Shiitake Mushroom Benefits: Immune Support, Dosage and Safety

Shiitake (Lentinula edodes) is one of the world's most eaten mushrooms, and the benefits research has measured in healthy people are immune markers: more active immune cells, more saliva antibodies and lower CRP after 4 weeks of eating shiitake, and more B cells after 6 weeks of a shiitake beta-glucan.

This guide covers what shiitake is, what each study measured, how much was used, how to eat or take it, the raw shiitake rash and where our Forage capsules fit. It is educational, not medical advice.

Key Takeaways

• Shiitake contains beta-glucans, including lentinan, along with phenolics, terpenoids, eritadenine, ergothioneine and bioactive peptides (Makkar et al., 2026).
• In 52 healthy adults aged 21 to 41, eating 5 or 10 g of dried shiitake a day for 4 weeks improved immune cell proliferation and activation, raised saliva IgA and lowered CRP (Dai et al., 2015).
• In 42 healthy older adults, 2.5 mg a day of a shiitake beta-glucan for 6 weeks raised circulating B cells compared with placebo, with side effects similar to placebo (Gaullier et al., 2011).
• Raw or lightly cooked shiitake can cause a rare, itchy, streaky rash; cooking it thoroughly avoids most cases (Nguyen et al., 2017).
• Shiitake is not a stimulant; the trials measured changes after weeks of daily intake.

What Is Shiitake Mushroom?

Shiitake is a brown, umbrella-capped mushroom native to East Asia that grows on hardwood logs. It has been cultivated in Japan and China for centuries, and its savory, umami flavor makes it a staple in soups, stir-fries and broths. Unlike tough medicinal mushrooms such as reishi, it is an everyday food.

Shiitake contains a mix of compounds: beta-glucans and other polysaccharides, phenolics, terpenoids, eritadenine, the antioxidant ergothioneine and bioactive peptides (Makkar et al., 2026). Its best-known beta-glucan is lentinan. Our shiitake ingredient guide covers the basics, and our guide to ergothioneine benefits covers that antioxidant in more detail.

Shiitake Mushroom Benefits: What Research Has Measured

Area	Who and how long	What was found
Immune cell activity	52 healthy adults aged 21 to 41, 5 or 10 g dried shiitake a day, 4 weeks	Gamma delta T cells multiplied about 60% more in lab tests; NK-T cells also improved
Saliva antibodies	Same trial	Higher secretory IgA in saliva
Inflammation marker	Same trial	Lower CRP in blood
B cells	42 healthy older adults, 2.5 mg shiitake beta-glucan a day, 6 weeks, crossover	More circulating B cells than placebo; safety blood tests unchanged
Immune cells (lab)	Human macrophages in the lab	Shiitake, maitake and reishi extracts activated macrophages, most strongly combined

Immune Cells and Saliva Antibodies in Young Adults

In a randomized dietary study, 52 healthy men and women aged 21 to 41 ate 5 or 10 g of whole dried shiitake every day for 4 weeks. Blood, saliva and serum were tested before and after. Gamma delta T cells, a type of immune cell, multiplied about 60% more in lab tests after the 4 weeks, and natural killer T cells also multiplied and activated more readily. Secretory IgA, an antibody found in saliva, rose. The researchers concluded that regular shiitake improved these immune measures (Dai et al., 2015). For the habits that matter most for immune health, see our immune system guide.

Inflammation Marker CRP

In the same trial, CRP in the blood, a common marker of inflammation, fell, and cytokine patterns shifted. The researchers wrote that the immune changes happened under less inflammatory conditions than before the study (Dai et al., 2015). The study had no placebo group, since everyone ate shiitake, so the results compare each person with themselves before and after.

A Shiitake Beta-Glucan in Older Adults

In a double-blind, placebo-controlled crossover trial, 42 healthy older adults took 2.5 mg a day of a soluble beta-glucan from shiitake mycelium or a placebo for 6 weeks, then switched after a 4-week break. B cell numbers, the immune cells that make antibodies, changed differently from placebo and rose on the beta-glucan. Natural killer cells rose in both groups, with no difference between them, and immunoglobulins, complement proteins and cytokines did not change. Liver, kidney and blood counts were unaffected, and side effects were similar to placebo (Gaullier et al., 2011).

Mushrooms Working Together

In a lab study with human immune cells, extracts of shiitake, maitake and reishi, chosen for their beta-glucan content, each activated macrophages, and the three together were more potent than each alone (Mallard et al., 2019). That is one reason mushrooms are often combined. Our guides to maitake, reishi and turkey tail cover what was measured for each. If you are choosing between shiitake and maitake, our guide to maitake vs shiitake compares the two side by side.

How Much Shiitake to Eat or Take

There is no official daily amount. The food trial used 5 or 10 g of dried shiitake a day for 4 weeks (Dai et al., 2015), and the supplement trial used 2.5 mg a day of a purified shiitake beta-glucan for 6 weeks (Gaullier et al., 2011). Both measured changes after weeks of daily intake, so consistency matters more than any single dose. Extracts in capsules come in milligram amounts and are not directly comparable with a food amount; if you use a product, follow its label.

Fresh, Dried and Extract

• Fresh or dried shiitake is the form used in the food trial. Cook it thoroughly; dried shiitake is usually soaked and then cooked.
• Extracts concentrate the mushroom into a small, consistent daily amount. An 8:1 extract is made from about eight times its weight in mushroom; our guide to what 8:1 extract means explains the ratio.
• Purified beta-glucans isolate one compound, as in the older adult trial.

Our guide to mushroom extracts vs powders covers the differences in more detail.

Shiitake Side Effects and Safety

Shiitake is a common food and is generally well tolerated, and in the beta-glucan trial side effects were similar to placebo (Gaullier et al., 2011). The one well-known reaction is a skin rash:

• Shiitake dermatitis. A systematic review of 50 published cases found that most followed eating raw shiitake and 22% followed lightly or undercooked shiitake. The rash is linear, whip-like and itchy, and it cleared on its own in about 12.5 days on average (Nguyen et al., 2017). It is thought to come from lentinan, which heat breaks down, so cook fresh shiitake thoroughly. Handling shiitake can also cause an allergic skin reaction in some people (Stephany et al., 2016).
• Immune medication. Because shiitake's beta-glucans interact with immune cells, ask your clinician first if you take immune-suppressing medication.
• Allergy, pregnancy and surgery. Avoid shiitake if you are allergic to mushrooms or have had a shiitake rash before, and talk with your provider first if you are pregnant, breastfeeding or preparing for surgery.

Where Our Forage Fits

Our Forage capsules contain 150 mg of an 8:1 shiitake extract per 2-capsule serving, alongside lion's mane, cordyceps, reishi, chaga, maitake and turkey tail extracts, Himalayan shilajit and 100 mg of ashwagandha root extract. Every ingredient is third-party tested for purity, potency, microbiological content, residual solvents and heavy metals. Each bottle holds 30 servings; follow the directions on the label. Forage is also part of our Immunity Stack, which pairs it with Glutathione Nasal Spray and NAC Nasal Spray.

Forage is an everyday mushroom blend built on the idea that mushrooms complement each other, so its shiitake amount is not directly comparable with the trials above, and cooked shiitake in your meals adds more as food. For how shiitake sits among other functional mushrooms, see our guides to adaptogenic mushrooms and mushrooms vs adaptogens, and our maitake ingredient guide for its closest kitchen cousin.

Frequently Asked Questions

What are the benefits of shiitake mushrooms?

In healthy young adults, eating shiitake daily for 4 weeks improved immune cell activity, raised saliva IgA and lowered CRP. In healthy older adults, a shiitake beta-glucan raised B cell numbers.

Are shiitake mushrooms good for the immune system?

Two trials in healthy people measured immune changes: more active T cells and saliva antibodies after eating shiitake, and more B cells after a shiitake beta-glucan.

How much shiitake should you eat a day?

The food trial used 5 or 10 g of dried shiitake a day for 4 weeks. There is no official amount, so eat it as part of a varied diet and cook it well.

Can you eat shiitake raw?

It is best not to. Most cases of shiitake dermatitis, an itchy streaky rash, followed eating raw shiitake, and about a fifth followed lightly cooked shiitake.

How long does shiitake take to work?

The trials measured changes after 4 to 6 weeks of daily intake, so give it several weeks.

Is it safe to eat shiitake every day?

Shiitake is a common food and was eaten daily for 4 weeks in the food trial. Cook it thoroughly, and check with a clinician first if you take immune-suppressing medication.

Is shiitake psychedelic?

No. Shiitake is an edible culinary mushroom with no psychoactive compounds.

What is the difference between shiitake and maitake?

Both are edible mushrooms rich in beta-glucans. Shiitake has a single cap and is known for lentinan, while maitake grows in ruffled clusters and is known for its D-fraction. Forage contains both.

How much shiitake is in Forage?

Forage contains 150 mg of an 8:1 shiitake extract per 2-capsule serving, along with six other mushroom extracts, Himalayan shilajit and 100 mg of ashwagandha root extract.

Sources

• Dai X, et al. Consuming Lentinula edodes (shiitake) mushrooms daily improves human immunity: a randomized dietary intervention in healthy young adults. Journal of the American College of Nutrition, 2015. https://pubmed.ncbi.nlm.nih.gov/25866155/
• Gaullier JM, et al. Supplementation with a soluble beta-glucan exported from Shiitake medicinal mushroom, Lentinus edodes (Berk.) Singer mycelium: a crossover, placebo-controlled study in healthy elderly. International Journal of Medicinal Mushrooms, 2011. https://pubmed.ncbi.nlm.nih.gov/22164761/
• Makkar S, et al. Macromolecular organization in Lentinula edodes: integrating co-occurring bioactives for structure-function relationships across gut microbiota and host metabolism. Comprehensive Reviews in Food Science and Food Safety, 2026. https://pubmed.ncbi.nlm.nih.gov/42316508/
• Mallard B, et al. Synergistic immuno-modulatory activity in human macrophages of a medicinal mushroom formulation consisting of Reishi, Shiitake and Maitake. PLoS One, 2019. https://pubmed.ncbi.nlm.nih.gov/31697749/
• Nguyen AH, et al. Clinical features of shiitake dermatitis: a systematic review. International Journal of Dermatology, 2017. https://pubmed.ncbi.nlm.nih.gov/28054338/
• Stephany MP, et al. Shiitake mushroom dermatitis: a review. American Journal of Clinical Dermatology, 2016. https://pubmed.ncbi.nlm.nih.gov/27566177/

These statements have not been evaluated by the Food and Drug Administration. This content is for education and is not medical advice. Our products are not intended to diagnose, treat, cure or prevent any disease. Talk with a healthcare provider before starting a new supplement if you are pregnant, breastfeeding or taking medication.