Heavy metals in chocolate: 5 questions, answered

A lot of people crave sugar, and chocolate is usually pretty high on the list of preferred sweets.  

But testing by various agencies over the years has revealed high levels of cadmium, lead and other heavy metals in some chocolate products.  

This has led several cancer patients to ask me, “Is it even safe for me to eat chocolate?” Here, I’ll answer that question and four others I frequently hear about heavy metals and chocolate.

Does all chocolate contain heavy metals?

It’s not really possible to make a blanket statement about all chocolate products. But many contain at least trace amounts of heavy metals. This is because of both how cacao plants are grown and how they are processed. 

The two most common heavy metals found in cacao beans are cadmium and lead. Cadmium is often found in the soil where cacao trees are grown, so it's taken up by the roots and deposited in the seed pods. Lead contamination, on the other hand, comes mostly from the handling and processing of cacao beans after they’re harvested, such as from the dust generated by machinery. 

Why are heavy metals in chocolate dangerous?

Ingesting foods that have too much heavy metal is considered unsafe because these substances accumulate in the fatty tissues of the body. They are not excreted in the urine or stool, either. So, they just sit there and keep building up over time.

This can lead to health problems, including birth defects in developing fetuses, developmental issues in young children, and even poisoning, if levels get too high. That’s why obstetricians counsel pregnant women to limit their intake of certain fish, due to concerns about mercury, another heavy metal. Pediatricians often warn the parents of small children about the dangers of lead in peeling paint or old water pipes, too.

What kind of chocolate does not have any heavy metals in it?

Again, that’s an impossible question to answer. Generally speaking, though, the darker the chocolate, the more cacao it contains. So, the greater risk there will be for higher concentrations of heavy metals if that product has them.

How can I avoid lead and cadmium in my chocolate?

I’m not sure it’s realistic — or even possible — to avoid them entirely. As I mentioned, cadmium is a naturally occurring element that is often present in soil. But there are several steps you can take to reduce your exposure.

Do your research.

A lot of chocolate manufacturers know consumers are concerned about this, so they publish their testing results online. Visit the websites of the chocolate brands or products you enjoy most to see what they reveal. Or, check out the test results of reputable watchdog agencies to help you with decision-making. 

Try different cocoa concentrations. 

Dark chocolate products with 80% or more will be lower in sugar, but higher, potentially, in heavy metals. So, consider trying chocolate with lower levels of cocoa, and look for products with a 50% to 70% concentration instead. Milk chocolate products tend to have the lowest concentrations, between 30% and 40%.

Change how you indulge your sweet tooth. 

Varying the type of sweets you eat is much healthier than always eating the same thing. So, instead of turning to chocolate every time, consider a serving of Greek yogurt instead, with some fresh berries on top, half a bagel spread with some strawberry cream cheese, or a slice of bread slathered with date or nut butter and drizzled with a little honey.

Is it even safe for cancer patients to eat chocolate?

Overall, I would say yes. But as with many things, moderation is the key.  

Even if you eat a chocolate product whose heavy metal levels are near the threshold set by health agencies, you are not at immediate risk of poisoning. Large safety margins are usually built into those limits.  

That being said, there are no specific limits in the U.S. for cadmium and lead levels in chocolate, so you’ll have to rely on the Food and Drug Administration’s more general food references for guidance. Some states have much more conservative guidelines in place. Proposition 65 in California, for instance, set much lower limits for heavy metals in food. 

Other countries have different standards, too. So, trying to compare the European Union’s guidelines to those of the United States, for instance, might not make much sense.

The other thing to keep in mind is that dosing and frequency matter.

Like all sweets, chocolate is meant to be an occasional treat, not a daily free-for-all. And, a single serving size is only one ounce, which is usually one or two squares of a chocolate bar, depending on the manufacturer.

So, while we don’t encourage eating chocolate daily, you’re more likely to develop problems from excess calorie intake than heavy metal toxicity if you overindulge. That’s why we recommend limiting yourself to two or three servings a week, especially if you’re concerned about heavy metals. 

The bottom line? The more chocolate you have, the more heavy metals you could be ingesting. So, do your research and think about how much risk you’re comfortable with before feeding that sweet tooth.

Starla Garcia is a senior clinical dietitian at MD Anderson. 

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