PARIS Claims that Asian herbal medicine can treat asthma are folklore that is not backed by scientific evidence, according to a study published in the specialist British journal Thorax and quoted by AFP.
University of Exeter researchers in southwestern England assessed the quality of 17 clinical trials of herbal remedies for asthma.
Six of the treatments came from traditional Chinese medicines, eight were derived from Indian Ayurvedic medicines, while the other three were Kampo medicine from Japan, marijuana and extract of dried ivy leaf.
Nine of the 17 trials reported a significant improvement in breathing or an easing in asthma symptoms.
But, say the British researchers, most of the trials were scientifically flawed, in the age and profile of the patient, description of the outcome and whether the herbs had any adverse effect.
"There is no fully convincing evidence for any of the herbal preparations described," they say, adding however that in some cases "there are promising data which warrant further investigation." The researchers warn that many people who take herbal medicine for asthma may be unaware of its side effects.
This include Gingko Biloba, one of the most popular Chinese herbal medicines, which could have the potential to interfere with anticoagulant drugs used by heart patients, they say.
"Considering the popularity of herbal medicines with asthma patients, there is urgent need for stringently designed clinically relevant randomized clinical trials," they say.
The study cited a survey by Britain's National Asthma Campaign which found that up 70 percent of people with moderate to severe asthma had tried alternative medicine, including herbal remedies.