Cassava, also known as yuca or manioc, was once known mostly in Caribbean, African, and South American cuisines — but has grown in popularity, popping up as an ingredient in countless gluten-free and paleo-friendly foods, including chips, breads, and cookies. However, a new Consumer Reports investigation reveals that some cassava-based products may contain concerning lead levels.

Whether you’re reaching for crunchy snacks or gluten-free comfort foods, cassava is showing up in more products than ever. But behind the health halo lies a hidden hazard. With the exception of some spices, CR has never seen lead levels as high as those found in some cassava products tested. CR tested 27 popular cassava items and found that over two-thirds contained concerning lead levels. 

Lead exposure is especially dangerous for children and pregnant women because it can damage the brain and nervous system in young kids and developing fetuses. Frequent exposure in adults is linked to immune system suppression, reproductive issues and kidney damage.

CR found that cassava flour, often considered a healthy and grain-free alternative, was especially problematic regarding lead levels. CR also found that four cassava products currently on the market had such high levels of lead that they advise avoiding those products entirely.

CR contacted all 18 companies whose products exceeded its lead threshold, but only nine responded. Some said that lead occurs naturally and is difficult to eliminate. Others said they have been making changes: Thrive Market pulled its cassava chips after internal testing and is investigating further. MadeGood removed cassava from its crackers entirely. And Lesser Evil is phasing cassava out of its product line.

Some brands, including Bob’s Red Mill and Pamela’s, said their cassava products already carry California’s Proposition 65 warning labels, alerting buyers to potential lead content.

The bottom line for cassava-consuming shoppers is that if you are going to consume products that contain cassava, CR says to reduce the number of servings per week. If you’re avoiding gluten, other options, including buckwheat, corn, millet, and sorghum, haven’t shown the same lead concerns. And don’t rely too heavily on any one food. Varying your diet is one of the best ways to limit exposure to harmful substances like lead.

Consumer Reports released the complete list of cassava products they tested, including the ones to avoid.