Zinc

Which forms of zinc are used in supplements?

Zinc sulfate, acetate and gluconate are the most common forms. In young adults, zinc citrate and gluconate were absorbed similarly, at about 61%, and zinc oxide less well, at about 50%. 1

Cold trials mostly used zinc gluconate or acetate lozenges, while the AREDS eye formula used zinc oxide. A form that worked in one trial has not been shown to be better for other uses. 1 2

What to check on a zinc label

The Supplement Facts panel states the amount of elemental zinc, not the weight of the whole compound. That is the number to compare between products and to add up against the upper limit. 1

Zinc also appears in combination products and many multivitamins, so the total from all supplements matters. 1

Testing in Germany has found that many vitamin C and zinc combination products contain more zinc than the German risk assessment institute recommends, and about half used health claims that are not sufficiently backed by science. 3

Lozenges, nasal sprays and denture creams

In cold studies, zinc is usually given as a lozenge or syrup that coats the mouth and throat, placing it where cold viruses are active. Some nasal sprays and homeopathic products also contain zinc. 1

Some denture adhesive creams contain 17 to 34 mg zinc per gram. Normal use is not a concern, but heavy use over years has caused zinc toxicity. Many creams have been reformulated without zinc. 1

Food first, supplements when needed

NIH ODS advises that nutrient needs should be met mainly through food, including fortified foods, with supplements useful when that is not possible, such as during certain life stages. 1