Mushrooms are surprisingly healthy from a nutritional standpoint. Even the inexpensive white mushroom is a good source of selenium, riboflavin, niacin, thiamine, potassium, copper, fiber, and protein. Plus, a recent study showed that eating button mushrooms may lower the risk of breast cancer in women by inhibiting the activity of an enzyme called aromatase that stimulates estrogen production. Some mushrooms are also thought to have medicinal value. But, a new study shows there may be a down side to eating mushrooms in large quantities – an increased risk of heavy metal poisoning.
 
Does It Increase the Risk of Heavy Metal Poisoning?

According to a study published in the journal Biometals, some mushrooms could be a source of heavy metals such as lead, thorium, uranium, and neodymium with some species being more likely to contain high metal levels than others. Researchers tested for the presence of heavy metals in twelve different species of mushrooms collected from a variety of wooded areas in a province of Spain. The mushrooms were then analyzed for heavy metals using x-ray fluorescence spectrometry.

The results? After testing the twelve different species of mushrooms they found significant quantities of heavy metals in all of them with the highest levels seen in the chanterelle mushroom. There seemed to be a lot of variation in how much heavy metal was seen based on the species. Mushrooms that grew on wood were found to have higher levels of the heavy metal thorium.

Does Eating Mushrooms Put You at Risk of Heavy Metal Poisoning?

The researchers believe that mushrooms have the capacity to absorb heavy metals directly from the soil which means that mushrooms grown in contaminated soil would be more likely to be a threat to health. Unfortunately, unless you grow your own mushrooms and have analyzed the soil you may not know whether the mushrooms you’re eating are sources of heavy metal. If you eat mushrooms grown in heavily contaminated soil and eat them frequently, there could be a risk of heavy metal poisoning.

Eating Mushrooms: Do It in Moderation

The key to eating mushrooms and avoiding the possibility of heavy metal poisoning is to eat them in moderation and avoid species like the chanterelle that are more prone to collecting heavy metals from the soil. If you gather mushrooms from the wild, never collect them from areas where the soil is likely to be contaminated such as by the sides of the road or where industrial waste may have been dumped in the past. Eating mushrooms may still provide health benefits, but this new study suggests that eating them in moderation may be important to reduce the risk of heavy metal poisoning.