The presence of heavy metals in foods is a hot topic that involves contamination of the food chain and potential harm to public health. When you read about possible health consequences of heavy metals, it’s frightening! Heavy metal toxicity may result in fatigue, thyroid abnormalities, mitochondrial dysfunction, autoimmune conditions, and more. Over time, cadmium exposure may lead to digestive difficulties, kidney damage, cardiovascular disease, bone damage, and cancer. Beyond impaired brain development in children, lead toxicity can lead to cardiovascular disease and cancer. High levels of arsenic can also lead to cardiovascular disease and cancer as well as diabetes and impaired cognitive development in children.
And, depending on what you read, you may feel safe no matter what you consume or on the other side of the spectrum that if you touch a grain of rice or piece of dark chocolate, your heavy metal levels will skyrocket and your health will be doomed. Let’s be real, we all know that the honest truth is likely neither scenario above and more so to be found somewhere in the middle. There is no doubt that it’s wise to minimize exposure to toxins as much as possible. But in an environment where toxins are found in foods that also contain beneficial nutrients, we must always balance the benefits of those nutrients against the potential harms of the toxins.
Where does the heavy metal contamination stem from?
Soils – due to chemical fertilizers and pesticides
Water – due to runoff from natural causes and from industrial processes, waste product of coal burning and burning of municipal waste
Air – as a result of industrial activities
Natural elements in the Earth’s crust, these metals are found in air, water, and soil. Human activity increases their presence. The four metals of greatest concern in foods and where they are commonly found:
Mercury - fish
Lead – dark chocolate, meat, fruit, seafood, wine, tobacco smoke, bone broth
Cadmium – dark chocolate, flaxseed, mushrooms, peanuts, sunflower seeds, shellfish, freshwater fish, dried algae, tobacco smoke
Arsenic – rice, chicken
Foods Commonly Discussed as Heavy Metal Concerns:
Fish – An excellent source of anti-inflammatory omega-3 fatty acids, fish is rich in protein, vitamin B12, zinc, and more. But what about the mercury? Opt for smaller fish lower on the food chain and hence, lower in heavy metals. Think sardines, herring, anchovies (but beware of sodium), and mackerel. The fish with the highest levels of mercury are swordfish, shark, tilefish, and king mackerel; avoid those if possible. Other larger fish to limit include tuna, sea bass, halibut, orange roughy, grouper, and marlin. Farmed seafood tends to be particularly high in heavy metals, pesticides, toxins, and environmental contaminants. Choose wild-caught fish whenever possible. Beyond the small fish, other low-mercury options include sockeye salmon, trout, tilapia (but difficult to find wild), and sole.
Bone Broth – Great for gut healing, bone broth offers anti-inflammatory benefits and nourishes our skin due to its collagen content. But, while bones are replete with essential minerals and metals, they unfortunately can store toxic metals, like lead, too. One small study found bone broth was quite high in lead. A follow-up study, however, reported that lead was either not detectable or found at the lowest detectable amount the lab could identify, meaning very low or no lead detected in the various bone broths tested – Kettle & Fire, organic, grass-fed homemade bone broth, and conventional homemade bone broth. All in all, it appears that the benefits of bone broth outweigh the concern for heavy metals. Despite no difference in the study above, I would recommend opting for an organic bone broth made from pasture-raised chickens or grass-fed cows. Kettle & Fire is one commercial bone broth that has been shown to be a good lead-free option.
Cigarettes & E-cigarettes – Now I know my audience and this is a non-issue for nearly all of you, but I thought it still important to include as you influence many family and friends. Researchers have identified more than 7,000 chemicals, including 69 carcinogens, present in tobacco smoke.Cigarettes and e-cigarettes contain cadmium and other metals, such as lead and copper. Add insult to injury - refill fluids for e-cigarettes contain solvents such as propylene glycol and flavor chemicals, such as cinnamaldehyde, vanillin, benzaldehyde, and ethyl maltol, which are cytotoxic at the concentrations used in some products. Cadmium is commonly present in the soil where tobacco leaves grow, and tobacco plants then absorb cadmium through the soil and water. It has been reported that people who smoke have four to five times higher cadmium concentrations in their blood than people who don't smoke.
Rice – Very efficient at absorbing arsenic from pesticide-laden soil and irrigation water, there has been great concern about the levels of arsenic in rice. This includes rice pasta, rice cakes, rice-based beverages, rice crackers, rice sweeteners, and infant rice cereals too. Don’t fret, rice is not a cigarette, but let’s not be remiss. Brown rice has been shown to contain 80% more arsenicthan white rice; this can be attributed to the fact that arsenic concentrates in the outer layers of a grain. Now, what if you purchase organic rice vs conventionally grown rice? Organic rice will contain lower levels of pesticides, but the arsenic levels are, unfortunately, not minimized by opting for organic. This article is over 10 years old, but does include a chart of arsenic levels of various rice products.
To minimize the arsenic content, soak rice overnight. Drain the rice and rinse thoroughly. Then, cook five to six cups of water to one cup of rice and discard the water. Rinse the cooked rice one more time. It’s a process, but if you eat rice regularly, this may well be worth your time. Does the type of rice matter? Yes! Basmati, white sushi, and jasmine rice are lower in arsenic than other kinds of rice. Additionally, rice varieties grown in California or Imported from Southeast Asia are often lower in arsenic than rice grown in other parts of the U.S. Rice grown in Texas, Arkansas, or Louisiana have been found to contain the highest levels of arsenic. Other grains that are commonly known to contain arsenic include wheat, barley, and maize (corn). Alternatively, opt for a different grain or pseudo grain, such as quinoa, buckwheat, or millet, which are all much lower in arsenic.
Dark chocolate – Recent headlines highlighted levels of lead and cadmium in various dark chocolate products. But what about the antioxidants in dark chocolate – they promote heart health. Researchers used California’s maximum allowable dose levels for lead (0.5 micrograms, or mcg) and cadmium (4.1 mcg) to gauge the risk posed by dark chocolate. For 23 of the 28 chocolate bars they tested, eating just an ounce per day would put an adult over the maximum dose for at least one of the heavy metals. Five bars contained levels over the limit for both lead and cadmium – Theo, Trader Joe’s, Lily’s, and Green & Black. The metals in chocolate are primarily found in cocoa solids, hence, why dark chocolate is known to have higher levels of heavy metals compared with milk chocolate. Cadmium is typically in the cocoa beans when harvested as the cacao plants soak up cadmium that’s present in the soil. Organically-grown produce and grains will contain lower levels of cadmium. Additionally, if you are deficient in zinc, iron, or calcium, you are more susceptible to toxicity from cadmium exposure. Lead, however, appears to get into cacao after the beans are harvested. The longer the beans were left outside to dry in the sun, the lead levels increased due to lead-filled dust and dirt that could get stuck to the outside of the beans.
If you’re a daily consumer of chocolate, this news is concerning as well as if you’re pregnant or nursing or have a child who regularly consumes dark chocolate. If we follow the European safety standards, the amount of heavy metals in this study appears safe. For example, a 130 pound person should consume no more than 21 mcg of cadmium to avoid health risks, so consuming 7-8 mcg may not be problematic. If you keep digging, however, the US Agency for Toxic Substances and Disease Registry would set the limit at 6 mcg for a 130 pound person.
The chocolates that contained the lowest levels of metals in the Consumer Reports study were Mast, Taza, Ghiradelli, and Valrhona. I also confirmed with Pure Love Chocolate that their chocolate does not contain lead; it has not been tested for cadmium. If you eat dark chocolate regularly, it would be wise to consume those with the lowest heavy metal concentrations and limit to no more than 1 ounce daily. Pregnant, nursing, or a child; limit eating dark chocolate to 1-2x weekly.
Bottom Line
We will, unfortunately, find trace amounts of heavy metals in many different foods, so targeting only one food will not resolve the issue. That said, we should certainly be cautious – avoid foods that are particularly high in metals and opt for products with acceptable limits whenever possible.
Action Points:
Vary your diet
Drink filtered water
Purchase organic food when possible
Be sure to consume adequate levels of zinc, iron, and calcium in your foods
Hop in a sauna, if available