Rev. Dr. LaVeena Archers
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The Herbs and Mushrooms With Real Human Evidence Behind Them

· Last reviewed

Written and reviewed by Rev. Dr. LaVeena B. Archers, PhD
Doctor of Natural Medicine · Board-certified in Holistic Functional Medicine and Functional Nutrition
Educational content only. Not medical advice, and never a substitute for your own care. Scope of practice.

Quick answers

Is there real evidence for reishi mushroom?
Some. A pilot trial in breast cancer patients on endocrine therapy found less fatigue and better quality of life after four weeks [1], and a separate trial in healthy adults found measurable shifts in immune cell markers over 84 days [2]. Reishi can also increase bleeding risk for people on blood thinners [9], so it is worth mentioning to your clinician.
Does ashwagandha actually lower stress and cortisol?
The best trial in this space gave adults with chronic stress a standardized ashwagandha extract for 60 days and found a significant drop in both stress-scale scores and cortisol compared to placebo [3]. It also has documented risk: a small trial found it shifts thyroid hormone levels [7] and a case report describes thyrotoxicosis that resolved after stopping it [4], so anyone with a thyroid condition should talk to a clinician before adding it.
Does echinacea actually help with colds?
A meta-analysis pooling 14 studies found echinacea reduced the odds of catching a cold by 58 percent and shortened the average cold by about 1.4 days [5], though a later Cochrane review found the effect inconsistent across different echinacea preparations [8]. It is generally not recommended for people with autoimmune conditions, since it works by stimulating immune activity.

Four of the herbs and mushrooms in this category have real human trial evidence behind them, and every one of them also carries a documented risk. Reishi eased fatigue and improved quality of life in breast cancer patients on endocrine therapy [1] and shifted immune cell markers in healthy adults [2], and it can increase bleeding risk for anyone on a blood thinner [9]. Ashwagandha significantly lowered both stress-scale scores and serum cortisol over 60 days [3], and has been linked to thyroid hormone changes [4, 7]. Echinacea reduced the odds of catching a cold by 58 percent across 14 pooled studies [5], and is generally not recommended for people with autoimmune conditions. Elderberry shortened influenza recovery by about four days in a single placebo-controlled trial [6], and raw or unripe elderberries are toxic.

Here is the detail behind each of those, and how I came to care about it.

I grew up in Hawaii, where foraging for fruit, flowers, seaweed, and herbs was simply part of life, long before I had any formal training in what any of it actually did. The lesson that mattered most arrived later and the hard way, when chronic fatigue during an Ironman sent me looking for answers beyond what I had been told to expect from my body. That is what eventually led me back to the plants and fungi I had grown up around, this time with a student's curiosity instead of a child's.

Traditional use of herbs and mushrooms goes back centuries, in some cases millennia, across cultures on every continent. That history is real and deserves respect. It is also not the same thing as a clinical trial. Both things are true at once: long human experience has noticed real patterns, and modern trials have confirmed only some of them.

Reishi: real, but narrower than the reputation

A small pilot trial gave Ganoderma lucidum (reishi) spore powder to 48 breast cancer patients experiencing fatigue during endocrine therapy. After four weeks, the treatment group reported less fatigue, less anxiety and depression, and better quality of life, with no serious side effects [1]. That is a specific clinical population managing a specific treatment side effect, not a general finding about immunity in a healthy reader. Separately, a randomized, placebo-controlled trial gave reishi beta-glucan to healthy adults for 84 days and found increases in several immune cell markers compared to placebo [2]. There is genuine evidence that reishi can shift measurable immune markers and ease fatigue in specific circumstances. There is no evidence for a specific percentage improvement in "immunity" broadly, and any source that hands you one is rounding a lab measurement into a marketing claim.

Reishi also has a real, documented downside: it can increase bleeding risk for people on blood thinners like warfarin or aspirin, and use of the powdered form has been linked to serious liver injury in a small number of case reports [9]. Tell your clinician before adding it if you are on any blood-thinning medication.

Ashwagandha: one of the stronger trials, with a real risk attached

Adults with chronic stress who took a standardized ashwagandha root extract for 60 days showed a significant drop in both stress-scale scores and serum cortisol compared to placebo [3]. It is also the herb with the clearest documented risk in this category: a small trial in adults with subclinical hypothyroidism found it shifted thyroid hormone levels measurably over eight weeks [7], and a published case report describes thyrotoxicosis in a previously healthy adult that resolved after stopping the herb [4]. If you have a thyroid condition, are on thyroid medication, or take sedatives or immune-suppressing drugs, talk to your clinician before adding ashwagandha, not after.

Echinacea and elderberry: real effects, real limits

Echinacea has one of the stronger evidence bases in this category, because it comes from a meta-analysis rather than a single trial. Pooling 14 studies, researchers found echinacea reduced the odds of catching a cold by 58 percent and shortened the average cold by about 1.4 days [5]. A later Cochrane review found the effect inconsistent across different echinacea preparations, with most individual trials showing no significant benefit [8], and because it works by stimulating immune activity, it is generally not recommended for people with autoimmune conditions or anyone on immune-suppressing therapy without a clinician's guidance first.

Elderberry has one of the better-known trials in this space. In a randomized, placebo-controlled study, adults with influenza symptoms who took oral elderberry syrup recovered about four days faster, on average, than those on placebo [6]. It is a single trial of modest size, so treat the four-day figure as suggestive rather than settled. Elderberry also carries a preparation-specific poisoning risk: raw and unripe elderberries, along with the leaves and stems, are toxic, and only cooked, properly processed preparations are safe.

How should you actually use herbs and mushrooms?

Modern clinical trial evidence for most herbs and mushrooms is thinner than the wellness industry lets on: often a single small study, occasionally reversing itself the moment you stop taking the substance. That is not a reason to dismiss them. It is a reason to treat them as a complement to the free, well-evidenced daily levers, nutrition, movement, sleep, stress management, and connection, rather than as a replacement for medical care or a proven cure for anything.

Herbs and mushrooms are not automatically safe just because they are natural. Several of the ones above can interact with medications, especially thyroid drugs, immune-suppressing therapy, and blood thinners. Tell your clinician about every herb and supplement you take, not just your prescriptions.

I go deeper on herbs, mushrooms, and the root-cause approach in Bad Medicine Blues. Read a free chapter.

Sources

  1. Zhao H, Zhang Q, Zhao L, et al. Spore powder of Ganoderma lucidum improves cancer-related fatigue in breast cancer patients undergoing endocrine therapy- A pilot clinical trial. Evid Based Complement Alternat Med. 2012;2012:809614. doi.org/10.1155/2012/809614
  2. Chen SN, Nan FH, Liu MW, et al. Evaluation of immune modulation by β-1,3;1,6 D-glucan derived from Ganoderma lucidum in healthy adult volunteers- A randomized controlled trial. Foods. 2023;12(3):659. doi.org/10.3390/foods12030659
  3. Chandrasekhar K, Kapoor J, Anishetty S. 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. Indian J Psychol Med. 2012;34(3):255-262. doi.org/10.4103/0253-7176.106022
  4. Hayashi M, Hamada H, Azuma SI, Hayashi K. Painless thyroiditis by Withania somnifera (ashwagandha). Cureus. 2024;16(3):e55352. doi.org/10.7759/cureus.55352
  5. Shah SA, Sander S, White CM, et al. Evaluation of echinacea for the prevention and treatment of the common cold- A meta-analysis. Lancet Infect Dis. 2007;7(7):473-480. doi.org/10.1016/S1473-3099(07)70160-3
  6. Zakay-Rones Z, Thom E, Wollan T, Wadstein J. Randomized study of the efficacy and safety of oral elderberry extract in the treatment of influenza A and B virus infections. J Int Med Res. 2004;32(2):132-140. doi.org/10.1177/147323000403200205
  7. Sharma AK, Basu I, Singh S. Efficacy and safety of ashwagandha root extract in subclinical hypothyroid patients- a double-blind, randomized placebo-controlled trial. J Altern Complement Med. 2018;24(3):243-248. doi.org/10.1089/acm.2017.0183
  8. Karsch-Volk M, Barrett B, Kiefer D, et al. Echinacea for preventing and treating the common cold. Cochrane Database Syst Rev. 2014;(2):CD000530. doi.org/10.1002/14651858.CD000530.pub3
  9. Memorial Sloan Kettering Cancer Center. Reishi mushroom. About Herbs database. mskcc.org/cancer-care/integrative-medicine/herbs/reishi-mushroom

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