Should You Be Concerned About Heavy Metals in Dark Chocolate?
You may have seen the most recent food-related headline making its rounds: lead and cadmium content in popular brands of dark chocolate. News organizations are reporting on Consumers Report’s new heavy metal analysis of 28 popular brands of dark chocolate, including Lindt, Ghirardelli, Hershey’s, Lily’s, Hu and more. Some recommendations for caution are being made, which can be confusing when contrasted against recommendations for consumption as per possible cognitive and cardiovascular benefits.
Before diving into this topic, I want to make clear: news articles should not be relied on as credible sources of nutrition information, as data and relevance are often misrepresented just to get clicks and ad revenue. Even the webpage for Consumers Report uses charged language like “…there’s a dark side to this “healthier” chocolate” in order to evoke an emotional response, get you to trust them and pay for their services. I’m not saying Consumer Reports isn’t credible… I’m saying anytime you read an article with buzzwords, take it with a grain of salt. I’ll help you make sense of the new information from Consumers Report and contextualize its relevance with other research. This way you can make a more informed choice about your dark chocolate consumption.
First let’s establish what heavy metals are. A “heavy metal” is one that is toxic or poisonous in small amounts. Lead and cadmium, which were tested in this report, are two examples of heavy metals. When someone is exposed to small amounts of heavy metals on a long-term basis, serious health conditions may occur. Think of lead poisoning from paint or from water pipes. So you can see why food would be a concern for route of exposure- you eat everyday!
Heavy metals can be introduced to food via multiple routes.
Cadmium can be introduced via natural occurrence in soil, rocks and water, and as a contaminant byproduct of combustion emissions, sewage sludge, landfills, metal processing + mining. Roots of plants draw up cadmium, and the edible portion of the plant (in this case, the cocoa beans) retains some. Lead may be introduced similarly, with the addition of potential exposure during handling and processing from open-air drying and worn machinery.
Consumer Reports divided each chocolate bar they analyzed into categories of lead and cadmium concentrations. Only 5 bars were included in a “safe” category. Their methodology was reported as follows: “To determine the risk posed by the chocolates in CR’s test, we used California's maximum allowable dose level (MADL) for lead (0.5 micrograms) and cadmium (4.1mcg). Shown are the percentages of the MADL supplied in an ounce of each chocolate. Our results indicate which products had comparatively higher levels and are not assessments of whether a product exceeds a legal standard. We used those levels because there are no federal limits for the amount of lead and cadmium most foods can contain, and CR’s scientists believe that California’s levels are the most protective available.”
Pictured here are the chocolates reported to have the highest levels of lead and cadmium. Upon first glance, the percentages and red bars may raise alarm. This is where you have to employ critical thinking skills and dig deeper… what exact information are they presenting, and how is this relevant to me?
Consumer Reports states that they use California's limits set by Proposition 65. These are widely regarded as extremely protective, and are typically more stringent than FDA limits. As such, it is also widely agreed that surpassing Prop 65 limits even by a modest amount is fine if also not surpassing FDA limits. So though Consumer Reports is saying in their analysis that heavy metals in some chocolates exceeded Prop 65 limits, none of them exceeded FDA limits.
The presence of heavy metals in a particular food is a valid concern, but is not in and of itself a reason to avoid a food. Ever heard the phrase “the dose makes the poison”? This is the point of the FDA setting acceptable limits of substances in food production. A certain amount must actually be ingested to cause harm, and this is not the case for the chocolates presented unless consumed in an outrageous quantity. Most of our foods have some amount of heavy metals for the simple fact that these are naturally occurring substances in our environment, and the more complicated fact that contamination is unfortunately a byproduct of modern life. If you tried to avoid every potential source of heavy metals in your diet… I’m not sure you could eat enough to live. You can find a reason to avoid literally any food, albeit the reason may not be logical. And this is the problem I’m seeing in headlines saying certain chocolates are unsafe and dangerous.
At this point you may be saying to yourself, “I understand none of them exceed FDA limits. But if I eat chocolate on a regular basis, how does this repeat exposure affect me?”. A key factor in thinking about being poisoned by heavy metals is bioavailability- or, how much of the metal we actually absorb. If you eat a piece of chocolate, you will not absorb 100% of the lead or cadmium in it. I was unable to locate any human data about the bioavailability of cadmium and lead from chocolate products, and so the next best thing was one in vitro study that showed low to moderate bioavailability. Who knows how this translates to a living being. Another factor to think about is how much chocolate is actually being consumed. My opinion is that for someone on an extreme end who eats at least an ounce of dark chocolate everyday, selecting one of the 5 chocolates that Consumer Reports classified as a “safer choice” is probably a good idea. But that’s not most people. If you are only an occasional eater or even are at a few times a week, I would not stress about this issue too much. You can feel safe in picking a dark chocolate that fits in your budget since they all fell within safe levels set by the FDA, which does consider lifetime exposure when setting its limits.
No matter how much chocolate you consume, you can reduce overall absorption and accumulation of heavy metals by having sufficient mineral status. The relationship between lead and dietary minerals iron, calcium and zinc is better understood than with cadmium. Zinc deficiency is rare in the United States and is largely seen in those with malabsorption disorders. Calcium and iron deficiencies are more common. If possible, a food-first approach should be taken with these foods rather than supplementation. Click through the following hyperlinks for lists of foods rich in calcium and iron.
In spite of concern generated by Consumer Reports, dark chocolate can be a safe and nutritious part of your food pattern. It is rich in minerals and flavonoids to support your health. The flavonoids in dark chocolate are even some of the most consistent in phytonutrient research to demonstrate positive relationships with cognitive and cardiovascular health. This may be attributable to improvements in blood cholesterol, blood pressure and other health markers. Benefits for blood pressure have been demonstrated with as little as an equivalent of 0.7-1.4 ounces of ~80% cacao dark chocolate per day over 18 weeks in subjects with untreated upper-range prehypertension or stage 1 hypertension.
What could a reasonable and safe recommendation for habitual consumption be? I would say up to around an ounce per day (which looks roughly like two 2x4 Lego bricks, I’m not one for precisely measuring your food if it’s not medically necessary). Pick your brand based off your frequency of consumption + budget…
So if you found yourself confused at the latest headlines about dark chocolate, I hope this post provided you more education and clarity. Dark chocolate is a nutritious food that may help support your health, and can even be part of the MIND Diet to reduce risk of dementia (read more here).
Are you hungry for chocolate now? Try my easy recipe for a healthy Chocolate Chia Pudding with Berries. It makes a great breakfast or snack!
