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Toxic metals are ubiquitous in urban and industrial environments. While metals are elements present in nature (e.g., soils), their accumulation in the environment is a direct result of industrialization, mining, environmental degradation, pesticide usage, urban runoff, and vehicle emissions. Some metals, including copper, zinc, and chromium are important for health, but excess exposure may increase health risks. Alternatively, toxic metals, such as cadmium (Cd), arsenic (As), mercury (Hg), and lead (Pb), are not associated with a biological role in the body and may disrupt normal physiological functioning.
Toxic metals have a high specific density (more than 5 g/cm3) and are unhealthy to living organisms and environments where they accumulate. Toxic exposures occur from agriculture, proximity to urban environments, cigarette smoking, consuming contaminated food or beverages, using certain cosmetics, and cooking with inappropriate cookware. However, toxicity depends on the dose, how someone is exposed, and how long they are exposed. Despite this point, toxic metals are associated with diseases affecting the cardiovascular, neurological, and renal systems. Chronic and acute exposures may also contribute to cancer, liver and kidney problems, diabetes, lower IQs, learning disabilities, and developmental delays. Understanding routes of exposure and how to minimize toxicity is paramount to avoiding harm to health.
Strategies to avoid toxic metals
The foods eaten, the water drunk, working and living situations, and the use of products can contribute to toxic metal exposure. Prevention of toxic metal exposure and accumulation begins in one’s living environment.
Cookware used to prepare foods may contribute to toxic metal exposure due to the colors and alloys used in processing, especially if produced before the 1970s. Steel, copper, and aluminum cookware have been shown to leach toxic metals during cooking. It is important to note that in addition to the cookware itself, the time of cooking and pH (i.e., acidic environment) causes more leaching.
The safest cookware materials include ceramic, glass, cast iron, and stainless steel. Although ceramic ware and glass are generally considered safer, they may also contribute to risks. Ceramic ware has been shown to solidify toxic metals and is less likely to contain Pb and Cd due to regulations limiting their usage in the production process. However, they may leach other metals in toxic amounts from glazes. A study examining 1,273 samples of ceramics and glassware in the EU found that while Pb and Cd leaching was present, it was not above tolerable limits. Glassware poses a risk depending on the enamels and decorations used.
Using cast iron and stainless steel cookware is generally considered safe, though, like ceramic and glass, it is important to be aware of certain risks. Cooking with a cast iron pan may leach iron into foods, which is a potential benefit if individuals are deficient in this essential nutrient. However, excess iron may cause several health issues. Like cast iron, stainless steel may leach metals into foods, primarily nickel and chromium. Longer cook times above 20 hours, cooking acidic foods, and new or unused pots contributed to the most leaching. The best course of action is to avoid older products with contaminated glazes, cooking with acidic foods, and cleaning with abrasive sponges that may cause the release of chemicals.
Because contaminated water and food grown in contaminated soils are contributors to toxic metal exposure, care must be taken to avoid these sources when possible. Toxic metals, such as arsenic, aren’t uncommon in groundwater, but they become problematic when inorganic sources (e.g., industrial uses, mining, agriculture) contaminate aquifers. Water purification methods have seen recent advancements that more effectively remove toxic metals from wastewater. Purified water that is free from toxic metals is recommended, though individuals should be mindful of excluding essential minerals. If using a water filtration system, use the Environmental Working Group’s guide to choose an appropriate one.
Soils are contaminated by toxic metals due to agriculture, mining, industry, and vehicle emissions. While contamination does not correlate with vegetable concentrations of metals, the diet is still a major pathway. Vegetables should not be grown in reclaimed fields near mining or industrial areas due to the potential risks.
Other sources of exposure (e.g., consumption of fish, cosmetic use, and smoking) can be avoided. If you regularly enjoy eating fish, consider smaller fish species, which are less likely to bioaccumulate toxic metals. Cosmetic and personal care products such as make-up, body powders, shaving cream, lipstick, blush, and lotion sometimes contain toxic metals and may affect health over time. It may not be possible to completely avoid products with undisclosed information, but choosing products with ingredient lists or safety disclosures may help inform purchases. Lastly, cigarette smoking and secondhand smoke inhalation may contribute to As and Cd exposure. Avoiding smoking is the best course of action to prevent exposure.
Strategies to prevent absorption
Not all sources of exposure can be avoided. As such, preventing toxic metals from being absorbed is a possible way to minimize risk. However, because many toxic metals and essential metals/minerals share similar sites of absorption, they may be taken up instead of the micronutrients needed by the body. What’s more, essential micronutrient deficiencies may increase toxic metal absorption. For example, iron deficiency is associated with enhanced Cd absorption. Similarly, a deficiency in calcium increases Pb absorption. Therefore, the prevention of absorption is imperative to avoid toxic metal uptake by the body.
In the case of essential metal/mineral deficiency, preventing absorption is possible by ensuring the sufficiency of nutrients. An example is the antagonistic relationship between iron and As. When iron status is sufficient, it outcompetes As at the site of absorption. Additionally, when calcium is supplemented, Pb absorption is reduced.
In addition to mineral sufficiency, binding agents, or chelators, may be used to prevent absorption. Chelation is the bonding of organic molecules and metals that occurs naturally in the body, supported by enzymes and a cofactor (e.g., essential metals/minerals). Sometimes, in cases of acute exposure to toxic metals, chelation is induced by supplying specific binding agents that bond to certain toxic metals, making it easier to excrete from the body.
Nutrients sourced from the diet may also act as chelators. Two popular algae supplements typically sold in health food stores, chlorella and fucus, are considered natural chelators and have been found to decrease Hg and Pb in patients undergoing dental treatments. Further, dietary sources of sulfur-containing foods (e.g., garlic and broccoli) are potential chelators due to the toxic metal affinity for these peptides. As an added benefit, sulfur-containing foods increase glutathione production, which is a potent chelator involved in natural biotransformation and excretion of toxic compounds. Cilantro is another possible chelator and has been shown to decrease Pb concentrations in rats.
Probiotics are becoming more widespread for their beneficial effect on the gut microbiota, and they are a potential tool to prevent damage in the gut as a result of toxic metals. They have been shown to decrease toxic metal absorption in the gut due to improved sequestration, detoxification, and structural integrity. Beyond the benefits in the body, probiotics may also support decontamination and bio-removal efforts in foods exposed to toxic metals.
Strategies for detoxification
Supporting glutathione levels
Some exposures are inevitable throughout one’s lifetime, but there are strategies to help rid the body of toxic metals. Supporting detoxification pathways and antioxidant systems in the body may be a first-line defense. One such way to support detoxification and antioxidants is by supporting glutathione levels. Glutathione is a tripeptide made up of the amino acids, glutamic acid, cysteine, and glycine. It is found in all tissues and is involved in detoxification, immune system health, oxidative stress management, cell death, and the aging processes.
Although glutathione is abundant in the body and is produced and recycled for its various roles, it is not an endless supply of support. Toxic overload and oxidative stress (e.g., from metal exposure), may strain production or deplete glutathione levels, especially if poor nutrition and stress levels are left unmanaged. To optimize glutathione levels, nutritional support for glutathione is imperative, as is stress management. Supportive nutrition includes sufficient sources of precursor amino acids, though cysteine (e.g., sulfur-rich foods) and glycine are considered rate-limiting. In the case of cysteine, N-acetylcysteine (NAC) is often recommended as a supplement and has been used in instances of metal toxicity. Consuming plentiful protein is also recommended to supply these amino acids. Modulating stress responses through meditation or supplementation (e.g., adaptogens) may help support glutathione stores.
Upregulating metallothioneins
Another strategy for ridding the body of toxic metals is through the upregulation of metallothioneins (MTs). MTs are cysteine-rich proteins with an affinity for binding metals. They act as defenses against oxidative stress and toxic metal toxicity, which also induce their expression. Zinc also increases MT production and may support toxic metal clearance. Research has shown that short-term oxidative stress caused by sleep apnea (i.e., hypoxia) may induce MTs, which suggests a hormetic and protective response to stressors.
Encouraging healthy methylation
Methylation is a biochemical process by which a methyl group is added to DNA, neurotransmitters, hormones, and immune cells. This process has roles in mitochondrial function, detoxification, DNA production and expression, fertility, immune cell function, and neurotransmitter production. While genetics influence methylation, toxic metals may also affect how well an individual methylates. If methylation is not happening properly, individuals may face several health challenges. Supporting methylation by supplying the body with nutrient cofactors and methyl donors for this process is an important step to ensure proper functioning. Nutrients that support methylation include methionine (meat, poultry, fish, eggs, nuts, seeds, spirulina, soybeans, and teff), vitamin B6 (meats, pistachios, garlic, whole grains, seeds, legumes, prunes), vitamin B12 (meats, organ meats, poultry, fish, shellfish, eggs), folate (legumes, liver meat, nuts, seeds, spinach, asparagus, mustard greens, avocado), magnesium (pumpkin seeds, sesame seeds, legumes, Brazil nuts, almonds, whole grains), and betaine (quinoa, beets, spinach, whole grains, sweet potatoes, meats, poultry). Lastly, a healthy gut microbiome is important for methylation. Therefore, it is recommended that fermented foods (yogurt, kimchi, sauerkraut, kefir), probiotics, and prebiotic-rich foods (leeks, onions, garlic, asparagus, bananas, Jerusalem artichokes) be consumed.
Sweating
Finally, sweating is an easy, safe, and effective way to excrete toxic metals. The novel blood, urine, and sweat (BUS) study showed that sweat is the preferential excretion pathway for toxic elements. While sauna sweating is effective, sweating during strenuous exercise may be more effective at eliminating toxic metals. One study found that dynamic exercise excreted more toxic metals than only sitting in a sauna. Nonetheless, sweating is an effective protocol for ridding the body of toxic metals.
Final word
The burden of toxic metals is difficult to avoid in modern society. The best strategy is to establish habits and routines centered around avoiding toxic metal exposures and supporting the body’s detoxification processes. As always, consult with your healthcare practitioner to ensure you are consuming appropriate foods, nutrients, and supplements for your specific situation. Toxic metal detoxification should be done under the supervision of a qualified healthcare practitioner.
