Iodine is crucial for healthy thyroid function. In the thyroid gland, iodine combines with the amino acid tyrosine to form the thyroid hormones T4 (thyroxine) and T3 (triiodothyronine); a mouthful for sure. T3 is the active form and basically does it all.
T3 is the one that regulates physical growth and development in both fetuses and infants, promotes intellectual/brain development. T3 regulates metabolic rate, body temperature, protein metabolism, heart rate, and lung function. It’s also responsible for testosterone & estrogen production, immune function, neurotransmitter production and more (1).
Almost all of your body’s functions, in nearly every tissue rely on thyroid hormones. Their actions and influence are so wide ranging that you cannot live without them.
Iodine is a nutrient of concern during pregnancy & beyond because of its role in infant and child growth and brain development. Even a modest deficiency, long before goiter shows up, can result in a loss of 10-15 IQ points (2). This is why prenatal supplements have extra iodine and should not be overlooked.
How does iodine affect the brain?
Because iodine is crucial for a healthy and happy thyroid, and therefore T4 & T3 production & function, this precious mineral has a big role in good mental health. Iodine helps ensure that there’s enough T4 and T3 in the brain to help it activate key neurotransmitters such as dopamine, norepinepherine, serotonin, GABA, and acetylcholine.
Without out enough T4 & T3, people may experience insomnia, fatigue, depression, and difficulty concentrating and focusing.
DID YOU KNOW? A healthy thyroid gland will use about 80 mcg of iodine daily to make thyroid hormones
Iodine’s role in mood regulation
As hormones, T4 & T3 regulate gene expression. Think of genes as a light switch and hormones as your hand; you use you hand to turn on, or turn off the switch. Similarly, hormones turn on, or turn off genes.
Not consuming enough iodine can result in not having enough T4 & T3 to turn on the genes that regulate the very neurotransmitters that regulate your mood.
Thyroid hormones and neurotransmitters
Serotonin: studies have shown that low levels of T3 results in low levels of serotonin which can lead to decreased mood/happiness, depression, changes in social behaviour, and increased anxiety.
Dopamine: T3 also regulates the action of dopamine (which is converted into norepinepherine/epinepherine) which affects memory, feelings of pleasure & reward, focus & attention, and improved behaviour and cognition (4)
GABA: GABA is the ‘zen’ neurotransmitter. Think of it as your brain’s natural benzo. T3 is needed for optimal GABA production and therefore helps you respond to stress better. Low T3 via low iodine intake can result in impaired GABA production and increased anxiety (5).
Acetylcholine: not as well known as other neurotransmitters, acetylcholine is need for learning and forming new memories. Low iodine intake and low T4 & T3 can result in low acetylcholine levels in the brain affecting cognition, memory, recall and mood.
Norepinepherine: not as well known as other neurotransmitters, acetylcholine is need for learning and forming new memories. Low iodine intake and low T4 & T3 can result in low acetylcholine levels in the brain affecting cognition, memory, recall and mood.