How poisonous is your favorite chocolate? Tests show which brands contain the highest levels of cancer metals

Dark chocolate has long been touted as a healthier choice for people who want to satisfy their sweet tooth without spiking their blood sugar levels.

But what the millions of people may not know is that they can also contain heavy metals linked to cancer.

Multiple tests conducted by consumer watchdogs have discovered high levels of cadmium and lead in chocolate products, which have been linked to kidney and bone disease, brain damage, miscarriages and tumor growth.

Now Brian Johnson, a 46-year-old biohacker who claims he can roll back his biological age by ten years, has analyzed ten popular dark chocolate bars to find the worst offenders.

All ten dark chocolate bars contained detectable metals (although Johnson does not specify which metals he tested for) and two products from Alter Eco received the worst scores for being three times higher than some competing brands.

In addition to metal levels, Johnson also tested for flavanols: plant compounds that can improve heart and brain health, help fight cell damage and infections, and protect the body against toxins and inflammation.

Based on the amount of flavanols and heavy metals each chocolate bar contained, the biohacker, who reportedly spends $2 million a year on his anti-aging lifestyle, assigned each product a score.

The scale ranged from zero to 100, with lower scores indicating a poorer health profile.

Mr Johnson tested 10 popular dark chocolate bars, including Lindt Excellence, Ritter Sport, Beyond Good, Alter Eco, Hu and Tony’s Chocolonely.

They ranged from 70 percent cocoa to 100 percent cocoa, with some claiming they were sustainably produced, good for the environment and free of processed additives.

Of the 10 products, Alter Eco’s 85 percent cocoa classic blackout dark chocolate scored the lowest, at 13.

Although it had a higher flavanol content (140.5 mg), it contained 10.6 micrograms of heavy metals.

A second Alter Eco product scored similarly: 100 percent cocoa, total blackout chocolate, with 210.5 mg flavanols and 14.7 mcg heavy metals – giving it a score of 14.

Brian Johnson is a biohacker who claims to have reversed his biological age from 46 years old to 37 years old

The highest scoring product Johnson tested was the exotic chocolate bar with 72 percent cocoa, black salt caramel from the Vosges, which contained 159 mg of flavanols and only 2.0 mcg of heavy metals, yielding a score of 78.

Mr Johnson said: “What we have learned today is several things. One: marketing and packaging mean nothing. It doesn’t matter what they say. It doesn’t matter what words they use, how beautiful their photos are. It doesn’t matter.

‘Second, not knowing is very dangerous… That’s why it’s so important to know what you’re eating and to have quantified data on its cleanliness and positive benefits.

‘Transparency in our food supply chain is a good thing for everyone. No one wins when our food supply is contaminated. No one wins when we are unhealthy. It’s time we change the world from a ‘that economy’ to a ‘don’t economy.’

There is no nationally established level for lead and cadmium exposure, except for 2017 research determined that 62 micrograms (mcg) of cadmium is the highest acceptable level for a 154-pound person per day when it comes to kidney health.

While the FDA lists the cadmium tolerance level as 0.21 to 0.36 micrograms of cadmium per day per approximately 2 pounds of body weight – or about 25 micrograms for a 154-pound person.

No safe level of lead exposure exists, but the FDA’s acceptable daily intake of lead in food is 2.2 micrograms for children and approximately 8.8 micrograms for adults.

California has even stricter recommendations for safe levels: no more than 0.5 mcg of lead per day and no more than 4.1 mcg of cadmium.

Chocolate can be exposed to heavy metals through cocoa powder, which is used to give bars their velvety chocolate flavor.

Lead can become mixed with cocoa when the beans are left to dry on the side of the road and then become covered in car fumes.

Cadmium may be in the beans when they are picked because the cacao tree may have extracted it from the ground.

A Tony Chocolonely product scored 37 out of 100

Separate research published in July by George Washington University analyzed 72 commercial cocoa products over eight years and tested them for heavy metals such as lead, cadmium and arsenic.

Researchers found that all products contained traces of toxic metals, and nearly half contained up to 20 percent more than the maximum allowable dose of lead.

More than a third exceeded the permitted amount of cadmium, which has been linked to cancer and kidney damage.

The researchers did not reveal which chocolates were tested.

And a 2023 study found that 16 of 48 chocolates tested – a third – contained high levels of lead or cadmium, and each had detectable levels of metals.

This included Hershey’s milk chocolate bars and hot chocolate mixes from Trader Joe’s, Starbucks and Ghirardelli.