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ingestible · for thyroid support

Zinc

Reviewed by the Nimbera editorial team · Last updated May 2026

Baltaci AK et al. 2021 Progress in Nutrition (PMID 33409923) - analysis of 86 hypothyroid patients showed zinc supplementation significantly increased free T4 levels (p < 0.05) and improved the T3/T4 conversion ratio; zinc is a required cofactor for all iodothyronine deiodinase enzymes that activate thyroid hormones.$5-15/month

How to use

Take 15-30 mg of zinc daily as zinc bisglycinate, picolinate, or zinc carnosine for best absorption. Take with food to reduce nausea. Avoid taking simultaneously with iron supplements or high-calcium foods as these impair zinc absorption. A standard multivitamin typically contains 8-11 mg zinc, which may be adequate for most adults.

How it works

Zinc is a cofactor for the iodothyronine deiodinase enzymes that convert the prohormone T4 into the active T3 form. Zinc deficiency reduces deiodinase activity, lowering circulating T3. Zinc also supports thyroid hormone receptor function and binds to thyroid response elements on DNA to enable hormone signaling.

Where to buy

NOW Foods Zinc Glycinate ($10-15 for 120 caps), Thorne Zinc Picolinate ($15-20 for 60 caps), Pure Encapsulations Zinc ($15-25). Available at Amazon, iHerb, Vitacost, and health food stores.

Typical cost: $5-15/month

Safety notes

Do not exceed 40 mg/day (the tolerable upper limit) long-term - excess zinc depletes copper, causing anemia and neurological damage. If taking more than 25 mg/day for longer than 3 months, supplement with 1-2 mg copper. Zinc supplements on an empty stomach frequently cause nausea - always take with food. May interact with quinolone and tetracycline antibiotics; separate dosing by 2 hours.

Drug & supplement interactions

  • Always tell your doctor or pharmacist about any supplements you take.
  • Interactions can occur with prescription medications, blood thinners, and immunosuppressants.
  • Herbal remedies can affect how the body absorbs or metabolises drugs.
  • Check drugs.com interactions checker before starting.

Clinical source

Baltaci AK 2021 - Progress in Nutrition (PMID 33409923)

This information is compiled from primary clinical literature and is for informational purposes only. It is not a substitute for professional medical advice. Read our full disclaimer.