Q&A: There is ‘little sense in freaking out about’ heavy metal levels in dark chocolate
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Key takeaways:
- Less than 50% of 72 cocoa-containing products exceeded daily limits for lead and cadmium.
- PCPs should emphasize the benefits of a balanced diet.
Heavy metal contamination in dark chocolate and cocoa may not pose a health risk when consumed as a single serving, according to a study published in Frontiers in Nutrition.
In the analysis, Jacob M. Hands, from George Washington University School of Medicine, and colleagues assessed lead, arsenic and cadmium levels in 72 consumer cocoa-containing products purchased from retailers between 2014 and 2022.
They evaluated heavy metal contamination using thresholds set to the California Proposition 65 maximum allowable dose levels (MADLs).
The researchers found that 43%, 35% and 0% of the products exceeded MADLs for heavy metal concentrations of lead, cadmium and arsenic, respectively, whereas 97.2% of products fell beneath the FDA’s interim reference level limit for lead.
Additionally, “median concentrations of each metal tested were lower than even the conservative Prop 65 MADLs,” they wrote.
Hands and colleagues explained that, although the results indicate that heavy metal contamination in these products may not pose a risk to most individuals when ate as a single serving, consuming more than one serving a day and in combination with other products containing heavy metals — like seafood — could add up to exposure that exceeds Prop 65 MADLs.
Hands spoke with Healio to discuss some of the key findings, their implications for primary care providers and more.
Healio: What led you to investigate metal levels in dark chocolate and cocoa?
Hands: We had seen contamination being reported in different journals. We’re all scientists and we’re very interested because we eat chocolate ourselves, so we wanted to [better] understand. The question was, in a multiyear sample, do we see meaningful levels of metal contamination, and do those levels pose any kind of threat?
Healio: Did anything in the results particularly stand out to you?
Hands: The major one was that certain samples grossly exceeded FDA parameters — for instance, in lead — but even in the case of cadmium, [there were] just outrageously exceedingly high values in some of the samples. If you look at the median levels, they’re biologically significant to some degree, but it doesn’t really matter. The fact that you have those abhorrent values and samples — maybe five or 10 of them, even more in some cases — exceed federal regulatory and/or state-local regulatory limits, that was a surprise.
I think there’s a real conversation about what is acceptable from a manufacturing [standpoint], like what should we as consumers demand in the context of food safety. For example, if out of 100 batches, one of them is going to give you a dose of lead that will raise your blood level to something that the FDA considers problematic, do you find that to be concerning? What this told me was that there’s something in the way of control that needs to be done.
To be clear, there is no evidence that the consumption of dark chocolate is at all problematic. Moreover, there is no evidence that [links] adverse effects to dark chocolate. Dark chocolate is a wonderful food for a variety of purposes and is a great sweet if you’re going to indulge. None of this research should bias you in the way of avoiding dark chocolate. It should impart some consciousness about the problem.
Healio: Are there specific products that people should limit their consumption of?
Hands: The part of the reason we’re not mentioning specific products is a bit of a dicey dynamic. If consumers are curious, there are a lot of websites and companies that report data on an individual product level. There’s no evidence that identifying a specific brand, with samples that vary from batch to batch, is a reliable enough metric. It seems to be a relatively industry-wide phenomena.
Healio: What should PCPs take away from the findings when discussing nutrition with patients?
Hands: I think the biggest thing is having a balanced diet. If all you ate was dark chocolate every day, perhaps that would be a bit excessive and present a theoretical risk with a majority of products. But the reality of the situation is that you should not be scared of eating dark chocolate, even if you see headlines that suggest otherwise. Having a moderate, one-to-three-ounce consumption is not something that you should [worry about having to] discuss with your patient. Even for patients who eat whole bars of chocolate, this is not an alarming situation.
Research on exposure to metals and their effects on the body is a developing field that needs to be further explored because there’s not a lot of good data out there, with the exception of lead. But if I told you that you have a specific blood level of cadmium or arsenic, as to what those tertiles mean, is a real tricky question and one that is not easily understood or gathered from a study like this.
The main takeaway is don’t worry so much about the metal in dark chocolate, but if you want to be a conscious consumer, you are more than welcome to demand more from producers and manufacturers. [For PCPs], don’t hassle your patients about dark chocolate consumption.
Healio: Do you have anything else to add?
Hands: I think it’s important to understand that because metal is everywhere — it’s basically in all foods in various capacities — there’s little sense in freaking out about it because it currently doesn’t deserve that type of reaction.
I think the bigger issue is having a varied diet and understand that when you consume whole foods, fruits and vegetables, those contain extraordinarily high levels of certain metals and yet vegetarians have a remarkably low incidence of metal poisoning. Perhaps the biggest takeaway from this study is the importance of overall balance for nutrition.