Polyphenols

Polyphenols are bioactive compounds extensively found in plant foods, known for their health-promoting effects through various mechanisms such as antioxidation, anti-inflammation, immunomodulation, and modulation of gut microbiota (2, 3). Despite their potential benefits, polyphenols exhibit extremely low bioavailability (1).

Sources and Types of Polyphenols

Polyphenols are present in a wide range of plant-based foods, including:

• Fruits


• Vegetables


• Nuts


• Seeds


• Roots


• Bark


• Leaves


• Herbs


• Whole grains

These compounds are categorized based on their chemical structure into several types:

• Phenolic acids: Found in fruits, vegetables, and grains.


• Flavonoids: Present in fruits, vegetables, tea, and wine.


• Anthocyanins: Found in red, blue, and purple berries and other fruits.


• Tannins: Present in tea, wine, and certain fruits.


• Lignins: Found in seeds, whole grains, and vegetables.

Health Benefits and Mechanisms

Polyphenols are associated with numerous health benefits, including:

• Antioxidant properties: They reduce oxidative stress by neutralizing free radicals, which is thought to be anti-inflammatory, cancer-preventive, cardioprotective, and neuroprotective.


• Prebiotic and synbiotic potential: Polyphenols are emerging as suitable candidates due to their ability to modulate gut microbiota, offering an alternative to traditional oligosaccharide-based prebiotics.

Consumption of polyphenol-rich foods is linked to a lower risk of chronic diseases such as cardiovascular disease, type 2 diabetes, and certain cancers (10, 11).

Non-bioaccessible polyphenols reach the large intestine where they help maintain gut health. Diets high in fruits and vegetables lower colorectal cancer risk (17) However, only bioaccessible polyphenols are absorbed in the small intestine. They reach the bloodstream and protect the heart (16)

Bioavailability and Factors Affecting It

Polyphenols in fruits and vegetables need to be bioavailable. Therefore, they must be released from plant cells by cells break. Processing or chewing causes this. Lipid membranes and cell walls fracture and contents are then released (11, 13).

Polyphenols meet the plant cell wall (PCW) when exiting where binding interactions can occur. This is relevant for processed foods. Purees and sauces have ruptured cell walls and polyphenol-PCW interactions last longer (11, 13).

Studies show apple polyphenols interact with cell walls, too. Oligomeric procyanidins bind selectively. They interact more with pectin than cellulose affecting bioaccessibility (14, 15).

The bioavailability of polyphenols is influenced by several factors:

• Chemical structure


• Food matrix


• Interactions with other food components, such as milk proteins, which may enhance bioavailability through protein-polyphenol interactions.

Despite their poor oral bioavailability, polyphenols are extensively modified by the gut microbiota, which influences their effects (6, 7).

Daily Intake and Epidemiological Evidence

The average daily intake of polyphenols is greater than 1 gram (4, 5). Epidemiological studies suggest that consuming foods rich in polyphenols can reduce the risk of cardiovascular diseases and colon cancer (8, 9).

Conclusion

Polyphenols, with over 6,000 known compounds, are a diverse group of metabolites characterized by phenolic functional groups. They are abundant in plant foods such as vegetables, coffee, and tea, and are associated with improved health outcomes, including reduced inflammation, lower risk of cardiovascular disease, and healthy aging (12).

References

(1) Pang et al. 2023 Nat Commun. 14(1): 2656
(2) Zeng et al. 2020 Oxidative Medicine and Cellular Longevity ID 3836172
(3) Zhou et al. 2021g Oxidative Medicine and Cellular Longevity 2021:6627355
(4) Taguchi et al. 2015 Nutrients 7: 10269-10281
(5) Huang et al. 2020 J Acad Nutr Diet 120: 1821-1833
(6) van Duynhoven et al. 2011 Proc Natl Acad Sci USA 108: 4531-4538
(7) Manach et al. 2017 Mol Nutr Food Res 61: 1600557
(8) Arts & Hollman 2005 Am J Clin Nutr 81: 317S-325S
(9) Cory et al. 2018 Front Nutr 5: 87
(10) Scalbert et al. 2005 Am J Clin Nutr 81: 215s-217s
(11) Padayachee et al. 2012 Food Chem 134: 155-161
(12) Harborne & Williams 2000 Phytochemistry 55: 481-504
(13) Padayachee et al. 2012 Food Chem 135: 2287-2292
(14) Le Bourvellec et al. 2005 Bba-Gen Subj 1725: 10-18
(15) Renard et al. 2001 Int J Biol Macromol 29: 115-125
(16) Crozier et al. 2009 Nat Prod Rep 26: 1001-1043
(17) Beliveau 2007 Can Fam Physician 53: 1905-1911

see also:
Cardiovascular Diseases (CVD) & Prevention / Preventive healthcare.