress hormone cortisol is released from the adrenals, you can have all kinds of dysfunction and disease.” [9]

Although there has been a recent surge of interest in North America, adaptogens have a long history of use, especially in Eastern countries. Ginseng was mentioned in the Shen-Nung Pharmacopoeia, written in China in 196 AD. In his Compendium of Materia Medica herbal of 1596, Li Shizhen described it as a "superior tonic". It also receives high praise in the Vedas, ancient books of scripture. “The strength of the horse, the mule, the goat, the ram, moreover the strength of the bull it bestows on him. This herb will make thee so full of lusty strength that thou shalt, when excited, exhale heat as a thing of fire.” According to American herbalist Dr Christopher, the root and leaves of American Ginseng, native to eastern North America, were considered sacred herbs by Native Americans who used it for headaches, croup, for soothing eyes and as a poultice for wounds. Documented medicinal use for Rhodiola dates back at least to A.D. 77 when a physician recommended it for headaches.  

In modern times the Soviet Union and then Russia have been in the forefront of adaptogen research. The term adaptogen was first recorded in 1947 by Soviet toxicologist N. V. Lazarev. In 1958 Soviet researchers provided the definition that adaptogens “must be innocuous and cause minimal disorders in the physiological functions of an organism, must have a nonspecific action, and usually [have] a normalizing action irrespective of the direction of the pathological state.”  After the breakup of the Soviet Union, Russian scientists continued to lead the way in adaptogen research.

Adaptogens proved to be a safe, natural, and legal substitute for synthetic anabolic steroid drugs, says Tabachnik pointing to a 50 per cent decrease in immune system damage and a 50 per cent decrease in drug dosage among patients receiving anti-cancer chemotherapy for gastric cancer. Eleutherococcus, also known as Siberian ginseng, although it is not a true ginseng or is from Siberia, was also extensively researched, he says. Studies showed a 40 per cent decrease in high blood pressure and heart disease and a 30 per cent decrease in reported symptoms among auto factory workers, improved productivity and a 30 per cent reduction in the risk of developing influenza among long-distance truck drivers. Adaptogens improved stamina and recovery, as well as increased oxygen intake and better performance among Soviet Olympic and other high-level athletes, he says.  [10] Despite these results, news about adaptogens remained a closely guarded secret of the Soviet state, so until recently this research never reached Western scientists.

Apothecary wall

Another herb of interest to the Russians was Rhodiola Rosea, which has been used for centuries in Russia and Scandinavia. Supposedly, Vikings knew about its endurance-enhancing abilities. The government took these experiments so seriously that scientists were banned from speaking of their results or publishing their findings outside the country, says Patricia Gerbarg, an Assistant Clinical Professor in Psychiatry at New York Medical College. She worked with Zakir Ramazanov, a Russian researcher who left the USSR after the Iron Curtain fell, to write The Rhodiola Revolution. “It was the Rhodiola—a yellow-flowered, succulent that only grows in snow-bound Arctic climes, with a root that smells almost like a rose when you nick it—that elicited the most promising results.  It stimulates you, without making you crash and burn,” said Gerbarg in a 2016 National Geographic Article.

The herb Schisandra Chinensis gained recognition as an adaptogen in the official medicine of the USSR in the early 1960s, principally as a result of a large number of pharmacological and clinical studies carried out by Soviet scientists in the preceding two decades. “Schizandra has now secured an established position within the medicine of Russia/USSR as evidenced by the inclusion of the drug in recent editions of the National Pharmacopoeia of the USSR and in the State Register of Drugs.”

Does the reality match the hype? Or is this another one of those ’Superfood’ scams?

There is a huge amount of apocryphal evidence supporting the health benefits of adaptogens, which is not surprising considering many of them have been in constant use for centuries. Talking about adaptogenic research, Dr Low Dog says “We look at what they were used for historically and we start there. In some cases, it doesn't pan out. In many cases, actually, we find that there was a thread of science that was woven into their keen observations and their use of these plants for thousands of years. People don't usually keep using something that doesn't work.”  [11]

However, the lack of larger, substantive, studies has prevented adaptogens from gaining acceptance in the established medical community. The term adaptogen is not accepted in pharmacological, physiological, or mainstream clinical practices in the European Union. The European Medicines Agency says the concept requires additional clinical and preclinical research. Most of the available studies performed in the Soviet Union, Korea, and China before the 1980s, have been dismissed because the studies were small and poorly designed, using animals or animal or human cell cultures rather than humans.  

“The science on adaptogens is still heavy on hope and light on evidence. And there are reasons to question whether chemicals that combat biological stress would be universally beneficial,” argues Melinda Wenner Moyer a science and health writer based in New York. “We don’t have clear evidence yet that adaptogens actually improve well-being or cure ailments, and the mechanics of the body’s stress response system are still somewhat of a mystery.”  [12]

“As things currently stand, adaptogens could not be classified as a rational shopping decision,’ concludes Abby Campbell a practising M.D, with a PhD in Pharmacology. “How can the science on adaptogens be so confusing? Rhodiola works for doctors but not for nurses? Ginseng works for normal people but not extreme athletes?’ she writes in a 2018 blog for HealthyButSmart.com.

The conflicting Rhodiola studies Campbell referred to are Armenian and Canadian. The Armenian study looked at the fatigue-reducing effect of Rhodiola on 56 young physicians. [13] The study design was was a double-blind cross over trial. A total of five tests involved complex perceptive and cognitive cerebral functions such as associative thinking, short-term memory, calculations and ability of concentration and speed of audio-visual perception. A statistically significant improvement was observed in the treatment group. However, different results were found in a parallel-group randomized, double-blinded, placebo-controlled trial of 18-55 year old students from the Faculty of Nursing from the University of Alberta [14]. Participants were randomized to take 364 mg of either Rhodiola or a placebo at the start of their wakeful period and up to one additional capsule within the following four hours on a daily basis over a 42-day period. In this study, Rhodiola worsened fatigue compared with the placebo.

Part of the difficulties with adaptogen studies is that the herbs can have differing results between people or within the same body, says Dr Low Dog.  In some studies, ginseng relieves anxiety and in other studies, it stimulates anxiety. Equally some studies show that ginseng raises BP while in others lowers BP. Adaptogens are essentially smart drugs that ‘normalize’ things, she says.

Part of what makes adaptogens so interesting and controversial is that they exert seemingly paradoxical effects, points out Jeff Bland, founder of the Personalized Lifestyle Medicine Institute. “The same herb may simultaneously enhance adrenal fun action while also helping an individual relax and sleep better. They can normalize levels of HPA hormones, raising those that are low while lowering those that are elevated.”

There are other complicating factors in adaptogenic research efforts. The impact and effectiveness of adaptogenic herbs depend not only on the state of the person being tested but also how the herbs are grown and how they are harvested. Traditionally adaptogenic herbs have grown in some of the most inhospitable areas of the planet which likely gives them their stress and fatigue-fighting properties. The growing popularity of these herbs has meant that they are sometimes harvested too early. The roots of these herbs take years of growth before they gain their full potential. Their growing popularity has meant that endangered wild crops are now being grown domestically.

Also, the particular health benefits of adaptogens often depend on how they are combined with other adaptogens.     

“We do this in cooking all the time. We want a certain flavor. We want a certain spiciness, which is using herbs like basil, oregano, and other things together. This is common. We've always done this. Plants have long been combined together for the therapeutic effects,” says Dr Low Dog.

mortar and pestle grinding

Also, the benefits of many adaptogens, like ginseng, are not typically felt right away although some, like Rhodiola, can provide an immediate boost. “If it's short‑term, that's one thing. If you're finding yourself chronically waking up in the morning and not feeling energized, then you're looking for an adaptogen. Adaptogens [are] intended to be taken over a period of time to strengthen the system,” says Dr Low Dog.

Ginseng, still widely used in Asia and a key component of many popular products sold in North America is a stark example of the gap between public and scientific attitudes. An internet search reveals a long list of claims, citing numerous scientific studies, for ginseng’s benefits. It also reveals a long list of sites citing numerous scientific studies to say the exact opposite; that the benefits of ginseng have been wildly overestimated and supportive studies are mostly worthless.

Just because it has been used for thousands of years is not a guarantee that it’s health benefits are legitimate, say skeptics. Western remedies for fever such as Tylenol or Aspirin are more effective than the traditional Chinese remedy of powdered rhino horns. Similarly, shark cartilage is useless in treating lung cancer. Nor is ginseng’s popularity a measurement of its effectiveness.

History offers many examples of popular cures that proved to be totally ineffective. Also, herbal remedies are not as effective as the concentrated pharmaceuticals developed in labs. Willow bark was the original source of aspirin thanks to its active ingredient salicylic acid, but it is not as effective as the tablet which processed the extracted salicylic acid with acetylation making it's analgesic effects much stronger. Bayer is a multimillion dollar company today, but willow bark tea occupies a very small niche market in health food stores. Herbs that do not attract the attention of pharmaceutical companies most likely are too mild and cannot be turned into a commercial product.

“For four decades, I’ve been skeptical of a prevailing belief in Western medicine: when a plant shows bioactivity in humans, we must attribute that effect to a single, predominant compound in the plant,” argues Dr Weill in a 2010 Huffington Post article.  Synthesizing a single molecule is popular because it allows drug companies to make billions in patents, he said.

“Expensive as it is to the consumer, this faith in “single-agent” drugs would be acceptable if they actually yielded better results. But the fact is, the natural, whole plant often has both benefits and safety that put the isolated compounds to shame.” [15]

Promoters of herbal medicine point to deaths, addiction, and impairment that are increasingly associated with medically prescribed medications. The non-profit group Trust for America’s Health reported in 2013 that prescription drug abuse had become the nation’s top public health concern, as the number of drug overdose deaths - a majority of which are from prescription drugs - doubled in 29 states since 1999. The rates quadrupled in four of these states and tripled in 10 others. “Misuse and abuse of prescription drugs cost the country an estimated $53.4 billion a year in lost productivity, medical costs and criminal justice costs, and currently, only one in 10 Americans with a substance abuse disorder receives treatment.”[16]

Although there is scepticism in the medical community because of the lack of credible research, there seems to be a growing realization, as the number of small studies increases, that adaptogens do have unique, probably beneficial, qualities that warrant further investigation.

“Approximately one in five U.S. adults reports using a herbal product within the past year", writes researcher Stephen Bent in a 2008 article in the Journal of General Internal Medicine. “Unfortunately, for most of the roughly 20,000 herbal products available in this country, there is little evidence regarding safety or efficacy.

“However, as one third to one-half of all pharmaceutical drugs were originally derived from plants, there is clearly a potential to find effective therapies from the natural environment. The current regulation of herbs does not ensure that available products are safe, and false and illegal marketing claims are common. Several simple changes to the regulation of these products could dramatically improve the appropriate use of herbs. Future research will be best served by the creation of national standards for the constituents of specific herbs, greater incentives for research, and the development of study designs that reduce costs and study duration. ” [17]

Herbal tea with dried herbs

Some of ginseng’s benefits have been supported in several small but well-designed studies. A small Canadian study in 2008, for example, found that North American ginseng increased various immune markers in sedentary men who did a short bout of cycling. Other studies showed that ginseng can help control blood sugar by increasing insulin production.  “Despite the lack of sufficient widespread clinical, mechanistic studies and standardization for immediate therapeutic uses greatly hinders the possibility of practical applications, current reports of ginseng and ginsenosides point to the possibility of ginseng as a candidate for complementary diabetes therapy,” concluded a 2008 review summarizing current knowledge of ginseng components and clinical studies related to diabetes. [18]

Similar results have also been seen with other adaptogens. The University of Michigan Medicine gives a three-star rating (meaning it is supported by reliable and relatively consistent scientific data) to Rhodiola’s ability to support mental function and promote feelings of well-being. It gave a two-star rating, indicating contradictory or insufficient evidence, to its role in reducing stress and anxiety, increasing general endurance and improving mental performance. [19]  

A recent review assessing the level of scientific evidence presented by clinical trials of adaptogens in fatigue found that Schizandra increased endurance and mental performance in patients with mild fatigue and weakness. [20] The findings of a randomized double-blind, placebo-controlled study published in the Indian Journal of Psychology medicine found that the ashwagandha root reduced stress and anxiety in adults [21]. In a small study from 2011 in the Journal of Ethnopharmacology, researchers found that when healthy people took holy basil for four weeks, blood samples revealed a statistically significant increase in immune proteins that are key in activating an immune response compared with the control group and compared with the baseline levels. [22] In a 2012 study in the Journal of Natural Remedies, a small number of subjects who had high blood pressure as well as elevated blood sugar, cholesterol, and triglyceride levels, took either holy basil or a placebo for three months. After that time, those on the herb had significant reductions in blood pressure, blood lipids, and blood sugar compared with their baseline levels and the control group.[23]

Lab and animal studies show that ashwagandha has anti-inflammatory and neuroprotective properties, helps control blood sugar, reduces cancer growth, and boosts aspects of the immune system. Withaferin A, a steroid chemical, is considered the active compound responsible for its anti-inflammatory properties and anticancer potential. As far as clinical trials, a small study in BioMed Research International in 2015 found that women who took ashwagandha for eight weeks had improvements in sexual health, including orgasm and arousal, compared to those taking a placebo. [24]  In another small study, in the Journal of the International Society of Sports Nutrition in 2015, men (ages 18 to 50) who took ashwagandha or a placebo while participating in a strength-training program. After eight weeks, those taking the herb had a significant increase in blood testosterone levels and muscle strength as well as a reduction in body fat and exercise-induced muscle damage that occurs after strength training compared with the placebo. [25]

Do adaptogens have side effects?

Any plant, can be allergenic or cause gastrointestinal distress for some people, but there’s little evidence to suggest that adaptogens have serious side effects or cause health problems. It should be noted though that there has been little testing on human subjects. It is possible that some could adaptogens could interfere with prescription medications and are not recommended for people with certain conditions. Rhodiola, for example, may cause mild episodes of dizziness, dry mouth, sleep problems or jitteriness, because of its mild stimulant-type effect. Astragalus has deep immune activation, which might cause counteractions for those taking immunosuppressant drugs. Women who are pregnant or breastfeeding should avoid ashwagandha, Schisandra, and holy basil.

Given the lack of government and industry scrutiny in the supplement industry, careful research is advised before trying any herbs or shopping for products, some of which could be dubiously effective and potentially dangerous. Swedish researchers recently examined 50 ginseng products sold in 11 countries and found that six samples contained no active ingredient and in the others, the concentration of ginsenosides ranged from 2 to nine per cent. One sample sold in the U.S. contained no ginseng derivatives at all but had undeclared ephedrine, a potentially dangerous stimulant. This came to light when an athlete tested positive for ephedrine. He realized that the only possible explanation was the ginseng preparation he had taken, reported the McGill Office for Science and Society. [26] It is also critical to read ingredient labels. Too small of a dosage will not provide promised benefits.

It is important to remember that [many of] the benefits of adaptogens take time to accumulate, warns Dr Low Dog

“Many of these plants, when they're taken over a period of time, they really do help people manage their stress more effectively. People will have more energy. They'll sleep better... They're intended to be taken over a longer period of time. Their effects are more gentle and subtle, but very powerful.”

Adaptogens are not like other herbs which lose potency if taken for long periods, says Dr Weill. In fact, they work better over time. Ginseng taken over time, for example, increases energy, vitality and sexual vigor, improves skin and muscle tone, and helps build resistance to stress, he says He often recommends the herb, especially the American species, to chronically ill patients and to those who are debilitated or lacking in vitality.[27]

How do you add adaptogens to your diet?

There is an ever-growing list of products- pills, drinks, teas, tinctures, salves - incorporating adaptogenic herbs. If you’re looking for a straight dose of herbs, you can sip adaptogen teas or combine tinctures with water. To add adaptogens to the foods you’re already eating, you can buy the pre-mixed powder to spice up everything from smoothies to soups to salad dressings. Some adaptogens can be taken as capsules. It is largely buyer beware in the marketplace for adaptogen shoppers, so caution is required. Be aware of the active ingredients in the product being sold. Although they are not yet on the radar for many doctors, others who are knowledgeable about alternative medicine like naturopaths, herbalists, and chiropractors should also be able to provide reliable information.

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  1. Rhodiola For What Ails You? https://www.drweil.com/vitamins-supplements-herbs/supplements-remedies/rhodiola-for-what-ails-you/
  2. What Are Adaptogens and Why Are People Taking Them? http://time.com/5025278/adaptogens-herbs-stress-anxiety/
  3. Effects of Adaptogens on the Central Nervous System and the Molecular Mechanisms Associated with Their Stress—Protective Activity https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3991026/
  4. Adaptogens and Human Stress Responses http://www.bodytechusa.com/?project=adaptaphase
  5. Almost Half of Americans Use at Least One Prescription Drug Annual Report on Nation's Health Shows https://www.cdc.gov/nchs/pressroom/04news/hus04.htm
  6. Stimulant Addiction and Abuse https://www.addictioncenter.com/stimulants/
  7. Ibid https://www.addictioncenter.com/stimulants/
  8. Health Effects and Public Health Concerns of Energy Drink Consumption in the United States: A Mini-Review (https://www.frontiersin.org/articles/10.3389/fpubh.2017.00225/full)
  9. Adaptogens and Human Stress Responses http://www.bodytechusa.com/?project=adaptaphase
  10. Adaptogens and Human Stress Responses http://www.bodytechusa.com/?project=adaptaphase
  11. That supplement show https://www.megafood.com/podcast/ep-16-adaptogens-with-dr-tieraona-low-dog.html
  12. Read this before spending money on adaptogens https://www.self.com/story/read-this-before-spending-money-on-adaptogens-for-stress-relief-or-anything-else
  13. Rhodiola rosea in stress induced fatigue--a double-blind cross-over study of a standardized extract SHR-5 with a repeated low-dose regimen on the mental performance of healthy physicians during night duty. https://www.ncbi.nlm.nih.gov/pubmed/11081987
  14. Rhodiola rosea for mental and physical fatigue in nursing students: a randomized controlled trial. https://www.ncbi.nlm.nih.gov/pubmed/25268730
  15. Why Plants Are (Usually) Better Than Drugs https://www.huffingtonpost.com/andrew-weil-md/why-plants-are-usually-be_b_785139.html
  16. Prescription Drug Abuse: Strategies to Stop the Epidemic http://healthyamericans.org/reports/drugabuse2013/
  17.  Herbal Medicine in the United States: Review of Efficacy, Safety, and Regulation https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2517879/
  18. Ginseng on Hyperglycemia: Effects and Mechanisms https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2781779/
  19. Rhodiola https://www.uofmhealth.org/health-library/hn-3956007
  20. Pharmacology of Schisandra chinensis Bail.: an overview of Russian research and uses in medicine. https://www.ncbi.nlm.nih.gov/pubmed/18515024
  21. A Prospective, Randomized Double-Blind, Placebo-Controlled Study of Safety and Efficacy of a High-Concentration Full-Spectrum Extract of Ashwagandha Root in Reducing Stress and Anxiety in Adults https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3573577/
  22. Double-blinded randomized controlled trial for immunomodulatory effects of Tulsi (Ocimum sanctum Linn.) leaf extract on healthy volunteers. https://www.ncbi.nlm.nih.gov/pubmed/21619917
  23. Effect of Tulsi (Ocimum sanctum Linn.) on Clinical and Biochemical Parameters of Metabolic Syndrome https://www.ncbi.nlm.nih.gov/pubmed/21619917
  24. Efficacy and Safety of Ashwagandha (Withania somnifera) Root Extract in Improving Sexual Function in Women: A Pilot Study https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4609357/
  25. Examining the effect of Withania somnifera supplementation on muscle strength and recovery: a randomized controlled trial. https://www.ncbi.nlm.nih.gov/pubmed/26609282
  26. Hype, Hope and Ginseng https://www.mcgill.ca/oss/article/health-history/hype-hope-and-ginseng
  27. Can Herbal Remedies Lose Their Power? https://www.drweil.com/vitamins-supplements-herbs/supplements-remedies/can-herbal-remedies-lose-their-power/