Nutrition: The Building Blocks

Your thyroid gland needs specific nutrients to function properly. Here’s what it requires on a foundational level:
• Iodine – for synthesizing thyroid hormones (T4 and T3)
• Selenium – for converting T4 (inactive) into T3 (active)
• Zinc and B Vitamins – for enzymatic function
• Protein – to transport thyroid hormones throughout the body
• Iron – for mitochondrial function and energy metabolism
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However - I want to go further than food in this article, because even a perfectly clean diet rich in these nutrients won’t fully support your thyroid if your **body doesn’t receive the right signals** to use them.

Let's discuss ⬇️⬇️

Here’s where sunlight comes in — particularly the light you get **in the morning**. Your thyroid is not just waiting for nutrients. It’s waiting for signals from your brain, and those signals are regulated by light.
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Here’s how light influences your thyroid:
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1. Activates the HPT Axis
• Morning blue light stimulates your brain’s master clock (the SCN), which signals the hypothalamus to start the HPT axis: Hypothalamus → Pituitary → Thyroid.
• This triggers the release of TRH (thyrotropin-releasing hormone) and TSH (thyroid-stimulating hormone).

2. This is also crucial for cortisol regulation (tells your brain to make the RIGHT amount of cortisol) - as too much cortisol can slow down thryoid.

3. Boosts Mitochondrial Function in the Thyroid
• The rich red & infrared light available in sunrise light support the activity of cytochrome c oxidase, a key enzyme for cellular energy and hormone synthesis in the thyroid.

Aim for at least 5-10 minutes of sunrise light (more is always better if you have the time) to kickstart this process & optimize hormones for the day!

Don't forget to add hydration & breakfast into your sunrise routine for optimal results.

Don't forget UVA light (right after sunrise)

1. Enhances T4 to T3 Conversion
• UVA light supports nitric oxide production, boosting blood flow to the liver, kidneys, and skin—key sites for T3 activation.
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2. Synchronizes Leptin and Circadian Rhythms
• Light exposure aligns leptin signaling with your circadian rhythm. Poor leptin signaling leads to thyroid downregulation, even on a perfect diet.

While morning sunrise light and UVA get most of the attention for circadian signaling, UVB light—which peaks around solar noon—is essential for Leptin & vitamin D synthesis, and vitamin D is a keyplayer in thyroid function.

1. UVB Light Makes Vitamin D in the Skin

• When UVB rays hit your skin (around 290–315 nm), they convert 7-dehydrocholesterol into vitamin D3 (cholecalciferol).

• This only happens when the sun is high enough in the sky—typically between 10 a.m. and 2 p.m., depending on your latitude and season.

Use MyCircadianApp to find out when UVB is available & use the vitamin D timer to gauge your time in the sun (click here to download & use code SarahK for a free trial).

2. Vitamin D Supports Thyroid Health

• It regulates immune function, helping to prevent or calm autoimmune thyroid conditions like Hashimoto’s.

• Low vitamin D levels are correlated with increased TSH and reduced T3, especially in people with thyroid autoimmunity.

• It improves sensitivity to thyroid hormone receptors, helping your cells respond better to the hormones you produce or supplement.

3. UVB = More Than Just D

• UVB exposure (like UVA) also activates nitric oxide, improves blood flow, and enhances mitochondrial activity.

• It’s a natural, free intervention that supports both immune regulation and hormonal signaling—essential for the thyroid.

Blue light, especially in the 450–470 nm wavelength range, can penetrate the thin skin of the neck and reach superficial tissues—including the thyroid gland, which sits just beneath the surface.

While blue light during the day plays a role in circadian regulation, chronic exposure at night—from phones, screens, and artificial lighting—disrupts melatonin production, alters leptin signaling, and interferes with thyroid hormone balance.

Since the thyroid is highly sensitive to circadian cues and oxidative stress, nighttime blue light exposure can contribute to mitochondrial dysfunction, hormone dysregulation, and slower metabolism, even without overt lab abnormalities.

Be sure to block artificial light at night & cover the thyroid gland around phones - TVS & artificial light if you already have thyroid issues.

And here's another reason why you want to protect your eyes on screens ⬇️

As I hope you understand by now - your thyroid is a circadian-regulated gland that relies on light signals—especially morning sunlight—to function properly.

In the eye, the melanopsin system uses vitamin A (retinal) to detect light and help synchronize the brain’s control over thyroid hormone release.

However - exposure to artificial blue light at the wrong time (and excessive unbalanced blue light during the day), uncouples vitamin A from melanopsin, releasing inflammatory retinoid byproducts that disrupt leptin signaling and mitochondrial function.

This confusion leads the brain to suppress thyroid activity, lowering T3 levels and slowing metabolism—even if nutrition is optimal.

In other words - if you are working to improve your thyroid health - blue blockers (even during the day - yellow) - are a very good idea if you are on screens a lot.

Lastly - Thyroid hormone release follows a circadian rhythm, tightly regulated by signals from the brain’s suprachiasmatic nucleus (SCN)—your master clock.

This rhythm means that light exposure in the morning is criticalfor reinforcing proper timing, while blue light at night can blunt the TSH peak, disrupt melatonin, and dysregulate the thyroid-circadian loop. Timing matters as much as lab numbers—especially for those with sluggish thyroid or unexplained fatigue.

This doesn't even touch on the fact that thyroid levels can shift and change with seasons - OR best practices for nutrition by season....which is what we cover here ⬇️⬇️

Want to learn more & dive deeper? Check out all the great content I am including in Quantum Nutrition 2.0 (including a deeper dive into the thyroid beyond this information) Click here to check