Lion’s mane (also called Hericium erinaceaus) is a medicinal, edible mushroom that contains many compounds, namely hericenones and erinacines. Cognitive effects with Lion’s mane have been mixed based on small and short-duration clinical trials. Preclinical studies suggest that Lion’s mane may be able to increase levels of a molecule called nerve growth factor (NGF), which increases the length of nerve cell processes. Although Lion’s mane is an edible mushroom, there is little published information on whether Lion’s mane supplements are safe for long-term use.
Clinical trials testing Lion’s mane interventions have included small numbers of participants with short durations of treatment. Well-designed larger and longer clinical trials are needed. Our search identified:
Cognitive effects with Lion’s mane supplements have been mixed based on several small clinical trials. One randomized placebo-controlled trial of 30 people with mild cognitive impairment reported that Lion’s mane treatment for 16 weeks improved performance on a cognitive test, but cognitive performance declined after the treatment period ended, suggesting that it may not have lasting benefits [1]. In a randomized placebo-controlled trial of 31 healthy adults over the age of 50, Lion’s mane treatment for 12 weeks improved cognitive function on only one of the three tests used [2]. Both the Lion’s mane and placebo groups improved in this cognitive outcome over time. In a randomized placebo-controlled trial of 41 healthy adults (18-45 years old), Lion’s mane mushroom treatment for four weeks resulted in worse performance (fewer words recalled) on the delayed word recall accuracy test compared to the placebo group [3]. In two small, randomized placebo-controlled trials in healthy young adults, Lion’s mane treatment failed to improve cognitive function [4; 5]. Larger, longer-duration, and well-controlled clinical trials are needed to further evaluate the effects of Lion’s mane on cognitive function.
Preclinical studies suggest that Lion’s mane may reduce inflammation and biological markers of Alzheimer’s disease (i.e., amyloid plaques), improve cognition, and increase the release of nerve growth factor, a protein that can increase the length of nerve cell processes [6; 7; 8; 9; 10]. These preclinical findings have not been confirmed in humans.
One small clinical trial in Alzheimer’s disease patients reported that Lion’s mane treatment for 49 weeks improved activities of daily living (e.g., preparing meals, cleaning, shopping, etc.). However, there were no significant improvements in cognitive function compared to the placebo group [11]. There is currently no evidence from large-scale randomized controlled trials that suggests that Lion’s mane supplements are safe or beneficial for dementia patients.
Lion’s mane is generally recognized as safe when consumed as a food. However, safety information is limited for Lion’s mane supplements. Based on small clinical trials, Lion’s mane supplements are generally well tolerated but have led to gastrointestinal discomfort, nausea, or skin rash in some people [1; 11]. In addition, there is a case report of an individual who suffered from severe acute respiratory failure, which was possibly related to consumption of Lion’s mane [12]. Currently, there is a lack of standardization in extraction methods and levels of bioactive compounds in Lion’s mane supplements. Long-term well-controlled and rigorously designed clinical trials are needed to fully evaluate the long-term safety of Lion’s mane supplements.
NOTE: This is not a comprehensive safety evaluation or complete list of potentially harmful drug interactions. It is important to discuss safety issues with your physician before taking any new supplement or medication.
Lion’s mane is available over the counter as a supplement and as a food product. Clinical trials have tested up to 3 grams of Lion’s mane (derived from the fruiting body of the mushroom) per day [1; 2]; however, dosage has not been established for any indication. Different studies have tested different preparations of the mushroom (e.g. the fruiting body, mycelium, etc.), and Lion’s mane supplements sold over the counter are prepared using various methods of processing and extraction, which can yield extracts with variable levels of individual bioactive compounds [13].
Full scientific report (PDF) on Cognitive Vitality Reports