As we have discussed in previous blogs, Chaga is well known for its medicinal value and bioactive compounds. There are many such compounds found in fungi that have been isolated, identified, and described by scientists. Chaga is touted for it’s ability to support healthy bodily function, and with so much misinformation on the web, it’s easy to overlook the potential side effects from overuse of Chaga.

In this blog we will identify the known (potentially negative) side effects of overusing Chaga, starting with an in-depth look at oxalates and ending with the types of people who should consult a physician before using Chaga products.

Oxalates are naturally occurring compounds found in plants and some fungi. They are common in many foods, occurring in everything from avocados to raspberries, and even chocolate. Certain foods such as spinach, almonds, and beet greens are especially high in oxalates. There are two categories of oxalates in terms of nutritional and digestive health: soluble and insoluble.

The insoluble oxalates (such as calcium oxalate, magnesium oxalate, and iron oxalate) are not absorbed in the digestive system and pass harmlessly. On the other hand, soluble oxalates (such as potassium oxalate and sodium oxalate), release free oxalate anions which pass into the bloodstream.

The body naturally neutralizes and rids itself of soluble oxalates, but in high amounts, soluble oxalates can overwhelm the body's ability to do so in a timely manner, which could result in serious negative side effects.

In the bloodstream, free oxalates may bind with free calcium to produce calcium oxalate crystals. Over time, excessive presence of these crystals could lead to kidney stones, gout, and/or physical damage to the kidneys, while simultaneously depleting essential calcium needed for healthy growth.

Chaga is considered to have a relatively high oxalate content, according to several sources. There exists at least one case in which someone who routinely consumed large amounts of powdered Chaga suffered kidney damage, and ultimately died.

1. A 72-year-old Japanese female who had been diagnosed with liver cancer began to ingest Chaga mushroom powder (4 - 5 teaspoons per day) and died 6 months later from kidney failure (1).

2. The British Columbia Center for Disease Control states that the dosage of dried material for Inonotus obliquus should not exceed 3.6 grams of dried material per day (2).

While this offers a good baseline for theoretical consumption, we explicitly discourage the consumption of ground Chaga. You can derive the same benefits as well as mitigate the risk of harmful concentrations of oxalates by choosing Chaga tea or Chaga tincture instead.

In 2020, we conducted internal testing on this subject at our small in-house lab. Based on a report produced by our lead Chemist (Maya Duncan-White), we determined that our samples of aqueous Chaga extract (aka Chaga tea) contained 800mg soluble oxalates per 100g of dried material.

That is, if one were to brew 100g (just shy of 4oz) of ground chaga for 30 minutes at 80C, they could expect the hot water extract to contain approximately 800mg of soluble oxalates. This equates roughly to the same amount of soluble oxalates one could expect to ingest from eating a half cup of spinach (100 grams of spinach contains approximately 750mg of soluble oxalates).

In each Birch Boys tea bag, there are only 2 grams of ground Chaga, so one tea bag (steeped at 80C for 30 minutes) would contain approximately 16 mg of soluble oxalates. An interesting paradigm is the fact that wild Chaga contains elevated levels of calcium, magnesium, iron, and other minerals. Although soluble oxalates can chelate these from the body, tea brewed from wild Chaga could simultaneously replenish these minerals to some degree. It’s also worth noting that this chelation action may even act beneficially in certain instances; removing hazardous heavy metals such as mercury and lead from the body.

If you fall into one of the following categories, please consult your medical provider before using Chaga.

• You have diabetes, are on diabetes medication or you have diabetic ketoacidosis.

• You have a blood clotting disorder, very thin blood, and/or are on medication to regulate blood pressure.

• You have an upcoming surgery (cease supplement use at least 2 weeks prior to operations).

• You are pregnant and/or breastfeeding.

• You have kidney issues or are prone to kidney stones

• You have osteoporosis, calcium deficiencies or are on a reduced oxalate diet.

Those prone to kidney stones, as well as those diagnosed with kidney disease and/or osteoporosis may be best advised to avoid Chaga all together, and should certainly consult with a licensed physician before using Chaga products. Otherwise, in healthy moderation, oxalates in Chaga do not seem to pose any serious health threats to the average person. The risks posed by oxalates in Chaga can be considered negligible if used intelligently by healthy individuals.

Proper research is critical in your selection of a quality Chaga product, extract, or supplement. We urge you to be aware that much of the mainstream mushroom market consists of dissolvable mushroom extract powders that come from China - without transparency regarding the methods used to turn a mushroom into an extract powder, which can negatively affect the beneficial compounds found in fungi. We also urge consumers to be wary of consuming Chaga products in a solid powder state, as one might do with edible mushrooms such as Lion’s Mane or Maitake. Chaga is not an “edible” mushroom, in this sense.

There are various products marketed as “Chaga” by people who may not even understand the composition of the Chaga products they are promoting / selling. In a newly-emerging industry fraught with profit-driven brands who view the responsibility of disclosure as an unnecessary burden, due diligence is left to none other than you: the consumer.

We hope that this blog has helped put your Chaga concerns into a more accurate and informed perspective. If you learned something, join the discussion by commenting below!