What is PEITC?

PEITC is phenylethyl isothiocyanate and has the chemical formula C9H9NS. It is part of a group of molecules called isothiocyanates which contain the chemical group N=C=S.

Where is it found?

The isothiocyanates are naturally occurring small molecules found mainly in some cruciferous vegetables. These belong to the Brassicaceae family.

Cruciferous Vegetables

Examples of cruciferous vegetables are kale, cabbage, broccoli, cauliflower, bok choy, wasabi and of course… watercress!

Why do plants have isothiocyanates?

Isothiocyanates are produced by plants in response to stress, acting as a defence mechanism which triggers a variety of physiological changes in the plant to aid survival.

How are isothiocyanates made?

A group of plant molecules called glucosinolates are acted on by an enzyme called myrosinase. This converts the glucosinolates into isothiocyanates. They are made in response to stress. A group of molecules called glucosinolates are acted on by an enzyme called myrosinase. This converts the glucosinolates into isothiocyanates. Different glucosinolates make different isothiocyanates, and plants vary on the relative amounts of each glucosinolate they have. Broccoli for example is high in glucoraphanin, and under the action of myrosinase it therefore makes disproportionately more sulphoraphane than other isothiocyanates. Watercress on the other hand contains much more gluconasturtium than other glucosinolates. When acted on by myrosinase, this means it makes much more phenylethyl isothiocyanate (PEITC).

Can I taste isothiocyanates?

Yes you can! Isothiocyanates have quite a characteristic bitter taste. In the example of watercress, PEITC is what gives us the pepperiness.

Can I just eat watercress to get PEITC?

Absolutely! Chewing watercress creates and releases PEITC. It also has a range of other health benefits too. Our research has demonstrated that to get as much PEITC from watercress as possible, you would have to chew into a paste for over 2 hours, which probably isn’t that appealing!

Eating watercress, while superbly good for you and actively encouraged, only gives you a fraction of the dose of PEITC that our extract delivers.

The background of PEITC

PEITC has been widely researched for its role in the epigenetic regulation of cancers. Epigenetics is the basis of how genes express themselves, and the inherent ability to switch some genes 'on' and 'off' to affect the “phenotype” which are the observable traits. Most observable traits ie. eye colour, height and blood group are based largely on your genes and are not influenced by environmental factors.

Some phenotypes can be influenced by the environment and can lead to huge difference in observable traits. Environmental factors can 'switch on' some genes and 'switch off' other genes, so while the underlying DNA is the same, it is being expressed in a different way.


One of the best examples of this is worker bees and queen bees!
Imagine two twin sister bees that have just been born. Both are born genetically identical and to look to appear identical. If you feed one twin bee nectar and honey it will continue to grow as a worker bee. If you take the other bee and feed it a diet of royal jelly it will develop into a Queen bee. They look completely different, yet both still have the same DNA. The worker bee just has its worker bee genes 'switched on', and its queen bee genes 'switched off'.

For the queen bee on the other hand, the royal jelly has caused epigenetic changes by 'switching on' the queen bee genes and 'switching off' the worker bee genes.

NB – This is quite a simplistic way of looking at things, but the principle still works. Think about a moth turning into a butterfly, and even a young adult going through puberty. Both genetically the same, but the end results are very different.

PEITC as an anti-inflammatory

PEITC has also been shown to demonstrate promise as an anti-inflammatory agent along with other isothiocyanates. Inflammation can happen in lots of areas on the body from the skin (conditions such as eczema or psoriasis) to the gut (Crohn’s disease and ulcerative colitis). We plan to investigate whether a PEITC rich solution can help counteract harmful inflammation in certain conditions. 

We have picked out some key pieces of research into watercress, PEITC and isothiocyanates and have provided the references below: