Do Mushroom Supplements Really Work? Dietitians Break Down the Benefits and Risks.

5 min readONCE RELEGATED TO the dusty bottom shelf of health food stores, functional mushrooms are now found in teas, coffees, supplements, and even protein bars and chocolate.But along with that newfound visibility have come some impressive-sounding claims. Functional mushrooms are marketed for everything from sharper thinking to better workouts to improved gut health, stress reduction, and sleep.But can mushrooms do all of that? Let’s take a look.What Are Functional Mushrooms?COMPLICATED QUESTION. FIRST know that mushrooms can be categorized as functional, culinary, psychoactive, and toxic—although there is some overlap between categories. Shiitake mushrooms, for example, are considered culinary and functional.Functional mushrooms are fungi that are thought to have specific physiological benefits, mostly involving cognition, sport performance, digestive health, and mood. Unlike psychedelic mushrooms, functional mushrooms do not contain psilocybin and will not get you high. (Sorry.)According to the Functional Mushroom Council, more than 20 strains of functional mushrooms are grown in the U.S., with lion’s mane, reishi, chaga, cordyceps, and turkey tail among the most popular.Are Functional Mushrooms Healthy?THE CLAIMS ARE way ahead of the evidence.Research is still focused on discovering whether many of these fungi produce clinically meaningful outcomes in humans. Despite the confident claims companies make about their mushroom products, supporting evidence remains elusive. A search for citations or evidence on most functional mushroom product websites comes up empty.In the U.S., functional mushroom supplements are regulated as dietary supplements, which means that manufacturers don’t have to prove that their products work before selling them.And while the FDA prohibits producers from making claims about products treating and preventing disease, it’s perfectly legal to make vague claims about a supplement’s benefits for things like stress, cognition, sleep, and athletic performance, to name a few.A 10oz bag of Shroomi medium roast Nicaragua mushroom coffee sells for $26.99 and promises to help users “think clearly, focus longer, and stay calm under pressure.”Fabü says its mushroom supplements help women in menopause “feel like themselves again.”Four Sigmatic markets their “powered by science” mushroom products for “focus, calm, gut health, and energy.” A 26-serving, $40 order of their focus coffee contains lion’s mane and “organic, wildcrafted chaga,” although these ingredients are present in unknown amounts due to being in a proprietary blend.While companies say propriety blends protect trade secrets, they also allow manufacturers to conceal the exact amounts of the active ingredients the product. This makes it impossible for consumers to know whether they’re getting a dose that’s effective, or one that is higher or lower than expected.And, for many functional mushrooms, effective dosing has yet to determined.Most companies’ product claims fly under the radar, at least most of the time. Although the mushroom coffee company Ryze was recently cited by the National Advertising Division for claiming that two of its products provide energy, focus, gut health, improved sleep, and better immunity, and for implying that one of the products delivers the same level of appetite-suppression as GLP-1 medication.So what are companies using to base their claims, anyway?Where the Science on Functional Mushrooms Stands NowFUNCTIONAL MUSHROOMS CONTAIN biologically active components, and some of them have exhibited some positive health-related effects in lab and animal research. But lab and animal studies don’t necessarily translate into meaningful benefits in humans.Human trials using functional mushrooms have been mostly small, and their results have been mixed. We need bigger and larger human trials to understand which functional mushrooms may actually be useful, and in what dose and form.Julie Daoust, PhD, Chair of the Functional Mushroom Council, argues that it’s important not to dismiss mushrooms altogether even though the evidence base is far smaller than that of a pharmaceutical drug.“The population-level evidence for mushrooms as food is genuinely strong and shouldn’t be dismissed just because it’s not a randomized trial,” she says. “The clinical research on specific mushroom products, while younger, is accumulating fast and already includes are genuinely impressive results.”She points to PSK, an antioxidant from the turkey tail mushroom, which is an approved adjuvant cancer drug in Japan. Its sister compound, PSP, has shown similar immune-supportive effects in cancer patients undergoing conventional treatment.This is different than marketing a mushroom gummy for its supposed functional benefits; the turkey tail used in Japan is a purified compound that’s not even close to a consumer product.Mushrooms contain beta-glucan, a fermentable fiber with proven effects on the gut microbiome, and potential benefits for immune system markers such as natural killer and T-cell numbers. Once again, we aren’t sure that these immune effects translate into clinically meaningful outcomes in humans.Lion’s mane mushrooms are one of the more popular functional mushrooms right now, particularly for cognition and mood. Small studies have suggested a link between lion’s mane mushroom and a decrease in stress and improved cognitive function, although research findings on those effects are mixed. None of this is proof that lion’s mane will transform your brain, energy levels, or mood.Daoust points out that the dramatic increase in mushroom research trials represents meaningful progress for a category that was barely being clinically tested a decade ago. Still, it’s not yet the hundreds of trials that we see behind established pharmaceuticals.Are Functional Mushrooms Safe?BE CAREFUL. ALL mushroom species are “bioaccumulators,” meaning they absorb and concentrate compounds from the soil they grow in, both beneficial and harmful.Studies have detected contaminants like arsenic and other potentially toxic metals in mushroom samples, although the levels found in commercial supplements have not been high enough to pose a health risk.Certain mushrooms have their own concerns. Chaga, for example, contains high levels of oxalate. Heavy, prolonged use has been linked to kidney injury, making chaga a potential risk for people who have kidney disease or a history of kidney stones.As with all other supplements, products containing functional mushrooms should be third-party-certified to ensure quality and purity.Daoust recommends looking for products that clearly identify the mushroom species by its Latin name, the part of the fungus used, the solvent and solvent ratio if it’s an extract, and the growing substrate. Proper labeling is the key to understanding the consistency of a product’s sourcing and to actually getting the expected effects.This information doesn’t prove that a product works; it gives consumers a good idea of what exactly they’re purchasing.Because mushrooms can pull toxins and pollutants from their growing environment, sourcing and independent testing are important.What About Mushroom-Enhanced Foods?THEY MIGHT SEEM like a more attractive option than swallowing powder or capsules, but dose matters. If the effective dose of a given mushroom is 3 grams, and your chocolate or gummy only contains a few dozen milligrams, you’re likely consuming more marketing than mushroom.Unfortunately, because many functional mushrooms don’t yet have an established dose, figuring out whether a product contains enough can be a challenge.Functional mushrooms aren’t woo woo nonsense; many of them contain biologically active substances that seem to have products some promising outcomes in the research. But as usual, the consumer market has gone far beyond the current evidence.If you enjoy mushroom coffee or want to experiment with a reputable mushroom supplement, go for it. But, I wouldn’t expect dramatic results as of now.Abby Langer, RD is the owner of Abby Langer Nutrition, a Toronto-based nutrition consulting and communications company