Zinc Plus Selenium by Dr. Mercola

If you’re looking for a zinc and selenium supplement to maintain healthy levels—not megadose—this fits. It’s a good match if your Zinc, Plasma or RBC Zinc is low, you eat a mostly plant-based or high‑phytate diet (grains and legumes bind zinc), or you’ve had bariatric surgery or chronic gut issues that reduce absorption. It also suits those with low Selenium, Serum or Plasma or borderline thyroid labs (TSH with low‑normal Free T3) who want steady selenium intake. This is maintenance-level zinc; if your level is clearly deficient, you’ll likely need a higher short-term plan with a clinician, then step down.

Zinc bisglycinate is a chelated form bound to the amino acid glycine, which tends to absorb well and be gentler on the stomach than oxide or sulfate. Zinc helps immune cells form and signal, and it’s required for hundreds of enzymes, including those that repair DNA. Selenium yeast provides mostly selenomethionine, the body’s preferred storage form, which feeds antioxidant enzymes like glutathione peroxidase (the system that neutralizes peroxides) and the deiodinases that convert thyroid hormone T4 to the active T3. Correcting low status can nudge hs-CRP (a systemic inflammation marker) down in some people, but this dose isn’t an acute cold treatment—zinc lozenges for colds use much higher, short-term dosing.

Take one capsule daily with a meal, as Dr. Mercola suggests. Food improves zinc tolerance and tames nausea. If you also take iron or calcium, separate them by at least 2 hours to avoid competition. Coffee or tea right with it can reduce mineral uptake, so take the capsule with water. Expect steadier lab changes within 4 to 12 weeks; recheck Zinc, Plasma or RBC Zinc and Selenium, Serum to confirm you’re in range.

Space zinc at least 2–4 hours from tetracycline or quinolone antibiotics; they bind minerals and won’t absorb well together. Separate from levothyroxine by 4 hours for the same reason. High-dose chronic zinc can lower copper, which is why a small amount of copper is included here. If your multivitamin already supplies selenium, avoid stacking multiple selenium products to prevent excess. Proton pump inhibitors and chronic diarrhea reduce zinc absorption, so verify with labs rather than guessing.

Is 15 mg of zinc enough? For maintenance, yes; for established deficiency, higher short-term dosing is typical under clinician guidance. Is 200 mcg of selenium safe daily? For most adults not taking other selenium, yes; don’t combine with additional selenium unless labs justify it. Thyroid benefits? Selenium supports the enzymes that activate thyroid hormone; confirm with TSH and Free T3/T4 rather than going by symptoms alone.