Is there any evidence for how herbal medicine works?
Systematic reviews conducted by the Cochrane Collaboration are considered the ‘gold standard’ of medical research. They are incredibly stringent and methodical and only look at the highest quality clinical trials (randomised placebo-controlled clinical trials) – this means that some studies done on herbs, especially older studies, just don’t cut the mustard.
Talking of mustard, a big problem with getting high quality evidence for herbal medicine is that some herbs have very distinct tastes (like chilli, ginger or mint) so it is difficult to create a convincing placebo. Another problem is the limited funding available for testing plant extracts that cannot be patented into a sellable drug.
Herbs vary in their composition according to where they are grown, how and when they are picked, dried, stored etc, which causes variations in results from different studies. And, crucially, different people with the same condition tend to respond completely differently to the same herbal treatment.
It is often said in the media that there is ‘no evidence’ for herbal medicines. What this often means is that there is a lack of high quality evidence that meets all the requirements. It also means that there is no evidence that they don’t work, either.
This is a very good article written by a US herbalist on the subject, called ‘Herbal Medicine: How do we know it works?”
How do herbs work, compared to pharmaceutical drugs?
Conventional medicines use single ‘active ingredients’, often extracted from plants, like aspirin (from willow bark), morphine (from opium poppies) and metformin (from goat’s rue). Active ingredients are much stronger and more direct than the whole plant, and therefore often involve side effects.
It is also easier for organisms like bacteria to develop resistance to single-ingredient drugs like antibiotics, by evolving mechanisms that help it survive.
People also become used to certain drugs after they’ve been taking them for along time – like blood pressure medication – and need a stronger dose to produce the same effects.
In herbal medicines, because there are so many ingredients, these problems generally do not exist. In the herbalists’ view, the complex nature of the herbal prescription is perfectly suited to the complex nature of an individuals’ condition, especially where a more gentle but long-term remedy is needed. This doesn’t mean that all herbs are softies – some are very powerful and the dosage of each is incredibly important.
However, the hugely diverse chemical composition of herbal medicines means it is very difficult to try and separate all the compounds from each other to find out exactly what effect they are having. That is why there is a lot less evidence for herbs, and a lot more evidence for conventional medicines.
Can herbs be used alongside pharmaceutical medicines?
Yes, most of the time. There are only a few examples where this is not a good idea: St John’s Wort, a herb found to be clinically effective in depression, speeds up the metabolism of certain drugs like the Pill, warfarin and statins.
A good herbalist will always check that what they want to prescribe you fits in with the medicines you’re taking so that no adverse reactions happen.
Some types of herbal or natural treatment options can even protect against the side effects of conventional medication.
Turmeric has been shown to be beneficial in lessening the side effect of oral mucositis after head and neck radiotherapy. There is also high quality evidence to suggest that probiotics are essential in replacing the body’s stores of healthy gut bacteria after a undergoing a course of antibiotics.
How long before I start noticing the effects of my herbal prescription?
The time it takes to treat successfully with herbs will vary according to each individual person – the longer you’ve had the condition, the longer it will take to treat.
For example, a simple case of IBS can often be resolved within less than one month of treatment, whereas a complex picture of high blood pressure or diabetes can take a lot longer may require a long-term maintenance dose.
In general, 3 months is a good time frame to bear in mind. If you haven’t experienced a change within 3 months, a different prescription or approach to treatment is needed.