By Mila McManus, MD
Last January, Consumer Reports urged several chocolate producers to reduce the amount of lead and cadmium found in their dark chocolate products. A corporate accountability organization called You Sow tested 28 different dark chocolate bars and found 23 of them to contain potentially harmful levels of lead, cadmium, or both. The exposures were considered concerning for those who consume one ounce or more per day.
Heavy metals, such as lead and cadmium, are especially harmful for pregnant women and children because they can negatively affect brain development and lead to lower IQ. They have negative effects on others as well, of course. Frequent exposure to lead in adults can lead to nervous system problems, hypertension, immune system suppression, kidney damage, and reproductive issues.
Brands with the highest levels included:
High in Both Lead & Cadmium – Theo Organic Dark 70%, Trader Joe’s The Dark Chocolate Lover’s, Theo Organic Extra Dark Pure, Lily’s Extremely Dark, and Green & Blacks Organic Dark. All of these had 120-145% lead levels and 101-229% cadmium levels.
High Lead – Tony’s Chocolony Dark, Lily’s Extra Dark, Godiva Signature Dark, Chocolove Strong Dark, Lindt Excellence Dark, Endangered Species Bold + Silky Dark, Trader Joe’s Dark, Hu Organic Simple Dark, Chocolove Extreme Dark, and Hershey’s Special Dark Mildly Sweet. All of these had 134-265% lead levels.
High Cadmium – Beyond Good Organic Pure Dark, Equal Exchange Organic Extra Dark, Lindt Excellence Dark, Scharffen Berger Extra Dark, Alter Eco Organic Dark Blackout, Pascha Organic Very Dark Dark, and Dove Promises Deeper Dark. Cadmium ranged from 112-253%.
While every bar had some level of lead and cadmium, those found to have the lower and safer levels when consumed in moderation are Mast Organic Dark, Taza Chocolate Organic Deliciously Dark, Ghirardelli Intense Dark, Ghirardelli Intense Dark Twilight Delight, and Valrhona Abinao Dark. In these selections, lead ranged from 14-63% and cadmium ranged from 40-73%.
Heavy metals lurk in the cocoa solids of the cacao bean and are higher in the darker, over 65% cacao by weight, chocolates. Cocoa butter is the other solid portion. The heavy metal concerns can extend to other products such as hot cocoa, brownie mixes, and cake mixes. The older a tree becomes, the more heavy metals are passed from the soil into the tree. Additionally, different countries vary in the heavy metal contents of their soils. Heavy metals also tend to increase during the drying process while beans lie on the ground or near roads in the sun. One way to reduce the heavy metal content is to mix beans from a variety of soils.
Michael J. DiBartolomeis, PhD, a toxicologist and former official at the California Department of Public Health who has researched heavy metals in chocolate, says that while he cautions pregnant women and children from eating dark chocolate, he doesn’t tell most people to give it up, just to know the risks and not overdo it. Consider adding detoxification strategies such as exercise, sauna, proper hydration, regular bowel function promoted through a high fiber diet, and frequent rotation of a wide variety of foods. Ask your provider if heavy metal testing is right for you.
Doctor’s Data Inc., Descriptive Texts for Lead and Cadmium, 1999-1921.