What Are the 6 Polyphenols? A Guide to Nutrition and Health

October 16, 2025 •

3 min read

Over 8,000 different types of polyphenols have been identified in plants, contributing to their vibrant colors and defense mechanisms. Understanding what are the 6 polyphenols, the main classifications of these beneficial compounds, is key to optimizing your diet for better health.

Quick Summary

This article explains the six major classes of polyphenols, such as flavonoids and phenolic acids, detailing their dietary sources and functional benefits for human health.

Key Points

Major Polyphenol Classes: The primary classes of polyphenols are flavonoids, phenolic acids, stilbenes, and lignans, along with significant groups like curcuminoids and polyphenolic amides.
Flavonoids are a Diverse Group: The largest class, flavonoids, includes six subclasses like flavanols (in tea and apples) and anthocyanins (in berries).
Antioxidant Power: A key function of polyphenols is to act as potent antioxidants, neutralizing free radicals and protecting against cellular damage.
Reduce Inflammation: By modulating inflammatory pathways, polyphenols help protect against many chronic diseases linked to inflammation.
Found in Everyday Foods: Many common foods like coffee, tea, fruits, vegetables, nuts, and spices are rich sources of different types of polyphenols.
Boost Intake Naturally: You can increase your polyphenol consumption by eating a wider variety of colorful plant-based foods and avoiding peeling the skin of fruits and vegetables.

The four main polyphenol classes

1. Flavonoids

Flavonoids are the most abundant group of polyphenols, with over 4,000 types. They give color to many plants. This class has six subclasses:

Flavonols: Found in onions, kale, and tea. Quercetin is an example.
Flavones: Present in parsley and celery. Apigenin and luteolin are examples.
Flavanones: Common in citrus fruits, such as hesperetin.
Isoflavones: Found in soybeans and legumes, including genistein.
Anthocyanins: Provide red, purple, and blue colors to berries and grapes.
Flavan-3-ols: Found in tea, cocoa, and apples. Catechins are key examples.

2. Phenolic Acids

Making up about 30% of dietary polyphenols, phenolic acids are in many fruits, vegetables, and grains. They include:

Hydroxybenzoic acids: Found in berries and walnuts. Gallic acid is an example.
Hydroxycinnamic acids: Abundant in coffee and blueberries. Caffeic acid and ferulic acid are examples.

3. Stilbenes

Stilbenes are a smaller group known for antioxidant and anti-inflammatory properties.

Resveratrol: A well-known stilbene in grape skin and red wine.

4. Lignans

Lignans are diphenolic compounds found in various plant foods.

Secoisolariciresinol: Concentrated in flaxseeds.

Other significant polyphenol groups

5. Curcuminoids

These polyphenols are from turmeric root and are known for anti-inflammatory and antioxidant effects.

Curcumin: The main active compound in turmeric.

6. Polyphenolic Amides

This group includes capsaicinoids from chili peppers and avenanthramides from oats.

Capsaicin: Found in chili peppers.
Avenanthramides: Found in oats.

Comparison of Polyphenol Classes

The four major polyphenol classes—flavonoids, phenolic acids, stilbenes, and lignans—along with other groups like curcuminoids and polyphenolic amides, can be compared based on their chemical structure, food sources, and benefits. For example, flavonoids, the most abundant group, are found in berries and citrus and are known for antioxidant properties. Phenolic acids, present in coffee and grains, also have antioxidant and antimicrobial effects. Stilbenes like resveratrol in grapes are noted for anti-inflammatory action, while lignans in flaxseeds have antioxidant effects. Curcuminoids from turmeric are anti-inflammatory and antioxidant, and polyphenolic amides from chili peppers and oats also offer antioxidant and anti-inflammatory benefits.

Why are polyphenols important for your health?

A diet rich in polyphenols offers many health benefits. Their antioxidant activity helps protect against cellular damage from free radicals, which can lead to chronic diseases.

Reduced Inflammation: Polyphenols can help reduce inflammation, a factor in many chronic illnesses.
Cardiovascular Health: Regular consumption may improve blood pressure and cholesterol.
Cancer Prevention: Some polyphenols may help prevent or slow certain cancers.
Improved Cognitive Function: Polyphenols can help protect brain cells.
Blood Sugar Regulation: They can help regulate blood sugar, potentially reducing the risk of type 2 diabetes.
Gut Microbiome Support: Polyphenols are metabolized by gut bacteria, supporting a healthy gut.

How to increase your polyphenol intake

Increase your polyphenol intake by including diverse plant-based foods:

Eat colorful fruits and vegetables: Their pigments often indicate high polyphenol content.
Keep the skins on: Many polyphenols are in the skin of produce.
Choose whole grains: They contain lignans and phenolic acids.
Drink tea and coffee: These are significant sources.
Enjoy dark chocolate: It's rich in flavanols.
Use spices: Turmeric, cloves, and cinnamon add polyphenols.

Conclusion

Knowing what are the 6 polyphenols—the major classes including flavonoids, phenolic acids, stilbenes, lignans, curcuminoids, and polyphenolic amides—can help you create a healthier diet. Consuming a variety of plant foods allows you to benefit from their antioxidant and anti-inflammatory properties, supporting long-term health. Simple changes, like adding berries or drinking green tea, can boost your intake of these vital nutrients.

For more detailed information on specific polyphenol compounds, you can refer to the {Link: Phenol-Explorer database https://phenol-explorer.eu/}.

Frequently Asked Questions

Polyphenols are a broad family of natural plant compounds. Flavonoids are a major subclass within the polyphenol family, distinguished by their specific chemical structure.

Excellent sources include berries, apples, cherries, red wine, coffee, tea, flaxseeds, dark chocolate, and various vegetables like spinach and onions.

While generally beneficial and considered bioactive, the effects of polyphenols can depend on various factors, including dose. Some studies suggest potential pro-oxidant effects at high concentrations, but this is an area of ongoing research.

The effect of cooking varies by the type of polyphenol. Some may be lost or altered by heat, while others can become more bioavailable. Steaming tends to preserve higher levels than frying.

Most polyphenols are not absorbed in the small intestine. Instead, they are metabolized by beneficial bacteria in the large intestine, which has a positive prebiotic effect on the gut microbiome.

While resveratrol is the most studied stilbene, other stilbenes exist, such as pterostilbene found in blueberries. Resveratrol, however, is a key focus of research for its health benefits.

The health benefits of turmeric are largely attributed to its primary active polyphenolic compound, curcumin. Curcumin possesses potent anti-inflammatory, antioxidant, and immunomodulatory effects.