A new Cochrane review did not find clear evidence that taking zinc supplements can reduce the occurrence of middle ear infections, known as otitis media, in healthy children.

Researchers analyzed the results from 12 previous studies on healthy children under the age of 5 who took zinc supplements in low- or middle-income countries.

They found the results to show a slight decrease in risk of ear infections when kids were given zinc supplements.

"These studies should be viewed with caution. While there is some evidence that zinc supplementation is beneficial, further research using rigorous randomized trial designs would be worthwhile," said lead researcher Katherine Abba.

Zinc, found in many foods, is an important infection fighter, but individuals must consume it regularly for it to be effective. In developing countries where poor diets and diarrhea are common, over 60 percent of kids under 5 have zinc deficiency.

Some doctors say that ear infections are caused by poor Eustachian tube function in the ear, not by vitamin deficiencies.

"I doubt that any quantity of zinc would change Eustachian tube function in a clinically meaningful way. The positive effect in severely malnourished children likely relates to an impact on immune system function, not the Eustachian tube," said Long Island College Hospital’s Dr. Richard Rosenfeld.