Updated 7th July 2022

What do polyphenols do, and where can I find them?

Polyphenols are a group of compounds found in plants. They boast a wide range of health benefits, thanks to their antioxidant and anti-inflammatory properties. 

Research suggests that regularly eating polyphenols is good for your body and may be particularly beneficial for supporting heart and brain health

So, where do you start if you want to boost your polyphenol intake?

Many people associate polyphenols with red wine, coffee, and chocolate. However, you can find them in several other foods, and in higher concentrations. 

Keep reading to learn more about what polyphenols are, what they do in your body, and their potential health benefits. 

We also provide a breakdown of the foods that contain the highest levels and discuss polyphenol supplements. 

What are polyphenols?

Polyphenols represent a superfamily of diverse compounds that are found in all parts of plants — right from root to fruit. 

Foods such as fruits, vegetables, legumes, cereals, herbs, and spices — think: colorful plant foods — are particularly rich in these compounds. 

For the plants that contain them, polyphenols play a role in protecting them against aggressors, such as sun damage, insects, and pathogens. 

Humans can also draw benefits from these compounds. 

Many polyphenols are antioxidants. Some also carry strong anti-inflammatory, antifungal, and antibacterial properties. 

So far, scientists have identified more than 8,000 types of polyphenols, which they’ve split into four major groups based on their chemical structure: 

1. Phenolic acids 

Phenolic acids account for about one-third of the polyphenols in your diet. You can find them in all plants, but they are particularly rich in acidic-tasting fruits. 

Some of the most common phenolic acids include caffeic acid, gallic acid, and ferulic acid.

2. Flavonoids 

This group is the most abundant in your diet. You can find flavonoids in just about every fruit and vegetable you can think of. 

Flavonoids are the pigments responsible for the vivid color in many fruits and vegetables. This class of polyphenols is divided into six subclasses: 

  • flavonols

  • isoflavones

  • flavanones

  • flavones

  • anthocyanidins

  • flavanols

3. Stilbenes

These aren’t as common as the other groups. Among all identified stilbenes, resveratrol and pterostilbene are the most well-known. This class of polyphenolic compounds is found in grapes, berries, peanuts, and red wine.  

4. Lignans

Lignans occur in whole grains, fruits, nuts, and seeds. The richest sources of lignans include flax seeds and sesame seeds.

Do polyphenols benefit health?

Research suggests that diets rich in foods containing polyphenols might provide the following health benefits.

Better blood sugar control

Experts believe that polyphenols help lower blood sugar levels and reduce your risk of type 2 diabetes. 

After a meal, polyphenols may slow the conversion of carbohydrates into simple sugars. This results in fewer blood sugar spikes after eating meals. 

Polyphenols may also help increase insulin secretion, a key hormone that helps regulate blood sugar levels. 

Some studies also suggest that certain polyphenols — namely epicatechin and anthocyanins — might reduce diabetes risk by improving insulin sensitivity and decreasing blood glucose levels. 

After eating, it’s normal for blood sugar levels to rise. However, repeated, large blood sugar spikes can increase the risk of health conditions, such as type 2 diabetes and heart disease. 

ZOE’s research has shown that everyone’s blood sugar levels respond differently to foods. If you’d like to learn more about how your body responds, start by taking our free quiz today.

Lower risk of heart disease

Polyphenols may improve heart health and function, contributing to a lower risk of heart disease. 

When cells use oxygen to generate energy, it produces so-called free radicals. These free radicals can cause damage to cells if they are not kept in check. 

Polyphenols, on the other hand, are antioxidants, which help neutralize free radicals.

In this way, polyphenols help reduce inflammation, which is a risk factor for heart disease. In addition, they also have other potentially beneficial effects on heart health. 

In one observational study, the researchers found that people who consumed the most polyphenols in their diet had a 46% lower risk of cardiovascular disease than those participants who reported the lowest polyphenol consumption. 

Skin protection

Some experts think that polyphenols might protect your skin by defending it against oxidative stress caused by the sun and pollution. 

They may also help slow down external skin aging and the appearance of wrinkles by reducing the breakdown of collagen and elastin. 

Due to its high polyphenol content, green tea has been widely researched for its potential photo-protective effects. 

Scientists think that the polyphenols found in green tea have antioxidant and photo-protective effects, helping to protect the skin.

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May protect against cancer

Experts believe the powerful antioxidant and anti-inflammatory properties found in polyphenols might play a role in reducing the risk of cancer. 

Researchers think that polyphenols may block the activity of certain cancers by inhibiting the growth and development of cancerous cells.

In animal studies, scientists have shown that polyphenols combat free radical damage that is associated with cancer development. 

The results of animal studies are more consistent than studies with human volunteers, which have yielded mixed results. For that reason, researchers need to carry out more human studies before drawing any solid conclusions. 

Promote gut health

Polyphenols may have a positive effect on digestion and your overall gut health. Experts think they might help stimulate the growth of beneficial gut bacteria.

Some studies have shown that polyphenols promote the growth of health-boosting gut bacteria, like Bifidobacterium and Lactobacillus

At the same time, they may also help inhibit the growth of potentially harmful bacteria, such as Escherichia coli, Clostridium perfringens, and Helicobacter pylori, although much of this research has only been done in animal models so far. 

ZOE’s scientists are at the forefront of gut microbiome research. Our research has identified 15 “good” bacteria that are associated with positive health markers and 15 “bad” bugs that are linked to negative health markers. 

If you’d like to take our at-home test to find out which bugs are in your gut and how to boost the “good” ones, start by taking our free quiz today.

Boost cognitive performance

Eating polyphenol-rich foods may help boost memory while enhancing your cognitive performance. 

Some research suggests that flavonoids can improve memory and learning, possibly by boosting blood flow in the brain. 

Which foods have the most polyphenols?

Plants are the best source of polyphenols. Most whole plant-based foods contain polyphenols, but some have more than others. 

The richest sources of polyphenols are herbs and spices. 

It’s safe to say that the polyphenol content in cloves eclipses all other foods: Every 100 grams (g) of cloves provides 15,188 milligrams (mg) of polyphenols — though you'd likely only have about 2 g in any given dish.

Food / DrinkFood GroupPolyphenol mg per 100 g or 100 ml
Cocoa powderCocoa products3,448
Dark chocolateCocoa products1,664
Black chokeberryFruits1,756
Black elderberryFruits1,359
Lowbush blueberryFruits836
BlackcurrantFruits758
Highbush blueberryFruits560
PlumFruits377
Sweet cherryFruits274
BlackberryFruits260
StrawberryFruits235
Red raspberryFruits215
PruneFruits194
Black grapeFruits169
AppleFruits136
Red wineBeverages (Alcoholic)101
Coffee, filterBeverages214
Black teaBeverages102
Green teaBeverages89
ClovesSeasonings15,188
Peppermint, driedSeasonings11,960
Star aniseSeasonings5,460
Mexican oregano, driedSeasonings2,319
Celery seedSeasonings2,094
Common sage, driedSeasonings1,207
Rosemary, driedSeasonings1,018
Spearmint, driedSeasonings956
Common thyme, driedSeasonings878
CapersSeasonings654
Sweet basil, driedSeasonings322
Curry, powderSeasonings285
Ginger, driedSeasonings202
Common thyme, freshSeasonings163
Lemon verbena, driedSeasonings106
Flaxseed mealSeeds1,528
ChestnutSeeds1,215
HazelnutSeeds495
Pecan nutSeeds493
Soy flourSeeds466
Roasted soybeanSeeds246
AlmondSeeds187
Soy, tempehSeeds148
Soy yogurtSeeds84
Black oliveVegetables569
Green oliveVegetables346
Globe artichoke headsVegetables260
Red chicoryVegetables235
Red onionVegetables168
Green chicoryVegetables166
SpinachVegetables119
ShallotVegetables113
Yellow onionVegetables74

Unlike other nutrients, there is no set dietary allowance for polyphenol intake. 

So, to reap the most health benefits, it’s worth eating a selection of foods from each of these groups, rather than focusing on single contributions from individual foods or drinks. Plus, this will provide you with a variety of polyphenols.

Polyphenol supplements?

In general, it’s best to get your polyphenols directly from whole foods. 

While supplements can provide a regular amount of concentrated polyphenols, there isn’t a great deal of evidence to suggest that they offer the same benefits as getting them from foods. 

Polyphenols also seem to work best in combination with other natural nutrients. One study found that polyphenols may have greater bioavailability when they are eaten in combination with other polyphenols. 

In other words, eating polyphenol-rich foods together increases the amount of polyphenols that enter your blood.

When pairing various whole foods together, the range of polyphenols and nutrients that you eat can work together to provide more health benefits.  

Polyphenol supplements are also minimally regulated, and many contain far more polyphenols than you would otherwise naturally get from foods. 

Even though polyphenols usually offer protective effects, scientists suggest that excess levels can harm cells. As it stands, there is not enough data to determine the safety and effectiveness of consuming polyphenol supplements.

At ZOE, we know that eating a varied diet with plenty of whole foods is the best way to maintain good health. Our research has also shown that everybody is different. 

With the ZOE program, you can understand how your blood sugar and blood fat levels respond to foods. We also give you a full breakdown of your gut bugs.

From this information combined, we can provide you with tailored nutrition advice to help you toward your long-term health goals.

Summary

Polyphenols are common, natural substances that come with an array of benefits. 

Many studies have found that polyphenols may improve blood sugar levels and help your heart, skin, gut, and cognitive health. 

However, more research is needed to understand how safe and effective it is to take them in supplement form. 

It is clear, however, that eating a diet rich in a variety of colorful fruits, vegetables, and other whole foods can help you get the most out of polyphenols. They are just another reason why eating the rainbow is beneficial for your health.

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