Nutritional and herbal supplementation is an effective method for treating anxiety and anxiety-related conditions without the risk of serious side effects, according to a systematic review of studies published in Nutrition Journal.

Researchers said strong evidence exists for the use of passionflower or kava and combinations of L-lysine and L-arginine as treatments for anxiety symptoms and disorders. In addition, magnesium supplements and other herbal combinations may hold promise. However, they also said St. John’s wort monotherapy “has insufficient evidence for use as an effective anxiolytic treatment.”

“Over the past several decades, complementary and alternative medications (CAM) have increasingly become a part of everyday treatment,” study authors write. “With the rising cost of prescription medications and their production of unwanted side effects, patients are exploring herbal and other natural remedies for the management and treatment of psychological conditions.”

Nearly 7 million Americans suffer from generalized anxiety disorder. Many also suffer from side effects related to treatment.

Researchers analyzed a total of 24 studies that investigated five different CAM monotherapies and eight different combination treatments involving 2619 participants. There were 21 randomized controlled trials and three open-label, uncontrolled observational studies.

Most studies involved patients who had been diagnosed with either an anxiety disorder or depression (n = 1786). However, eight studies used healthy volunteers (n = 877) who had normal levels of anxiety, were undergoing surgery, tested at the upper limit of the normal range of a trait anxiety scale, had adverse premenstrual symptoms or were peri-menopausal, reported anxiety and insomnia, or had one month or more of elevated generalized anxiety. Heterogeneity and the small number of studies for each supplement or combination therapy prevented a formal meta-analysis.

Of the randomized controlled trials reviewed, 71% (15 out of 21) showed a positive direction of evidence. Any reported side effects were mild to moderate.

Researchers acknowledged that any positive effects seen could be due to a placebo effect, which may have a significant psychological impact on participants with mental disorders. However, based on the systematic review, “strong evidence exists for the use of herbal supplements containing extracts of passionflower or kava and combinations of L-lysine and L-arginine as treatments for anxiety symptoms and disorders.”

Researchers also concluded: “Magnesium-containing supplements and other herbal combinations may hold promise, but more research is needed before these products can be recommended to patients. St. John’s wort monotherapy has insufficient evidence for use as an effective anxiolytic treatment.”