Episode 135: Understanding MTHFR & Methylation for Fertility & Chronic Illness with Dr. Sam Shay

Understanding MTHFR & Methylation for Fertility & Chronic Illness with Dr. Sam Shay

MTHFR is one of the most talked-about—and misunderstood—genes in the functional medicine world. But what does it actually mean to have an MTHFR mutation? How does methylation influence fertility, thyroid health, homocysteine levels, detox pathways, and chronic illness? And when is genetic testing truly helpful versus fear-driven?

In this episode, I’m joined by functional medicine expert Dr. Sam Shay to break down the science of methylation in a practical, clinically grounded way. We discuss how MTHFR variants impact folate metabolism, vitamin B12 utilization, homocysteine regulation, and oxidative stress—and why these pathways matter deeply for women navigating infertility, recurrent pregnancy loss, Hashimoto’s, PCOS, autoimmunity, and complex inflammatory conditions.

We also unpack common myths about MTHFR, including when high-dose methylated supplements may backfire.

If you’ve ever been told you have an MTHFR mutation and felt confused about what to do next—or if you’re struggling with unexplained fertility challenges, thyroid antibodies, chronic fatigue, or inflammatory symptoms despite “normal labs”—this episode will help you understand the bigger biochemical picture and how to approach methylation support in a personalized, root-cause way.

This conversation is especially important for active women who are trying to conceive, managing autoimmune thyroid disease, or navigating chronic illness through a functional medicine lens.

 

A few things we chat about in this episode 👇👇👇

• What MTHFR actually does, and why it is often misunderstood
• How methylation works, and why inflammation drives the process
• Why slow methylation may have been protective evolutionarily, but problematic today
• How methylation affects estrogen detoxification and hormone balance
• What homocysteine reveals about methylation efficiency and cardiovascular risk
• The three pathways the body uses to clear homocysteine
• Which genetic variants matter most for fertility, autoimmunity, and chronic illness
• How vitamin D receptor genes influence immune regulation and inflammation

 

Important show links 👇👇👇

• Learn more about Dr. Sam Shay at www.DrSamShay.com
• Apply to work with us 1:1 for fertility support
• Follow me on Instagram
• Rate the show! Please give us a 5 star rating in your podcast app