As we head into cold and flu season, Australian researchers have found that zinc supplements appear to shorten respiratory tract infections. In a study published last week in the journal BMJ Open, the researchers reviewed over two dozen clinical trials with more than 5,400 adults. Zinc lozenges or nasal sprays were estimated to prevent five new respiratory tract infections in every 100 people per month. The supplements appeared to reduce severe symptoms, like fever and flu-like illness, the most compared to placebo. And using a zinc spray or liquid under the tongue resolved symptoms up to two days earlier compared with a placebo.