Yes, knotweed can be consumed – but there are implications!
In this article we answer the question ‘can knotweed be cooked and eaten?’ and provide key information around foraging, harvesting, growing and cooking knotweed, plus you’ll read useful insights from a UK nutritionist on knotweed’s potential health benefits. As knotweed experts we put a stamp on the regulations that surround knotweed including dealing with knotweed waste without risking legal consequences. Whilst some nutritionists are happy to state that knotweed may have some health benefits if consumed, let’s be clear – as a knotweed control and removal contractor we do not advocate using knotweed as a food source.
What are the legal implications of cooking knotweed?
Human consumption of knotweed is currently not regulated, which means if knotweed is consumed it could easily be transported back to the environment via human waste management systems. Disposal of knotweed materials (which would in this scenario include waste from food prep) and its contaminated soils is governed by UK law, and failure to abide by these laws can result in legal action, fines and even imprisonment.
Currently only one UK restaurant is serving up knotweed on its menu – and they advocate ‘zero waste’ but if this menu item catches on and other restaurants follow suit they must dispose of the waste in a compliant manner – it cannot be binned, composted or fly tipped. The important questions to ask here are; where is the knotweed being sourced, and what is happening to the knotweed waste created from cooking and eating it?
Where can knotweed be found?
Knotweed thrives in the wild where if uncontrolled it will take over large swathes of land. This makes it available for foragers who may decide to take some home to cook. It also thrives on waste land, along waterways and on commercial and private property. It is not illegal to have knotweed growing on your land – only to allow it to encroach onto neighbouring land – so it can be cut for use in cooking. BUT (and this is a big ‘but’) – to safely harvest Japanese knotweed for consumption, there are a few important factors to note:
- Knotweed is often treated with herbicides, so foraging carries a genuine safety consideration.
- It also contains oxalic acid (similar to rhubarb or spinach), which may not be suitable for everyone, particularly those prone to kidney stones.
- Underground roots are not edible.
- Disturbing the roots or surrounding soil will cause the plant to spread.
- Unless you hold all regulatory accreditations and licenses to handle and dispose of knotweed- there’s no option for disposing of any waste!
Legally, all parts of Japanese knotweed (and its contaminated soils) must be disposed of as controlled waste under the Environmental Protection Act 1990 and the Wildlife and Countryside Act 1981, requiring transport by registered waste carriers and disposal at licensed landfill sites in the UK. However, this doesn’t mean that it’s illegal to eat, only that disposal has to be done so carefully.
Equally important is where knotweed is found. So, if it’s on your land/property there’s a legal obligation to control it and not allow it to spread onto neighbouring land. It is not however illegal to have it there, as long as it is controlled.
Now we’ve got the legal implications stated, let’s see what potential health benefits knotweed holds.
Is knotweed good for you?
We spoke with Katie Sanders, a nutritionist verified on Doctify, to understand the health benefits behind eating knotweed. Katie comments,
“Young spring shoots of Japanese knotweed are edible, containing some nutrients, with a sharp, rhubarb-like flavour, and have been used in cooking in parts of East Asia. The fresh young shoots are delicious in tarts, crumbles and chutneys and also, according to the nutritionist, contain some nutrients, including:
- Vitamin C – supports immune health and collagen production
- Potassium – helps regulate blood pressure and muscle function
- Polyphenols – plant compounds linked to cell protection
- Resveratrol – an antioxidant also found in grapes
“Although a helpful bit of context here is that when knotweed is described as being particularly high in resveratrol, this is usually based on extracts (often from the root) rather than the amounts you would realistically eat in food form.”, Katie adds.
“But, it’s easy to overstate things! Much of the research looks at isolated compounds or concentrated extracts, often in laboratory or animal studies. The amounts used in human research are far higher than you’d get from eating the plant itself. And while phrases like “rich in antioxidants” sound reassuring, they don’t necessarily translate into meaningful health outcomes in real life.”
In conclusion
Human consumption of knotweed is a concern not just for the knotweed industry but for the UK. Where knotweed is found comes with legal consequences, and there is no option for disposing of knotweed waste unless you’re a certified knotweed contractor.
As stated at the beginning of this article, we do not advocate foraging, cooking or eating knotweed. This is a highly invasive plant, and we must all do our bit to control and eradicate it. Hiring a contractor is the safest way to deal with knotweed on your land or property – so if you want to know if you have knotweed, or what to do with it ask the experts.