Zinc supplements for preventing otitis media
Background Middle ear infections are common, especially among young children, usually causing earache and some temporary (occasionally permanent) hearing loss. Zinc is an essential micronutrient, which has a role in the optimal functioning of the immune system and resistance to infection. It must be consumed regularly as it cannot be stored in the body. Some people, especially children in low- and middle-income countries, may not have adequate zinc intake from food alone. Researchers have examined the potential role of zinc supplements in preventing infective illnesses. Therefore we wanted to discover whether zinc supplements have any role in preventing middle ear infections. Study characteristics The review authors searched the medical literature for studies up to March 2014. We searched for trials which compared middle ear infections in people randomly selected to receive zinc supplements or who did not receive supplements. We found 10 eligible studies, all conducted amongst young children. The total number of participants was 6820. Nine trials were conducted in low- and middle-income countries. Seven trials were conducted on healthy children. Participants included both males and females. Results The results of the trials provided no convincing evidence that zinc supplements reduce the occurrence of middle ear infections in healthy children. However, in one small study of severely malnourished children, those receiving zinc supplements had fewer middle ear infections. The only adverse effect was vomiting. Quality of evidence The trial evidence included is generally of good quality, with a low risk of bias. All the included trials included otitis media only as a secondary outcome. Therefore, there was a potential to miss trials which were less publicised or less well indexed within the electronic databases.