The Nutrition Diva's Quick and Dirty Tips for Eating Well and Feeling Fabulous

Heavy metals in chocolate: how worried should you be?

Episode Summary

Is even a single ounce of dark chocolate too much to have on a daily basis?

Episode Notes

Popular dark chocolate bars have been found to have concerning levels of lead and cadmium.

Nutrition Diva is hosted by Monica Reinagel. A transcript is available at Simplecast.

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Episode Transcription

Hello and welcome to the Nutrition Diva podcast. I’m your host Monica Reinagel and this week’s show is about chocolate. Now, you may be thinking: “Wait, I already heard this episode!” But don’t touch that dial! You’re right that I recently had an episode about the difference between powdered cacao and cocoa powder. But the day AFTER that episode was released, Consumer Reports published their findings that many popular brands of dark chocolate contained concerning amounts of lead and cadmium. 

My inbox filled up with emails from listeners asking how to evaluate or avoid this threat. So today, I have part 2 of my unplanned series on the benefits and risks of chocolate. Specifically, how worried should you be about overexposure to heavy metals from your favorite chocolate bar? 

A lot of health-conscious people I know consider dark chocolate to be a healthy indulgence. The flavanols it contains offer a variety of benefits. Dark chocolate tends to be relatively low in sugar and—for me anyway—it’s a treat that it’s easier to enjoy in limited quantities. I can pound a bag of M&Ms—but I rarely reach for more than 1 or two squares of dark chocolate. 

But what about these warnings about lead and cadmium? Is even a single ounce of dark chocolate too much to have on a daily basis?

Virtually all chocolate contains some amount of lead and/or cadmium. Cadmium is absorbed from the soil by the cacao trees and makes its way into the cacao beans themselves. The harvested beans are exposed to lead in the air and soil during the drying and fermenting process.

But chocolate is not the only food that contains heavy metals. Fruits, vegetables, juices, sea vegetables, nutritional supplements, and protein powders have all been found to contain lead and cadmium. Indeed, there’s no way to avoid exposure to these elements. They are in the air, water, and soil where our food is grown.

That said, high exposure to these heavy metals can be harmful to our health. Lead is toxic to the brain and nervous system and can cause neurological damage and learning disabilities—especially with early childhood exposure. Cadmium is harmful to bones and kidneys and can be carcinogenic if inhaled. Our bodies cannot break down and eliminate these compounds. As a result, they accumulate in the body, with higher lifetime exposures linked to higher health risks. 

Accordingly, the EPA has standards for what it considers to be tolerable levels of these heavy metals in the air, water, soil, and food. The state of California has gone a step further by establishing Maximum Allowable Dose Limits (MADLs) for ingestion of these metals.  

The recent Consumer Reports investigation tested a couple dozen popular brands of dark chocolate to see how much lead and cadmium you would ingest if you ate a single ounce. Why did they only test dark chocolate? Because milk chocolate has a much lower cacao percentage and therefore represents a much lower risk of heavy metal exposure.  

(This is good news because kids—who are at higher risk from exposure, due to their smaller body size and the fact that their neurological systems are developing rapidly—don’t tend to eat a lot of dark chocolate.)

Why just one ounce? After all, these bars are usually 3 or 4 ounces. But in my experience, people tend to consume dark chocolate in smaller quantities. An ounce of dark chocolate a day is usually what health experts recommend as a way to get the health benefits of cocoa flavanols. 

So what did they find? 

Not surprisingly, lead and cadmium were detectable in every sample they tested. What was notable was the range. Some of the brands (including some pretty fancy organic brands) contained significantly higher levels of lead and/or cadmium than others.  

There are a variety of reasons for this, including the source of the beans as well as some of the harvesting and processing practices. Chocolate growers have been aware of this issue for a while and have been researching and implementing practices designed to reduce the level of heavy metals in cacao. However, clearly, progress on this front has been uneven—and, short of independent testing by consumer watchdogs, there’s not a lot of transparency around the amount of heavy metals in these products. 

Only a handful of the brands contained less than the MADL for both lead and cadmium—two of which you’re probably familiar with: Ghirardelli and Valrhona. Two others, Mast and Taza, were unfamiliar to me.

All of the rest, including dark chocolate from Dove, Lindt, Eco Alter, Scharffenberger, Godiva, Chocolove, and (I know a lot of you took this one pretty hard) Trader Joe's had levels of cadmium, lead, or both that were above the MADL. For those of you who have been enjoying a square of dark chocolate every evening, this may sound pretty dire. But let me try to put this in perspective.

The MADLs that Consumer Reports chose as their standard are extremely conservative, intended to protect the most vulnerable individuals and to provide an even wider margin of safety than the already wide margin of safety that is built into the FDA’s recommendations. The MADLs are many times lower than the safe levels established by the FDA—even for small children. 

Here’s an official statement from the National Confectioners Association:

“The California… guidelines cited in the Consumer Reports study are not food safety standards…The products cited in this study are in compliance with strict quality and safety requirements, and the levels provided to us by Consumer Reports testing are well under the limits established by our settlement.”

The settlement they are referring to is one they arrived at a few years back with the California non-profit organization As You Sow, whose mission is to promote environmental and social corporate responsibility.

As You Sow and the National Confectioners Association actually teamed up in an admirable mode of non-combative cooperation to research the sources of lead and cadmium contamination and possible solutions, before negotiating a settlement in which the NCA pledged that chocolate with lead or cadmium levels in excess of agreed upon limits would contain a warning on the package. None of the chocolate bars tested by Consumer Reports reached this threshold. 

But what about cocoa powder that you might use in brownies, hot chocolate, or one of the savory applications I suggested in my recent episode on powdered cacao? Although cocoa powder was not addressed in the most recent analysis by Consumer Reports, it has been the subject of previous testing by another consumer watchdog organization, Consumer Labs. Unfortunately, the same concerns apply. As with chocolate, tests of cocoa powder revealed a wide range of levels across various brands. And, as with the chocolate bars, Trader Joe’s cocoa powder was among the highest in cadmium, while Ghirardelli was among the safest.  

So, what should you do in response to this information? That’s going to depend on both your risk tolerance and your situation.

I’ve got a couple of chocolate bars in my cupboard right now that ended up on Consumer Reports' “naughty” list and I’m not going to throw them away.  But I also am not an every day consumer. If you are, you might want to seek out the brands that are lower in heavy metals.  

If you’re pregnant or planning to become pregnant, you might, out of an abundance of caution, choose to limit your consumption of dark chocolate and cocoa to 1 or 2 servings per week. You might also want to choose one of the brands that were found to be lowest in heavy metals. 

I’d probably also limit the amount of dark chocolate that your young kids are eating because the stakes are highest for them. Fortunately, this will probably not be too hard as kids tend not to like dark chocolate that much. Hot cocoa and other chocolatey treats made with cocoa powder probably shouldn’t be a daily treat, but perhaps a weekly one at most.

And finally, keep your eye out for future developments. The industry is really working hard to address this issue. I would expect the levels of heavy metals in dark chocolate and cocoa to continue to decline as they implement solutions. I’m sure those brands who got some unwanted publicity out of this recent story will be especially eager to improve their standing.

This is Monica Reinagel and I’ll be back next week with an episode that, I promise, will not be about chocolate. And if you have a question you’d like me to tackle, send me an email at nutrition@quickanddirtytips or leave me a voicemail at 443-961-6206. I love to hear from you.

Nutrition Diva is a Quick and Dirty Tips podcast. It’s audio engineered by Nathan Semmes with script editing by Adam Cecil. Thanks also to Holly Hutchings, Davina Tomlin, Morgan Christianson, and Kamryn Lacy. And most of all thanks to YOU for listening!