What Are Polyphenols?

Fresh berries are loaded with nutrients and polyphenols.
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Polyphenols are phytochemicals, which are naturally occurring compounds that give plants their colors or help to protect them from various dangers they might face in nature. Phytochemicals, including a number of the polyphenols, are often covered by the media when research studies suggest that consuming these plant chemicals may be good for you.

Health Benefits of Polyphenols

Isolated compounds are often extracted from the plants and examined for their potential health benefits.

In general, the polyphenols that may have health benefits for humans are thought to work as antioxidants that protect the cells in your body from free radical damage. When it comes to research, they sometimes—but not always—have impressive results in the lab.

Foods rich in polyphenols certainly are good for you, but it's difficult to know how much of that benefit is actually due to the specific plant compound or to all the nutrients, fiber, and other phytochemicals also found in those foods.

Polyphenols as Antioxidants and Anti-Cancer Agents

The polyphenols typically act as antioxidants, which means they can help prevent cellular damage from free-radicals that occur with pollution, smoking, eating rancid foods, and as a byproduct of normal metabolism. It's also thought that polyphenols contribute to the body being in an anti-inflammatory state, which is also associated with a lower risk of several chronic diseases.

Several polyphenols, such as quercetin, catechins, lignans, resveratrol, and curcumin, are touted as being anti-cancer agents. But the evidence doesn't go beyond lab testing on cancer cells so it's not known if they could prevent cancer or have any effect on cancer cells in a human body.

Polyphenols also appear to improve the function of blood vessels and may help to slow down the formation of blood clots.

 For example, the catechins in tea may have the ability to slow down the process that causes clogging of the arteries, and drinking either black tea or red wine may increase circulation for at least two hours after consumption.

Types of Polyphenols

Thinking in terms of chemistry, the polyphenols all have similar ring-shaped structures, but you can tell them apart by the number of rings and by the other molecules that are attached to those rings. Thus, polyphenols are grouped into four different categories based on those differences: phenolic acids, flavonoids, stilbenes, and lignans.

Phenolic acids include compounds found in coffee, tea, grapes, red wine, berries, kiwi fruits, plums, apples, and cherries, as well as other fruits and veggies, and even grain and corn.

Since phenolic acids are abundant in the diet and readily absorbed through the walls of your intestinal tract, you shouldn’t have much trouble consuming enough of them. In general, phenolic acids work as antioxidants but they also appear to promote anti-inflammatory conditions in your body.

Flavonoids are another group of polyphenols that work as both antioxidants and anti-inflammatory agents. Flavonoids are divided into several groups: flavones, flavonols, flavanones, isoflavones, anthocyanidins, chalcones, and catechins.

They're found in a wide variety of plant-based foods, including fruits, vegetables, legumes, red wine, and green tea. Flavonoids, sometimes called ‘bioflavonoids’ are often sold as dietary supplements.

Stilbenes are a small group of plant chemicals and resveratrol is probably the best-known stilbene, and the most studied. Resveratrol is found in red wine, blueberries, cranberries, and peanuts, and consuming these foods has been linked to better heart health.

Of course, it’s hard to know how much of that benefit comes from the resveratrol. Although laboratory studies show that it works as both an antioxidant and anti-inflammatory agent in some laboratory animals, there is very little research that shows that it has any real effects on human health.

Lignans are found in legumes, cereals, grains, fruits, algae, and some vegetables. The best sources include flax and sesame seeds. Eating a diet rich in lignans may be good for cardiovascular health, but research studies on humans are generally of low quality and it’s not easy to eat a lot of lignans unless you take them as dietary supplements or gulp down spoonfuls of flax seeds.

Should I Take Polyphenol Supplements?

Some polyphenols, such as epigallocatechin gallate (EGCG) and resveratrol, are sold as dietary supplements, usually marketed as antioxidants. But, current research evidence suggests that you'll get the most benefit if you get your polyphenols from foods rather than pills or potions.

A Word From Verywell

Although it's not clear how beneficial individual polyphenols are to your health, it is clear that eating foods high in these plant chemicals is good for you. Choose a balanced diet with lots of colorful fruits, fresh vegetables, whole grains and legumes and you'll get plenty of polyphenols. Here are a few tips:

  • Start with a breakfast featuring whole-grain cereal and coffee. 
  • Snack on fresh fruits rather than candy or cookies.
  • Eat a salad or vegetable soup with dinner.
  • Load your dinner plate with veggies and cut back on the heavy meat and cheese.
  • Enjoy berries as a bedtime snack if you're hungry.

Sources:

American Cancer Society. "Phytochemicals." 

Khurana S, Venkataraman K, Hollingsworth A, Piche M, Tai TC. "Polyphenols: Benefits to the cardiovascular system in health and in aging." Nutrients. 2013;5(10):3779-3827. 

Manach C, Scalbert A, Morand C, Rémésy C, Jiménez L. "Polyphenols: food sources and bioavailability." Am J Clin Nutr. 2004 May;79(5):727-47. 

Pandey KB, Rizvi SI. Plant polyphenols as dietary antioxidants in human health and disease. "Oxidative Medicine and Cellular Longevity." 2009;2(5):270-278.

Peterson J, Dwyer J, Adlercreutz H, Scalbert A, Jacques P, McCullough ML. "Dietary lignans: physiology and potential for cardiovascular disease risk reduction."  Nutrition reviews. 2010;68(10):571-603. 

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