A test of dark chocolate found traces of lead and cadmium. Do you need to give it up?

For years, dark chocolate has been touted as good for you, in moderation.

Research has shown that there can be benefits for your heart, cholesterol levels and blood pressure.

Those are all still true, but a report published in December looking at the heavy metals in dark chocolate may leave a bad taste in your mouth.

Scientists with Consumer Reports, an independent non-profit based out of the U.S., tested 28 dark chocolate bars for lead and cadmium. They found either or both in all of the chocolate bars, some of which are sold in Canada.

Those heavy metals are some of the "highest concern to human health," according to a Health Canada website about a review of food products other than chocolate, and have been shown to have serious health effects after long-term exposure.

Knowing that, the scientists used California's guidelines on maximum allowable dose level (MADL) of 0.5 micrograms for lead and 4.1 micrograms for cadmium to determine the risk posed by the chocolate bars.

Part of the reason the Consumer Reports team tackled dark chocolate was because of its "health halo," they said.

"It's considered a healthier snack. And that's because of the flavanols that are in dark chocolate has been linked to increasing blood circulation, antioxidant activity, anti-inflammatory activity. However, there are also heavy metals in some of the products and to a level that's alarming," said James E. Rogers, director of food safety research and testing at Consumer Reports.

So, what's the risk?

When you drill into the test results a little further, they found just one ounce — or about 28 grams — from 23 of the tested chocolate bars would give you the daily amount of heavy metals.

Among all of the chocolate tested, five of the brands well-exceeded the maximum levels for both lead and cadmium.

Finding metals in food products is not unexpected, according to Health Canada, as these metals are found in the environment and may end up in processed food due to the ingredients used in a product or during food production.

A spokesperson for Health Canada said Monday they have looked into cadmium and lead in food sold in Canada and that chocolate "contributes marginally" to overall dietary exposure.

They emphasized in their emailed statement "consumption of chocolate by the Canadian population does not represent a health concern."

An Ottawa-based researcher says it's important to remember just how much dark chocolate an average person would need to consume to hit risky levels of lead or cadmium.

"It's a candy that you are not eating like one kilogram every day on a daily basis. As a person who eats one or two pieces of dark chocolate on a daily basis, I'm not too worried about it," said Yaxi Hu, an assistant professor in Carleton University's chemistry department's food science program and lead of the university's Food Analytical Chemistry and Technology Laboratory.

Rogers says the whole motivation for the test —and everything Consumer Reports tests— is so consumers can be informed and make the best choice when looking for something to satisfy that sugar craving.

WATCH | It's okay to eat small amounts of dark chocolate, health officials say:

The health effects

Lead has no known benefit to the human body.

According to the Centers for Disease Control and Prevention (CDC), well-documented health effects include:

• Damage to the brain and nervous system

• Slowed growth and development

• Learning and behaviour problems

• Hearing and speech problems

Infants and children are especially at greater risk of the long-term effects of lead on their health, according to the CDC.

Cadmium is considered a cancer-causing agent, and when eaten in large amounts, it can irritate the stomach and cause vomiting and diarrhea, says the CDC.

Hu says it's important for people to know the health risks and the levels of the heavy metals in food.

"We all know heavy metals exist here and there, but we do not often see their exact level being present," said the Canadian researcher, who was not part of the Consumer Reports test. Her research focuses on developing analytical methods to better detect food safety and adulteration issues.

"It's definitely giving more information for consumers when they want to do food selection."

In the U.S., there are no federal limits on the amount of lead and cadmium that can be in food. The California thresholds were used because they were considered by the scientists to be "the most protective available."

In Canada, lead is not allowed to be added to foods sold here. However, it "is present in all foods, generally at very low levels," reads a Health Canada website. Historically, beverages (including beer, wine, coffee and tea), cereal-based foods and vegetables are the food groups that have contributed the most to the dietary intake of lead among Canadians, according to Health Canada.

A Health Canada spokesperson said because the levels of cadmium and lead in chocolate products represent such a small percentage of daily dietary exposure, there hasn't been a need to establish maximum levels specific to these two heavy metals.

How do the heavy metals get into chocolate?

A March 2022 report's authors found that lead gets into cacao —which is used to make dark chocolate— after the cacao beans are harvested.

The report was done as part of a settlement to a lawsuit over whether certain levels of lead and cadmium in chocolate require warnings under California law. The 2018 settlement agreement also established thresholds for both lead and cadmium that require warning labels on chocolate products if exceeded.

Cadmium likely gets into dark chocolate products because the cacao plants take up the heavy metal from the soil, the researchers found.

It's well-known to those in the chocolate industry that levels of both heavy metals can be found in the bitter-tasting food. But in the last few, more consumers are becoming aware of heavy metals in the product, said Michael Sacco, owner of chocolate producer ChocoSol in Toronto.

"Canadians need to understand, like anything, sourcing is so key," he said.

"A grape that's growing in artificial chemical fertilizers is not the same as a grape that's growing in soil that has been properly tended to. Not all agricultural models are the same."

Sacco also says it's important to put things into perspective.

"Cacao will have some cadmium in it, yes. But is the cadmium in the cacao that you're eating in that dark chocolate worse for you than the highly-refined preservatives and hydrogenated oils and things of that nature? So it's really important to kind of put things in proportion," he said.

Can I still have dark chocolate?

Canadians are known to have a sweet tooth for chocolate, spending on average $88 on chocolate bars in a year. So the news may be heartbreaking for some chocolate lovers.

But it's important to remember that overall, the lead and cadmium levels in chocolate contribute slightly to overall diet exposure, according to Health Canada.

Rogers says don't panic as there are other chocolate options, with Consumer Reports scientists finding five "safer choices" of dark chocolate.

"Combine our research and information with other organizations that have tested dark chocolate and become an informed consumer and make wise choices," he said.