You might have heard health experts recommend that people limit the amount of shellfish and other large fish, like tuna, that they consume because of high levels of mercury. Or perhaps you’ve used a thermometer that contains mercury to measure your body temperature, or heard of its use in other technologies like clocks and vaccines. Have you ever considered a mercury detox?
But what exactly is mercury, and why should you be concerned about it? Humans can be exposed to this element in many ways, and it can have a detrimental impact on our health. For this reason, it is important that we understand the effect mercury can have on our bodies, recognize the signs and symptoms of mercury poisoning, and take a proactive approach to create an environment within our own bodies wherein we can easily eliminate toxins to improve our health status.
What is Mercury?
Mercury is a naturally-occurring chemical element found in rock in the earth’s crust, that exists in three main forms: elemental (aka metallic) mercury, inorganic mercury compounds, and methylmercury and other organic compounds .
Elemental mercury is the purest form of mercury, meaning it hasn’t reacted with any other element. It is a shiny, silver-white metal, and is often used in thermometers, fluorescent light bulbs, and some electrical switches. When mercury is exposed to the air (such as when you drop a thermometer and it breaks), it can evaporate and become an invisible, odorless toxic vapor. When heated, it becomes a colorless, odorless gas .
Inorganic mercury occurs abundantly in the environment, and can naturally combine with chlorine, sulfur, and other elements to create inorganic salts. These salts can enter the air via dust from mining deposits of ores that contain mercury, as well as from emissions from coal-fired power plants, the burning of municipal and medical waste, and from factories that use mercury. It can also enter the water or soil from these sources as well.
The use of mercury salts in medicinal and other consumer products has been discontinued, but it is still widely used in skin-lightening soaps and cream, in photography, as a topical antiseptic and disinfectant, wood preservative, and fungicide .
Methylmercury is the organic form of mercury and is formed when microscopic organisms combine mercury with carbon. It is highly toxic to the human body and is the form that we are exposed to the most often. It can become attached to airborne particles, and then rain or snow can deposit these particles on land .
How Does Mercury Enter Our Bodies?
Because it occurs naturally in the environment, we are all exposed to low levels of mercury in the air, in our water, and in our food. Approximately ten to twenty nanograms of mercury per cubic meter have been measured in urban air, which is still hundreds of times lower than what is considered to be safe to breathe. Mercury levels in surface water have been measured at five parts per trillion, about one thousand times lower than safe drinking water levels .
Exposure to metallic mercury could occur through a broken thermostat, fluorescent light bulb, glass thermometer, or some blood pressure devices. Even just a few drops of mercury can raise its are concentration to levels that are dangerous to human health.
You could be exposed to toxic levels of mercury by breathing contaminated air around hazardous waste sites or power plants that burn mercury-containing fuels, such as coal, however, most outdoor air is unlikely to contain levels of mercury that would be harmful. Exposure from these sites is much more likely to occur through coming into contact with contaminated soil, drinking well water near those sites, or eating fish from contaminated water near those sites .
Mercury exposure can also occur through exposure to mercury-containing fungicides, outdated medicinal products, by breathing the air at a contaminated workplace, or if you have a diet high in fish, shellfish, and marine mammals that come from mercury-contaminated waters.
Not all forms of mercury easily enter the body. Methylmercury is the most readily-absorbed form and is absorbed through the gastrointestinal tract. It then enters the bloodstream and travels to other parts of the body. It is eliminated from your body through urine or feces over a number of months .
How Does Mercury Affect Our Bodies?
Both elemental and methylmercury are toxic to our bodies’ central and peripheral nervous systems. Mercury poisoning can also affect the digestive system and immune system, as well as the brain, lungs, and kidneys. In high enough concentrations it can be fatal .
Symptoms of mercury poisoning could include:
- Memory loss
- Neuromuscular problems
- Cognitive and motor dysfunction
- Kidney problems or kidney failure
In some cases, the damage that has been done to vital organs like the brain and the kidneys can be permanent .
Can Diet Aid in Heavy Metal Removal?
There are certain substances, some of which are present in food, that can bind to heavy metals like mercury and help to transport them out of the body. Some of these substances are called chelators, and the process that transports them out of the body is called chelation .
A heavy metal detox may be essential in preventing life-threatening complications for individuals who have heavy metal poisoning. In these cases, a doctor will use drugs like penicillamine or dimercaprol to help this process .
In more mild cases, for people with sub-clinical, low-level, chronic exposure to heavy metals, a heavy metal ‘detox’ may help a variety of health conditions. The safest way to do this is through diet, and there are certain foods that have been shown to be effective at removing heavy metals from the body. These foods include:
- Dietary fiber (think fruits, grains, and bran) 
- Chlorella (a type of green algae)
- Sulfur-containing foods (garlic, broccoli, etc.)
- Cilantro  (this may help, however there is limited evidence to support this)
There are also some supplements that may help the body eliminate heavy metals, including glutathione, modified fruit pectin, sulfur-containing amino acids such as taurine and methionine, and alpha-lipoic acid, and selenium. You should consult with your doctor before beginning any kind of supplementation program . Selenium is particularly interesting, and its not just something that can be supplemented, in fact, it’s encouraged to get this micromineral through your diet.
Why Selenium Can Support Mercury Removal
Selenium is a trace element that is essential in our bodies in small amounts. It has many biological functions, primarily in the form of the amino acid selenocysteine . Selenium has been shown to bind with heavy metals like mercury to remove them from the body in the urine .
The recommended dietary intakes (RDIs) of selenium are as follows:
- 20 micrograms per day for children age one to three
- 30 micrograms per day for children age four to eight
- 40 micrograms per day for children age nine to thirteen
- 55 micrograms per day for anyone fourteen and older
- 60 micrograms per day for pregnant women
- 70 micrograms per day for women who are breastfeeding 
The top ten wholefood source of selenium are:
|1. Brazil nuts (when grown in selenium-rich soil)||1 oz (6 nuts)||543.5|
|2. Yellowfin tuna||3 oz||92|
|3. Pacific oysters (raw)||3 oz||65.4|
|4. Clams||3 oz||54.4|
|5. Halibut||3 oz||47.1|
|6. Shrimp||3 oz||42.1|
|7. Salmon||3 oz||39.8|
|8. Crab||3 oz||37.7|
|9. Prok||3 oz||32.5|
|10. Beef||3 oz||32.5|
Some of these foods may surprise you since you have already learned that many types of seafood carry higher levels of mercury. Many people limit the amount of fish they eat for fear of mercury levels, but experts are now saying that as long as your selenium levels are higher than the amount of mercury you’re consuming, you will be ok.
“There’s so much selenium in ocean fish that rather than falling behind in your selenium, you get enriched,” says Nicholas Ralston, Ph.D., a research scientist at the University of North Dakota’s Energy and Environment Research Center. “The more fish you eat, rather than being in more danger of mercury toxicity, you’re safer.” 
Basically, you should limit the amount of shark, whale, and large fish like tuna, that you are eating, but should attempt to consume other kinds of fish twice per week. However, not all tuna is the same as they vary in terms of levels of mercury, take a look at the chart below.
|Species||Mercury in ppm||Mercury (in mcg) per 3 ounces (85 grams)|
|Light tuna (canned)||0.126||10.71|
|Skipjack tuna (fresh or frozen)||0.144||12.24|
|Albacore tuna (canned)||0.350||29.75|
|Yellowfin tuna (fresh or frozen)||0.354||30.09|
|Albacore tuna (fresh or frozen)||0.358||30.43|
|Bigeye tuna (fresh or frozen)||0.689||58.57|
For a complete list of Mercury content in seafood, click here.
Selenium can also be taken in the form of a supplement. Selenomethionine is one form of the nutrient that is well tolerated and absorbed , however, you don’t typically need to go beyond 55 micrograms per day. Always consult with a healthcare practitioner before taking any supplement, because too much selenium in your diet can be toxic .
Plant-Based Sources of Selenium
If you’re looking to avoid the seafood and other animal products in our previous list. Other than Brazil nuts (which we already mentioned) try including more of these to get your selenium:
|Food||Selenium (mcg) per 100g serving|
|Sunflower seeds ||49*|
|Green or brown lentils, dried, boiled ||40|
|Cashew nuts, roasted and salted ||34|
|Pecan nuts ||12|
|Mushrooms, fried in corn oil ||12|
|Wholemeal bread, toasted ||11|
|Wholemeal spaghetti, boiled ||6*|
|Red kidney beans, canned ||6|
|Mung beans, boiled ||5|
|Brown rice, boiled||4|
Other Ways to Aid with Mercury Detoxification
You can also help rid your body of mercury and other toxic metals by making some simple lifestyle changes, including:
Eating more fiber. Since your body naturally eliminates heavy metals through feces, a diet higher in fiber can help move things more easily through your digestive tract, which results in more bowel movements.
Drinking more water. Your body also gets rid of heavy metals through the urine, so drinking more water will cause you to urinate more often and therefore eliminate heavy metals more rapidly.
Avoiding exposure. This is the best way to avoid mercury poisoning. Stay away from dangerous areas like coal-fired power plants, and avoid eating foods that have been grown in soil that has been contaminated with mercury. You should also limit the amount of large fish you eat, since they are more likely to contain higher levels of mercury .
Mercury poisoning can have serious negative health consequences and can lead to permanent organ damage and even death. In 2013, governments around the world agreed to the Minamata Convention on Mercury, which obliges government parties to take a range of actions that address mercury emissions in the air and phase out products that contain mercury .
Individuals can lower the health impacts of mercury exposure by taking precautions when handling mercury-containing objects, limiting their exposure to mercury-contaminated areas, and making dietary changes to support the elimination of heavy metals from the body.
If you are concerned that you may have been exposed to higher levels of mercury, or are considering taking supplements to help your body get rid of heavy metals, you should talk to your doctor before beginning any type of heavy metal detox or protocol.
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