Your brain on heavy metal

29 August, 2013

It’s not easy to keep your eyes on every health story. These days they seem to be coming at us thick and fast it can be hard to maintain a broader focus.

But while stories of GMO health threats and a worsening obesity crisis seem to grab most of the headlines, a little acknowledged story caught my attention this week. It concerned the rising levels of mercury contamination in fish in the Pacific.

As if there was no discernible connection between air and water, scientists have been asking for years why toxins emitted in the air should end up in marine animals like tuna and swordfish.

Now we know. The researchers determined that up to 80% of the most toxic form of mercury – methylmercury – found in the tissues of our fish, is produced deep in the ocean, most likely by bacteria clinging to sinking bits of organic matter.

The study also confirmed that the mercury found in Pacific fish likely travelled through the air for thousands of miles before being deposited on the ocean surface in rainfall. So there we have it. The connection between air and water scientifically established.

The issue of heavy metal toxicity has dropped off many people’s radar lately, but that doesn’t mean it has gone away. Indeed as developing nations power up it is likely to get worse. And as the above study shows, pollution is no respecter of geographical boundaries.

What can we expect from our health as levels of toxic metals in our food, water and air rise?

Toxic metals are particularly harmful to the reproductive system. They can also interfere with the body’s detoxification pathways, including the colon, liver, kidneys and skin. Some are hormone disrupters. The immune system’s function is compromised by the presence of toxic metals, which can also weaken our energy-production pathways.

Another well-researched area which has had some publicity lately is the damage they can do to the brain. Toxic metals also interfere with uptake of essential nutrients such as magnesium, lithium, zinc, iron and several of the B vitamins. The resulting deficiencies have been linked to increased neurological damage.

Earlier this year a US study found that children with autism have higher levels of several toxic metals including lead, thallium, tungsten and tin in their blood. Moreover the researchers found that 38-47% of the variation in the severity of the disease was associated with the level of several toxic metals, with cadmium and mercury having the strongest influence.

Studies in adults link toxic metals to numerous health problems. The key appears to be the way that metal ions bind to amyloid fibrils in the brain causing them to accumulate and become ‘sticky instead of decomposing. These sticky deposits interfere with the brain’s structure and function in a way that appears toxic to neurons. Build-up of amyloid fibrils is linked to the development of neurodegenerative diseases such as Alzheimer’s, Parkinson’s and Creutzfeldt-Jakob.

In all, toxic metals in the brain are associated with emotional and behavioural problems, learning difficulties, including decreased concentration and organisational skills, speech, language and comprehension difficulties, and lowered intelligence, as well as higher rates of violence, dementia and depression.

This makes them a social problem as much as a medical one.

While toxic metals may not be the whole answer to the spectrum of neurological disorders that are on the rise in our society, they certainly appear to be an important piece of the puzzle.

Whatismore, we now have even trickier metal pieces to fit into that puzzle – silver nanoparticles (see right) that can lodge themselves in organs throughout the body, including the brain, and cause who knows what damage.

If you ask me, we should be paying much closer attention.

Pat Thomas, Editor