Butterbur ExtractMay 2006
By Russell Martin
Allergy Assistance from Rosmarinic Acid
In addition to butterbur, another efficacious herb for the treatment of the immune response to allergens has come under examination. Studies have found that rosmarinic acid can reduce the symptoms of an allergic response. Rosmarinic acid is a polyphenol found in a number of plants in the Lamiaceae family—including basil, mint, perilla leaf, rosemary, and sage. Rosmarinic acid acts in response to allergies via a mechanism very different from that of butterbur. Instead of reducing inflammation and quieting spasms in affected airways, rosmarinic acid prevents the activation of immune responder cells and induces cell death (apoptosis) in already activated responder cells.13 What is remarkable is rosmarinic acid’s ability to kill off only unneeded allergy-activated T-cells triggered by the body’s immune response, while sparing the vast numbers of T-cells required to ward off bacteria, viruses, and other invaders.14 Antihistamines, by contrast, have no ability to act on and destroy excessive immune cells.15
In 2004, a team of Japanese researchers documented how daily treatment with rosmarinic acid extract prevented allergic asthma caused by house mites in laboratory mice.16
In a critically important trial in humans, the Japanese research team conducted a 21-day, double-blind, placebo-controlled test of rosmarinic acid’s ability to control seasonal allergic rhinoconjuctivitis. Patients were treated with 50 or 200 mg of the natural supplement or placebo daily, and each kept a daily diary of symptoms. By day three, the two groups taking the high and low doses of rosmarinic acid demonstrated significantly lower levels of immune cells in laboratory examinations of nasal fluids when compared to the control group. Symptoms of swollen, itchy, and watery eyes were particularly reduced in the rosmarinic acid groups. No side effects were reported by any of the three subject groups, and extensive blood cell counts and tests of liver and kidney function showed the treatment to be safe and non-toxic.17
This 2004 trial was the first sophisticated study of rosmarinic acid’s effects on allergies in humans. Its authors concluded that relief from seasonal rhinitis symptoms can be achieved by reducing the number of immune cells activated by the allergic response.17 Additional trials are under way in hope of learning much more about the this supplement’s mechanisms and optimal usage.
In a further trial, the Japanese team again treated patients suffering from seasonal allergic rhinitis with either rosmarinic acid or placebo. The participants receiving rosmarinic acid reported improvements in all of their allergy symptoms. These benefits were accompanied by decreased numbers of immune cells present in nasal secretions. In order to elucidate rosmarinic acid’s mechanism of action, the scientists used a research model of laboratory animals. In this animal model, they found that rosmarinic acid acted by two distinct mechanisms: inhibiting the inflammatory response and scavenging reactive oxygen species, a source of oxidative stress.18
Strategies for Avoiding Allergens
People who suffer from the seasonal or perennial effects of allergic rhinitis can mitigate their symptoms by avoiding allergens as best they can. However, pollens are everywhere in the outdoor air and can be difficult to avoid. While staying indoors during the height of a season in which a particular type of pollen is present is not practical for most people, limiting exposure can provide at least modest relief. Pollen counts tend to be high on dry, sunny, windy days, and people with allergic rhinitis should stay indoors on those days, if possible. Keeping the windows and doors of houses and cars closed as much as possible during the pollen season also can be helpful, especially if air conditioning or fans are set in re-circulating mode to block the intake of outside air. Showering following outdoor exposure removes pollen that collects on the skin and hair, and may be helpful as well.
Controlling indoor allergens is often more successful. Dust mites can be combated by covering mattresses and pillows with impermeable covers, and bed linens should be regularly washed in 130-degree water, which kills any mites present. Thorough vacuum-cleaning of carpets and rugs is wise, but wall-to-wall carpeting should be avoided by people with proven dust-mite allergies. Dust mites thrive when the indoor humidity level rises above 50%, so dehumidifiers, air conditioners, or both also help limit mite populations. Completely avoiding domestic animals is the best way to limit allergy symptoms for those sensitive to pet dander. For pet lovers who cannot or choose not to live without animals, keeping pets in carpet-free rooms and out of bedrooms offers at least some benefit from dander exposure. High-efficiency particulate air (HEPA) filters and ozone purifiers also help keep pet dander out of household air.1
People who suffer either seasonal or perennial rhinitis are generally advised to avoid as best they can environmental pollutants, pesticides, car exhaust, cigarette smoke, perfumes, and new carpeting—all of which can trigger allergic responses and worsen ongoing allergies. Drinking pure filtered water is wise, as is using hypoallergenic products when they are available.
For many individuals, lifestyle changes and environmental controls do not provide adequate relief from allergic rhinitis’s often miserable symptoms. Almost everyone with at least moderate allergies requires some form of treatment.
For those who have long hoped for a clinically proven herbal treatment—free of the sedating side effects and other drawbacks of pharmaceutical drugs—the scientifically proven efficacy of butterbur and rosmarinic acid in limiting congestion, swelling, watery eyes, and post-nasal drip represents an exciting breakthrough. Additional studies may offer further insight into how these plant-derived supplements can provide much-needed relief from both seasonal and year-round allergies.
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