Mushroom supplements come in many varieties, and it is important to consider not only the dose form but also how they are prepared for consumption, and how they are consumed. There are a few major factors that impact optimal bioavailability of active constituents.

Let’s begin by addressing two active constituents that are responsible for the therapeutic benefits of mushrooms: polysaccharides and triterpenes.

Active constituents

Polysaccharides

Polysaccharide (1-3, 1-6) ß-glucans are ubiquitous in medicinal mushrooms. ß-glucans are an integral aspect of the mushroom cell wall, and are structurally bound within a substance called chitin, best known as the main structural component in crustacean shells. When a mushroom goes through any kind of heating process, medicinal ß-glucans are unbound from chitin, and become bioavailable.

Vega, K., & Kalkum, M. (2012). Chitin, Chitinase Responses, and Invasive Fungal Infections. International Journal of Microbiology, 2012, 920459. https://doi.org/10.1155/2012/920459

After ingestion, ß-glucans survive stomach acid, bile, and other digestive secretions essentially unchanged. The major physiological effects induced by ß-glucans occur within the small intestine, where they bind to specific receptors on immune cells present within the gut associated lymphoid tissue (GALT).

Following ß-glucan binding to the receptors, a number of different immune regulatory processes take place, including indirect immune effects via modulation of the  intestinal microbiota. ß-glucans can act as substrate for beneficial flora present in the small intestine, helping to outcompete pathogenic intestinal flora. Beneficial bacteria that consume ß-glucans excrete the short chain fatty acid butyrate (1), which is also important for immune regulation and intestinal health.

Triterpenes

The triterpenes present in medicinal mushrooms are most commonly lanostane triterpene glycosides, or lanostenoids. While ß-glucans stimulate immunoregulatory pathways via the GALT and intestinal microbiota, triterpene glycosides have exhibited direct antineoplastic and anti-viral activity both in vitro and in vivo. 

Unfortunately, triterpenes are not well absorbed following oral consumption, and we have yet to see any mushroom supplement companies recommending injection of their products (though it goes without saying: do not inject your mushroom extracts!). Around 10% of the triterpenes present in mushroom extracts is bioavailable (2), and this relatively poor bioavailability may be due to first pass metabolism through the liver and conversion of triterpene glycosides to metabolites via intestinal bacteria. Furthermore, consuming food with mushroom extracts delays and inhibits absorption of these medicinal compounds.

Factors that interfere with absorption of Beta-glucans and triterpenes

Eating mushrooms raw 

Some supplement labels may list their mushroom ingredients as “mushroom powder”. It is safe to assume that unless the product specifically states that it contains powdered extract, the mushrooms present have been dehydrated and powdered. Typical dehydration methods do not use enough heat to break down the chitin in the cell wall, leaving the ß-glucan fraction unavailable for its immune-modulating and prebiotic effects.

Given the undigested nature of dehydrated mushroom powders, consuming powdered mushrooms is largely equivalent to consuming very expensive fiber. Choose products that state “powdered mushroom extracts” or “mushroom extracts” on their labels to ensure they contain appropriately processed ß-glucans.

Blending mushrooms with coffee, tea, or chocolate

Mushroom extracts blended with tannin-rich foods like coffee, tea and chocolate will likely not be absorbed as well as mushroom extract taken alone. When blended or emulsified, polysaccharides and tannins can bind strongly to each other, and these bonds can survive the stomach without breaking. When this tannin-ß-glucan complex reaches the small intestine, the ß-glucans will not be recognized by immune cell receptors essential for promoting immunoregulatory processes. (3)

Taking mushroom extracts with food

Consuming mushroom extracts with food can significantly alter the speed and extent of absorption of triterpene glycosides. (1). For this reason, it is not recommended to use mushroom extract powders mixed into foods. For optimal absorption of the already low bioavailable triterpenes, take triterpene-containing mushroom supplements on an empty stomach.

N.B. It has been speculated that consuming vitamin C with mushroom extracts may enhance absorption but unfortunately this seems to be a myth. (4).

Summary

For the best absorption and bioavailability, take your mushrooms extracted, plain and simple, with water, and nothing else.

Work Cited:

1. Verhoeven J, Keller D, Verbruggen S, Abboud KY, Venema K. A blend of 3 mushrooms dose-dependently increases butyrate production by the gut microbiota. Benef Microbes. 2021;12(6):601-612. doi:10.3920/BM2021.0015
2. Teekachunhatean, S., Sadja, S., Ampasavate, C., Chiranthanut, N., Rojanasthien, N., & Sangdee, C. (2012). Pharmacokinetics of Ganoderic Acids A and F after Oral Administration of Ling Zhi Preparation in Healthy Male Volunteers. Evidence-Based Complementary and Alternative Medicine, 2012, 780892. https://doi.org/10.1155/2012/780892
3. Li R, Zeng Z, Fu G, Wan Y, Liu C, McClements DJ. Formation and characterization of tannic acid/beta-glucan complexes: Influence of pH, ionic strength, and temperature. Food Res Int. 2019;120:748-755. doi:10.1016/j.foodres.2018.11.034
4. Tawasri P, Ampasavate C, Tharatha S, Chiranthanut N, Teekachunhatean S. Effect of Oral Coadministration of Ascorbic Acid with Ling Zhi Preparation on Pharmacokinetics of Ganoderic Acid A in Healthy Male Subjects: A Randomized Crossover Study. Biomed Res Int. 2016;2016:2819862. doi:10.1155/2016/2819862