Protect Your Thyroid and Your Brain

I’ve been sounding the alarm about the #1 most misdiagnosed disease for years. I’m talking about type 2 hypothyroidism – and how little conventional doctors know about this disorder.

But there is another misunderstood thyroid condition – which can cause physical changes to the structure of your brain.

Unfortunately, many traditional physicians completely miss the mark regarding hyperthyroidism. Unlike hypothyroid disease, which means your thyroid doesn’t produce enough thyroid hormone, hyperthyroidism means it produces too much.

So when you go to a doctor and complain of symptoms like depression, anxiety, difficulty concentrating, memory lapses, or unusual irritability, chances are you’ll be told it’s “just your age” – or you’ll be handed a prescription for an antidepressant.

And if the problems persist, they’ll tell you to see a psychiatrist.

Here at the Sears Institute, I take a broader view because the likelihood is that these issues have absolutely nothing to do with your age or your mood.

Instead, the real problem could be an overactive thyroid gland known as thyrotoxicosis or hyperthyroidism.

This is an autoimmune disease where antibodies from your immune system attack and overstimulate your thyroid.

Most doctors don’t realize that when this condition strikes, it can cause your brain to shrink.

That’s why it’s so often misdiagnosed as depression or even aging.

I’ve been seeing the mental effects of high levels of thyroid hormones for many years. Recent studies now prove the physiological connection.

Researchers at the University of Gothenburg, Sweden, studied MRI brain scans of 62 people with Graves’ disease – the most common form of hyperthyroidism. They were amazed to discover that high levels of thyroid hormones caused the amygdala and hippocampus parts of the brain to shrink.1

These two regions sit together in your brain. They control the formation of memories, the processing of emotions, and the emotional

connection you have with your memories.

So, it’s no surprise that brain shrinkage associated with high levels of thyroid hormones can cause depression-like symptoms.2

The good news is that the recent Swedish study also revealed that this brain shrinkage could be reversed by restoring your thyroid hormones to normal levels.

But hyperthyroidism affects more than the brain. Additional symptoms include:

  • Heart palpitations
  • High blood pressure
  • Increased appetite
  • Fatigue
  • Thinning hair
  • Sweating
  • Diarrhea
  • Insomnia

It can also lead to a swollen thyroid gland. This is a condition known as goiter.

Protect your thyroid and your brain

I recommend two solutions to my patients to protect and sustain thyroid function and help reverse hyperthyroidism.

          1. Reduce your iodine intake: Unlike hypothyroidism, which is related to an iodine deficiency, hyperthyroidism is worsened by an iodine overload. The mineral iodine plays a key role in making thyroid hormones. Therefore, a low-iodine diet helps to reduce thyroid hormones. That means eliminating iodized salt, processed sugar, grains, sea fish, and shellfish. I recommend adding these foods to your daily diet:

✓ Non-iodized salt
✓ Coffee or tea
✓ Egg whites
✓ Unsalted nuts and nut butters
✓ Raw honey
✓ Bamboo shoots
✓ Bok choy
✓ Broccoli
✓ Brussels sprouts
✓ Cauliflower
✓ Collard greens
✓ Kale

          2. Increase your iron level with food. Low levels of iron have been linked to both hyperthyroidism and hypothyroidism. So I recommend foods that are rich in iron to support thyroid function.
Your best source of iron is grass-fed organ meat like liver and kidney. Other good sources include shellfish, dark leafy vegetables like spinach, pumpkin seeds, and turkey. Eating foods high in vitamin C will help you absorb iron more efficiently. If symptoms persist, ask your doctor for a blood test to determine levels.

          3. Supplement with L-carnitine. L-carnitine is an amino acid derivative made in the brain, liver, and kidneys. It helps prevent thyroid hormones from entering certain cells. Studies show it can prevent and even reverse symptoms of hyperthyroidism, such as heart palpitations and fatigue.3 You can get L-carnitine by eating grass-fed organ meat and red meat. But I recommend supplementing as well. Take 2,000 mg every day on an empty stomach. Daily. Look for a formula with L-carnitine. D-carnitine is synthetic.

To Your Good Health,

Al Sears, MD

Al Sears, MD, CNS



1. Mats Holmberg, et al. “A longitudinal study of medial temporal lobe volumes in Graves’ disease.” J Clin Endocrinol Metab. 2022 Mar 24;107(4):1040-1052.
2. Bremner J, et al. “Hippocampal volume reduction in major depression.” Am J Psychiatry. 2000 Jan;157(1):115-8.
3. Benvenga S, et al. “Effects of carnitine on thyroid hormone action.” Ann N Y Acad Sci. 2004 Nov;1033:158-67.