Prevention

Studies on vitamin E specifically have been largely negative. A 2002 study, in fact, reported a higher incidence and greater severity of respiratory infections in older adults who took 200 mg of vitamin E daily.

Other Factors Associated with a Lower Risk for Respiratory Infections

Breastfeeding. Evidence suggests that women who breastfeed reduce the risk of respiratory infections in their children. The American Academy of Pediatrics recommends that babies be fed exclusively breastmilk for the first 6 months.

Low Stress and Active Social Life. More than one study has reported that people with low stress who also have an active social life have fewer colds than people who have high stress levels or those who have low stress and few social connections.

Zinc

Zinc appears to have certain important effects on the immune system and it may have a direct effect on viruses. How it works is not entirely clear, however. Zinc preparations in lozenge or nasal gel form are now available as cold treatments. Studies are very mixed on the effects of zinc on colds.

• A nasal gel (Zicam), which contains zinc gluconate, has shown some success, possibly because the gel sticks to the nasal passages long enough for the zinc to interact with the virus. In a 2003 study, for example, the nasal gel shortened the duration and severity of the cold compared to placebo when it was started within 14 to 48 hours of the onset of symptoms. The supports earlier studies reporting that it shortened the duration of a cold by about 2 days.
• Zinc lozenges are showing mixed results. One 2000 study suggested that the use of zinc acetate lozenges may be more effective and have a better taste than other formulations, such as zinc gluconate. On the other hand, a 2002 study reported that zinc gluconate reduced cold duration significantly. To further confuse matters, the two zinc lozenge preparations were directly compared in a 2000 study, and neither was effective.

In any case, no one with an adequate diet and a healthy immune system should take zinc for prolonged periods for preventing colds. Long-term use of zinc (100 mg or higher daily) has been associated with heart problems, anemia, and other conditions.