Zinc Oxide
Also known as: ZnO, Zn oxide
The densest zinc source at about 80% elemental zinc, which is why it is the default in multivitamins and low-cost tablets where space is tight. Its trade-off is absorption: it is insoluble at neutral pH and a stable-isotope comparison found it absorbed less well than zinc citrate or gluconate, with very poor uptake in people with low stomach acid. It remains acceptable when taken with meals and when compactness outweighs bioavailability.
Research summary
Supplies zinc after dissolution in gastric acid; absorption is lower and more variable than for organic zinc salts.
Dosage
Daily amounts, elemental (80% of the compound is the element).
| Lowest studied | Typical range | Highest studied | Upper limit |
|---|---|---|---|
| 5 mg | 10–25 mg | 40 mg | 40 mg |
NIH ODS — UL of 40 mg/day for adults from all sources
Doses are elemental zinc. Take with food; absorption is poor on an empty stomach or with acid-suppressing medication. Because uptake is lower than from other salts, label amounts overstate delivered zinc. Zinc oxide (MW 81.4) is ≈ 80% Zn. Capped at the 40 mg UL.
Source material: synthetic (French process from zinc metal)
As supplied: ≈ 80% Zn; 15 mg elemental ≈ 19 mg compound
Forms of Zinc
| Form | Typical dose | Element % | Formats | Price |
|---|---|---|---|---|
| Zinc Oxide | 10–25 mg | 80% | Capsule, Powder, Tablet, Gummy | low |
| Zinc Gluconate | 10–25 mg | 14% | Capsule, Powder, Tablet, Gummy, Liquid | low |
| Zinc Picolinate | 10–25 mg | 21% | Capsule, Powder, Tablet, Gummy, Liquid | low |
| Zinc Bisglycinate | 10–25 mg | 25% | Capsule, Powder, Tablet, Gummy, Liquid | mid |
| Zinc Citrate | 10–25 mg | 31% | Capsule, Powder, Tablet, Gummy, Liquid | low |
| Zinc Monomethionine | 10–25 mg | 21% | Capsule, Powder, Tablet | mid |
Format suitability
- Capsule
- Powder
- Tablet
- Softgel
- Gummy
- Liquid
Extremely compact and tasteless, which makes it easy in tablets and gummies. Insoluble, so not suited to clear liquids.
Formulation notes
Iron of 25 mg or more in the same serving lowers zinc absorption. Reduces absorption of tetracycline and quinolone antibiotics.
- Has an upper limit
Sources
Related ingredients
Vitamin C (Ascorbic Acid)
VitaminAscorbic acid is the reference form of vitamin C and the most common form in supplements; NIH ODS notes its bioavailability equals that of vitamin C naturally present in food.
Typical: 250–1,000 mg
Zinc Gluconate
MineralThe most common zinc salt in multivitamins, lozenges, and immune products, containing about 14.3% elemental zinc.
Typical: 10–25 mg
Vitamin A (Retinyl Palmitate)
VitaminRetinyl palmitate is an ester of retinol and the most common preformed vitamin A used in supplements and multivitamins.
Typical: 750–1,050 mcg
Zinc Citrate
MineralA zinc salt of citric acid with a relatively high zinc content of about 31%, giving it a compactness advantage over gluconate and picolinate.
Typical: 10–25 mg
Vitamin C (Sodium Ascorbate)
VitaminSodium ascorbate is the sodium salt of ascorbic acid.
Typical: 250–1,000 mg