It’s a veritable frontier when it comes to mushroom supplements. I’ve always enjoyed mushrooms for their unique taste and texture—using them in culinary dishes is one thing, but taking them as supplements is quite another.

One of my patients, “Ms. J,” mentioned her daily use of mushroom supplements. Growing up in rural Texas, she was a true, all-American rancher—reminding me a bit of the protagonist in Fried Green Tomatoes. Her diet on the ranch was simple: a hearty steak each evening. However, as time passed, her aging body began to show symptoms that conventional healthcare often overlooked or dismissed. When I asked why she turned to mushroom supplements, she explained that her concerns were frequently ignored by standard medical channels.

That evening, after a long day at the clinic, I reflected on how, for millennia, mushrooms have played a role in traditional medicine across many cultures. Surely, if these fungi were without merit, they wouldn’t have stood the test of time. This prompted me to dive into the expanding world of medicinal mushrooms—an area that isn’t typically covered in medical school and where peer-reviewed research remains limited.

The challenge isn’t solely with mushroom supplements themselves, but rather with the overall proliferation of dietary supplements. Few gold-standard randomized controlled trials (RCTs) have been conducted to assess the safety and efficacy of these products. Many studies are just in-vitro experiments or animal models, and it’s important to remember that results in a petri dish or a rodent model do not necessarily translate to similar outcomes in humans.

Unlike FDA-approved drugs, which are manufactured under strict regulations regarding production, dosage, and effects, supplements are not held to the same standards. Companies are not required to provide the FDA with rigorous evidence that their products perform as advertised. This low regulatory threshold means manufacturers often face minimal scrutiny regarding ingredient disclosure or verification, which leaves questions about the true content of these supplements. Although including undeclared ingredients is technically illegal, lax enforcement renders these rules largely ineffective.

Within the realm of medicinal mushrooms, opinions diverge. Some herbalists and alternative medicine practitioners champion their therapeutic potential, while many mycologists remain skeptical or even concerned about the bold claims. In today’s social media landscape, strong opinions and confident endorsements often capture public attention—even as our medical profession demands robust scientific evidence before we can recommend any treatment.

As mushroom-based products increasingly flood the market—from tinctures and chocolate bars to powdered coffee alternatives—claims range from enhanced mental clarity and anti-aging effects to immune support and even tumor suppression. Take reishi, often called the “mushroom of immortality.” Used medicinally in Asia for over 2,000 years, reishi now appears in everything from gummies to dietary supplements promising better sleep, overall wellness, and vitality. Recent research has examined reishi-derived beta-glucans—a type of soluble fiber that appears to upregulate immune response and inhibit tumor growth in animal models. In one 2023 study, 126 human participants who received reishi beta-glucans showed significant increases in immune cell populations.  However, there is little evidence that triangulates or confirms the findings.

Shiitake mushrooms contain a beta-glucan known as lentinan, which some researchers highlight for its potential anti-diabetic and immunotherapeutic effects. In animal studies, lentinan has been shown to suppress Type 1 diabetes and enhance immune response in cancer patients undergoing chemotherapy.

Chaga, another medicinal mushroom with a history dating back to 12th-century Europe, has been used to address digestive disorders, reduce inflammation, and even combat cancer. A bioactive chaga extract, Inonotus obliquus polysaccharide (IOP), has demonstrated the ability to lower blood sugar levels in mice and inhibit the growth of human cancer cells in vitro.

However, existing research does not yet tell the whole story. Many experts caution that while laboratory and animal studies are promising, they do not provide sufficient evidence of health benefits for humans. Human physiology is very complicated and often surprises us when we try to jump even from primates to humans. Much of the research on compounds from shiitake, turkey tail, and other mushrooms remains preliminary and largely anecdotal when it comes to clinical outcomes.

For instance, lion’s mane contains bioactive compounds that may promote nerve cell growth and possibly enhance cognitive function, but early studies do not yet support its use as a preventive measure against diseases like Alzheimer’s. Turkey tail, one of the most studied medicinal mushrooms, has been used alongside chemotherapy in Japan; a landmark 1994 study found that adding polysaccharide K (PSK), a compound from turkey tail, to standard chemotherapy improved survival rates in patients with gastric cancer.  My advice is never be casual about any of these supplements if you are dealing with medical conditions. Always seek medical advice.

Despite the intriguing research, significant limitations remain. Most studies are not double-blind, placebo-controlled clinical trials—the gold standard for drug approval. Until more robust clinical trials are conducted, we cannot definitively claim that these products offer the purported health benefits. In Asia, certain mushroom-derived compounds such as lentinan and PSK have been approved for adjunct cancer therapy, but none have yet met the stringent standards required by the U.S. Food and Drug Administration.

The burgeoning market of mushroom supplements shows no signs of slowing down. Products range from powdered mixes and concentrated tinctures to innovative items like the Chagaccino—a so-called “adaptogen mushroom mix”—and MUD|WTR, a blend of masala chai, cacao, and mushrooms marketed as a coffee alternative that touts stress relief, anti-aging, and cognitive benefits. Yet, the largely unregulated distribution of these products remains a concern. Studies have even found that some products are mislabeled or lack the advertised ingredients entirely. As one expert put it, “It’s the wild west right now,” reflecting the limited evidence available and the gap between marketing claims and scientific validation.