Chaga mushrooms have been used for centuries in Siberia and other parts of Asia as a medicine to boost immunity and improve overall health (1).

Though ugly in appearance, the chaga mushroom is gaining popularity in the Western world for its potential health benefits.

What’s more, a cup of tea made from chaga is packed with antioxidants.

However, consumption of this special mushroom may come with some risks.

This article examines the uses, benefits and potential side effects of chaga mushrooms.

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Chaga mushroom (Inonotus obliquus) is a type of fungus that grows mainly on the bark of birch trees in cold climates, such as Northern Europe, Siberia, Russia, Korea, Northern Canada and Alaska.

Chaga is also known by other names, such as black mass, clinker polypore, birch canker polypore, cinder conk and the sterile conk trunk rot (of birch).

Chaga produces a woody growth, or conk, which looks similar to a clump of burnt charcoal — roughly 10–15 inches (25–38 centimeters) in size. However, the inside reveals a soft core with an orange color.

For centuries, chaga has been used as a traditional medicine in Russia and other Northern European countries, mainly to boost immunity and overall health.

It has also been used to treat diabetes, certain cancers and heart disease (1).

Traditionally, chaga was grated into a fine powder and brewed as an herbal tea.

Nowadays, it’s not only available as a tea but also as a powdered or capsuled supplement. The tea may feature chaga alone or in combination with other mushrooms, such as cordyceps.

Taking chaga with either warm or cold water is believed to release its medicinal properties.

Keep in mind that reliable information on chaga’s nutritional content is extremely limited.

That said, they’re low in calories, very high in fiber and loaded with antioxidants (2, 3).

Summary Chaga mushroom is a fungus that grows primarily on birch trees in cold climates. With an appearance similar to burnt charcoal, it has been harvested for centuries as a traditional medicine.

Though research is ongoing, some scientific studies indicate that chaga extract may provide certain health benefits.

Boosts Your Immune System and Fights Inflammation

Inflammation is a natural response of your immune system that can protect against disease. However, long-term inflammation is linked to conditions like heart disease and rheumatoid arthritis (4).

Animal and test-tube studies suggest that chaga extract can positively impact immunity by reducing long-term inflammation and fighting harmful bacteria and viruses.

By promoting the formation of beneficial cytokines — specialized proteins that regulate the immune system — chaga stimulates white blood cells, which are essential for fighting off harmful bacteria or viruses (5, 6).

As a result, this mushroom could help fight infections — from minor colds to serious illnesses.

Additionally, other animal and test-tube studies demonstrate that chaga can prevent the production of harmful cytokines, which trigger inflammation and are associated with disease (5, 7).

For example, in a study in mice, chaga extract reduced inflammation and gut damage by inhibiting inflammatory cytokines (8).

Prevents and Fights Cancer

Several animal and test-tube studies show that chaga can prevent and slow cancer growth (9).

In a study in mice with cancer, chaga supplements resulted in a 60% reduction in tumor size (10).

In a test-tube study, chaga extract prevented the growth of cancer in human liver cells. Similar results were observed with cancer cells of the lung, breast, prostate and colon (11, 12, 13, 14).

It’s thought that the anticancer effect of chaga is partly due to its high content of antioxidants, which protect cells from damage by free radicals (15).

In particular, chaga contains the antioxidant triterpene. Test-tube studies reveal that very concentrated triterpene extract can help kill cancer cells (15).

Keep in mind that human studies are needed in order to make strong conclusions about chaga’s anticancer potential.

Lowers Blood Sugar

Several animal studies link chaga to lower blood sugar levels. Therefore, it may help manage diabetes (16, 17).

A recent study in obese, diabetic mice observed that chaga extract reduced blood sugar levels and insulin resistance compared to diabetic mice who did not receive the supplement (18).

In another study in diabetic mice, chaga supplements led to a 31% decrease in blood sugar levels over three weeks (17).

Similar results have been seen in other studies (19, 20).

However, as human research is unavailable, it’s unclear whether chaga can help manage diabetes in humans.

Lowers Cholesterol

Chaga extract may also benefit cholesterol levels, reducing your risk of heart disease.

In an eight-week study in rats with high cholesterol, chaga extract reduced “bad” LDL cholesterol, total cholesterol and triglycerides while increasing antioxidant levels (21).

Similar studies gave the same results and observed that — in addition to reducing “bad” LDL cholesterol — chaga increases “good” HDL cholesterol (17, 18).

Researchers believe that the antioxidants present in chaga are responsible for its effects on cholesterol.

Again, more research in humans is needed to clearly understand chaga’s cholesterol impact.

Summary Animal and test-tube studies found that chaga extract may boost immunity, prevent chronic inflammation, fight cancer, lower blood sugar levels and reduce cholesterol. However, more human studies are needed.

Chaga is generally well-tolerated. However, no human studies have been conducted to determine its safety or appropriate dosage.

In fact, chaga can interact with some common medications, causing potentially harmful effects.

For example, chaga could pose risks for people on insulin or those with diabetes due to its impact on blood sugar.

Chaga also contains a protein that can prevent blood clotting. Therefore, if you are on blood-thinning medications, have a bleeding disorder or are preparing for surgery, consult with your doctor before taking chaga (22).

Though some research shows that chaga may help reduce inflammation, it may also cause your immune system to become more active. Thus, people with autoimmune diseases should seek medical advice before taking chaga.

There is no research on the safety of chaga for women who are pregnant or breastfeeding. Therefore, the safest option is to avoid use.

Finally, remember to buy supplements from reputable sources, as chaga is not monitored by the FDA.

Summary No studies have analyzed the safety or appropriate dosage of chaga. Unwanted side effects could occur if you have a bleeding disorder or autoimmune disease, take blood thinners or are pregnant or breastfeeding.

For centuries, people have used chaga mushrooms for medicinal purposes.

Packed with antioxidants, chaga mushroom is available in tea or supplement form.

Its extract may fight cancer and improve immunity, chronic inflammation, blood sugar and cholesterol levels.

Still, human studies are needed to confirm these benefits and to determine its safety, side effects and optimal dosage.

If you’re interested in trying chaga mushroom tea or supplement but have concerns about side effects or possible interactions with medications your taking, talk to your doctor first.