Published August 1 2016
Many people with thyroid and autoimmune thyroid conditions are familiar with the risks associated with mercury. As a result, many are choosing resin composite fillings (also known as white fillings), and some people get their mercury amalgams removed after learning about the potential health risks. But why is mercury harmful, and should those with mercury amalgams get them removed? And how can mercury affect thyroid health? I will answer these and other questions in this article.
Did you ever wonder why mercury amalgams were used in the first place to fill dental cavities? Well, they were introduced to North America in the 1830s, as it was cost effective, and the mercury amalgam was able to be placed in the area of decay, which allowed people to keep their teeth in case they weren’t able to afford gold restorations (1). So money was a big factor in mercury amalgams being introduced. These amalgams are comprised of 50% mercury, and also includes silver, copper, tin, and zinc (2).
There is no question that mercury is harmful to our health. And research shows that mercury vapor is released upon chewing foods such as grains, nuts, seeds, and gum (3) (4). There are different forms of mercury. Methylmercury is an organic form of mercury, and is commonly found in fish, and the research shows that these compounds are able to reach high levels in the central nervous system and cause neurotoxicity (5). Methylmercury in turn gets deposited throughout the body, and can also penetrate the blood brain barrier (5). However, once it undergoes demethylation to form inorganic mercury it can no longer penetrate the blood brain barrier, which means that the mercury will be trapped inside of the brain (5). There is also inorganic mercury, which is the mercury found in dental amalgams.
But how does mercury actually cause damage? First of all, glutathione helps to protect against mercury toxicity (6) (7). However, mercury can cause glutathione to be depleted (8) (9). Glutathione is a powerful antioxidant, and so depleting glutathione is one of the main ways in which mercury can result in an increase in oxidative stress and damage to the mitochondria.
Can Mercury Trigger Graves’ Disease or Hashimoto’s Thyroiditis?
There is evidence that mercury can cause immune dysregulation and be a possible autoimmune trigger. One study involving 1,352 females between the ages of 16-49 found that methylmercury, at low levels that were once considered to be safe, was associated with subclinical autoimmunity (10). The authors concluded that methylmercury exposure may be relevant to future autoimmune disease risk. A small study showed that mercury exposure was associated with increased level of numerous autoantibodies, and suggested that mercury exposure can cause the development of complex autoimmune dysfunction (11). However, the author of a review article mentioned how a recent study suggests that mercury exposure itself may not be sufficient for expression of autoimmunity in humans (12). Unfortunately he didn’t include the reference for this study, but it might be true that other factors must be present in order for mercury to trigger an autoimmune response, such as an increase in intestinal permeability (a leaky gut).
Is there any evidence which specifically shows that dental amalgams can result in thyroid autoimmunity? Well, I came across one study which showed that there is no relationship between having mercury amalgams and developing Hashimoto’s Thyroiditis (13). However, another study involving 39 patients with autoimmune thyroiditis showed that those with hypersensitivity to inorganic mercury who underwent amalgam replacement showed a significant decrease in both thyroid peroxidase (TPO) autoantibodies and thyroglobulin antibodies (14).
Another study showed an association between mercury and the presence of thyroglobulin autoantibodies, but not TPO autoantibodies (15). I think one needs to pay close attention to the second study, which shows that mercury amalgams can be a factor for those who have a sensitivity. In other words, having mercury amalgams alone won’t necessarily cause Hashimoto’s, even in those who have a genetic predisposition for this condition. On the other hand, for those who have a genetic predisposition and also have a mercury hypersensitivity, then this seems to increase the risk.
Whether or not someone has Hashimoto’s Thyroiditis, Graves’ Disease, or any other autoimmune condition, in some cases it might be a good idea to undergo testing to see how their immune system reacts to heavy metals. The MELISA test involves a simple blood test which can determine whether someone is allergic to metals. Cyrex Labs also has a test called the Chemical Immune Reactivity Screen that measures the immune response to mercury, as well as other environmental toxins. In fact, one can argue that testing one’s reactivity to mercury (or any other heavy metal) is more important than measuring the levels. And the reason for this is because someone with low levels of mercury who has an allergy or sensitivity will be impacted more than someone who has larger amounts of mercury in their tissues but doesn’t react to mercury on the MELISA or Cyrex Labs test.
Can Mercury Directly Affect Thyroid Health?
There is some evidence that mercury can have a direct effect on thyroid health. For example, there is evidence that mercury can cause a decrease in T3 and T4 (16). Another study showed that low mercury vapor exposure might affect the function of type I iodothyronine deiodinase (17), which is an enzyme that plays a role in the formation of thyroid hormone.
Should Everyone With Mercury Amalgams Get Them Removed?
Since mercury is an environmental toxin that can cause harm, it would make sense for those who have silver fillings to consider getting them removed. However, this isn’t always a simple solution, as there can be potential risks involved with removing mercury amalgams. This is especially true if you don’t get them removed by an expert, as getting them removed by a dentist who doesn’t take the proper precautions can cause problems, and can potentially exacerbate the autoimmune response. If you are thinking about getting your mercury amalgams removed I would recommend visiting the website for the International Academy of Oral Medicine & Toxicology (www.iaomt.org) and search for an accredited IAOMT dentist. And if you want to learn more about how to safely remove amalgam fillings you can click here for more information.
Can Eating Fish Cause A Mercury Toxicity?
There is controversy over whether fish is a significant source of mercury toxicity. Some healthcare professionals recommend for their patients to completely avoid fish, although in some cases this isn’t just due to the mercury, but other environmental toxins, including radiation contamination. On the other hand, other healthcare professionals tell their patients to freely eat fish. With regards to mercury, some claim that as long as the fish you consume has more selenium than mercury then there shouldn’t be a concern. These would include fish such as wild salmon, mackerel, and sardines.
I fall somewhere in between, as while I don’t tell my patients to completely eliminate fish from their diet, I do usually recommend for them to minimize their consumption of fish. In most cases I will advise them to eat no more than two or three servings per week, and to avoid eating fish higher in mercury such as swordfish and king mackerel. In addition to this I have most of my patients take a good quality omega-3 fatty acid.
Things You Can Do To Prevent Mercury Toxicity
1. Consider getting your mercury amalgams removed. While there is no question that it would be best not to have any mercury amalgams, just keep in mind that there are potential risks of getting these removed. I’ve had many patients who didn’t remove their silver fillings and were still able to get into remission. On the other hand, some people aren’t able to get into remission until they get their mercury amalgams removed. If you do decide to get your mercury amalgams removed please make sure you work with a dentist who practices safe amalgam removal.
2. Minimize your consumption of fish. As I mentioned earlier, this is controversial, and I advise my patients to limit their consumption of fish to two to three servings per week. And make sure you avoid eating fish that are very high in mercury such as swordfish, shark, and king mackerel.
3. Do things to increase glutathione levels. As I mentioned earlier, mercury can deplete glutathione. However, having healthy glutathione levels can increase the clearance of mercury from the body, as well as other toxins. Foods which can increase glutathione levels include broccoli, kale, and garlic. Selenium is an important cofactor for glutathione production. N-acetylcysteine and alpha lipoic acid are precursors to glutathione.
4. Use natural chelators to bind to mercury. I’m not a big fan of using chelating agents such as DMSA and DMPS, although I do recommend to use natural chelators such as cilantro to help bind to mercury. NAC is a chelator of mercury and other heavy metals (18) (19), and studies show that it doesn’t affect the minerals. Alpha lipoic acid also has metal-chelating activity (19). Chlorella also can help with the chelation of mercury. However, as I just mentioned, you also want to make sure you have healthy glutathione levels to help with the excretion of these heavy metals.
In summary, mercury is a harmful environmental toxin, and unfortunately many people still have mercury amalgams. Methylmercury is an organic form of mercury commonly found in fish, while inorganic mercury is commonly found in dental amalgams. There is evidence that mercury can cause immune system dysregulation, and can possibly trigger an autoimmune thyroid condition such as Graves’ Disease and Hashimoto’s Thyroiditis. There is also some evidence that mercury can have a direct effect on thyroid health. As for how to reduce mercury exposure, you can get your mercury amalgams removed, minimize your consumption of fish (especially larger fish), do things to increase glutathione levels, and use natural chelators to bind to mercury.
