The herb echinacea lowered the risk of catching the common cold, cut the number of days people had colds, reduced cold symptoms and improved immune response under stress in three new studies.
Researchers from the University of Connecticut School of Pharmacy in Storrs, Connecticut, analyzed data from 14 placebo-controlled trials and found that among 1,356 participants, those who had taken echinacea were 58% less likely to catch a cold than were those in the placebo groups. In another group of 1,630 participants who had already caught a cold, colds lasted 1.4 fewer days for those who had taken echinacea compared to placebo. Researchers noted one study where participants who took vitamin C along with echinacea were 86% less likely to catch a cold compared to placebo. The 14 studies included three types of echinacea: E. purpurea, E. angustifolia and E. pallida.
In a second study, researchers recruited 282 participants aged 18 to 65 who were healthy but who had caught a cold at least twice in the previous year. Doctors asked participants to take 10 doses of a standardized extract of echinacea, E. purpurea, on the first day cold symptoms appeared and then four doses per day for the next seven days. Nurses examined the 128 participants who caught a cold—59 in the echinacea group and 69 in the placebo group—on the 3rd and 8th day after symptoms first appeared. Those who had taken echinacea reported 23.1% less severe symptoms compared to placebo with no serious side effects in either group.
In a third study, researchers recruited 32 physically active, non-smoking adults aged 19 to 46 to perform a strenuous exercise test. Those who had taken echinacea had a 7% decrease in a protective antibacterial agent (saliva Immunoglobulin A or sIgA) compared to a 45% decrease for placebo.