Iodine (part 1)
Now that we’ve briefly covered the major health topics in a general sense, let’s dive into health at a deeper level. I’ll start with Iodine, as we previously touched on it in the article about the thyroid.
Iodine is a halogen, meaning it has seven electrons in its outermost shell. Because it only needs one more electron to achieve a full, stable octet of eight, it's highly reactive with its surroundings. This reactivity is not just a chemical curiosity—it’s vital for a developing brain. The brain literally depends on iodine and its readiness to react to initiate signal cascades, guiding where to grow new nerve cells, how to lay down the neural wiring, and how to myelinate (add a protective sheath) the electrical system to prevent short circuits and malfunctions.
While iodine is famously known for dictating thyroid function—and I wholeheartedly agree that maternal thyroid hormone T4 is absolutely crucial for fetal brain development—iodine also directly modulates the expression of Brain-Derived Neurotrophic Factor (BDNF). As its name suggests, this protein stimulates brain growth independent of thyroid influence, though you’ll certainly want a healthy thyroid if you’re growing or repairing neural networks.
The "T4" in thyroid hormone denotes four iodine atoms attached to two tyrosine molecules. This T4 is then converted in the brain by an enzyme called deiodinase 2 (DIO2). DIO2 cleaves one iodine atom from the original T4, leaving three atoms—hence the new, highly active molecule, T3. This molecule, with its essential iodine entourage, again dictates how the brain is to grow.
If you’re still not convinced of iodine’s importance for overall brain health, not just thyroid health, consider this: Iodine has also been shown to regulate the expression of neurotransmitters within the monoamine group. This means iodine influences the expression of Dopamine, Serotonin, Histamine (yes, histamine is in the brain too, primarily for maintaining wakefulness, which is why antihistamines can be sedating!), Adrenaline, and Noradrenaline. We'd need a separate article to cover each of these, but I think generally people have some basic understanding of them which are sufficient for the time being.
The fascination with iodine doesn’t stop there. I’m about to share information that could genuinely change how you view your health, which I doubt you’ll find easily elsewhere.
Iodine, besides the thyroid gland, is also found in high concentrations at the very back of your eyes. Behind our retina is a tissue called the Retinal Pigmented Epithelium (RPE), which is supplied by the choroid (vascular) plexus. Both of these structures contain high concentrations of iodine in humans and many animal models. Our Japanese counterparts, recognizing this fact, are even using iodine in the form of Lecithin-Bound Iodine (LBI) to treat retinal diseases.
What's relevant to all of you reading this is that as blue light enters your eyes, it triggers an oxidation process on the DHA in the retina. Iodine, acting as an electron donor due to its atomic structure discussed above, reverses this process (a chemical reaction called reduction, the opposite of oxidation). I can’t help but marvel at how perfectly this arrangement is engineered within our bodies.
However, the intensity of blue light dictates whether the oxidation will overwhelm the reduction provided by iodine. Think carefully about this: our species has never encountered blue light pollution at the levels we see (literally) today. A recipe for an iodine disaster is high-intensity blue light emitted from a short distance away from our eyes without enough counterbalancing colours.
As if that weren't enough, our tendency to not blink while looking at screens dries the eyes, stripping them of their final protection from external sources of oxidation. The next domino effect is on the hippocampus, the region of the brain where learning happens. Iodine deficiency reduces the production of hippocampal neurotransmitters. Isn’t it deeply ironic that we put our kids on iPads to learn?