Lots of trials have shown that St John's wort helps people with depression. Supporters of complementary medicines have been overjoyed to discover that one of their products actually works, taking this as universally acknowledged proof that anything that comes from a plant and is hallowed by centuries of German tradition must be a good thing. It isn't, and it isn't a triumph for alternative medicine. It's a success for one of the greatest inventions of the 20th century: the randomised double-blind controlled trial, a magnificent tool for finding out certain kinds of truth. With something as subjective as mood, it's about the only way of keeping our prejudices from polluting our ability to see clearly.
In general, the trials have been supportive. But it shouldn't come as a surprise that some of the evidence of the effectiveness of St John's wort is confusing: the truth often is. A recent review sought out every single good-quality study ever done. It found 26 that compared St John's wort with a placebo, covering a grand total of 3,320 patients. If their depression was mild, St John's wort almost doubled their chance of feeling better. But those who had begun with worse symptoms saw less of a result: only 10% more than with a placebo. In the 14 trials comparing St John's wort with an antidepressant (2,283 patients in total), the two came off pretty much the same. To add to the difficulties, preparations of St John's wort are not standardised. That means you've no idea whether your money is paying for the substance that the trials showed to work. If you happen to get the good stuff, then (like any other substance that has a therapeutic effect on the human body) it has side effects.
People who describe themselves as "pro-life" are not trying to engage you in debate, they're trying to suggest there isn't room for one. Terms such as "alternative" and "complementary" are mental lies. Something about St John's wort can help some people feel better about life, just like willow can prevent heart attacks and the yew tree can suppress breast cancer. Regardless of whether we understand them, treatments either work or they don't. What's the alternative to that? Cochrane review: mrw.interscience.wiley.com
