Iron supplementation has been found to be useful in multiple cases regarding ADHD. Numerous studies have indicated that a large percentage of individuals with ADHD are iron deficient. Iron is responsible, among other things, for the synthesis and regulation of levels of the key brain chemical dopamine. Dopamine deficiencies are often seen in multiple brain regions (especially in the area behind the forehead, called the prefrontal cortex) in individuals with ADHD. Additionally, iron is a key component of hemoglobin, which is responsible for carrying oxygen in the blood to other organs and tissues in the body. Not surprisingly, many ADHD individuals have lower than average oxygen levels delivered to their brains.
However, one of the unexpected benefits of iron, especially with regards to ADHD, is its potentially protective role in reducing the negative effects of early lead exposure. In a couple of correspondences in the August 2007 edition of the journal Environmental Health Perspectives, some key findings were summarized involving the protective role of iron to lead-induced damage. One of them (based on previous literature) reported on how lead can negatively impact levels of free dopamine (which is often correlated with ADHD, as many of the positive effects derived from most stimulant medications is due to their abilities to boost levels of dopamine in between neuron cells).
Additionally, lead is also thought to inhibit the interactions of dopamine and its targets as lead can alter the presence of these targets or dopamine receptors. Both of these reduce proper dopamine function, and it is thought that adequate levels iron can offset some of these negative effects (on the flip side, iron deficiencies are thought to exacerbate several of these negative occurrences). Finally, iron is also thought to restore a balance in the blood-brain barrier, which serves as a sort of controlled gateway, regulating the passage of nutrients and necessary neuro-signaling chemicals into (as well as keeping toxic substances out of) the brain. The role of iron is thought to restore and offset some of the negative and damaging effects of lead on the blood-brain barrier, which is especially sensitive to toxins during the early stages of life and childhood.
There is some dispute and controversy over some of these findings, however. Another study (which is frequently cited in numerous journals on toxins/heavy metals and ADHD or cognitive disorders) was done on the protective effects of iron and zinc on Mexican schoolchildren exposed to lead showed no statistically significant results as far as improving cognitive function.
In addition to the potential role of iron in protecting against lead damage, will be discussing how boosting iron intake can offset the effects of ADHD and other related comorbid disorders in future posts.