Polyphenols are organic molecules that exist in the plant kingdom. As their name suggests, these compounds are distinct in having several phenol groups.
Polyphenols thus include simple phenols, coumarins, flavonoids, anthocyanins, lignans...
Several studies have shown that these antioxidant phytonutrients are responsible for many of the health benefits offered by fruits and vegetables.
One French research team has measured the polyphenol concentration of a wide range of common foods (1). Let’s take a look, in ascending order, at the fruits and vegetables with the highest polyphenol content.
Broccoli, a vegetable of the Brassicaceae cabbage family, contains fibre, carbohydrates, sulphur, potassium, vitamin C...
It also boasts a significant amount of polyphenols, with 98.9mg of GAE/100g (total polyphenols). GAE stands for gallic acid equivalents, gallic acid being a phenolic acid able to exert antioxidant activity.
Broccoli is particularly notable for its high content of the polyphenol kaempferol.
Dates are fleshy fruits from desert regions, which are rich in potassium, mineral salts and sugars.
Higher in total polyphenols than broccoli, with 99.3mg of GAE/100 g, dates predominantly contain condensed tannins.
Shallots, the delicious, onion-like vegetables, contain potassium, as well as vitamins B6, B9 and C.
In terms of polyphenols, shallots have 104.1mg of GAE/100g. They also contain flavonoids, particularly the famous quercetin. Try using shallots to add flavour to your salads and sauces, or as an accompaniment to meat… To gain even more from quercetin’s benefits, you could also take a quercetin-enriched supplement.
In next place comes the apple. This key fruit contains vitamin C, B vitamins and pectin.
Its polyphenol concentration is 179.1mg of GAE/100g. Apple polyphenols are thought to be particularly promising, and are the subject of much anti-ageing scientific research (2-4) focusing on the role of phloridzin (or phlorizin), an apple glucoside. This research has resulted in the development of apple polyphenol supplements, with a high content of these compounds.
The apricot, a sweet, fleshy fruit, is high in fibre and vitamins A and C.
It also contains a good amount of polyphenols, with 179.8mg of GAE/100g: chlorogenic acid, caffeic acid, catechol, anthocyanosides...
A vine fruit, the grape is consumed as a fresh fruit, grape juice, wine… It contains sugar, vitamins A, B and C, as well as various trace-elements.
Research has identified significant levels of polyphenols in grapes, with no less than 195.5mg of GAE/100g. They include, in particular, the highly beneficial oligomeric proanthocyanidins (OPC), flavonoids which are available at high levels in certain grapeseed-rich formulations.
Are you a fan of the lychee, the small, tropical fruit from China?
If so, you’ll be benefiting from a good intake of vitamin C, vitamin B9, carbohydrates, as well as polyphenols, with 222.3mg of GAE/100g, including a significant amount of flavonoids.
A cruciferous vegetable from the Brassicaceae family (like broccoli), the Brussels sprout is a cultivar of the same species as cabbage, rich in vitamins C and E, manganese, copper...
Brussels sprouts also contain a large number of polyphenols (mainly lignans), with 257.1mg of GAE/100 g.
The strawberry is part of the Rosaceae family. This delicious red fruit contains nutrients such as vitamin C, potassium and manganese.
Strawberries are also super-rich in polyphenols (263.8mg of GAE/100 g), in particular, fisetin, an excellent flavonoid with health benefits that are currently being studied extensively (6-8). It’s worth noting, however, that to obtain 160mg of fisetin, you would have to eat 1kg of strawberries. Another way of boosting your intake is to take a ‘senolytic’ supplement such as Fisetin, which contains 250mg of fisetin... per capsule.
Who would have thought that parsley, the subtle but very popular herb, would rank third in the polyphenol stakes? This aromatic plant not only contains apiol, myristicin and vitamin A...
... but also polyphenols, including apiin, the aglycone of which is called apigenin. In all, it contains 280.2mg of GAE/100g.
The artichoke heart is the highest-placed vegetable on this list. An edible species of thistle from the Asteraceae family, artichokes contain fibre and vitamins C and B.
Artichoke hearts, in particular, also contain an extraordinary amount of polyphenols, with a total of 321.3mg of GAE/100 g. They include chlorogenic acid (5-caffeoylquinic acid (5-CQA), 1,5-Dicaffeoylquinic acid... as well as cynarin), malic, succinic, lactic, fumaric and citric acids, flavones (apigenin, luteolin...) and anthocyanins (cyanidin, peonidin, delphinidin...)
Cynarin is a particularly beneficial artichoke compound, though it is only present at 1.5% of the level of chlorogenic acid found in artichokes. To increase your cynarin intake, you could take a supplement containing artichoke extract standardised to 5% cynarin.
Top of the group is persimmon (also known as Japanese persimmon or Sharon fruit), though it remains relatively little-known in the West. The national fruit of Japan, this fleshy round fruit resembles a tomato but is yellowy-orange in colour. Persimmon has a very sweet taste and is a good source of vitamin C, iron, potassium and fibre.
The polyphenol champion, persimmon is thought to contain 1 gram of polyphenols per 100 g of fruit. These are primarily flavanols (such as catechins and gallocatechins) and a number of condensed tannins.
It seems that a percentage of polyphenols are lost during cooking. So whenever possible, it’s a good idea to eat your fruit and vegetables raw (or lightly-cooked, at the very least).
Other foods such as green tea, dark chocolate, red wine, soya, onions, turnips, cloves, cinnamon, ginger and turmeric are also known for their high content of various polyphenols.
In addition, you can significantly increase your polyphenol intake by taking certain nutritional supplements, for example, Double Pomegranate, which has a high content of pomegranate polyphenol compounds (Punica granatum). More specifically, this supplement contains one pomegranate extract standardised to 40% punicalagins and another standardised to 90% ellagic acid.
Although we’re recommending you eat more of the foods mentioned above, it’s also important to maintain a varied, balanced diet. Make sure your dishes are full of colour to ensure a good variety of polyphenols!
You might also be interested in another beneficial source of polyphenols: phlorotannins. Found in brown algae, these marine polyphenols are becoming increasingly popular in the world of nutraceuticals (9-12). Ecklonia cava for example, an algae that’s extremely popular in Japan and Korea, is a good source.
To benefit from a substantial intake of this type of polyphenol, you could take an extract of Ecklonia cava standardised to 15% phlorotannins.