It's not a cure for the common cold, but a Canadian company claims taking two pills throughout the winter can reduce the number and severity of colds.

In Tuesday's issue of the Canadian Medical Association Journal, Dr. Gerry Predy of Capital Health in Edmonton and Dr. Tapan Basu of the University of Alberta report on a study of 279 adults with a history of at least two upper respiratory infections in the previous year.

Participants were given either Cold-fX or a placebo during winter 2003-2004. They were graded based on the severity and duration of symptoms reported. Neither the participants nor the researchers knew who took the real pills.

The capsules contain extracts from the root of North American ginseng.
The capsules contain extracts from the root of North American ginseng.

The percentage of people who got colds during the four-month trial were:
  • Placebo group: 63.8 per cent.
  • Cold-fX group: 54.6 per cent.
The percentage of people who caught a second cold were:
  • Placebo group: 22.8 per cent.
  • Cold-fX group: 10 per cent.
The length of time the cold lasted was:
  • Placebo group: 11.1 days
  • Cold-fX group: 8.7 days.

Some people take a high dose of the ginseng extract capsules when they feel a cold coming on, but the study wasn't designed to look at whether that approach makes a difference.

Research on herbal therapies often uses material that varies from batch to batch. In this study, the pill doses were standardized.

How does it work?

Clinical studies on common viral infections is difficult, especially when the virus isn't known, cautioned Ronald Turner of the department of pediatrics at the University of Virginia School of Medicine.

"The proposed mechanism of action of ginseng is unclear," Turner wrote in a journal commentary. In July, he published a review that concluded echinacea extracts are no better than a placebo for fighting the common cold.

"The authors provide a summary of the immunological effects of North American ginseng, but is not clear how these relate to viral respiratory infections."

Since Cold-fX is thought to affect the immune system, people with autoimmune disorders such as diabetes or asthma are advised to check with a doctor before taking the pills. Research is also needed on how Cold-fX affects children, the study's authors said.

One drawback of the approach is cost. If people take two pills per day like the study participants, it would cost about $30 per month, or $120 for a cold season.

The research was paid for by CV Technologies Inc., a spin-off company of the University of Alberta that makes the pills.

The results were previously announced in Edmonton and have now been peer reviewed.