Chronic exposure to heavy metals is an increasing public health issue, especially in areas with mining and/or industry. Toxic metals are difficult to excrete and tend to accumulate in the body, leading to numerous health problems.
Heavy metals affect almost every organ and body system, which can lead to wide-ranging health problems. Some areas are more vulnerable to certain metals. For example, arsenic affects the skin, lungs, brain, kidneys, liver, metabolic system, cardiovascular system, immune system, and endocrine system. Cadmium, on the other hand, impacts the bones, kidneys, liver, lungs, testes, brain, immune system, and cardiovascular system. Naturally, there is some cross over, with most heavy metals affecting the liver and brain.
Several health problems are associated with chronic and acute heavy metal exposure, including neurological problems, developmental delays, cancer, liver and kidney problems, learning disabilities, lower IQs, heart disease, diabetes, birth defects, and more. Some of the damage occurs due to oxidative stress. However, there are other factors involved, including the effects on mineral status, as will be seen.
Some of the most common toxic metals humans routinely come into contact with are lead, cadmium, chromium, and arsenic. Common sources of exposure include:
- Cigarette smoking (cadmium)
- Pollution from fossil fuel combustion and/or vehicular exhaust
- Paint and/or pipes in old buildings (lead)
- Drinking water (arsenic, lead)
- Fish (mercury)
- Plants grown in polluted soil
- Indoor dust in homes, schools, and work places
How Essential Minerals and Toxic Metals Interact
One reason heavy metals are so toxic is they interrupt the absorption, metabolism, and use of essential minerals, such as calcium, iron, and zinc. This leads to a deficiency of the minerals, which cause health issues. There are several ways metals and minerals interact with one another that impact your susceptibility to toxic metals and increase your risk of experiencing negative health effects.
One place metals and minerals interact is at the site of absorption. For metals and essential minerals to be absorbed, they must bind with transporters in the small intestines. Many toxic metals use the same binders or transferors as essential metals. This means toxic metals can be taken up in place of essential minerals, leading to a deficiency. However, it also might mean that if you consume a high enough amount of minerals, it can decrease the toxicity of the metals because the minerals beat out the metals for the binding site. For example, studies have found that those consuming a calcium-poor diet absorb more lead than those who have a calcium-rich diet. Other examples include:
- Iron deficiency leads to an increase in lead absorption and cadmium absorption.
- Iron and arsenic have an antagonistic relationship, meaning that iron competes with arsenic, so if you have sufficient iron, then it mitigates the toxicity of arsenic.
- Calcium deficiency increases the intestinal absorption and body retention of lead.
Altered Metabolism and Transport
Many minerals and metals also use the same transport mechanism and undergo similar metabolic functions. As a result, they are competing with one another, which could lead to health issues if the toxic metals take the place of the essential minerals. The following are a few examples:
- Cadmium interferes with the metabolism of copper, zinc, and iron. It also decreases transport of calcium in intestines.
- Zinc can help clear out heavy metals through increasing the synthesis of metallothionein (MT). However, toxic metals, especially cadmium, compete with copper and zinc for binding with MT. Cadmium can displace zinc because it has a higher affinity, which stimulates MT synthesis due to the levels of free zinc.
- Selenium protects against mercury toxicity through playing a role during the metabolism of mercury. Mercuric selenide, a compound produced from mercury and selenium, is also biologically inert and insoluble in living organisms.
- Heavy metals mimic the essential minerals and ultimately enter the cellular membrane using the same transport system. Once they have entered the cell, they have the ability to alter the nucleic structure and negatively affect DNA and RNA activity, potentially leading to changes on the genetic level that contribute to chronic disease.
Inverse Associations and Disease Risks
These interactions might lead to an increase in susceptibility to certain chronic illnesses beyond just toxicity from the metals. Some highlights of studies looking into the association of essential minerals, toxic metals, and chronic illness include:
- In a study looking into the lead exposure of children between 0 to 7 years old, the researchers found a negative relationship between lead levels in the blood and serum calcium and iron. Another study looking at children found an inverse association between selenium and iron levels and lead. The children with low iron status also had higher levels of cadmium, most likely due to easier absorption due to low iron.
- The essential metal deficiencies caused by heavy metals, especially zinc, might lead to hypertension. Zinc deficiency leads to inflamed, brittle, hard, and inflexible arteries, which leads to higher blood pressure. Selenium plays a role in the body's antioxidant defense system, and a deficiency also could lead to cardiovascular disease, mainly due to the role of ROS. In one study, researchers found higher levels of cadmium and mercury in the blood, urine, and scalp hair samples and lower levels of zinc and selenium than in the controls who did not have hypertension. The ratios of the essential elements and toxic metals were also lower in hypertension patients compared to controls.
- In hair samples of participants with metabolic syndrome, there were higher levels of arsenic and lead than the control and lower levels of calcium, magnesium, and zinc. The metabolic syndrome group also had higher levels of potassium and sodium in their hair, but there was no difference in cadmium, aluminum, and mercury. There was a significant negative correlation between calcium, copper, and magnesium levels and insulin resistance, but there was a positive correlation with sodium and potassium. Selenium was positively correlated with fasting blood glucose, while calcium and magnesium were negatively correlated. Mineral deficiencies have a correlation to insulin resistance and metabolic disorder, especially magnesium, zinc, and calcium, most likely due to their role in carbohydrate metabolism.
- Children with autism spectrum disorder have higher levels of toxic metals and lower levels of certain essential minerals. One study found that when analyzing hair samples for 11 heavy metals, children with ASD had significantly higher levels than the control group. In general, they also had higher levels of essential minerals, including zinc, iron, sodium, magnesium, potassium, and sulfur. However, they had lower levels of copper and calcium.
- An inverse association of essential minerals and toxic metals is associated with liver cancer and cirrhosis. In one study, supplementing with selenium and zinc provided some support to the liver in patients with liver disease. The levels of selenium and zinc in the blood increased while the levels of arsenic and cadmium decreased after 60 days of supplementation. Those patients had twice the levels of arsenic and cadmium compared to controls.
How to Protect Yourself from Toxic Metals
Although heavy metals might be difficult to excrete, it is possible to reduce your load and mitigate the negative effects. There are two main ways to do so: decrease your current toxic load and fortify your mineral stores.
Decrease Your Toxic Load
We live in a toxic environment, so it’s important to do what you can to decrease your toxic load. Doing so will not only help decrease any symptoms associated with toxicity itself, but will also help decrease any symptoms caused by a reduction in essential minerals due to heavy metals. Heavy metals are often some of the hardest toxins to get out of the body, making them that much more dangerous. However, it is possible to reduce your levels.
To begin with, look back at the common sources of these heavy metals, such as pollution, certain fish, and cigarette smoke. Find ways to decrease your exposure to these offenders. Then, incorporate actions that support your body's natural metal detoxification processes.
Here is a list of ways to start reducing your exposure and toxic load:
- Don't smoke and also avoid second-hand smoke.
- Check for lead sources in your house. The biggest sources are paint and water, especially in homes built prior to 1978. If you feel you are at risk, you can have a certified risk assessor and inspector come to your home. There are also home test kits, three of which are EPA-approved, that assess your home's paint for lead. Contact your local water supplier for information on your risk of lead in your water. They might also perform a test for you or provide information on how to do it.
- Use a water filtration system that removes heavy metals. There are many options out there. The Environmental Working Group provides a guide to help you find the right one for you.
- Use an air purifier, especially if you live in an area with high levels of pollution.
- Limit your fish intake, especially larger, farmed fish with higher amounts of mercury. The National Resources Defense Council offers an easy to use guide to help you choose the fish with the least amount of mercury.
- Follow a specialty heavy metal detoxification protocol that supports the body's natural chelation processes under the guidance of a medical or health professional.
- Consume turmeric and other spices to protect your liver. Some studies have pointed to the potential of this powerful spice to provide protection against the damages heavy metals cause.
- Eat a colorful diet to provide lots of phytochemicals, including antioxidants, to support your detoxification pathways and increase your antioxidant capacity.
Fortify Your Mineral Stores
It is not just about reducing your toxic exposure and load; you also want to make sure you fortify your mineral stores. If you have sufficient minerals for important actions in the body, you’ll have an additional way to naturally protect yourself from heavy metals, thanks to the competing actions discussed above.
To start with, choose a colorful array of foods rich in essential minerals. Here is a short list of foods in order from the highest level of minerals to the lowest to get you started:
- Calcium: sesame seeds, white beans, almonds, rhubarb, teff, mustard spinach, amaranth, mung beans, spinach, collard greens, kidney beans
- Zinc: oysters, beef, sesame seeds, turkey, pumpkin seeds, adzuki beans, wild rice, soy, pine nuts, cashew nuts, white beans, black beans
- Iron: beef, lamb, soy, white beans, sesame seeds, kidney beans, black turtle beans, teff, amaranth, lentils, mung beans, lima beans, cocoa, navy beans, pumpkin seeds
- Selenium: brazil nuts, pork, turkey, chicken, eggs, fish, sunflower seeds, wheat, barley, oysters, pinto beans, sesame seeds
As you can see, some foods are rich sources of more than one mineral, such as sesame seeds, pumpkin seeds, and oysters. These food sources make it easy to incorporate multiple minerals into your diet. Below are some additional actions to take to fortify your mineral stores:
- Diets low in zinc and iron can lead to cadmium toxicity at much lower levels of exposure than when you have adequate levels. Supplementing with essential minerals, especially zinc, can often reduce or even eliminate the symptoms of cadmium toxicity. Similarly, supplementing with essential minerals might help mitigate the effects of other heavy metals, including lead. Always discuss supplementing with your doctor, especially as high levels of certain minerals, such as iron, can be toxic.
- Ensure adequate vitamin D levels by checking with your health practitioner. Vitamin D improves the absorption of many essential minerals, including iron, magnesium, calcium, zinc, copper, and phosphate.
- Start early. Children are more vulnerable than adults to heavy metals, and exposure can have long-lasting impacts on their cognitive function and physical abilities due to a disruption in development. This is a good reason to ensure your children have sufficient levels of the essential minerals by providing them with a healthy, balanced diet. The placenta is a source of heavy metals, as is breastfeeding, so pregnant women and new mothers should put in additional effort to detox and fortify their mineral stores, under the guidance of their doctors. According to the Institute of Medicine, the tolerable upper intake level for zinc in adults is 40 mg/day. For iron, that number is 45 mg/day.
There are many health benefits to having sufficient minerals in your diet. In our toxic modern world, you also gain the added bonus of having a natural way to protect yourself against metal toxicity. As always, I recommend checking in with your healthcare practitioner to ensure you tailor your foods, nutrients, and supplements to your body.
Deanna Minich, PhD, is a functional nutritionist and mind-body medicine health expert and author of Whole Detox. See her website, www.deannaminich.com, and Facebook page, Deanna Minich, PhD, for more details.