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Herbal quality & safety: What to know before you buy

Written by Rebecca Lazarou and Sebastian Pole

It is a common assumption that “natural=safe”. Unfortunately, this is not entirely true.  Whilst herbs usually have a favourable safety profile, they are pharmacologically active and must be taken responsibly. There are a variety of factors that can make a herbal medicine unsafe, from quality, to pharmaceutical interactions and herbs that are not suitable with certain conditions.


Unfortunately finding good quality products can be difficult. Similar to food there are risks with contamination and spoilage. There are potential risks in many areas; from microbial contamination (E.Coli, aflatoxins etc); heavy metal loads (lead, mercury, arsenic etc) either found at naturally high levels in the soil or from industrial contamination; potentially toxic extraneous materials harvested accidentally with the intended species (pyrrolizidine alkaloids, tropane alkaloids found in Boraginaceae, Asteraceae and Fabaceae and Solanaceae respectively). Also our environment has unfortunately become polluted with many new-to-nature chemicals that are intentionally or unintentionally applied to crops; pesticides, fungicides and herbicides are persistent in our soils, water and atmosphere and high levels can occur due to over application or from wind-drift and floods.

Hence it is all too common for products to be contaminated. It is also possible that products have intentionally or accidentally been adulterated with incorrect species. The herbal industry faces similar challenges to the food industry; rice is often detected with high levels of arsenic, wheat with pyrrolizidine alkaloids, lentils with E. Coli – and all non-organic foods with pesticides. Despite rigorous regulations across most countries all sorts of adulterants from sawdust to colouring dyes to pharmaceuticals have been found in over the counter herbal products. Another common problem is that botanical nomenclature is complex and plant names can be mixed up. This has led to poisonous plants being substituted in to products (1) which has lead to dangerous results.

Marker compounds

Plants have hundreds to thousands of secondary metabolites that make up the chemistry of their physiological effects; the essential oils, polyphenols, colourful pigments and array of other phytochemical families all combine to induce their effects. So just having the right species that is perfectly hygienic isn’t enough. You also need the right amount of the ‘actives’ to have an effect. This is where another difference in quality may come in.

What are food grade herbs? Food grade herbs are typically used in food as the spice-mixes and teas you will find lining the shelves of supermarkets and natural health stores. They may also be used in some food supplements that are fine to use, but their contents and purity may or may not be pharmacopoeial grade.

What are pharmacopoeial grade herbs? A pharmacopoeia is a collection of quality standards for herbs (as well as vitamins and drugs) that ensures the herbs are of the right quality and can meet the criteria to deliver their expected effects. For example, there is a European Pharmacopoeia, a British Pharmacopoeia, a United States Pharmacopoeia, and an Indian Pharmacopoeia.

How do herbs become pharmacopoeial grade?

To be classed as pharmacopoeial grade, further to the quality criteria mentioned above, the identity of the species must be verified using various microscopic techniques and specialist equipment, such as chromatography (you will all have done something similar to this in school chemistry lessons, using blotting paper). High Performance Thin Layer Chromatography, Gas Chromatography, distillation, microscopic and organoleptic tests are all used to assess qualitative and quantitative measurement of the species. These methods ensure the right level of compounds, such as the active ingredients of essential oils, polyphenols or flavonoids. And it is these compounds that are associated with certain tastes and effects.

Here are some examples of the different quality if herbs available:

Standard Herb NameFood Grade ISO 6571/1984European Pharmacopoeia
Chamomile flowers
Matricaria recutita
Min. 0.2% essential oil0.4% essential oil
Apigenin Min. 0.25%
Fennel seed (Sweet)
Foeniculum vulgare var. dulce
Min. 1% essential oilMin. 2% essential oil (with NLT 80% anethole and max 10% estragole and 7.5% fenchone)
Peppermint leaf
Mentha piperita
Min. 0.6% essential oilCut Leaf Min. 0.9% essential oil
Whole Leaf Min. 1.2% essential oil
Rebecca Lazarou

I completed my degree in Biomedical Science-Human Biology, always with the intention to study herbal medicines after. I wanted to bridge the gap between plant medicines and science. I then went on to study a masters at UCL School of Pharmacy, in Medicinal Natural Products and Phytochemistry where I learnt deeply about phytomedicines, quality control, laboratory techniques and medicinal plant science.
Since then I have been an associate editor for the science publication Journal of Herbal Medicine. I research medicinal plants at Kew Gardens, and have been a G7 youth ambassador for healthcare. You can read more about my research here. I have launched my own botanical medicine company Laz The Plant Scientist offering herbal medicines, education and experiential events.

I am passionate about herbal medicines as I believe medicines should prioritise prevention as well as having a holistic focus. I love that herbal medicines work to rebalance us and optimise our quality of life, and I have witnessed them having a transformative effect time and time again. I also believe that living in symbiosis with and nurturing a relationship with nature is one of the most healing things we can do.

Sebastian Pole

I am a registered member of the Ayurvedic Professionals Association, Register of Chinese Herbal Medicine and a Fellow of the Unified Register of Herbal Practitioners. I qualified as a herbalist with the aim of using the principles of Ayurveda (the ancient art of living wisely) and the Herbal tradition to help transform health. I have been in clinical practice since 1998.
Having co-founded Pukka Herbs in 2001 I have become experienced in organic herb growing, practitioner grade quality and sustainable value chains. I am a Trustee of the FairWild Foundation, a Director of The Betonica School of Herbal Medicine and an Advisor to The American Herbal Pharmacopoeia and The Sustainable Herbs Project. Fluent in Hindi, a qualified Yoga therapist and passionate about projects with a higher purpose, I am on a mission to bring the incredible power of plants into people’s life. And that is why I started Herbal Reality and what it is all about.
I live in a forest garden farm in Somerset growing over 100 species of medicinal plants and trees. And a lot of weeds!
Author of Ayurvedic Medicine, The Principles of Traditional Practice (Elsevier 2006), A Pukka Life (Quadrille 2011), Celebrating 10 Pukka years (2012) and Cleanse, Nurture, Restore with Herbal Tea (Frances Lincoln 2016).

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