Herbal medicine extracts

Understanding herbal extracts: it’s all in the detail

Brigitte Flower explains how to understand herbal extracts in medicines such as St John’s Wort and many more

We’re all looking for value for money when we shop, whether it be for food, clothes or medicines. And when presented with a row of similar products, we all look for quality, but we’ll want it for a good price, including herbal extracts.

Let’s imagine you’re shopping for St John’s Wort. You’ve heard from a friend how it helps with low mood and anxiety, you’ve done a quick Google search and feel that you might benefit from it too. But when you get to your local retailer, or search online, there are so many St John’s Wort products to choose from. How can you make a choice which means you’re getting something of good quality but at a decent price? Read on, for not all herbal medicines are created the same….

Look for the THR symbol when choosing herbal extracts

THR logo - safety in herbal medicinesYour first priority needs to be to buy a herbal medicine with a THR symbol, which shows that it is approved under the national Traditional Herbal Registration scheme.

You can easily and clearly find this on the packaging (usually the front or the side of the packet). This symbol begins your journey to buy a quality product which meets the high standards of the MHRA (Medicines and Healthcare products Regulatory Agency). You can read more about this here.

Understanding about herbal extracts

This is where it gets a bit more tricky. Let’s look at an example.

You find two packets of St John’s Wort: ‘Product A’ contains 425mg of extract and ‘Product B’ contains 334mg. So, you might think that Product A is stronger and has more herbal extracts and is therefore the better product. But this is only part of the story. If you look on the back of a packet of THR-approved herbal medicine, you will see information about what’s in it.

For example, if you look at the back of a pack of HRI Good Mood St John’s Wort, you’ll notice that 334mg of extract comes from the raw material – St John’s Wort – in a ratio of 5-7:1. This means that for every 5 to 7 parts of raw material, one part of extract is created. The raw material is the actual plant itself. The volume of the raw material which is used to create the St John’s Wort extract for one tablet is 1670mg-2338mg (the bit in brackets).

Let’s compare this to product A:

Each tablet contains 425mg of extract (as dry extract) from St John’s Wort aerial parts (Hypericum perforatum L.) (3.5-6:1) (equivalent to 1490- 2550mg of St John’s Wort).

Here, you’ll notice the higher extract amount but the volume of raw material used in the extract per tablet is lower – 1490-2550mg, compared with 1670 – 2338mg. This is reflected in the lower ratio too (3.5-6.1). Not all THR medicines have a ratio stated on the pack but they will all state the equivalent volume of raw materials.

You might be wondering why there is a range, rather than a set amount of raw material in each tablet. This is to allow for variations in the strength of the raw material; herbs are living organisms which can have plenty of natural variations, just like other plants you find growing in your garden.

Finally, be careful with herbal supplements (these are products which don’t have a THR) as these products will include the weight of excipients in the extract amount and the actual amount of herb in the product will always be lower than a THR. Excipients are materials added to the extract to stabilise it and create the tablet, such as silica or maltodextrin.


Having checked the volume of raw herbal extract material to extract ratio, you now need to check the dosage. This is much more simple. If the maximum dose is 2 tablets daily and the herbal extract is 334mg, then you’ll be getting 668mg a day. Make sure you don’t choose tablets which seem to have a high extract content but where the daily dose is only one tablet.

So, when you are shopping for your next herbal medicine, remember three things:

    1. Look for the THR logo
    2. Check the raw material ratios
    3. Check the dosage.

Hopefully, you’ll then find that you are getting the best quality and right strength for your money.

NB:  Please note that St John’s Wort should not be taken if you are using a contraceptive pill or other hormonal contraceptives.

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