Due to rising health care costs in certain areas and unwanted side effects of prescription drugs, more and more people are exploring alternative medicines to treat anxiety. But which herbal supplements really work?

A news release on October 6 announced a new review of research on nutritional supplements used to treat anxiety, such as kava or St John's wort. Researchers writing in BioMed Central's open access Nutrition Journal pooled the results of 24 studies involving a total of more than 2,000 participants, showing that some nutritional and herbal supplements can be effective, without the risk of serious side effects.

Results were mixed, but passionflower, kava, L-lysine and L-arginine appeared to be effective, while St John's wort and magnesium supplements were not.

The research was carried out by Shaheen Lakhan and Karen Vieira from the Global Neuroscience Initiative Foundation, a nonprofit organization for the advancement of mental health patient welfare based in Los Angeles. Lakhan adds that more research needs to be done to determine the most effective dosages and whether or not this varies between different types of anxiety disorders.

Among the studies reviewed were initial tests using extracts of passion flower ( Passiflora) to treat anxiety, revealing that it performed as well as oxazepam, a prescription drug marketed as Alepam, Medopam, Murelax, Serax, among other names.

Kava or kava-kava ( Piper methysticum) is widely known for its mild sedative properties and is consumed throughout Polynesia, Micronesia, and Australia. Tests showed it was more effective than a placebo, although some concerns have been raised over whether or not it is detrimental to the liver when not extracted properly.

L-lysine and L-arginine are amino acids, with the former commonly used to treat cold sores and the latter also used to treat erectile dysfunction and heart disease.

To read the full review: http://www.nutritionj.com/

For information on herbal supplements:  http://www.mayoclinic.com/health/drug-information/DrugHerbIndex