As part of my effort to summarise the clinical evidence for certain herbs that have been researched more than others, I want to start with St John’s Wort as it’s rather a celebrity of the plant world.
I also want to add some background as, although the clinical evidence is valuable, the authors of the scientific papers are seldom herbalists.
St John’s Wort (Hypericum perforatum)
Hypericum has been used for centuries for a number of different indications, and is very much a native British herb. Herbalists use it in gastrointestinal disorders as an anti-inflammatory, conditions involving nerve damage such as herpes and multiple sclerosis, and externally as a poultice or oil to help heal wounds, soothe sprains and other injuries.
It is also commonly used as a ‘nervine’ to ease anxiety and depression, and in recent times its reputation as a safe and effective mood-enhancer has grown considerably due to the huge number of clinical trials conducted on the subject.
The depressing facts
The World Health Organisation (WHO) predicts that by 2020, depression will be the second leading cause of disability worldwide. It has been shown by work in Indian and African communities that depression affects the populations of developing countries equally – it is not just an affliction of stressful modern societies.
Furthermore, research into the underlying disease process has uncovered much more than the ‘chemical imbalance’ of neurotransmitters often thought of as the main factor in depression. Stress, physical disease and allergy have all been linked to core inflammatory processes that may play a role in the development of mental and neurological illness.
So what can humble Hypericum do about this globe-spanning mental health catastrophe?
Well, it has been deemed a possible safe alternative to conventional SSRIs (selective serotonin re-uptake inhibitors) and ‘tricyclic’ antidepressants, whose side effects often outweigh their benefits.
It was found that the difference in effect between placebo and these drugs was only significant when the patient was very severely depressed – and this was attributed to a decreased response to placebo rather than an increased response to the drug. It has also been suggested that many more of the positive trials get published than the negative ones – called ‘publication bias’.
Trials of Hypericum began in the 1980s to investigate an alternative and, from 1995–2009, three Cochrane reviews have summarised the results of the many trials. Cochrane reviews are considered the ‘gold standard’ in medical research and are intended to pool all the results from the highest quality clinical trials.
The Hype About Hypericum
One of the early reviews looked at 27 trials with a total of 2291 patients, all with ‘neurotic depression’ or ‘mild-moderate severe depressive disorder’. They concluded that Hypericum was more effective than placebo but, although patients reported fewer side effects than those taking the conventional medication (26.3% compared to 44.7%), they could not determine whether Hypericum was as effective as standard anti-depressants.
A further review detailed some recent, well-conducted trials suggesting Hypericum didn’t actually show any improvement above placebo. They also saw that the efficacy of Hypericum depended on the size and setting of the trial. Those most likely to show a benefit over placebo were small, included only patients with mild depressive symptoms and were conducted in German-speaking countries.
It was around this time that St. John’s Wort was also found to speed up the enzyme systems processing various drugs in the body (the Pill, HIV medication, immunosuppressant drugs, digoxin) making them dangerously less effective. For a while, the hype surrounding Hypericum became tarnished by scientific discovery, and herbalists around the world hung their heads in disappointment as hopes of world peace slipped silently away.
However, since results seemed less pronounced in patients with major depression, an update of the 2005 paper limited the trials to patients with only major depression. Twenty-nine trials with a total of 5489 patients were analysed and it was shown that Hypericum was more effective than placebo as well as being similarly effective to standard anti-depressants, with fewer side effects.
Variations in results
Trials from German-speaking countries still seemed to be more favourable – possibly because Hypericum is widely prescribed by physicians in these countries for depression and anxiety. This may mean the health professionals were biased – but it is equally likely that their experience led them to choose slightly different types of participants for the studies, despite the criteria.
It is clear from studies of patients with more severe depression that Hypericum works differently in different groups of people, and it may be particularly suited to people with atypical depressions such as SAD and physical symptoms of depression like fatigue and irritable bowel syndrome (IBS).
The composition of herbal extracts also varies hugely according to climate, soil type, methods of harvesting, processing and packaging, and shelf life of the final product. The findings of the 2009 review apply to extracts of 500-1200mg/day, using 50-60% ethanol for extraction. Most Hypericum tinctures used by herbalists are made with 45% alcohol, but we often prescribe more than 1200mg/day, so perhaps this cancels things out!
Interestingly, levels of the compound hypericin (blamed for the enzyme interactions above) have been shown to be much lower in tincture than in tablets, capsules or infusions (teas). This may explain why herbalists have good results with Hypericum tincture in patients who want to wean themselves off conventional anti-depressants.
However, initial research suggested it was hypericin that was responsible for the anti-depressant effects of St. John’s Wort and many manufacturers started producing tinctures with added hypericin. Now we know that it is a combination of various compounds in the herb that produces the benefits. So if I may give any advice to readers, it’s:
- Don’t buy Hypericum products that have added hypericin…
- Always consult a medical herbalist before taking any Hypericum extract.
So What Does it all mean?
Hypericum is a valuable herb and more than just an anti-depressant but, with the evidence behind us, we can say it really works in both mild-moderate severe depression and major depression as well as in people with atypical depressive symptoms.
You don’t have to be severely depressed in order to take Hypericum, but if you are, and you’re not happy with conventional medication for any reason, it may provide a safe and effective alternative. And that’s good news.