Diet and Nutrition

Polyphenol Supplements

New dietary supplements derived from polyphenol-rich foods are being developed for people to use.

Polyphenols Supplements: Sources, benefits, and risks


Studies show that an increase in the consumption of fresh fruits and vegetables can help reduce the risk of developing chronic health problems, such as neurodegenerative diseases, heart disease, and certain types of cancer. Dietary antioxidants can slow down the processes that contribute to the development of numerous chronic diseases.

Dietary polyphenols such as flavonoids and phenolic acids are the main sources of antioxidants for humans. These polyphenols come from many different plants, which include vegetables, fruits, herbs, and spices. For this reason, new dietary supplements derived from polyphenol-rich foods are being developed for people to use.

The consumption of these supplements can help increase a person’s dietary polyphenol intake, which results in more health benefits. However, excessive polyphenols in the diet may also elicit toxicity through pro-oxidative action.  

What are Polyphenols?

Polyphenols are compounds that possess antioxidant properties, which are useful when it comes to neutralizing free radicals (unstable molecules that can cause cellular damage). Polyphenol supplements are becoming popular among consumers because of their health benefits. However, it is still best to consult your doctor before taking any supplements, including polyphenols.  

Types of Polyphenols

Polyphenols can be identified by their ring-shaped structure and the number of their rings. There are four categories based on these differences, and they are flavonoids, phenolic acids, stilbenes, and lignans.

  • Flavonoids: These polyphenols not only work as antioxidants--they are also anti-inflammatory agents. They are divided into different classes, and they include flavones, isoflavones, flavanones, chalcones, catechins, and anthocyanidins. Flavonoids are abundantly found in red wine, green tea, and legumes. Another term for flavonoids is bioflavonoids, which are often sold as dietary supplements. 
  • Phenolic Acids: These are present in apples, plums, cherries, grapes, red wine, kiwi fruits, tea, coffee, and other fruits and vegetables, including grains and corn. These polyphenols are readily absorbed into the walls of the intestinal tract.
  • Stilbenes: The most popular example of this highly studied polyphenol is resveratrol. These compounds can boost heart health and are found in cranberries, blueberries, red wine, and peanuts. However, it is difficult to determine as to what extent this polyphenol benefits the body. According to studies done on laboratory animals, this polyphenol works as an anti-inflammatory agent as well as an antioxidant, but its real effects on human health have very little evidence.
  • Lignans: This polyphenol is found in cereals, fruits, legumes, grains, algae, and vegetables. The best sources of lignans are sesame seeds and flaxseeds. A high-lignan diet may be beneficial for heart health, but studies on humans still remain of low quality. Moreover, a lot of lignans can be difficult to consume, except when they are taken as dietary supplements or in spoonfuls. 

Polyphenol Supplements

Some polyphenols are available as dietary supplements, such as resveratrol and epigallocatechin gallate (EGCG). In the market, they are usually sold as antioxidants.

According to current research studies, polyphenols are better consumed from foods rather than from supplements. However, consuming polyphenols in large amounts may not be advisable or safe since excessive intake can cause:

  • Iron depletion (in populations who have marginal iron stores)
  • Interference with thyroid hormone metabolism
  • Certain drug interactions (enhancing the biological effects of pharmaceutical drugs)

The chances of consuming excess micronutrients more than the body needs can be reduced by eating a well-balanced and polyphenol-rich diet. If you want to take polyphenol supplements, know that a variety of compounds will be present in them. Read the package and choose trusted brands or manufacturers of the supplements you are taking. 

Polyphenols as Food Supplements

In recent years, red wine and dark chocolate have been included in the daily diet since researchers have found that it contains polyphenols. Due to their associated health benefits, they have been accepted by many. Moreover, it was found that cardiovascular health can improve and longevity can increase by drinking a glass of red wine or by eating dark chocolate. This benefit has been attributed to the polyphenols present in them. Polyphenols are naturally occurring compounds present in plants that contain powerful antioxidant properties.

Polyphenols are micronutrients that contain one or more phenolic hydroxyl group. They possess health-promoting properties and are found in a wide variety of plant food sources. Since they are also rich in antioxidants, they can be included in your daily diet. Studies have also shown that the polyphenol content in grapes can have a significant effect on a person's blood pressure. 

However, excessive intake of polyphenol supplements may also cause adverse side effects, such as impaired hormone production and an increased risk of cancer growth. 

There are plenty of food sources that contain polyphenols. They include:

  • Coffee
  • Certain spices
  • Cocoa powder
  • Berries 

Other polyphenol-rich foods include:

  • Blueberries
  • Strawberries
  • Blackberries
  • Apples
  • Plums
  • Blackcurrant
  • Pomegranates
  • Apples
  • Spinach
  • Chicory
  • Artichokes
  • Red onions
  • Beans (white and black beans)
  • Nuts such as hazelnuts, walnuts, pecans, and almonds
  • Beverages such as green tea, coffee, red wine, and black tea.
  • Dried peppermint
  • Cloves
  • Dark chocolate
  • Olive oil
  • Star anise

Final Thoughts

Although polyphenols and polyphenol supplements are an expanding nutritional discovery, there is still more work that needs to be done before researchers completely understand the implications of the use of polyphenol supplements.

Moreover, polyphenol use should not be self-prescribed. According to the notes of the American Journal of Clinical Nutrition (AJCN), more research studies are needed to properly determine the associated risks of polyphenol supplement use. The potential risks may include thyroid toxicity, estrogen-like activity, carcinogenic effects, antinutritional effects, and certain interactions with prescription drugs. 


Martin, Keith & L Appel, Christy. (2009). Polyphenols as dietary supplements: A double-edged sword. Nutrition and Dietary Supplements. 2. 10.2147/NDS.S6422.

Pandey, K. B., & Rizvi, S. I. (2009). Plant polyphenols as dietary antioxidants in human health and disease. Oxidative medicine and cellular longevity, 2(5), 270-8.

5 foods containing potentially heart-healthy polyphenols | Nutrition | UT Southwestern Medical Center. (2018). 

Kidd, Parris. (2009). Bioavailability and Activity of Phytosome Complexes from Botanical Polyphenols: The Silymarin, Curcumin, Green Tea, and Grape Seed Extracts. Alternative Medicine Review Volume 14, Number 3.

Louise I Mennen, Ron Walker, Catherine Bennetau-Pelissero, Augustin Scalbert; Risks and safety of polyphenol consumption, The American Journal of Clinical Nutrition, Volume 81, Issue 1, 1 January 2005, Pages 326S–329S,