What Exactly Is Chaga Mushroom — and Can It Help You Lose Weight?

When you hear the word mushroom, your mind probably goes straight to portobello, white button or shiitake — the types you might slice into a salad or mix into a stir-fry. But chaga mushroom isn't just another dinner ingredient. Rather, it's considered a medicinal food that may have a variety of benefits, including supporting weight loss.

Here's what you should know about the fungus (yep, it's a fungus), including what it's used for and the side effects and risks it comes with.

Chaga mushrooms are a type fungus that grows on the trunks of birch trees in cold climates, including North America, Russia and Europe. The fungus features a woody growth called a conk, which looks like burnt charcoal.

"Chaga has been used in cultures in the areas it grows, where it is believed to help improve the immune system, prevent cancer and generally promote good health," Ginger Hultin, RD, spokesperson for the Academy of Nutrition and Dietetics and Seattle-based founder of the nutrition counseling service Champagne Nutrition, tells LIVESTRONG.com.

The theory is that the antioxidants in chaga mushroom may help repair cells and combat oxidative stress, helping to fight infection, lower cholesterol, fight cancer, reduce blood pressure and possibly serve as an anti-aging remedy, Robert Glatter, MD, assistant professor of emergency medicine at Northwell Health and attending emergency physician at Lenox Hill Hospital in New York City, tells LIVESTRONG.com.

There's a catch, though: While the research is promising, no human studies to date have provided hard evidence of these benefits.

"Most of the studies have been done in cell culture using Petri dishes, far from conditions in the human body," Dr. Glatter says.

Chaga is on the market in powder, capsule, elixir and dried form. However, it's commonly taken in another form: chaga tea. "If I had to choose, I'd pick tea over concentrated supplements, as it's typically less potent," Hultin says.

Plus, getting your nutrients from food is almost always preferable to taking supplements, according to the official position of the Academy of Nutrition and Dietetics.

Keep in mind that, like many other supplements, chaga is not closely regulated. So there's no standard dosing or formulation that's been deemed safe or effective. And, as any dietitian will tell you, just because a product is natural doesn't always mean it's safe.

Plus, when it comes to the right dose, "it really depends on the person, their medical history and conditions, what medications and supplements they're on and why they want to take chaga," says Hultin.

"My advice is to consult a qualified pharmacist, physician or registered dietitian before using chaga," says Maggie Moon, RD, a Los Angeles-based registered dietitian and author.

Despite the claims you may have heard about chaga pills, powders or other supplements, there haven't been any clinical trials to assess its safety for treating or preventing conditions, including diabetes, cancer or cardiovascular disease. Here's what we do know:

Much like other edible mushrooms, the chaga variety contain a wealth of important nutrients. "There is evidence that it contains a number of vitamins and minerals, including calcium, iron, magnesium, zinc, copper, phosphorus and potassium," says Hultin, citing a September 2017 review in the ​International Journal of Molecular Sciences​.

These nutrients contribute to your overall health and give your body the fuel it needs to thrive.

Chaga mushrooms might help decrease your sick days by supporting your immune system, helping it fend off viruses and infections.

The reason lies in a compound called beta glucans, a type of sugar that can be found in many other mushrooms, says Hultin. This little nutrient helps increase the activity of disease-fighting white blood cells, she explains.

However, Hultin cautions, if you have an autoimmune disorder or your immune system is otherwise compromised, make sure to consult with your doctor before taking chaga.

"Theoretically, chaga may stimulate the immune system and keep blood vessels healthy — two important aspects of an active lifestyle needed for weight management," says Moon. "It likely works through antioxidant and anti-inflammatory activities," she says, which in turn can help with weight-loss efforts.

However, any scientific evidence to support this is based on in vitro cell or animal research, and none of the research has looked at weight loss specifically, says Moon, so don't assume drinking chaga tea will help you drop those last few pounds.

Chaga also could help lower blood sugar levels, especially in people with diabetes, says Hultin, so it's worth discussing with your doctor if you have the condition.

Plus, there's some evidence that chaga mushrooms may improve your heart health. "It can be a blood thinner, which is helpful for some people with cardiovascular disease," Hultin says.

But, she says, chaga could be dangerous if you're undergoing any type of surgery, as it could cause excess bleeding. If you have been taking it and are getting a procedure done, be sure to tell your physician ahead of time for instructions on when to stop usage prior to surgery.

Because chaga mushrooms are high in antioxidants, they naturally reduce inflammation in the body, which may help lower your risk for various diseases, like heart disease and cancer, Hultin says.

Indeed, chronic inflammation in the body can damage your brain, heart and other organs, according to the Cleveland Clinic.

One study, published in June 2010 in ​Nutrition Research and Practice,​ discovered that chaga might reduce the growth of breast, cervical and lung cancer cells in a cell culture or a Petri dish, as well as in mice, says Dr. Glatter. But more research is needed in order to determine a direct correlation, and again, research needs to be done in humans to confirm these benefits.

It's generally safe to eat chaga mushroom and drink it as a tea, according to Memorial Sloan Kettering Cancer Center, and there are no known side effects from either. Of course, there isn't a lot of research in this area, so you should always talk to your doctor before adding it to your diet.

Also, there are some people who should avoid chaga mushroom. These include people who are:

"It should not be used during pregnancy or while breastfeeding," Hultin says, because there's no research on the effects in this population.

Chaga could negatively interact with blood thinners (like warfarin) or immune system modulators, Dr. Glatter says. It may magnify the effect of anticoagulants, putting you at risk for bleeding and bruising.

Another potential adverse effect of the mushrooms is hypoglycemia, or low blood sugar, which could be dangerous in people with diabetes who are already taking medication to lower their blood glucose, Dr. Glatter says.

Symptoms of hypoglycemia may include shakiness, hunger, confusion, dizziness, feeling weak or anxious, and difficulty speaking, per the Mayo Clinic.

Chaga contains a high level of oxalates, so anyone who needs to limit oxalate intake — like those who are prone to or at risk for developing kidney stones — should use caution, Moon says.