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Mercury is a common element on planet Earth, and it is concentrated in coal. As the planet burns coal to generate 40% of the world’s energy supply (over 4 billion tons per year), we release thousands of tons of mercury into the atmosphere and as a result, mercury levels are increasing worldwide in our planet’s oceans.

Unfortunately, mercury is a neurological toxin, meaning it is harmful to your brain and your nerves. High levels over time can cause brain injury and neuropathy (diffuse nerve disease).

As part of my comprehensive medical evaluation, I measure mercury levels in all my patients at the first visit. After over 1000 evaluations, I’ve discovered that about 30% of my patients have elevated mercury levels, and 5-10% have early signs of harm related to high mercury levels, so it’s feasible that this includes you.

Where does mercury come from, and who is at risk for mercury toxicity?

Algae (seaweed) absorbs mercury from the water in a form called methylmercury, which is toxic to human brains. As small fish and shrimp eat algae, they accumulate methylmercury in their tissues. As larger and larger fish eat bigger fish as they move up the food chain, methylmercury levels increase substantially. Typically, the larger the mouth of a fish, the higher fish eat on the food chain, and usually the higher their tissue level of mercury.

Shark, tilefish, bluefin tuna, and swordfish are at the top of the food chain and have very high mercury levels. Grouper, snapper, bass, and albacore tuna have moderate methylmercury levels. In contrast, fish that eat low on the food chain (wild salmon, trout, sole, cod, and shellfish) have low methylmercury levels.

People will detoxify and eliminate some of the mercury eaten, but the challenge is whether you consume more than your liver can eliminate. Everyone is different.  People with normal mercury elimination can eat seafood such as salmon or shrimp 2-3 times per week, plus consume grouper or snapper 3-4 times per month without accumulating mercury in their tissues, yet for a few people, grouper and snapper even 2-3 times per month may be too much.

Most laboratories set normal ranges for whole blood mercury levels and a level less than 11 µg/L (sometimes called parts per million, ppm) would be considered normal. Some of my clinic patients who consume tuna, grouper, or swordfish 1-2 time per week may have mercury levels that are 2-3 times the normal level, sometimes with levels are as high as 25-45 µg/L. This would put them at risk for permanent neurological injury.

Another source of mercury is dental fillings that contain amalgam. While substantial controversy exists regarding the toxicity and safety of dental amalgam fillings (I recommend avoiding them), amalgam fillings have been shown to release mercury into the bloodstream and can be measured in the blood and the urine. In contrast to big mouth fish intake, dental fillings likely don’t increase whole blood mercury levels more than 2-4 µg/L points.

What are signs of mercury toxicity?

As mercury is a neurological toxin, the first signs of neurotoxicity relate to these tissues. Mercury toxicity signs include:

  • Decreased brain function (published research from my clinic has shown significant decreases in brain information processing speed when mercury levels are >15 µg/L
  • Memory loss
  • Tinnitus (ringing in the ears)
  • Hearing loss
  • Paresthesias (tingling or burning in the feet or toes from neuropathy)

How to Measure Mercury Levels?

A whole blood sample is a good indicator of methylmercury levels. Red blood cells are formed in the bone marrow and live about 120 days. As mercury tends to accumulate in deep tissues, such as brain and bone marrow, sampling red blood cells for methylmercury levels provides an excellent means to assess continuous low-level mercury consumption and accumulation levels. A physician simply orders a laboratory test for mercury from whole blood or from red blood cells. Some medical providers prefer hair or toenail mercury levels, but I find these less reliable. Please make sure that your doctor does not accidentally order a serum mercury level (happens often) as a serum blood levels filters out the red blood cells, and it is not an appropriate measurement.

Testing mercury levels is not a routine part of usual health care. Yet, if you have either symptoms of memory loss, tinnitus, or paresthesias, or if you eat big mouth fish more than 3-4 times per month, asking your doctor to check your mercury level makes good sense.

Again, hopefully, you’ll find that you have a normal mercury level, which would be less than 11 µg/L.

How to Make Sure Mercury Isn’t Hurting Your Brain?

If you have symptoms of memory loss, tinnitus, or neuropathy, ask your doctor to measure your mercury with a whole blood mercury level).

If you eat big mouth fish more than 3 times per month, preferably eat less, or if that isn’t realistic, then check your mercury level, before you get in trouble. It is much easier to prevent problems than to treat them, especially those that are associated with your brain!

How to Treat High Mercury Levels and Mercury Toxicity? There are three primary ways to treat mercury toxicity:

If you have elevated mercury, especially if you also have neurological symptoms:

  • Stop ingesting so much mercury and eat less big mouth fish
  • If you have amalgam fillings, talk to your dentist about gradually removing them over time, and replacing with porcelain material
  • Increase your ability to detoxify and remove mercury. Foods and supplements help; see the link below.
  • You can also use oral chelation (chemically bind and remove it), but with chelation be cautious. INTRAVENOUS CHELATION CAN BE HARMFUL TO YOUR HEALTH IF NOT DONE PROPERLY!     

Be cautious regarding how chelation is performed and who offers your treatment.

For additional information on how to treat elevated mercury levels, please visit my Dr. Masley website resource section with details on Mercury Rx at: https://drmasley.com/mercury/

I wish you the best of health!

Steven Masley, MD, FAHA, FACN, FAAFP, CNS