By Dr Colin Thomas

I am not surprised that in a recent trial St John's Wort has been shown to have beneficial effects for those suffering from depression.

All drugs we use today have a basis in nature and it actually gets my goat when people say: "Oh I only take natural remedies".

Strychnine is a natural remedy! Try taking that my old son and see how you feel in the morning!

In medicine's early days all the drugs used were extracted from plants or herbs.

For example Atropine is derived from Belladonna. Atropine is a poison, but in smaller doses will have positive pharmacological effects on the body.

Aspirin and Quinine come from trees, and digitalis, a medicine used in heart failure is extracted from the Foxglove.

My old medical boss Dr Bolt used to swear that Colchicine, derived from crocuses, was one of the best anti-gout medicines.

So to discover that a plant like St John's Wort has pharmaceutical properties does not rock me back on my heels.

Remember Alexander Fleming's discovery of penicillin, probably the most important medical breakthrough this century? It would have been quite at home growing on a piece of stale bread.

Even today pharmaceutical companies are looking to nature for the drugs of tomorrow. They may find synthetic ways of manufacturing their products, but essentially they have their roots in nature.

The recent clinical trial the doses of the St John's Wort extract were similar in size to pharmaceutical doses of antidepressant.

Prozac in the leaves

In many ways it's like discovering a plant that contains Prozac in its leaves. If you take enough of them you'll eventually get a therapeutic effect.

It is important to understand the difference between this sort of "alternative" medicine, and treatments like homeopathy which employ very dilute doses which are nowhere near therapeutic levels, and tend to have no worrying side effects or drug interactions.

The trouble is that consumers tend to fall for the "natural" label every time, and assume, quite incorrectly, that natural means safe.

Herbal remedies such as St John's Wort are effectively non-regulated therapeutic medicines, without the same rigorous testing for side effects and drug interactions that conventional medicines have.

Doctors and scientists are aware for example of the interaction between Aspirin and Warfarin (rat poison which thins the blood), but a recent study has shown that an interaction between Warfarin and St John's Wort also occurs, and this could be dangerous for those who rely on blood thinning agents.

Patients quite often don't tell their doctors they are taking herbal remedies, and doctors are unlikely to have information about how herbal remedies interact with conventional ones.

In my view as long as herbal medicines are safe patients shouldn't be stopped from taking them, but it would be sensible for them to stick to herbal or conventional and never the twain shall meet