Benefits of zinc to ease cold’s severity
DEAR DOCTOR: Does zinc help with colds?
DEAR READER: Zinc is an important element needed for a healthy immune system. The link between zinc deficiency and infections was first noted in the Middle East 50 years ago. Some zinc-deficient patients had such severe immune dysfunction that they died by age 25 from infection.
That’s because cells that are deficient in zinc have a decreased production of interleuken-2, a necessary immune and inflammatory regulator. In the United States, this level of deficiency is rare because zinc is found in so many foods; elsewhere, it’s seen among the severely malnourished.
A United Kingdom study found no benefit in the severity or the number of days of infection with a common cold among those taking a multivitamin that contained 20 milligrams of zinc versus those who took a placebo.
When it comes to higher doses, the results are more mixed. A review of 13 studies assessed the
impact of zinc on the common cold. Seven studies found benefit with the use of zinc lozenges, while six did not.
The authors concluded that the greatest factor in regards to zinc efficacy was the dosage. In the studies that used less than 75 mg per day, no benefit was seen. However, seven of the eight studies that used more than 75 mg did show benefit. Of these seven studies, zinc lozenges decreased the duration of a cold from 0.4 days up to 3.6 days.
In this and other studies, participants reported significant nausea and a bad taste in the mouth with the use of zinc. The FDA has warned against the use of nasal preparations with zinc due to an irreversible loss of smell.
Studies suggest a mild benefit for adult colds with the use of high daily doses of zinc. But, at these doses, you may be trading the benefits of decreased cold symptoms with the side effects of nausea. If you can tolerate a daily dose of greater than 75 mg, then zinc may be a good addition when fighting a cold.
Robert Ashley, M.D., is an internist and assistant professor of medicine at the University of California, Los Angeles.