What’s in a Mushroom?
The lesser-known compounds (and their effects)
Many cultures, from traditional Chinese medicine to Japanese culinary heritage, have long recognised mushrooms for their medicinal qualities – modern science is now revealing why those traditions were so effective.
If asked to name the health benefits of mushrooms, I imagine most people would come up with fibre, B vitamins – and maybe vitamin D. All of these are important, of course, but there is even more magic in mushrooms. Hidden within their cells are bioactive compounds that rarely make the headlines yet have powerful effects on health. These compounds can have antioxidant, anti-inflammatory, anticancer and immunomodulatory effects, potentially impacting various bodily functions and aiding in disease prevention.
For dogs, these understated nutritional heroes could provide immune support, help counter oxidative stress and even contribute to healthy ageing. Some of the compounds have long, tongue‑twisting names, but don’t be put off: they’re worth learning about and represent exciting new knowledge about what good food can do.
Let’s debunk the idea of “don’t eat it if you can’t pronounce it”.
Ergothioneine: the longevity vitamin
One of the most fascinating mushroom compounds is ergothioneine, sometimes referred to as a “longevity vitamin”. The name may be a bit of a mouthful, but it’s worth remembering that this unusual amino acid is a potent antioxidant that helps protect cells from oxidative damage.
Being unable to produce ergothioneine themselves, dogs must obtain it from diet. Once consumed, it is transported into organs such as the liver, kidneys and brain, areas known to be vulnerable to oxidative stress. This suggests an important protective role in maintaining long‑term cellular health.
Researchers have linked ergothioneine to reduced inflammation, improved mitochondrial function and the protection of DNA from oxidative damage. While canine‑specific studies are limited, its presence in mushrooms adds another layer of value to these already impressive foods.
Richest sources:
Shiitake (Lentinula edodes), Oyster (Pleurotus ostreatus, incl. King oyster), Maitake (Grifola frondosa), Porcini (Boletus edulis)
Beta‑glucans – quietly supporting the immune system
Another group of compounds found in mushrooms are beta‑glucans. The term may sound technical, but it’s worth remembering. Beta‑glucans are complex carbohydrates (polysaccharides, meaning chains of natural sugars) which help the immune system stay balanced[1].
Rather than simply switching the immune system on or off, beta‑glucans are ‘modifiers’, helping it to respond appropriately. They activate macrophages (a type of white blood cell that ‘eats’ harmful invaders) and natural killer cells, facilitating a swift reaction to pathogens without causing unnecessary inflammation.
Studies suggest that the impact of beta-glucans on allergic processes may help reduce skin disease, or be used as a supplement to help treat osteoarthritis and manage canine IBD. Other studies have found that beta-glucan in the diet had positive effects on glucose regulation[2], immune function [3] and obesity.
Richest sources:
Shiitake (Lentinula edodes), Oyster (Pleurotus spp.), Maitake (Grifola frondosa), Reishi (Ganoderma lucidum), Turkey tail (Trametes versicolor)
Lentinan – shiitake’s immune‑modulating compound
One compound in the beta‑glucan family, lentinan, deserves special mention because it is unique to shiitake mushrooms. Lentinan has been widely studied for its immunomodulatory effects and is even used in some countries as an approved adjunctive therapy for human cancers.
It works by enhancing the activity of immune cells and stimulating the release of cytokines (small proteins that carry messages between immune cells). In practice, this means lentinan helps the body respond more effectively to infections and may support resilience against certain diseases.
While much of the research focuses on human medicine, the findings are relevant for dogs too, particularly in the context of maintaining strong immune defences throughout life. Importantly, lentinan’s activity is largely preserved during cooking, making shiitake an especially practical dietary source.
Richest sources:
Shiitake (Lentinula edodes),
Ergosterol – the vitamin D connection
Dogs, unlike humans, cannot produce significant amounts of vitamin D through skin exposure. This makes dietary sources essential — and mushrooms are one of the few plant‑based options thanks to a compound called ergosterol.
Ergosterol is a sterol found in mushroom cell membranes. When exposed to sunlight or UV light, it converts into vitamin D₂. Although vitamin D₃ (from animal sources) is considered more potent, vitamin D₂ can still help support adequate intake, especially in dogs with limited access to oily fish or fortified foods.
Given vitamin D’s importance for bone strength, immune function, and overall health, mushrooms exposed to UV light after harvesting can provide a meaningful contribution to a dog’s diet.
Richest sources:
White button (Agaricus bisporus), Chestnut mushroom (Agaricus bisporus), Portobello (Agaricus bisporus, mature form), Cremini (Agaricus bisporus, brown variety), Oyster (Pleurotus ostreatus), Shiitake (Lentinula edodes)
(Levels are highest when these mushrooms are sun‑exposed or UV‑treated.)
Polyphenols and phenolic acids – natural defenders
Beyond these headline compounds, mushrooms are also a source of polyphenols and phenolic acids. These natural antioxidants neutralise free radicals and help reduce oxidative stress, which plays a role in ageing and chronic disease.
Some mushroom polyphenols also exhibit anti‑inflammatory and antimicrobial effects, supporting both gut health and immune balance. This is particularly relevant given the emerging understanding of the canine gut microbiome and its influence on overall wellbeing. Polyphenols can help maintain a diverse and resilient gut microbial population, contributing to better digestion and immune function.
Richest sources:
Shiitake (Lentinula edodes), Oyster (Pleurotus ostreatus), Maitake (Grifola frondosa), Lion’s mane (Hericium erinaceus), Porcini (Boletus edulis)
(These species are noted for higher levels of phenolic acids and flavonoids with antioxidant and anti‑inflammatory potential.)
Fresh vs dried – does it make a difference?
Many people keep a supply of dried mushrooms, especially shiitake, for convenience. The good news is that most of these ‘lesser known’ compounds are stable and can still be found in dried mushrooms. That means dried shiitake can still deliver.
For dogs, always rehydrate dried mushrooms before cooking. Apart from the importance of digestibility, rehydrating restores their cellular structure, allowing water‑soluble nutrients such as B vitamins and certain polyphenols to be released during cooking. It also improves texture, which makes them easier to mix into meals.
Tip:
Don’t pour the rehydration water away. It often contains some of these nutrients too and, provided it’s clear and not gritty, can be added to stocks or broths. Rinsing the mushrooms before soaking can help ensure this.
So, while fresh mushrooms are excellent, dried ones are a practical and still very nutritious option for adding these behind‑the‑scenes health boosters to your dog’s meals.
The quiet power of mushrooms
We may think of mushrooms as everyday, but their compounds are special: ergothioneine protects cells from damage, beta‑glucans and lentinan balance the immune system, ergosterol provides a plant‑based source of vitamin D and polyphenols help maintain gut and systemic resilience.
The names might be unfamiliar, and the research relatively new, but these compounds have been doing their thing for a long time.
Nutrition is important for all dogs, but you’ll know by now that my particular interest is in working dogs — and in how the right foods can support their cognitive function, behaviour and performance.
For the Canine Athlete
Mushrooms aren’t just everyday foods — they may offer benefits for working and sporting dogs too. Their beta‑glucans and other polysaccharides help support balanced immune function, important for dogs under physical stress. Compounds such as ergothioneine and polyphenols act as antioxidants, helping to reduce oxidative stress from intense exercise. And ergosterol, when converted to vitamin D₂, contributes to bone and muscle health. While not a primary energy source, these compounds can aid recovery, resilience and overall wellbeing in active dogs.
References:
[1] Marchi, P.H.; Vendramini, T.H.A.; Zafalon, R.V.A.; Príncipe, L.d.A.; Cesar, C.G.L.; Perini, M.P.; Putarov, T.C.; Gomes, C.O.M.S.; Balieiro, J.C.d.C.; Brunetto, M.A. Effects of Increasing Levels of Purified Beta-1,3/1,6-Glucans on the Fecal Microbiome, Digestibility, and Immunity Variables of Healthy Adult Dogs. Microorganisms 2024, 12, 113. https://doi.org/10.3390/microorganisms12010113
[2] Vetvicka V., Oliveira C. β(1-3)(1-6)-D-glucans Modulate Immune Status and Blood Glucose Levels in Dogs. Br. J. Pharm. Res. 2014;4:981–991. doi: 10.9734/BJPR/2014/7862.
[3] Stuyven E., Verdonck F., Van Hoek I., Daminet S., Duchateau L., Remon J.P., Goddeeris B.M., Cox E. Oral administration of β-1,3/1,6-glucan to dogs temporally changes total and antigen-specific IgA and IgM. Clin. Vaccine Immunol. 2010;17:281–285. doi: 10.1128/CVI.00344-09.
Important Considerations:
- Always consult your veterinarian before making any significant dietary changes, particularly where there are pre-existing health conditions or dietary restrictions.
- If you are feeding commercial food, check the label for ingredients before giving more. Excessive intake of any foods can have adverse effects.
- Ensure (where possible) that you use high-quality, organic products specifically formulated for pets (or better still, human grade ingredients) to avoid any potential adverse effects.
- Introduce new foods gradually to avoid adverse effects such as gastrointestinal upset or diarrhoea.
- I provide nutritional information purely as a helpful guide. Nutritional information on ingredients is obtained from the US Department of Agriculture’s FoodData Central site (https://fdc.nal.usda.gov/index.html) and any nutritional information provided in recipes is based on an online calculator: calories and other information will vary based on brands, ingredients and other factors.
- Check nutrient levels and recommendations for your dog’s weight, age and activity. For example this nutritional guideline produced by FEDIAF.
- I am not a professional canine nutritionist but supporting research is cited.
- The recipes shared were created by me and tested in my kitchen – and tasted and approved by our doggy friends!