Can Zinc and Selenium Counteract Mercury's Effects on ADHD and Autism?

Mercury, an unwanted side-effect of the omega-3 rich fish oil treatment strategy for both ADHD and autistic spectrum disorders may be counteracted by Selenium and Zinc:

It's a catch-22 of the ADHD world. We've been told to feed ourselves and our kids as much of the omega-3 rich cold water fish as we can muster in order to balance their dietary fats and the subsequent hormonal effects. On the other hand, we're supposed to curb our fish product consumption for fear of mercury. Are there any other options beyond digging into our wallets for the pricey low-mercury wild organic salmon of the Pacific?

Why mercury is so toxic for the brain:

In general, (as one would probably expect) if a metal or compound can be cleared from the body easily, then the risk of toxicity is generally much lower. However, if the material cannot be easily cleared from the system, it can begin to build up in specific tissues or regions of the body.

Unfortunately, the brain is one of those target organs that has an almost magnetic pull for the heavy metal. While the digestive system can partially metabolize mercury into organic mercury-containing compounds, these compounds can make their way across the protective blood-brain barrier (a barrier meant to restrict the access of chemicals in the blood from passing into the brain, however, several harmful organic compounds can make their way across this barrier with relative ease).

In general, fatty acids penetrate the blood brain barrier relatively well, and these important fish fats and oils can make perfect delivery vehicles for some of these toxic compounds. In other words, mercury in fish and fish oil products can be exceptionally hard to isolate or remove from the brain.

Further complicating the matter is the problem of oxidation, especially in the brain tissue. While all organs and tissues of the body can suffer from oxidative damage (think of the biochemical equivalent of rusting or corrosion), the brain, due to its high fat content, is especially susceptible to this harmful oxidation. It is here in the brain that the mercury can become trapped and promote these dangerous oxidative processes.

Mercury and corn syrup: A hidden danger for the ADHD child?

The sugar/hyperactivity debate has been around for ages, although most of the recent evidence often refutes this commonly held assertion. Nevertheless, several nutritionists swear by their convictions about this association. So who is right?

This blogger personally believes that there is an association between sugar and ADHD-like symptoms, but this connection is likely due to secondary factors. Let me explain:

Consumption of high concentrations of sugary foods and beverages can be a metabolically taxing and stressful process on the body. The enzyme systems necessary to metabolize high quantities of sugars are dependent on an ample supply of vitamin and mineral "cofactors" (these will be discussed in more detail later on in this post), or agents that help the enzymes function propertly.

If overtaxed (as by consuming large quantities of soda or candy, for example), these vitamin and mineral cofactors can be rapidly depleted. Common cofactors such as iron, copper, zinc and selenium can be depleted in glucose (sugar) metabolism.

Interestingly, deficiencies in zinc and iron (especially when comorbid sleep disorders including restless legs syndrome are present alongside the ADHD) are common in the ADHD population. In fact, iron may be the underpinning biological factor in an alleged genetic link between ADHD and restless legs syndrome. We will be discussing the role of selenium in ADHD shortly.

Additionally, this depletion can have an effect on the antioxidant levels of the individual including a lowering of levels of pools of the important antioxidant reduced glutathione (we will be investigating the importance of glutathione later on in this post). There is some evidence of ADHD symptoms in adults being at least partially attributed to antioxidant imbalance.

In addition, the insulin rush, surge and fallout from consumption of a sugary meal can also wreak havoc on hormonal balances (including adrenaline, a chemical cousin to several neuro-chemical agents which are often seen to be off-kilter in most ADHD cases). We will save this discussion and go into more detail on the role of sugar consumption and hyperactivity and attentional deficits in later posts.

Returning to the main topic of our post (from our tangent here!), some forms of sugar may also have other hidden dangers with relevance to our post here on mercury and ADHD and related disorders. The processing and manufacturing of high fructose corn syrup (one of the most common and readily available sweetening agents in North America and much of the Westernized world), may actually leave detectable levels of mercury in the sweetener (which, the study also attributes to causing a zinc loss).

As a result, consumption of high levels of corn syrup at least has the potential to up our intake of mercury. If the mercury/autism/ADHD connection holds true, then this is one more (indirect) way in which sugary foods can increase the risk of inattention and hyperactivity associated with the disorder.


Can chelation therapy be used to effectively remove the mercury in our systems?

Our first thought might be to enlist the help of chemical agents which could pull the mercury or other toxic (and easily oxidizable metals) out of our systems.

A recent study has highlighted some possible alternatives on the mercury-fish-ADHD dilemma. One of the strategies involves the use of chelating materials. The word "chelate" comes from the Greek word "claw", and refers to an important chemical property in which a non-metallic compound can tightly bind to or "pick" up a specific type of metal and pull it away.

Ethylenediamenetetraacetic Acid or EDTA, is one of the most well-known chelating agents for removing metals and mineral deposits from hard water, and even has some reported health implications for removing crusty hardening from human arteries.

In theory, it sounds like this may be a good treatment option for removing toxic metals or oxidizing agents from the brains and digestive tracts of children with ADHD and related disorders (i.e. the autism-mercury controversy?).

On the flip side, chelation therapy can be dangerous, especially for children, due, in part, to the fact that the chelating agents are often non-specific for their target metals. This highlights a classic problem in medical research, the rift between theory and practice.

For example, some versions or derivatives of EDTA can "pick up" or remove significant amounts of the important mineral calcium (which, in addition to its role in skeletal function is an extremely important mineral in regulating heart rhythms, and optimizing nervous system function, among other things) along with the desired heavy metals lead and mercury. Cases of deaths due to this chelation therapy for autism have been reported, and recent clinical trials for chelation therapy for autism have been halted.

Enzyme systems: Nature's alternatives to organic chelating agents?

Fortunately, our bodies contain a number of powerful enzymes which not only can protect our brain and other important organs from oxidative damage, but actually help remove harmful or toxic materials from our systems.

However, in order for these enzymes to work at optimal levels, they must be constantly equipped with adequate levels of helpful nutrients or cofactors. Cofactors, often come in the form of our dietary vitamins and minerals, such as zinc, iron, magnesium, vitamin B6, vitamin B12, vitamin C, etc., and are required by numerous enzymes in order for the enzymes to work at peak efficiency. Not surprisingly, several of these cofactors have been discussed for their relevance to ADHD in earlier postings of this blog (see links on nutrients listed above)

This is why nutrient deficiencies can be so hazardous, because literally hundreds or even thousands of enzyme systems may be in jeopardy if our bodies are deficient in just a handful of nutrients.

Two of these important enzyme system and enzyme products are the metallothionein enzyme and the peptide glutathione (which is not an enzyme, but is synthesized via several enzymes and is sensitive to the balance between oxidant and antioxidant levels).

Metallothionein has been implicated in a number of studies concerning the enzyme's relationship to autism. One theory holds that children with autism have either lower levels of this enzyme or higher levels of antibodies to the enzyme (in which the body essentially attacks its own enzyme system as part of the idea of autism being an auto-immune disorder).

While a small amount or research out there supports these claims, it is important to note that these findings are far from universal. In fact, most of the recent body of literature refutes the claim outright. One study in particular negated both the observation that metallothionein was lower in autistic children or that higher levels of antibodies to the enzyme were present in autistic children. On the other hand, lower levels of the antioxidant glutathione are often seen in cases of autism.

(Blogger's note: the reason I'm going into so much detail about autism is because the high degree of symptomal overlap between ADHD and disorders of the autistic spectrum, as well as the high degree of overlap between nutrient deficiencies concerning the two disorders).

The role of selenium and zinc in the processes of the enzyme metallothionein and the antioxidant glutathione:

We have seen in previous cases how boosting levels of one metal in the body can offset the negative effects of another such as the case of iron combatting the harmful effects of lead in ADHD.

It appears that the metallothionein function in autism is intricately tied to copper-zinc ratios, and an excess of copper (or deficiency of zinc) can hinder this enzyme's effectiveness (the presence of heavy metals such as mercury are believed to be at least partially responsible for this skewed zinc-to-copper ratio). Interestingly, significantly higher copper to zinc ratios have also been seen in ADHD children in recent studies. In addition, the transport or delivery of zinc to its desired targets may be dependent on the antioxidant functions of glutathione and the mineral selenium.

While copper and zinc balances have been studied extensively with their relationship to ADHD (here's an earlier post on ten ways zinc can counteract ADHD symptoms, or how zinc can boost the effectiveness of ADHD medications), selenium may be a "sleeper" as far as important minerals for ADHD symptom treatment goes.

While selenium is unlikely to unseat "heavyweight" minerals such as zinc, iron and magnesium for ADHD treatment, selenium is an important mineral for maintaining proper antioxidant balances, either directly (as an antioxidant itself) or indirectly (via its incorporation into selenium-dependent enzymes). The latter is evidenced by a number of important enzymes such as the dependence of the important antioxidant enzyme glutathione peroxidase on selenium.

However, given selenium's wide range of potential benefits (selenium has been implicated as an anti-cancer agent in a number of studies), it appears that this often unheralded mineral may be a useful auxiliary agent in ADHD treatment.

To conclude this message, we must remember that nutrients often work best in combos, not in isolation. This (in this blogger's humble opinion), is why so many nutritional methods which attempt to combat ADHD often fail, in that they often fail to see this interconnection between nutrient interactions. They often instruct the individual to ramp up the dosage of only one or two nutrient which are believed to be deficient, and neglect to take into account the important roles of these supporting nutrient systems as a whole.

We have seen in other postings how omega-3 fatty acids often work well with antioxidants, as well as omega-3's and carnitine for treating ADHD via nutritional methods. Vitamin C can work in tandem with vitamin E as an antioxidant supplement duo, and recent evidence suggests that vitamin C and flax oil may also be a good combo for ADHD as well. Several studies have indicated that magnesium works well with Vitamin B6 (as well as other B vitamins) as an ADHD treatment method. Zinc may also work well with omega-3's as well as vitamin B6, and now, as we have seen, potentially with selenium, as an antidote to mercury's oxidative and toxic effects.

It is imperative that we recognize the importance of these nutrients both alone and in combination, including their potential abilities to counteract chemical agents which may either cause or exacerbate ADHD symptoms.