Methylation & Iron
- Jul 6
- 5 min read
Please refer to my last posts, Methylation 101 and Methylation: The Methionine and Folate Cycles, and Nutrients for Methylation for context. This is a copy of an email that went out to my mailing list.
If you've been supplementing iron for months with nothing to show for it, or your doctor has never once mentioned iron in the context of your thyroid symptoms (fatigue!!!), this one is for you.
Iron and methylation are connected in ways that don't get talked about enough, and once you see the connections, a lot of things start making sense.
Hepcidin (the reason iron supplementation sometimes doesn't work):
When methylation is slow, homocysteine builds up. As we've covered in this series, elevated homocysteine drives oxidative stress and inflammation.
That inflammation triggers the release of a hormone called hepcidin, which acts like a gatekeeper for iron in your body.
When hepcidin is high, it locks iron inside your cells (our bodies recycle old red blood cells for a large portion of the iron we need) and blocks absorption of iron from your gut. Iron stays trapped in storage instead of circulating where it's needed.
So, you can be supplementing iron consistently, even eating iron-rich foods, watching out for iron blocking foods, and still have low levels in circulation, because the gates are locked from the inside.
This is why addressing the inflammation driving hepcidin matters as much as the iron supplement itself. And homocysteine can be a key player in that inflammation.
Iron and your thyroid:
Iron sits in the active site of thyroid peroxidase, TPO, the enzyme responsible for the first two steps of thyroid hormone synthesis. When iron is low, TPO can't do its job efficiently. Research shows iron deficiency can reduce TPO activity by up to 56%. This can drive up TSH and you may end up on more medication, when your iron deficiency (which may be the reason for the issue) is never addressed.
T4-to-T3 conversion can also be affected through a separate mechanism that can tie into the methylation issues we discussed last time, with slow methylation driving inflammation from higher homocysteine as well as impairing liver function. With conversion issues, TSH may still look normal while T3 is low at the tissue level, which is exactly the scenario where someone feels hypothyroid but gets told their “labs are fine.” Then that hypothyroidism circles back to iron absorption via stomach acid.
The stomach acid loop:
I know I talk about this a lot, but it's so important to understand. Low stomach acid is one of the most common and underrecognized drivers of both iron deficiency and thyroid dysfunction. I covered this in detail in this blog post if you want the full picture.
The short version: low stomach acid impairs iron absorption, but low thyroid function reduces stomach acid, so the two problems feed each other in a loop.
Treating hypothyroidism alone may not be enough to break out of the loop, especially if conversion is impaired or thyroid treatment isn't fully optimized.
Addressing iron and stomach acid alongside thyroid treatment gives the whole system a better chance of actually recovering.
The gut connection:
Gut dysbiosis impairs iron absorption directly. Some bacterial strains and pathogens consume iron as a nutrient source, competing with your body for what you're taking in.
Leaky gut drives the chronic low-grade inflammation that raises hepcidin, which circles back to section one where I talked about homocysteine.
Plus, chronic stress can contribute to leaky gut, lowers stomach acid production, and depletes the very B vitamins that feed methylation…which is where this whole series started.
So, methylation, iron, gut, & thyroid. Four systems, but one interconnected picture.
No wonder so many women feel like they're chasing symptoms but never get a good answer as to why.
Where to start:
If iron has never been properly investigated as part of your thyroid picture, or you've been supplementing but not getting anywhere, the Iron Guide eBook is $9 and covers optimal lab ranges, why supplementation doesn't always work, eating for absorption, and root causes of deficiency. It's a great place to start.
Want to Go Deeper?
If you're curious about your own genetic SNPs, including MTHFR, fill out this form and I'll send you over some options for testing!
If you're not sure if gut health, thyroid, or histamine is an issue for you, and you've been chasing symptoms that don't have a clear explanation, it's worth digging a little. The quiz takes about two minutes and tells you where imbalances may be showing up in your symptoms. Take the quiz →
If you want to see your full iron levels, order the Iron Deep Dive Panel. It includes the order (no doctor visit required), and a customized interpretation by me.
If you just want more of this kind of content, I cover the symptoms most practitioners don't connect in my weekly newsletter. Join the newsletter →
Jennifer Scanlon, MS, FDN-P, holds a Master of Science in Holistic Nutrition and a Bachelor of Health in Cardiopulmonary and Diagnostic Sciences. Before starting her nutrition practice, she spent more than a decade as a respiratory therapist working alongside physicians and nurses as part of the critical care team. Her role included neonatal resuscitation, ventilator management, blood gas analysis, and the assessment of critically ill patients, providing a strong foundation in physiology and clinical reasoning.
After facing her own health challenges that weren't fully explained by conventional testing, Jennifer returned to graduate school, completing her master's capstone on Hashimoto's and the gut-thyroid connection. She has since pursued advanced training in functional health assessment and spent years studying thyroid disorders, gut health, iron deficiency, histamine intolerance, MCAS, and the complex interactions between body systems.
Today, Jennifer helps women uncover potential contributors to symptoms that often fall through the cracks of standard evaluations. Her approach combines nutrition, lifestyle factors, functional testing, and conventional lab data to identify patterns and connect the dots between thyroid, gut, histamine, and hormone issues, helping women make sense of symptoms that are often dismissed when standard lab work comes back "normal." Visit the website here.
Disclaimer: I do not diagnose, treat, prevent, or cure any disease or condition. Nothing I share with my clients is intended to substitute for the advice, treatment or diagnosis of a qualified licensed physician. I may not make any medical diagnoses or claim, nor substitute for your personal physician’s care. It is my role to partner with you to provide ongoing support and accountability in an opt-in model of self-care and any changes should be done under the supervision of a licensed physician.
Comments