Dark chocolates and cocoa may contain dangerously high levels of the heavy metal cadmium, a kidney toxin, according to recent tests conducted by White Plains, NY-based ConsumerLab.com, an independent evaluator of health and nutrition products. Often consumed for their beneficial cocoa flavanols, which ConsumerLab also measured, chocolate and cocoa products ranged from virtually zero flavanols to levels that may provide cardiovascular and cognitive benefits.

ConsumerLab found that some popular dark chocolates and popular cocoa powders contained in excess of 20 micrograms of cadmium per serving, greatly exceeding California’s 4.1 microgram limit. Products exceeding that amount require warning labels. Limits set in Canada mandate that children and adults be exposed to no more than 3 mcg and 6 mcg of cadmium per serving, respectively. The World Health Organization suggests that cocoa powders not contain more than 0.3 mcg of cadmium per gram, but ConsumerLab found that nearly every cocoa powder exceeded that limit and some contained several times that amount—including a popular national grocery store brand. However, cocoa extracts and supplements contained little or no cadmium.  

Consumption of cocoa and chocolates is potentially beneficial when they provide at least 200 mg of flavanols a day. Amounts of flavanols in dark chocolate bars tested ranged from 55 mg to as much as 500 mg in a typical 40 gram serving and from 36 mg to over 200 mg in one tablespoon of cocoa powder. 

Information regarding “% cocoa” (or cacao) on labels was often a poor indicator of flavanol levels, ConsumerLab found. Several bars claiming 80% to 85% cacao contained lower amounts of flavanols than bars claiming 56% to 77%. An organic label did not ensure higher flavanol content. 

“Due to the cadmium and lead in cocoa powders and dark chocolates, it is best to use products that provide the most flavanols with the least contamination. Even with products having relatively little contamination, it may be best to limit daily consumption,” says Tod Cooperman, M.D., president and founder of ConsumerLab.com. 

The product test results and comparisons are available now in ConsumerLab.com’s Dark Chocolate, Cocoa Powder, Nibs, Extracts & Supplements Review. In the review, ConsumerLab.com identifies its Top Picks, i.e., the chocolate and cocoa products that provide high amounts flavanols with the lowest amounts of cadmium or other contaminants, such as lead. Top Picks included one dark chocolate, two cocoa powders, one cacao nib product, and one cocoa flavanol dietary supplement. 

The review includes test results and quality comparisons for 43 products, 42 of which were selected for testing by ConsumerLab.com and one of which passed the same testing through CL’s voluntary Quality Certification Program. For each product, the report shows the amounts of flavanols, heavy metal contamination, caffeine, and theobromine as well as providing comparisons of calories and price. Clinical evidence for cocoa flavanols, dosage for cardiovascular and cognitive benefits, and information about safety and potential side effects are also provided.