The herbal remedy St. John’s Wort effectively treats symptoms of major depression, an analysis of previous studies found on Wednesday. St. John’s Wort extracts tested in the different trials were better than placebos and as effective as standard antidepressants with fewer side effects, the researchers reported in the Cochrane review, a journal that analyses medical and scientific studies.
My Take:
The new Cochrane review,reported by Reuters, makes conclusions that are very similar to those I make in my book, Alternative Medicine: The Christian Handbook,  where co-author, Dónal O’Mathúna, Ph.D. and I conclude: 

“St. John’s wort appears to be a relatively safe treatment for mild forms of depression. The evidence regarding anxiety or insomnia is much weaker. Milder forms of depression respond better than more severe forms, and there may be other variations in people’s responses. However, no information is available on the long-term effects of taking this herb, so it should be used only as a short-term option. Given the complicated nature of depression and anxiety, taking St. John’s wort, or any other pill, alone should not be viewed as an adequate way to deal with these conditions. The psychological, relational, and spiritual issues should also be addressed.” 

According to a report in Reuters: “The studies came from a variety of countries, tested several different St. John’s Wort extracts, and mostly included patients suffering from mild to moderately severe symptoms,” Klaus Linde of the Center for Complementary Medicine in Munich, Germany wrote. The herb works in a similar way to some prescription antidepressants by increasing the brain chemical serotonin, involved in controlling mood.
The Cochrane review analyzed 29 studies that together included 5,489 men and women with symptoms of major depression and compared the remedy’s effectiveness with placebos and standard treatments.
The researchers found that St. John’s Wort extracts were not only effective but that fewer people taking them dropped out of the trials due to adverse side effects.
They also noted that results were more favorable in German-speaking countries where doctors often prescribe the remedy and cautioned against using the remedy without medical advice because the extracts can affect other drugs’ work.
In Germany such herbal treatments are also more controlled for content, unlike in many other markets where the quality and content of herbal products may vary considerably.
“Using a St. John’s Wort extract might be justified, but products on the market vary considerably, so these results only apply to the preparations tested,” Linde said.
Because of this, I recommend that anyone considering taking St. John’s wort only use products tested by an independent testing lab such as ConsumerLab.com. You can find the review for St. John’s wort here.   
Furthermore, St. John’s wort should never be taken with any prescription medication without a doctor or pharmacist first checking for possible interactions. 
Depression is a leading cause of suicide and affects about 121 million people worldwide, according to the World Health Organization. Standard (and possibly more effective) treatments include Prozac, which U.S. drugmaker Eli Lilly and Co introduced in 1987. The treatment, which belongs to a class of compounds called selective serotonin reuptake inhibitors (SSRIs), is now off patent and widely available generically as fluoxetine.