The Spartan Guide to St. John's Wort

The Claim The flowering, yellow tops of this plant have been a staple in traditional medicine since the time of Ancient Greece. Today, St. John’s wort is mostly used as a dietary supplement to treat depression, as well as conditions like menopause, attention-deficit hyperactivity disorder, and obsessive-compulsive disorder.

The Evidence A 2009 review of 29 studies from around the globe suggests that St. John’s wort works as effectively as standard antidepressants for mild to moderate clinical depression. It also seems to have fewer side effects than standard depression drugs. But scientists note that the studies were mostly conducted in countries where St. John’s wort has long been used by medical professionals. Here in the US, the results are more mixed. Two studies funded by the National Institute of Mental Health concluded that neither St. John’s wort nor standard antidepressants reduced symptoms any better than a placebo.

Still, preliminary studies hint that the herb prevents neurons from reabsorbing dopamine and serotonin, meaning its mechanism might be similar to SSRI’s. And many integrative healthcare practitioners have seen good results from supplements. “I prescribe St. John’s wort in combination with other herbs to help combat seasonal affective disorder and mild to moderate depression,” says Janelle Louis, a functional medicine practitioner at Focus Integrative Healthcare in Overland Park, Kansas.

How to Use It Talk to your doctor about finding a moderate dosage, likely in combination with other treatments, Louis says. St. John’s wort can increase the rate at which many other drugs are eliminated from the body, making those meds less effective at a given dose. “Because of this, individuals taking medication should speak with their physicians before taking the herb,” she says. Experts point out that those on birth control pills, cyclosporine (which keeps the body from rejecting organ transplants), some HIV drugs, and some cancer medications should be especially careful about adding St. John’s wort to their supplement arsenal.