Sports supplements: should you make room for mushrooms?

Fungi – more commonly referred to as mushrooms - are found all over the world in a variety of different habitats. In total, more than 2,000 mushroom species have been identified and of these, over 20 have been successfully developed for large-scale commercial cultivation. Although most of us don’t tend to give them much thought, these fungi play a vital role in natural biochemical cycles and maintaining balances in various ecosystems. More relevant to athletes though is the fact that while some fungal species can cause human health problems by inducing infections or toxicity, many mushrooms are well known for their beneficial health effects when ingested or used in food preparations⁽¹⁾. Good examples include yeasts, which are essential for food fermentation and a variety of biotechnological processes, and edible fungi that are valued for their nutritional content and potential medicinal properties⁽²⁾.

Fungi and health

Optimizing nutrition is an essential strategy for ensuring maximum performance for athletes, and much of that strategy involves (or should involve) ensuring that the day-to-day diet - the foundation of any nutritional program - is as unprocessed and nutrient-rich as possible. The inclusion of edible fungi (referred to hereon simply as mushrooms) can play a role in that strategy, since mushrooms are rich in a wide array of biologically compounds known to benefit health. These compounds include polysaccharides, alkaloids, sterols, polyphenols (antioxidants) terpenoids, peptides, and micronutrients such as vitamins and trace minerals^(3,4). Indeed, research has established that the potential health benefits of mushroom consumption may be dramatic, including cancer prevention and inhibition of tumor growth⁽⁵⁾, anti-aging mechanisms⁽⁶⁾, and blood lipid (fat)- and blood pressure-lowering effects^(7,8).

Mushrooms, supplements and athletes

From the above, you might conclude that while offering potential health benefits, mushroom consumption for athletes is not that relevant, since most athletes are already in good health, and likely in better health than their sedentary counterparts. However, this isn’t the case. Unlike their sedentary peers, athletes (especially endurance athletes) typically engage in prolonged periods of high-intensity physical activity, which places a high demand on energy supply and metabolism. This in turn can leave athletes vulnerable to increased levels of oxidative stress and damage at the cellular level (an inevitable consequence of increased oxygen metabolism – see this article to understand why). This in turn can lead to greater levels of inflammation and an increased risk of minor muscle injuries⁽⁹⁾.

Because of the physical demands placed on athletes, a growing body of research has argued that athletes may benefit from supplementary nutritional strategies above and beyond an optimal diet in order to enhance antioxidant capacity, reduce fatigue, accelerate post-exercise recovery, and support immune health⁽¹⁰⁾. Immunity is especially relevant for athletes because it is known that intense training over extended periods can reduce immune function⁽¹¹⁾, making athletes more susceptible to illnesses, which of course throws a spanner in the works of even the best training program! Together, these facts explain why natural dietary supplements, including those based on mushrooms, have attracted a growing interest amongst sports nutritionists and athletes looking for nutritional protection and enhanced performance.

However, as is the case with many sports supplements promoted to athletes, claiming certain health and performance benefits is one thing, but delivering them is another! To date, most of the research into mushroom and mushroom extract supplements has focused on the isolated effects of single types of edible fungi or specific bioactive compounds derived from these fungi rather than systematically evaluating their comprehensive physiological benefits – for example on  endurance, fatigue mitigation, immune response, and recovery processes⁽¹²⁾. Ideally, what is needed is a systematic review comprehensively assessing the effects of edible mushroom and mushroom extract supplementation on athletic performance.

New research

The good news for athletes pondering whether certain mushroom extracts can offer a performance advantage is that a new study by a team of Chinese researchers has provided some answers⁽¹³⁾. Published in the prestigious journal ‘Frontiers in Nutrition’, this study took the form of a systematic review, which collected together all the previous research on edible fungi and their extracts on athletes, critically analyzed the findings and synthesized these findings into robust conclusions and practical recommendations for athletes to apply in their own training. In particular, the researchers were keen to focus on three key areas of performance and health: endurance performance, immune function, and hematological profiles (blood-related measures like red blood cell counts and oxygen-carrying capacity).

What they did

The first step of the study was to carry out a comprehensive trawl of the previous scientific literature across databases like PubMed, Web of Science, Scopus, and Cochrane Library. In particular, the researchers searched for key phrases such as ‘fungal supplementation’, ‘mushroom extract’, ‘athlete’, ‘endurance performance’, ‘immune function’, and ‘hematological parameters’. To be included in the final analysis, strict criteria were applied to the studies thrown up by this search. These were as follows:

·        Studies had to be randomized controlled trials (RCTs – considered the gold standard for clinical research).

·        They had to compare comparing fungal/mushroom supplementation (single or blended species) against a placebo or no intervention at all.

·        The participants in the studies had to be healthy adult athletes (aged 18–50).

Studies also had to report quantitative outcomes (ie not just subjective) in the three key areas of interest above. In addition, studies must not have included multi-supplement protocols, which might have confounded the results (ie the athletes were not allowed to continue with any other supplements during the trial).

When the studies were sifted and irrelevant studies excluded, the researchers were left with 14 randomized controlled trials involving a total of 528 athletes. Of these 14 studies, eight provided enough comparable data for a statistical ‘meta-analysis’, pooling results from 288 individuals. This is where data from several different studies is combined then statistically analyzed as a whole to yield an overall conclusion that has increased levels of validity compared to the individual studies that went into it.

The athletes were engaged in a variety of sports, ranging from endurance (cyclists [3 studies] and runners [2 studies]) to team-sport athletes such as football players and basketball players. The researchers further analyzed the data from these 14 studies to record the intervention specifics such as the mushroom type and dose used, the supplement form (ie capsule, tablet, or powder), whether the mushroom was whole or an extract and the study duration. Where extracts were use, the researchers only included studies that used standardized extracts (in order to minimize variability and increase the robustness of the findings). In terms of the mushrooms and doses used in the studies, these were as follows:

·        Cordyceps sinensis - doses of 2–3 grams daily or 10mg per kg body weight, administered for 2–12 weeks pre- or post-training.

·        Ganoderma lucidum - doses ranged from 75mg (triterpenoid extract) to 5 grams (whole powder), for 8–12 weeks.

·        Pleurotus ostreatus - using β-glucan isolates at 100–200mg daily for 2–3 months.

·        Cordyceps militaris doses of 1,800 mg mycelium extract over 16 weeks.

·        Tremella fuciformis polysaccharide – given for 3 weeks.

What they looked for

To assess the effectiveness or otherwise of these mushroom supplements, the researchers extracted the data from the 14 individual studies relating to a) performance, b) immunity and c) hemotology. For performance, key metrics were changes in time-to-exhaustion tests, ventilatory thresholds (the point where breathing becomes labored), and VO2max (maximum oxygen uptake) measured via treadmill testing or on a cycle ergometer. For immunity, key metrics included immune markers such as immunoglobulins (IgG, IgM), complement proteins (C3, C4), and cytokines (IL-6, TNF-α). Hematological (blood) metrics included hemoglobin, hematocrit, blood urea nitrogen (BUN—a fatigue marker), lactate levels, and superoxide dismutase (SOD) activity (a measure of oxidative stress). The researchers also extracted data on any secondary outcomes, particularly any adverse reactions suffered when these supplements were taken.