In a preliminary study, researchers at the University of Kansas, US, found that guggulsterone, the active ingredient in the herbal remedy gugulipid, caused changes in the cells that induce the body to break down many drugs, including cancer and AIDS medications.
To investigate whether it was safe to take guggulsterone with prescription medicines, scientists led by Dr. Jeff Staudinger examined the effects of guggulsterone on liver cells.
Staudinger suggested that guggulsterone interacts with drugs by binding to a protein called pregnane X receptor (PXR). This then induces the body to "turn on" a gene that encodes another protein that breaks down many different types of drugs, thereby reducing their levels in the body.
Staudinger added that some anticancer drugs, such as cyclophosphamide, need to be broken down by PXR to become active. Guggulsterone may interfere by increasing that process and raising levels of the drugs in the body.
Moreover, guggulsterone appears to also turn some other drugs, such as acetaminophen, into toxic compounds.
However, Staudinger noted that guggulsterone has been used for years, and is probably safe for those not taking prescription medications.
"Our data suggested that gugulipid therapy should be used cautiously in patients taking prescription medications," he concluded, adding that there was a need for additional studies of guggulsterones.
This study was published in The Journal of Pharmacology and Experimental Therapeutics.
Guggulipid, a substance derived from one of the fabled myrrh plants of the Middle East, has a 2,600-year tradition in traditional medicine. Indian practitioners of ayuvedic medicine have used the herb in holistic regimens combining meditation, yoga and diet to treat obesity, atherosclerosis, high cholesterol and arthritis.
Despite its history, not everybody is sure that guggulipid extract is effective as a cholesterol lowering herbal. A study carried out last year at the University of Pennsylvania and part funded by Sabinsa, a US manufacturer of a guggulipid extract product, found that it was no more effective than a placebo in clinical trials.
"We found that the guggulipid product did not lower the level of LDL-C (low density lipoprotein cholesterol) in our trial participants, but actually raised LDL-C slightly," said Dr Philippe Szapary, assistant professor of Medicine at the University of Pennsylvania School of Medicine and principal author of the study
The researchers also reported that a small subset of patients taking the herb developed a rash "indicating they were experiencing hypersensitivity drug reactions". The rash disappeared when they stopped taking the supplement.
"Our findings do not support the use of guggulipid to control LDL-C in the general population," Szapary concluded. He added that the results "strengthen our belief that dietary supplements need to be studied in a rigorous way, to test both their safety and their efficacy".