“Your days are numbered,” I said, looking at the rabbit. “Your demise is going to be slow and painful — for both of us.”
Nature Boy, the other human in the room, quite reasonably thought I was talking to him. “What did I do this time? I thought you’d like it.”
“I was talking to the chocolate bunny you gave me,” I said. “I’ll nibble a bit. And then,” I sighed, “I’ll leave it for a bit.”
“A bit” in this case, means a day.
The treat Nature Boy gave me is made of fine-quality, very dark chocolate. In my personal universe, that kind of chocolate and moderation do not go well together.
But that pairing is what health experts suggest.
Research revealed some years ago that dark chocolate contains disconcertingly high amounts of cadmium and lead. These heavy metals are linked to kidney damage, developmental problems, fragile bones, reproductive issues, hair loss, suppressed immunity, and other health problems in humans.
A recent study by U.S.-based non-profit consumer protection organization Consumer Reports clarifies the problem, its sources and some possible solutions. Researchers measured the amounts of both heavy metals in 28 dark chocolate bars, including bars by Alter Eco, Chocolove, Endangered Species, Hershey’s/Lily’s, and Lindt.
The scientists detected cadmium and lead in all the bars. Levels in five fell below U.S. health authorities’ maximum recommended daily thresholds for health, but eating just 28 grams (1 oz) of any of the other 23 bars would exceed recommended healthy daily upper limits for adults of at least one of the heavy metals. Five bars, including organic bars by Theo and Green & Black’s, had above-threshold levels of both cadmium and lead.
The main source of the metals in chocolate, the researchers found, is chocolate liquor, which is produced from milled cocoa nibs, the cocoa bean’s deshelled portion. In the offending bars, the higher the cocoa content — i.e., the darker the chocolate — the higher their heavy metal levels.
The researchers found that lead in chocolate gets there after the beans are harvested, mostly through direct contact with soil and dust. This means reducing lead levels is doable, involving working with cocoa farmers–suppliers, many of which are small family operations, to change after-harvest processes and equipment.
Like lead, cadmium is found in soil, sometimes naturally, sometimes through industrial pollution. But the Consumer Reports researchers found cadmium gets into chocolate before harvesting. Cocoa trees, it turns out, are really good at pulling cadmium out of dirt and incorporating it into their leaves, wood and fruit. The more cadmium in the soil, the more cadmium in the cocoa beans.
The scientists noted that fertilizing soil with zinc reduces cadmium uptake, as does regularly adding compost (but not from high-cadmium cocoa plants) to the soil. However, the way a cocoa tree grows prevents effective fertilization and composting around its roots, so more research is needed to make either solution feasible. Chocolate manufacturers can also seek out cocoa producers from regions with less soil cadmium.
The researchers also suggested manufacturers consider diluting contaminated chocolate liquor with less-contaminated supplies to lower the heavy metal levels. This option would work for bulk and common chocolate, but isn’t feasible for premium “fine-flavour” or single-source chocolate products, like the chocolate bunny Nature Boy gave me this year.
We, as eaters of chocolate, can also adjust our chocolate habits. We can choose chocolate products with credibly verified lower heavy metal levels — the five brands identified by Consumer Reports as being below the U.S. safety thresholds, for instance.
We can select milk chocolate or lower-cocoa-content dark chocolate over the very dark options or mix the kinds of chocolate we eat.
We can ration our intake.
We can do all of the above.
All of the bars tested in the study are on the larger side, from 85 to 100 grams each. Twenty-eight grams (1 oz) equals about one-third of each bar. If an adult eats one or two small pieces of chocolate a day, they probably don’t need to worry.
If they make a habit of snarfing an entire bar frequently, they might want to pair smaller daily portions of chocolate with bigger doses of moderation.
