Lead and Cadmium in Dark Chocolate: What UK Shoppers Should Know

What it claims

In late 2022, Consumer Reports (CR), the US consumer testing group, published lab results showing lead and cadmium in every one of 28 dark chocolate bars it tested. Headlines quickly turned this into "dark chocolate is dangerous". On social media the claim often goes further, suggesting you should give up dark chocolate entirely or only eat a handful of "clean" brands.

What the evidence shows

What did Consumer Reports find?

CR tested 28 bars bought in the US and compared them with California's maximum allowable dose levels, which are among the strictest in the world. For 23 bars, eating one ounce (about 28g) a day would put an adult over the level for at least one metal. Five bars were high in both, including Green & Black's Organic 70%. Five were relatively low in both: Mast 80%, Taza 70%, Valrhona Abinao 85% and two Ghirardelli bars (CR).

A 2023 follow-up tested 48 more chocolate products. Sixteen had potentially harmful levels, some cocoa powders were high, and no milk chocolate was. Divine 70% was named one of the lower choices (WebMD summary).

Where do the metals come from?

Cadmium is in the soil and is taken up by the cocoa tree, so levels depend on where it is grown; some Latin American regions are higher. Lead mostly lands on beans as dust while they dry in the open after harvest (review). Both metals sit mainly in the cocoa solids, which is why darker chocolate tends to carry more.

What are the UK limits?

GB law, shown on legislation.gov.uk, sets cadmium maximums of 0.80 mg per kg for chocolate with 50% or more cocoa solids, 0.30 mg per kg for chocolate under 50%, 0.10 mg per kg for milk chocolate under 30% cocoa and 0.60 mg per kg for cocoa powder sold to consumers. There is no specific lead limit for chocolate. These legal limits are much higher than California's daily-intake levels, so a bar can be legal in the UK and still "fail" CR's test.

How much is reasonable?

No UK body has set a daily chocolate figure. Lead has no known level without some risk, especially for children's developing brains, and cadmium builds up in the kidneys over years. The practical answer is to treat dark chocolate as a treat: a few squares a few times a week, varying brands, rather than a large daily "health" dose.

Who might reasonably try it

• Adults who enjoy dark chocolate in moderate amounts. The flavanols (plant compounds) are linked to better blood vessel function, so there are reasons to keep it.
• People who already eat a varied diet without other large sources of lead or cadmium.

Who should be careful

• Young children, who absorb lead more readily.
• Pregnant or breastfeeding women.
• Heavy daily eaters of 85% plus bars or cocoa powder, including those adding raw cacao powder to smoothies.
• Smokers, who already have higher cadmium exposure.

If you want to try it: what to look for

• Brands with published independent testing, or ones that tested lower in CR's work.
• Lower cocoa percentages if you eat chocolate most days.
• West African cocoa (such as Ghana or Ivory Coast), which tends to be lower in cadmium than some Latin American origins, though this is a general pattern, not a rule.
• Smaller portions and variety, so no single bar dominates your intake.

Is dark chocolate still good for you?

Cocoa flavanols (plant compounds found mainly in the cocoa solids) are linked to better blood vessel function and slightly lower blood pressure in trials, which is why dark chocolate has a health halo. But most of those trials used purified cocoa flavanol drinks or capsules, not chocolate bars, which also bring sugar, saturated fat and calories. The honest position is that dark chocolate can be part of a balanced diet as a treat, not a health food you should eat more of.

Cocoa powder, cacao nibs and "raw cacao"

Cocoa powder is almost pure cocoa solids, so per gram it can carry more cadmium than a bar, and GB law sets a 0.60 mg per kg limit for cocoa powder sold to consumers. Consumer Reports' 2023 testing flagged high levels in some cocoa powders. If you add heaped spoonfuls of cacao powder or nibs to smoothies or porridge every day, that habit may contribute more than an occasional square of chocolate. "Raw" cacao is not lower in metals; the label refers to processing temperature, not soil or dust.

Simple ways to lower exposure

• Rotate brands rather than eating the same bar every day.
• Smaller portions: two or three squares is a satisfying serving for most people.
• Mix in lower-cocoa options if you eat chocolate daily.
• Watch cocoa powder habits, especially for children.
• Eat a varied diet with enough iron, zinc and calcium, which can reduce how much cadmium and lead the body absorbs.

What about other heavy metals and foods?

Lead and cadmium also reach the diet through cereals, root vegetables, shellfish and, for smokers, tobacco. Chocolate is usually a smaller share of total intake than bread, potatoes and other staples, simply because we eat more of them. That is a reason for perspective, not for ignoring easy changes.

Our picks at a glance

How we chose

We started with bars that tested relatively low for lead and cadmium in Consumer Reports' published tests, then checked which are sold in the UK with a live price. We added one lower-cocoa option, because cocoa content is the strongest general predictor of metal levels. We did not include brands that tested high in both metals.

Divine 70% Dark Chocolate 90g

A Fairtrade bar from a brand co-owned by Ghanaian cocoa farmers, named as a lower choice in CR's 2023 testing. Caveat: CR tested the US version, the UK recipe or batch may differ, and Divine does not publish its own results.

Valrhona Abinao 85% Dark Chocolate Bar

One of only five bars relatively low in both metals in 2022, and one of the few from that group easy to buy in the UK. Caveat: a single 2022 sample, and levels can change with each harvest.

Montezuma's Darkside 51% Cocoa Milk Chocolate

An organic UK "dark milk" bar at 51% cocoa, so fewer cocoa solids per square than a 70% or 85% bar. Caveat: no published metal testing, more sugar, and fewer flavanols.

Bottom line

Dark chocolate does contain small amounts of lead and cadmium, and some bars contain much less than others. You do not need to give it up. Eat it as a treat, favour bars that tested lower, choose lower cocoa if you eat it daily, and be more careful with young children and in pregnancy.