The Claim

The conversion of thyroxine (T4) to triiodothyronine (T3) is dependent on selenium-containing enzymes DIO1 and DIO2, and genetic mutations in DIO1 or DIO2 reduce the efficiency of T3 production.

Source: Ep.15 - Thyroid Health Explained: Reclaiming Vitality with Elle Russ | Baby, Let's Talk! Podcast

What the research says

Supports is higher

Support is ahead, but a single strong opposing study can change this.

Supports
54score
Challenges
0score

These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.

How it works
3 studies reviewed
In plain English

The body converts the thyroid hormone T4 into its active form T3 using enzymes that require selenium. Changes in the genes that code for these enzymes result in lower T3 production.

See the scientific wording

The conversion of thyroxine (T4) to triiodothyronine (T3) requires selenium-dependent enzymes (DIO1 and DIO2), and genetic mutations in these enzymes can impair T3 production.

Why this might work

The body uses selenium to build special enzymes that convert the inactive thyroid hormone T4 into the active form T3. If the genes for these enzymes are mutated, the enzymes do not work properly, so less T3 is made. If there is too much selenium, the enzyme that converts T4 to T3 slows down, also reducing T3 levels.

Verified mechanismbased on 3 studies

What the research says

3 studies

  1. Study: Human Type 1 Iodothyronine Deiodinase (DIO1) Mutations Cause Abnormal Thyroid Hormone Metabolism

    Scientists found that some people have broken genes that make a special selenium-powered enzyme needed to turn the thyroid hormone T4 into its active form, T3. When this enzyme doesn’t work right, less T3 is made, which can cause thyroid problems.

  2. Study: Influence of high dietary selenium intake on the thyroid hormone level in human serum.

    The body needs selenium to turn one thyroid hormone (T4) into its active form (T3), and this study shows that when selenium levels change, the enzyme that does this job acts differently — proving selenium is important for the process.

  3. Study: The Human Type 2 Iodothyronine Deiodinase Is a Selenoprotein Highly Expressed in a Mesothelioma Cell Line*

    This study shows that the body uses a special enzyme, which needs selenium to work, to turn the thyroid hormone T4 into its active form T3. Without selenium, this enzyme doesn’t work well.

Score breakdown, mechanism chain, raw evidence, ideal studies needed & 3 supporting studies

Fit Body Science verdict — we translate health claims into clear verdicts backed by peer-reviewed research.

Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.