Serum T4 Research Analysis

Summary of Serum T4

Scientific Information on Serum T4

The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what supplements affect serum t4

Grade	Level of Evidence [show legend]
	Robust research conducted with repeated double-blind clinical trials
	Multiple studies where at least two are double-blind and placebo controlled
	Single double-blind study or multiple cohort studies
	Uncontrolled or observational studies only

Outcome	Magnitude of effect ? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.	Consistency of research results ? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.	Notes
Iodine	Minor	Moderate See all 5 studies	Supplemental iodine above 500µg appears to be capable of suppressing T4 to a small degree whereas lower doses are not associated with such an effect.
Vitamin E	-	High See all 5 studies	Although one study noted a decrease with 600 IU, future studies in similar persons with multiple doses have failed to replicate these observations.
Zinc	Minor	Very High See 2 studies	The decline in T4 hormone levels during prolonged exercise is abolished with supplementation of zin
7-Keto DHEA
Tetradecyl Thioacetic Acid

All comparative evidence is now gathered in our A-to-Z Supplement Reference.

The evidence for each separate supplement is still freely available here.