Polyphenols: What they are and why they matter to your diet
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What are polyphenols?
At a time when we're being encouraged to eat more plants than ever (30 a week), it's likely you will have heard of polyphenols, too. These compounds found in plants are described by scientists as 'strong antioxidants, external' and are thought to have anti-inflammatory and anti-aging effects, external.
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Health benefits of polyphenols backed by science
Heart health and cardiovascular risk
A recent long-term study in the UK, external found that people with diets high in polyphenol-rich foods had lower cardiovascular disease risk, healthier blood pressure and cholesterol levels.
Polyphenols, inflammation and healthy aging
Another research paper, external suggested polyphenols may help to reduce inflammation, support gut health and healthy ageing.
Gut microbiome and brain health
There's also growing evidence, external that polyphenols' impact on our gut's good bacteria could help to prevent neurodegenerative diseases, external such as Alzheimer's, says Daniele Del Rio, professor of human nutrition at the University of Parma in Italy.
Foods highest in polyphenols
Polyphenols can be found in all plants, but some have higher concentrations:
Fruit: Dark berries, external, including blackcurrants, blueberries, blackberries and elderberries; and olives (and extra virgin olive oil, external).
Vegetables: Red onions, red chicory, globe artichoke.
Nuts with their skin on: Chestnuts, almonds, pecans and hazelnuts.
Tea: Green and black.
Coffee and cocoa: including dark chocolate.
Dried herbs, spices and seeds: Including flaxseed, cloves, oregano, thyme and rosemary.
Soya beans: Including tempeh, external.
Red wine (although Del Rio advises against increasing red wine consumption or relying on this as your main source of polyphenols!)
There's no recommended daily intake of polyphenols in the UK but scientists are trying to change this.
"Many research groups are working to prove that a sufficient amount of scientific evidence now supports a dietary recommendation for some specific subclasses of polyphenols, external," says Del Rio.
What we do know is that we all absorb polyphenols differently. This is partly due to differences in gut bacteria, which play a key role in breaking polyphenols, external down into compounds the body can use.
How to cook and get the most from polyphenols
Want to get your fill of polyphenols in the tastiest way possible? Here's how…
Go off the boil
Polyphenols are generally stable at high temperatures, so you'll still find plenty in plants that have been cooked.
"One significant exception is boiled vegetables," explains Del Rio, "where some of the phenolics are lost in the water, if the water is not used for other preparations within the meal."
So, if you're not planning to use your boiled veg water for stock, gravy, stew or soup, you could switch to steaming instead.
Use the whole plant
While many of us might peel and trim fruit and veg as default, polyphenols are found in all parts of plants, especially the outer layers.
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Don't throw away vegetable peelings, turn them into crisps
Food journalist Sally-Jayne Wright recommends reducing your food waste and upping your polyphenols by using cauliflower stalks, external in cauliflower cheese or smoky bacon soup.
She also suggests using often-discarded vegetable leaves in cooking – celery and radish leaves are relatively high in polyphenols, external and work well in salads or pesto.
Celery leaves feature in this Hairy Bikers' recipe for Waldorf salad with grilled mackerel
"You don't need to peel onions to use them in home-made stock/bone broth. The skin has flavour, too," says Wright.
And you don't need to throw out potato skins if you're making mash.
"The skins taste great oven-roasted with sea salt and olive oil until they are crisp. If using the mash on a shepherd's or cottage pie, put these crispy skins on top," she says.
But there are some parts of some plants we should avoid, such as rhubarb leaves, as they're poisonous, and green potato peels, as they can cause an upset stomach, external.
Always add herbs and spices to your dishes
Wright also has tips for adding more polyphenol-rich herbs to our diets.
"A burst of basil or chervil among mixed salad leaves wakes up the taste-buds.
"You can also use herb oils to drizzle on fish, chicken and roasted meats, or herb butter for the freezer for the next time you're making garlic bread," she says.
Stock up and try new things
Keeley Haworth, chef and co-founder of London restaurant Plates, advises stocking up on spices and nuts. "Once you have an assortment of nuts in the cupboard they can be sprinkled and grated over so many dishes for added flavour and texture. Forget any rules and try different combos," she says.
"Spiced nuts are even better adding more polyphenols, roast or pan fry with your favourite spices and then snack on them, add to salads or use a pestle and mortar for a finer texture and then top over curries, noodles, stir fries and sprinkle over your veggies too."
Haworth also advises trying tempeh. "It's a powerhouse food in the plant-based world, packed with protein, minerals and polyphenols. The fact that it's fermented means that it is great for our gut health too."
Originally published August 2024. Updated February 2026
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