The Health Benefits of Chaga Mushrooms

Can the "cancer fungus" live up to its name?

In This Article

Chaga (Inonotus obliquus) is a type of mushroom that grows mainly on birch trees in northern Europe, Asia, Canada, and the northeastern United States. Long used in folk medicine, Chaga contains massive amounts of the pigment melanin. When exposed to the sun, the exterior of the mushroom will turn a deep black, while the interior will remain a bright orange-ish color. Chaga also contains among the highest levels of oxalate (a compound linked to kidney stones) of any living organism.

Wild Chaga Mushroom (Inonotus obliquus) growing on a Birch tree
James Mahan / Getty Images

Chaga is known by many names around the world. Most interestingly, it is called kreftkjuke in Norway, which literally translates to "cancer fungus" due to its purported health properties.

The mushroom has a hard texture that can be dried, powdered, and used to make Chaga tea, extracts, or tinctures. Less commonly, the powder is packed into capsules for use as a dietary supplement.

Also Known As

  • Birch canker
  • Black mass
  • Cinder conk
  • Clinker
  • Conk rot

Health Benefits

Alternative practitioners believe that Chaga offers numerous health benefits. Among them, Chaga is believed to fight inflammation, lower blood sugar, reduce blood pressure, alleviate arthritis, and even prevent or slow the progression of cancer.

Chaga is rich in fiber and essential nutrients, including vitamin D, iron, magnesium, potassium, manganese, and calcium. Chaga's high melanin content has led some to believe that it can bolster the melanin naturally found in the skin, thereby protecting it from sun damage, skin cancer, wrinkles, or aging.

Melanin is also a potent antioxidant and has one of the highest oxygen radical absorbance capacity (ORAC) scores of any food. (ORAC is a method developed by scientists at the National Institutes of Health to measures the antioxidant capacity of different foods.)

Despite these properties, there is little evidence that Chaga can treat any medical condition. With that said, a number of preliminary studies have hinted at possible benefits.

Liver Injury

Chaga may help prevent or slow the progression of certain liver problems, suggests a 2015 study in the International Journal of Medicinal Mushrooms. The Korean research team reported that a water-based extract of Chaga was able to protect biopsied liver tissue from the oxidative effects of a chemical (tertbutyl hydroperoxide) known to cause liver damage.

The study was meant to replicate what occurs in people with drug-induced liver toxicity or alcoholic liver disease. It might also help alleviate the inflammation and oxidative stress that fuels chronic liver diseases, such as viral hepatitis or non-alcoholic fatty liver disease.

Whether the oral administration of Chaga will have the same effect in humans has yet to be established.


Chaga may help control or prevent diabetes, according to a 2014 study in Evidence-Based Complementary and Alternative Medicine. The hypothesis is based on the beneficial effects that plant-based polysaccharides have on blood sugar. Those found in certain mushrooms, such as Chaga, are believed to be especially potent.

According to the research, rats with chemically-induced diabetes achieved near-normal blood sugar levels after being fed an oral solution of Chaga-derived polysaccharides for six weeks. The investigators believe that the solution reduced inflammation of damaged pancreas cells, allowing the insulin-producing organ to function more normally.


A 2018 study published in the Journal of Ethnopharmacology suggests that Chaga may offer anti-cancer effects. In a series of test-tube studies involving lung cancer cells, an alcohol extract of Chaga was reported to have triggered apoptosis (programmed cell death) in all cell lines.

The results were supported by an earlier study from Japan in which mice with lung cancer were given a continuous intravenous (IV) infusion of a Chaga over three weeks. According to the investigators, the mice achieved a 25% reduction in tumor size compared to the untreated mice. Those with metastatic disease had a 60% reduction in tumor size.

Despite the positive results, at levels this high, Chaga may cause more harm than good.

Possible Side Effects

Little is known about the long-term safety of Chaga. While many consider it to be safe and well-tolerated, it has been known to cause side effects in some.

The substance oxalate is of particular concern since it can affect the kidneys. Oxalate is considered an anti-nutrient because it interferes with the absorption of other nutrients and can quickly bind with calcium to cause kidney stones. There have even been cases of kidney failure in people who have overused Chaga powder.

Chaga should never be used in people with kidney disease, who have had a prior history of kidney stones, or are at risk of kidney stones.

Because Chaga can influence blood glucose levels, it should be used with caution in people on anti-diabetes drugs, including insulin. Doing so may cause hypoglycemia (an abnormal drop in blood sugar).

There is also concern that Chaga may interfere with blood clotting. As such, it should be avoided in people with bleeding disorders and used with caution in people on blood thinners such as Coumadin (warfarin) and Plavix (clopidogrel).

It is unknown how Chaga might affect children and whether it has any impact on pregnancy or breastfeeding. To avoid complications, speak to your doctor before using a herbal supplement in any form.

Selection, Preparation, and Storage

Widely available for purchase online or in natural food or supplements store, Chaga is most commonly sold as a powder for use in teas and decoctions. You can also buy bottled tinctures and extracts, which some believe are better absorbed by the body. Chaga tea bags and dried Chaga chunks are also available.

Chaga supplements are relatively uncommon because the dried fungus less easily absorbed in the intestines. It is only by dispersing the mushroom in hot water, alcohol, or a fermented extract that the intestines can more readily absorb them.

The challenge of using Chaga is that doses can vary between brands (or even different lots of the same brand). Herbal remedies like these aren't strictly regulated in the United States, and there are no tests to ensure a standardized dose or even the purity of a product.

On top of this, few manufacturers will submit their product for voluntary testing by an independent certifying body like the U.S. Pharmacopeia (USP), ConsumerLab, or NSF International. That leaves it up to you to make the wisest choice.

If you are interested in using Chaga, here are some tips that can help:

  • Read the product label. The more information you get, the better. The label should ideally include the species name Inonotus obliquus as well as the country of origin. Check to see if there are added ingredients. If there is and you don't recognize them, speak with your pharmacist.
  • Check the color. Chaga powder can range in color from bright orange to dark brown. Darker colors suggest that the mushroom was not peeled prior pulverization. This is only of concern because the blackened skin (sclerotium) may be more toxic to cells.
  • Go organic. Given the lack of testing, all herbal supplements pose a risk of contamination. To reduce the risk, opt for brands that are pure and organic. Pure simply means there are no added ingredients, while USDA organic certification ensures that you are not exposed to pesticides and other unwanted chemicals

There are no guidelines for the appropriate use of chaga. As a rule of thumb, use the product as directed and never exceed the recommended dose. This doesn't mean that the product is safe, but it may reduce your risk of side effects and complications.

Other Questions

How do you make Chaga tea?: The easiest way to make Chaga tea is with Chaga tea bags. If using Chaga powder, add a teaspoon to a cup of boiling water, allow to steep for 5 minutes, and strain with a fine tea strainer.

If using Chaga chunks, break them into one-inch pieces. Add four to five chunks to one liter of water and simmer gently for a minimum of 15 minutes and up to three hours. The longer you simmer the fungi, the deeper the flavor will get. Some people drink the darker brew as they would coffee. Lighter brews are generally sipped as a tea.

Some people described the taste as earthy and coffee-like; others will tell you that it tastes like dishwater. To make the tea more palatable, add honey or sweetener which brings out its slight vanilla-like essence.

Can you get fresh Chaga?: Fresh Chaga can be found in the United States, particularly in states like Maine. Unless you can accurately identify the mushroom, it is best to buy it from a retail producer rather than harvesting it on your own.

Fresh Chaga requires drying before use. To do this, place the fungus in an oven at 110o to 115o F for 24 hours. When dried, you can remove the blackened skin and grate the fungus with a fine kitchen grater. You can also pulverize it into a powder with a coffee grinder.

Store Chaga in an airtight container, ideally in the refrigerator or freezer. Discard of any product that smells moldy or develops visible spores. If kept in the freezer, Chaga may last up to two years.

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Article Sources
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  1. Kikuchi Y, Seta K, Ogawa Y, et al. Chaga mushroom-induced oxalate nephropathy. Clinical Nephrology. 2014;81(6):440-4. doi:10.5414/CN107655.

  2. Nakajima Y, Nishida H, Matsugo S, Konishi T. Cancer Cell Cytotoxicity of Extracts and Small Phenolic Compounds from Chaga [Inonotus obliquus (persoon) Pilat]. J Med Food. 2009;12(1). doi:10.1089/jmf.2008.1149.

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