Herbal supplements may help reduce anxiety

By Nathan Gray, 07-Oct-2010

Herbal supplements such as passionflower and kava have good evidence to suggest their effects in reducing anxiety, according to a new review.

The research, published in the Nutrition Journal concludes that “nutritional and herbal supplementation is an effective method for treating anxiety and anxiety-related conditions without the risk of serious side effects.”

However, when asked to independently comment on the review Edzard Ernst, Professor of Complementary Medicine at Peninsula Medical School, told NutraIngredients-USA that it was “interesting, but not of high quality.”

Despite limitations with the study Prof. Ernst told NutraIngredients-USA he believed there were “several supplements which have shown promise in the treatment of anxiety.”

Common disorders

Depression and anxiety are two of the most common mental disorders, affecting nearly 55 million people in the United States alone, whilst psychological disorders are reported to be of the most frequent conditions seen by clinicians, and often require a long term regimen of prescription medications.

The authors stated “the complexities of the central nervous system make diagnoses, treatment, and amelioration of these debilitating illnesses exceptionally difficult.”

“It is not surprising that there is universal interest in finding effective natural [anti-anxiety] treatments,” added the researchers.

There have been reviews to assess the clinical effectiveness of herbal and nutrient, however the authors noted that although these have reviews of such data, none have been conducted systematically.

The new research paper reviews 24 studies that investigated five different complementary therapies and eight combination treatments.

Evidence of efficacy

The 24 studies examined the effectiveness of passionflower, lysine, magnesium, kava and St John's wort, with most studies involving patients diagnosed with either an anxiety disorder or depression.

The researchers reported that 71 percent of the trials reviewed (15 out of 21) showed evidence supporting the efficacy of the supplement, adding that “any reported side effects were mild to moderate.”

Three separate studies on passionflower were reported to show positive benefits, “providing good evidence of its effectiveness as an anxiolytic agent,” according the researchers.

The authors stated that kava was the most researched supplement in the review, with 11 studies assessing its effectiveness. They stated that out of the trails measuring kava on its own, 63 percent reported significantly reduced anxiety symptoms. “This provides good evidence for the use of kava in patients with general anxiety disorders,” wrote the authors.

Undisputable?

The authors noted the possibility that the reported positive effects could be due to a placebo effect, as such effects can have “significant psychological impact on participants with mental disorders.”

However they concluded that based their review: “Strong evidence exists for the use of herbal supplements containing extracts of passionflower or kava … as treatments for anxiety symptoms and disorders.”

The authors added that locating and quantifying the active ingredients in herbal substances could help to improve potency, and help to create “an undisputable body of evidence for their effectiveness”

However, Prof. Ernst said that the review paper failed to critically evaluate the studies it included, and was too limited as it only considered primary research published in English, when “many articles are published in other languages.”

Prof. Ernst stated that the lack of critical evaluation was “clearly important, as flimsy research may not be reliable.”

He added that the review was also incomplete: “I know of several herbal medicines that have been tested for their effects on anxiety – and results available in English – which were not mentioned in this study.”

Source: Nutrition Journal
Published online ahead of print, doi: 10.1186/1475-2891-9-42
“Nutritional and herbal supplements for anxiety and anxiety related disorders: systematic review”
Authors: S.E Lakhan, K.F Vieira