Herbal supplements to cure tinnitus aren't necessarily bad, but the research on them is definitely lacking. An audiologist investigates.
Over the past several years, there have been a number of herbal remedies claiming to lessen the effects of tinnitus-a ringing or buzzing in the ears that has no external sound source. According to some estimates, one in five people experiences tinnitus.
As a clinical and research audiologist, I reviewed the scientific literature on herbal treatments in 2004 and was unable to substantiate that any of the product manufacturers' claims were backed by U.S. evidence-based research. As a former human studies researcher in the area of tinnitus during the 1980s, I've remained interested in this subject matter, and I recently re-examined the literature about supplements and their effects on tinnitus.
My search of "tinnitus" on Medscape, an online database of medical journal papers, yielded 174 articles. However, not one of them was a scientific study on herbal treatments for tinnitus. On Medline, a website that provides medical information from the National Library of Medicine, 7,078 articles were cited. But when I refined the search terms to "herbal treatment for tinnitus," only 24 articles were cited, almost all of which were useless because they merely mentioned the word "tinnitus" or "herbal treatment," but were not related to a study.
Only one article was an actual study, and it was written in Chinese. Based on the abstract in English, there are serious flaws in the design of the study-not the least of which was that the study lasted only five days.
I ran an online search on the terms "herbal treatment for tinnitus" at the website for the New England Journal of Medicine. The search turned up only one result, unrelated to the question. Searching the same terms at the Journal of the American Medical Association (JAMA) website led to many articles with the word "tinnitus," but in the top 100 results, not a single article reported conducting a study of herbal treatments for tinnitus.
I believe Paolo Enrico, Ph.D., of the University of Sassari, Italy, and his research team aptly summed things up regarding herbal treatments and tinnitus in their paper "Antioxidants, Minerals, Vitamins, and Herbal Remedies in Tinnitus Therapy," published in the journal Progress in Brain Research in 2007. Enrico et al. said the use of supplements "lacks substantial scientific support, and... these substances are probably not clinically effective either." In addition, they stated that "in view of the potential harm that may occur from inappropriate use of CAM products [complementary and alternative medicines, such as herbs], physicians need to be aware of their principal characteristics with particular emphasis on toxicity and possibilities of interaction with prescription drugs."
WHERE ARE THE PUBLISHED STUDIES?
I contacted two companies that offer over-the-counter tinnitus remedies using herbs, nutrients, or a combination. My question to the companies was: "What U.S. evidencebased research is your claim based on?"
The representative for one company told me, "We've done extensive research over five years and the product works."
I asked: "Where can I find this published study?"
She replied, "It's not for public viewing."
It defies common sense. If you have a proven relief for tinnitus, you'd want to be sharing this news with the world. Yet, this company could provide nothing to me other than a claim and their word.
The other company I contacted said more or less the same thing. They admitted there was no tinnitus research that the company conducted to back the claim. But I was told that the ingredients in the bottle were effective for increasing blood flow, maintaining cognitive health, and relaxing the body.
In a 2003 JAMA study titled "Internet Marketing of Herbal Products," Charles A. Morris, M.D., and Jerry Avorn, M.D., of Harvard Medical School concluded: "Consumers may be misled by vendors' claims that herbal products can treat, prevent, diagnose, or cure specific diseases, despite regulations prohibiting such statements. Physicians should be aware of this widespread and easily accessible information. More effective regulation is required to put this class of therapeutics on the same evidence-based footing as other medicinal products."
BUYER BEWARE
The single most touted ingredient in some of these purported remedies is ginkgo biloba. My general review of the literature in 2004, and again in summer 2010, failed to uncover even one U.S. scientific study that supported the notion that any herbal treatment, including ginkgo biloba, was of any more benefit for tinnitus than a placebo. Even company executives of tinnitus relief companies could not provide the data.
What's more, researchers can't even agree that ginkgo biloba is of benefit to other health issues unrelated to tinnitus. For example, in December 2009, JAMA published the results of a large randomized trial, the Ginkgo Evaluation of Memory study, which found that ginkgo biloba supplements had no effect on age-related cognitive decline.
However, quite in contrast to U.S. studies, some European research has shown a link between herbal treatments and tinnitus. This is the basis for U.S. product claims. The problem is that results from these foreign studies have not been replicated in U.S. studies, so the methodologies in these foreign studies should be challenged.
The reason there may be no studies conducted on herbal treatment for tinnitus is because there are far stricter guidelines in the United States than in most other countries. We cannot know the flaws in research without knowing how the studies were designed, and exactly what the data showed (see the companion piece, "Study the Studies," page 30).
German scientist Klaus Linde and a group of other European researchers in 2003 reviewed clinical trials on herbal medicines, including their effects on tinnitus. They required what they felt were specific stringent methodology and concluded, "From a total of 79 potentially relevant reviews preselected in the screening process, 58 met the inclusion criteria. Thirty of the reports reviewed ginkgo (for dementia, intermittent claudication, tinnitus, and macular degeneration), hypericum (for depression), or garlic preparations (for cardiovascular risk factors and lower limb atherosclerosis). The quality of primary studies was criticized in the majority of the reviews."
WHERE'S THE EVIDENCE?
Most people don't experience side effects from taking ginkgo biloba, but they can include gastrointestinal disturbances, headaches, dizziness, intracerebral hemorrhage, and allergic skin reactions. Ginkgo functions as a natural vasodilator. It opens the blood vessels. For people already on vasodilators, which are used to treat high blood pressure, it can increase the risk of bleeding when, for example, used in conjunction with histamines, anticoagulants (like Coumadin or Warfarin), vitamin B3 (variations of niacin), alpha blockers (such as Phenoxybenzamine), antiplatelet agents (like aspirin), and even other herbs.
When taking any supplements, do so under the supervision of a medical professional. And when searching for tinnitus relief, no matter the treatment, be vigilant and discerning; demand to see the evidence that the product works; and don't throw good money away on testimonials alone. That's not science.
[Sidebar]
The problem is that results from foreign studies have not been replicated in U.S. studies, so their methodologies should be challenged.
Trusted Websites for Medical Studies and Articles
The Journal of the American Medical Association
jama.ama-assn.org
Medline
www.nlm.nih.gov/medlineplus
Medscape
www.medscape.com
The New England Journal of Medicine
www.nejm.org
[Author Affiliation]
By Richard A. Carmen, Au.D.
[Author Affiliation]
Richard E. Carmen, Au.D., is the publisher of Auricle Ink, which publishes healthcare books written by scholars in language consumers understand. For more information, see www.hearingproblems.com. He is also the technical adviser and on the board of the Better Hearing Institute, www.betterhearing.org.
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