Echinacea Side Effect: Gut Changes
Change in Balance of Bacteria in Gut May Be Echinacea Side Effect
Dec. 20, 2006 - The popular herb echinacea has a side effect: It changes the
balance of gut bacteria, a small study shows.
Whether this is good or bad isn't yet known.
One of the bacteria that seem to increase, bacteroides, has been linked in
other studies to diarrhea, inflammatory bowel
disease, and colon cancer, researchers
report. But there's no direct evidence that echinacea causes or worsens any of
these diseases, says study researcher Jerald C. Foote, PhD, RD, of the
University of Arkansas in Fayetteville.
"We don't know this is caused by echinacea for sure," Foote tells
WebMD. "We are not claiming that echinacea will cause things like that. But
if you are taking echinacea and have a history of gastrointestinal problems,
maybe you need to take a further look at it."
The study does not impress echinacea researcher Bruce P. Barrett, MD, PhD,
of the University of Wisconsin in Madison. Barrett is a member of the
scientific advisory board of the American Botanical Council, a non-profit
educational group, and the leader of a 2002 clinical trial that found echinacea
to have no effect in treating the common cold.
"The low number of subjects, lack of control group, and irrelevant
outcome measure detracts from scientific value [of this study]," Barrett
tells WebMD in an email. "[The] implied relevance to actual human disease
is speculative at best."
Naturopathic doctor Jean-Jacques Dugoua, ND, a researcher at Toronto's
Hospital for Sick Children, studies echinacea and other supplements. Dugoua
finds the Foote study very interesting -- but notes that bacteroides are normal
gut bacteria that can protect against more dangerous bacteria.
"This study suggests that perhaps echinacea plays around with the
gut-floor bacteria more than we thought it did," Dugoua tells WebMD.
"Maybe that is a good thing, and maybe it is a bad thing. But we did find
echinacea to be well tolerated in our safety studies."
Echinacea Side Effect?
Foote, a dietitian, says he began the small study after people taking
echinacea asked him whether the herbal remedy might be causing their diarrhea. A review of the
scientific literature revealed no information on the effect of herbal
supplements on the gut.
So Foote and colleagues got 12 men and women to take 1,000 milligrams per
day of an echinacea supplement with standardized ingredients (Echinamide from
Natural Factors R&D, Canada). The researchers cultured bacteria from study
participants' stool samples before, during, and after 10 days of echinacea
They found significant changes in the balance of normal gut bacteria --
including an increase on bacteroides.
"If a person is taking echinacea for a short period of time and has a
healthy gastrointestinal tract, I don't think it is a terrible risk," Foote
says. "But they should be looking for side effects when they take echinacea
or any other drug. ... If we can get consumers to look for possible side
effects when they take an herbal remedy, that would be a good thing."