VANCOUVER — With no clear evidence to support the use of herbs for heart disease, many doctors say the best herbal medicine is to stay away.
A new study shows some of the most common herbs have no clear benefits and can even worsen symptoms of heart disease.
The study, published Monday in the American Heart Journal, analyzed a review of studies of over 30,000 herbal medicines published between 1970 and 2014.
They found the vast majority of the herbs were associated with a reduced risk of heart attacks or stroke, but they also increased the risk of some serious side effects, including kidney problems and some death.
“We are very disappointed with the results of this study,” said Dr. Michael C. McDonough, a cardiologist at the University of British Columbia who wasn’t involved in the research.
“We’re concerned that this study was designed to look at the herb alone, and there’s no evidence that herbs actually increase a person’s risk of death or serious cardiovascular disease.”
The authors of the study, from a group of researchers led by Dr. David T. T. Prentice, associate professor of medicine at the Massachusetts General Hospital, said they’re studying the health effects of herbs and have found “that the majority of herbs we are finding to be harmful are not associated with any clear benefits or harms to human health.”
The study examined nearly 4,000 herbs that have been evaluated by researchers at the National Institutes of Health, the U.S. Food and Drug Administration and the University, among others.
In the analysis, researchers looked at herbs used to treat heart conditions such as congestive heart failure, coronary artery disease, angina pectoris, angioedema, myocardial infarction, stroke, and congestive failure.
They also looked at studies that compared the effects of herbal medicines against their traditional equivalents, the traditional Chinese medicine and traditional Chinese herbal medicine.
They looked at both common and rare herbs, such as peppermint, rosemary, basil, parsley, and oregano.
The researchers found that the herbs studied had no significant effect on heart disease rates, although some were associated to lower death rates.
For example, peppermint was found to be associated with decreased mortality, while rosemary was associated with higher mortality.
The majority of common herbs studied were found to have mild or moderate effects on heart health, while the more common herbs were found not to have any clear effects.
However, the authors said the results should be interpreted with caution because it’s unclear how the herbs affected heart health in the real world.
“There’s been no study of whether the herbal supplements were effective or harmful,” McDonaughey said.
“What we are looking at is what they are doing for us, and we’re not looking at whether the supplements are good or bad.
We’re looking at what they’re doing for ourselves.”
For the study researchers, this means the results don’t mean herbs should be used for everything.
In fact, they said some herbs are best for specific conditions, such the pain from a blocked artery, and should be avoided if possible.
The authors said this is particularly important for heartburn, which is often caused by the use and ingestion of certain herbs.
They said this may be why some experts recommend avoiding peppermint because it can cause a skin reaction called “the rosey skin reaction.”
“The rosey-skin reaction is an unpleasant condition caused by ingesting peppermint,” said Prentice.
“It’s a condition that’s easily triggered by certain herbs.”
The results were not surprising, he said.
They were done after years of research, he added, and they are based on studies of just one or two herbs.
“I think there are certainly some herb compounds that are going to have adverse effects,” said McDonaugh.
“There are some compounds that may be beneficial.”
In fact, some herbs, he explained, are linked to heart disease in some studies.
He said one study, which looked at four herbs that were found in certain heart attack drugs, found they were associated not only with reduced risk but also increased mortality.
“In that study, it’s really difficult to say whether that herb was actually beneficial,” he said, adding the authors of that study are not recommending use of those herbs for any purpose.
The results of the new study also show there are no clear effects from using a single herbal.
McPrentice said the study found that, in some cases, the effects could be reversed when one or more herbs were taken in combination.
For instance, peppermints may increase blood pressure, but it may be because the other herbs in the group were also related to blood pressure.
“The data suggests that when you have several herbs together, it may increase the blood pressure of one herb, but not the other,” said C. David Koehler, a researcher at the UBC Cardiovascular Center and a co-author of the review