Thyroid supplements have varying evidence. Some help with deficiencies; others can harm thyroid function (excessive iodine). Best supplements for thyroid requires careful consideration. Always discuss with endocrinologist or primary care.
Supplements with evidence
Selenium: Some evidence for autoimmune thyroid disease. 200 mcg daily. Don’t exceed 400 mcg.
Iodine: Adequate intake essential but excess harmful. Most US adults get adequate from iodized salt. Don’t supplement without testing.
Iron: If deficient. Iron needed for thyroid hormone synthesis.
Vitamin D: If deficient. Associated with autoimmune thyroid disease.
Zinc: If deficient.
The iodine warning
Excess iodine can cause thyroid problems:
- Hyperthyroidism (Jod-Basedow)
- Hypothyroidism (paradoxical effect)
- Worsening of autoimmune thyroid disease
Don’t take high-dose iodine (kelp, “thyroid support” blends with iodine) without testing. Most US adults are iodine-sufficient.
Don’t replace prescription thyroid hormone
For diagnosed hypothyroidism, prescription levothyroxine (or T3-containing therapy) is essential. Supplements don’t replace.
Frequently Asked Questions
Should I take selenium for Hashimoto’s?
Some evidence for antibody reduction. Discuss with endocrinologist.
Is iodine supplementation safe?
Only if deficient. Excess can cause problems.
What about “thyroid support” blends?
Often contain iodine. Check with provider before starting.
Can supplements replace levothyroxine?
No. Don’t stop prescription thyroid medication.
Will supplements affect my thyroid lab tests?
Biotin can interfere with TSH and other thyroid tests. Stop biotin 2+ days before testing.
The bottom line on thyroid supplements
Address documented deficiencies. Selenium for autoimmune thyroid disease. Don’t take iodine without testing. Don’t replace prescription thyroid hormone.