Chaga Mushroom

What is chaga?

Chaga is a parasitic fungus that forms a black, charcoal-like growth on birch trees in cold northern regions, including Siberia, Scandinavia, Canada and the northern United States. It has been used in Russian and other folk medicine, usually as a tea, for stomach complaints and other ailments. It contains polysaccharides, triterpenes such as betulinic acid, polyphenols and melanin-like pigments.

What the research says

Mostly lab and animal research

A 2024 review describes anti-inflammatory, antioxidant, anti-diabetic, anti-obesity and other effects for chaga extracts, but nearly all of that work comes from cell cultures and animal models (Ern et al., 2024). We did not find published randomized trials showing that chaga lowers cholesterol or supports heart health in people. Claims that it maintains healthy LDL cholesterol are not backed by human evidence.

Kidney safety and oxalate

Chaga’s most important human data concern safety. In 2014, Japanese doctors described a 72-year-old woman who took 4 to 5 teaspoons of chaga powder a day for six months and developed oxalate nephropathy requiring dialysis; the authors noted chaga contains extremely high oxalate concentrations (Kikuchi et al., 2014). A 2020 Korean report described a 49-year-old man who reached end-stage kidney disease after years of chaga powder use; the leftover product contained 14.2 grams of oxalate per 100 grams (Lee et al., 2020). These were heavy, long-term users, but they show the risk is real. The Korean authors estimated their patient’s oxalate intake at two to five times that of a usual diet, and they described chaga as a potential risk factor for chronic kidney disease.

Wild-harvested and quality concerns

Much chaga is wild-harvested, and products differ in whether they use the actual chaga conk or mycelium grown on grain, which may contain very different compounds. Labels rarely state oxalate content, so consumers cannot judge their exposure.

Other cautions

Because so little human research exists, chaga’s interactions with medicines are largely unknown. Caution is sensible for people on blood thinners or diabetes medicines, simply because no one has shown it is safe to combine them.

How it’s used in supplements

Chaga is sold as chunks for tea, powders, tinctures and capsule extracts, and it is a common component of mushroom blends and mushroom coffee. Many products do not disclose how much chaga they contain. People with a history of kidney stones, kidney disease or high oxalate levels should avoid chaga or ask a doctor first, as should anyone on blood thinners or diabetes drugs and people who are pregnant or breastfeeding. Small amounts in a blend are less concerning than daily spoonfuls of powder, but no safe long-term dose has been established.