Toxic Heavy Metals – A Trigger for Widespread Chronic Disease

There are many toxic metals (including lead, cadmium, arsenic, and mercury) that contribute to multiple health problems and persist almost indefinitely in the environment. For example, in polar ice in Greenland, lead levels have been identified that are linked to pollution from Greek and Roman civilizations two thousand years ago. In the United States, lead levels skyrocketed after tetraethyl lead was added to gasoline in the 1920s. According to a 1988 congressional report, sixty-eight million children had toxic exposures to lead from 1927 to 1987. In my practice, the frequency of elevated lead levels after a chelation challenge is almost 50 percent. Much of this contamination is from lead stored in bones, where it makes a home along with calcium. When bone breaks down as we age, the lead is released into the rest of the body, contributing to health effects on the immune system, heart, and brain. Lead is especially dangerous in children, where it is associated with reduction in IQ and learning deficits. 


Connections between toxic metals and chronic disease

All the toxic metals contribute to a more rapid aging of tissues, and increased risk for heart disease and cancer. A common mechanism for all these toxins is depletion of antioxidant protection as they create free-radical damage. Glutathione, the key cell-membrane antioxidant, as well as other antioxidants (including vitamin E and lipoic acid) are depleted by oxidative stress from toxic metals, leaving cells more vulnerable to membrane damage and chronic disease. 

Diseases such as autoimmune conditions, kidney disease, memory defects, muscle weakness, and thyroid disorders all can have a heavy metal trigger. Much of this damage is going unnoticed by most doctors, mainly because the focus of academic medicine has been on toxic effects of acute large exposures to metals (such as industrial accidents) and not on the subtle lifelong accumulation that most people experience. 

Recent studies have also shown a significant connection between toxic metals (especially lead and mercury) and Alzheimer’s disease and other forms of dementia. If there is an elevated body burden of these toxins, the brains’ response is to increase amyloid production to reduce the inflammation and damage these metals create – the consequence of more amyloid is dementia. This vicious cycle can be stopped by reducing the body burden through chelation and other means of clearing the toxins. 

In addition to these deleterious effects, it is now becoming clear that several of these metals can cause epigenetic alterations. The metals most studied regarding epigenetic effects are arsenic, cadmium, and mercury. Let’s look a little closer at these toxins:


Arsenic – Where is it found?

Organic and inorganic arsenic is found throughout the environment. Inorganic arsenic is combined with elements other than carbon, and is emitted into the air and deposited in water and soil from industrial sources (including smelting and mining), as well as from forest fires and volcanic eruptions. Arsenic is used in the semiconductor industry, strengthening alloys of copper and lead, as well as in pesticides. It is linked to cancers of the skin, bladder, prostate, liver, and lungs. 

The major source of exposure to arsenic is through drinking water from contaminated wells and from rice products from contaminated water. This is especially true in Asia. In a paper by Bagchi in 2007 it was estimated that more than 137 million people in seventy countries have been exposed to high levels of arsenic. Arsenic in food or water decreases uptake of iron, manganese, copper, and zinc. Arsenic in fish and shellfish is usually the nontoxic organic form, though it could interfere with essential minerals as well. 


Epigenetic effects of arsenic

Aggressive bladder cancers were seen in individuals with excess arsenic exposure in drinking water, which leads to abnormal methylation. It appears that depletion of S-adenosylmethionine and disruption of methylation from arsenic is the mechanism that creates arsenic-related cancers. In addition, Marsit and colleagues (2006) found a link between arsenic and bladder cancer, associated with repression of tumor suppressor genes. 

Arsenic has also been linked to increased risk of cardiovascular disease. In Taiwanese villages with high arsenic levels in drinking water, there was an increase in the incidence of heart disease with elevated arsenic levels of more than 200 percent. Like the other toxins, the cellular burden of arsenic depletes the body of the protective antioxidants, including glutathione. 

The good news is that folic acid supplementation lowers blood arsenic levels and can repair the depletion of the methyl donor SAM, limiting the damage that arsenic as well as other heavy metals inflict on the epigenome. It is possible to measure arsenic and other toxic metal levels through blood or urine testing to assess their tissue levels and body burden. If these levels are elevated, a course of chelation therapy can reduce an individual’s burden and protect their epigenome. In addition, antioxidant therapy with vitamin C, vitamin E, and alpha lipoic acid is needed. 


Cadmium – Common sources and effects of exposure

Cadmium exposure occurs from proximity to coal-burning power plants, the manufacturing of nickel-cadmium batteries, and other industrial processes. Air, water, and soil can be contaminated with cadmium, which is known to be carcinogenic in humans and animals. A primary source of cadmium exposure is through one’s diet, including fish, shellfish, and other foods. Painters can be exposed from red paint dye. Another major source is exposure to cigarette smoke, even secondhand smoke. 

Cadmium mimics the important nutrients zinc and calcium and concentrates in the liver and kidneys. Cadmium is linked to lung, prostate, pancreatic, kidney, liver, stomach, and bladder cancers. Cadmium exposure increases DNA methylation of tumor suppressor genes that were turned off, leading to the increased incidence of cancer. Cadmium has also been linked to an increased incidence of hypertension and heart disease. 


Mercury – Where does it come from?

A lot has been written about mercury toxicity and the dangers it poses, especially to pregnant women. The FDA has issued warnings to limit the intake of large predatory fish during pregnancy because of the elevated exposure to mercury from these fish and its effects on the fetus. Mercury is released into the atmosphere from coal-fired power plants and other industrial sources as elemental, particle-bound oxidized mercury. It is also released from gold mining operations, smelters, cement production, and waste disposal. Mercury vapor is released from dental amalgams and absorbed into the central nervous system. Though mercury-containing dental amalgam fillings are banned in many European countries, they are still in use in the United States. 

Mercury is found in the world’s oceans, where it is converted by bacteria to methyl mercury, a highly toxic compound. It then enters the food chain through fish and shellfish. Mercury levels concentrate higher up the food chain, moving from plankton to larger predatory fish. Shark, swordfish, king mackerel, albacore tuna, and tilefish have the highest levels of methyl mercury. The lowest levels of mercury are found in salmon, shrimp, catfish, and pollack. 


Epigenetic effects of mercury

On an epigenetic level, mercury, like other toxins, causes abnormal DNA methylation, leading to altered cell metabolism and increased oxidative stress. As many as 40 percent of my patients have demonstrated elevated urinary mercury levels after a chelation challenge with either DMSA or EDTA. The first step in reducing one’s mercury burden is avoiding fish with high mercury content. In addition, it is wise to remove amalgam filings containing mercury. (I refer my patients to a dentist skilled in amalgam removal who uses suction devices and other means to prevent reabsorption of the mercury vapors from drilling.) If needed, chelation therapy with DMSA or EDTA can be employed to enhance removal of this toxin. 

Mercury carries other risks as well, including increased oxidized cholesterol, increased platelet aggregation (clotting), hypertension, and endothelial dysfunction, leading to a greater incidence of heart disease. Some researchers even postulate that elevated mercury levels are as great a risk as cigarette smoking in regards to heart disease. In a study by Sørensen and colleagues (1999), elevated umbilical cord blood mercury of newborns was associated with increased blood pressure in children at age seven. Mercury also increases autoimmunity, including thyroiditis, and other conditions. 


Conclusions about mercury and other heavy metals

As is the case with other heavy metals, the human body has limited capacity to remove and excrete this toxin. In fact, the average human (150 pounds) has 13 milligrams of mercury in his or her body that disrupts antioxidant protection significantly. Mercury can reduce immune system function, increase vascular inflammation, increase cell death (apoptosis), disrupt mitochondrial membranes (leading to increased fatigue), and stimulate inflammatory hormone production in the vascular system. It is possible to protect against some of these toxic changes through the use of selenium as a supplement (selenomethionine 200 milligrams) and oral micronized glutathione (under the guidance of your physician). 

We are only now scratching the surface in understanding the impact these heavy metals have on the epigenome and human health in general. To protect the precious inheritance that is the genome, it is prudent for everyone to reduce exposure to these metals as much as possible, and to seek medical evaluation to assess and reduce the body burden of these toxicants. 

Please contact us at 858-457-1314 for more information about the toxicity treatments available at the Moss Center for Integrative Medicine.