Health effects of phenols and polyphenols

Short description: Potential health effects of polyphenols

Because of the large structural diversity and extensive metabolism of dietary polyphenols, their fate in vivo and possible health effects remain undetermined as of the early 21st century.[1] Although polyphenols are speculated to be part of the health-promoting effects of consuming fruits and vegetables, no evidence exists to date that dietary polyphenols actually provide health benefits.[1][2]

## Contents

* 1 Bioavailability
* 2 Cognitive function
* 3 Cardiovascular health
* 4 Antioxidant activity
* 5 Cancer
* 6 Phlebotonic
* 7 Gut microbiome
* 8 See also
* 9 References
* 10 Further reading

## Bioavailability

Polyphenols have poor bioavailability, indicating that most of the amount consumed is extensively metabolized and excreted.[1][3] Gallic acid and isoflavones may show absorption of about 5%,[1][3] with amounts of catechins (flavan-3-ols), flavanones, and quercetin glucosides lower.[1] The least well-absorbed phenols are the proanthocyanidins, galloylated tea catechins, and anthocyanins.[3]

## Cognitive function

Polyphenols, including those in blueberries, are under preliminary research for possible cognitive effects in healthy adults and those with chronic diseases (e.g. mild cognitive dysfunction and cardiovascular disease).[4][5]

## Cardiovascular health

The European Food Safety Authority found that flavonols in cocoa - at doses exceeding 200 mg per day - could contribute to normal function of the vascular endothelium,[6] and olive oil polyphenols (5 mg of hydroxytyrosol and its derivatives (e.g. oleuropein complex and tyrosol) "contribute to the protection of blood lipids from oxidative damage", if consumed daily.[7] Because long-term studies of high polyphenol intake have not been conducted, there is a lack of knowledge about safety or effect on health of intake above levels in a normal diet.[1][8] A 2017 Cochrane review concluded that there is moderate-quality evidence that flavonol-rich cocoa products decrease blood pressure by only 2 mmHg in the short-term, although longer-term studies are needed.[9]

## Antioxidant activity

As interpreted by the Linus Pauling Institute[1] and the European Food Safety Authority (EFSA),[2] dietary flavonoids have little or no direct antioxidant food value following digestion.[10] Unlike controlled test tube conditions where antioxidant effects may result when high concentrations of flavonoids are used, the fate of ingested flavonoids in vivo shows they are poorly conserved (less than 5%), with most of what is absorbed existing as chemically modified metabolites destined for rapid excretion.[1]

## Cancer

As of 2019[update], there is little evidence that dietary flavonoids lower the risk of cancer.[1]

## Phlebotonic

Phlebotonics of heterogeneous composition, consisting partly of citrus peel extracts (flavonoids, such as hesperidin) and synthetic compounds, are used to treat chronic venous insufficiency and hemorrhoids.[11] Some are non-prescription dietary supplements, such as Diosmin,[11] while one other - Vasculera (Diosmiplex) - is a prescription medical food intended for treating venous disorders.[12] Their mechanism of action is undefined,[11] and clinical evidence of benefit for using phlebotonics to treat venous diseases is limited.[11]

## Gut microbiome

Polyphenols are under preliminary research as a potential metabolic factor in function of the gut microbiota.[13]

## See also

* Polyphenol
* Polyphenol antioxidant
* Flavonoid

## References

1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 "Flavonoids". Linus Pauling Institute, Micronutrient Information Center, Oregon State University. 2015. http://lpi.oregonstate.edu/mic/dietary-factors/phytochemicals/flavonoids.
2. ↑ 2.0 2.1 EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA)2, 3 European Food Safety Authority (EFSA), Parma, Italy (2010). "Scientific Opinion on the substantiation of health claims related to various food(s)/food constituent(s) and protection of cells from premature aging, antioxidant activity, antioxidant content and antioxidant properties, and protection of DNA, proteins and lipids from oxidative damage pursuant to Article 13(1) of Regulation (EC) No 1924/20061". EFSA Journal 8 (2): 1489. doi:10.2903/j.efsa.2010.1489.
3. ↑ 3.0 3.1 3.2 "Bioavailability and bioefficacy of polyphenols in humans. I. Review of 97 bioavailability studies". The American Journal of Clinical Nutrition 81 (1 Suppl): 230S–242S. January 2005. doi:10.1093/ajcn/81.1.230S. PMID 15640486.
4. ↑ Travica, Nikolaj; D'Cunha, Nathan M.; Naumovski, Nenad; Kent, Katherine; Mellor, Duane D.; Firth, Joseph; Georgousopoulou, Ekavi N.; Dean, Olivia M. et al. (March 2020). "The effect of blueberry interventions on cognitive performance and mood: A systematic review of randomized controlled trials". Brain, Behavior, and Immunity 85: 96–105. doi:10.1016/j.bbi.2019.04.001. PMID 30999017. https://publications.aston.ac.uk/id/eprint/39190/1/Blueberry_interventions.pdf.
5. ↑ Marx, Wolfgang; Kelly, Jaimon T; Marshall, Skye; Cutajar, Jennifer; Annois, Brigitte; Pipingas, Andrew; Tierney, Audrey; Itsiopoulos, Catherine (June 2018). "Effect of resveratrol supplementation on cognitive performance and mood in adults: a systematic literature review and meta-analysis of randomized controlled trials". Nutrition Reviews 76 (6): 432–443. doi:10.1093/nutrit/nuy010. PMID 29596658.
6. ↑ "Scientific Opinion on the modification of the authorisation of a health claim related to cocoa flavanols and maintenance of normal endothelium‐dependent vasodilation pursuant to Article 13(5) of Regulation (EC) No 1924/2006 following a request in accordance with Article 19 of Regulation (EC) No 1924/2006". EFSA Journal 12 (5). May 2014. doi:10.2903/j.efsa.2014.3654.
7. ↑ "Scientific Opinion on the substantiation of health claims related to polyphenols in olive and protection of LDL particles from oxidative damage (ID 1333, 1638, 1639, 1696, 2865), maintenance of normal blood HDL cholesterol concentrations (ID 1639), mainte". EFSA Journal 9 (4): 2033. April 2011. doi:10.2903/j.efsa.2011.2033.
8. ↑ "Evidence for a protective effect of polyphenols-containing foods on cardiovascular health: an update for clinicians". Therapeutic Advances in Chronic Disease 3 (2): 87–106. March 2012. doi:10.1177/2040622311430006. PMID 23251771.
9. ↑ Ried, Karin; Fakler, Peter; Stocks, Nigel P (25 April 2017). "Effect of cocoa on blood pressure". Cochrane Database of Systematic Reviews 4: CD008893. doi:10.1002/14651858.CD008893.pub3. PMID 28439881.
10. ↑ "Flavonoids: antioxidants or signalling molecules?". Free Radical Biology & Medicine 36 (7): 838–849. April 2004. doi:10.1016/j.freeradbiomed.2004.01.001. PMID 15019969.
11. ↑ 11.0 11.1 11.2 11.3 "Diosmin". Drugs.com. 1 January 2019. https://www.drugs.com/npp/diosmin.html. Retrieved 7 November 2019.
12. ↑ "Vasculera – diosmiplex tablet". National Institutes of Health. 26 April 2012. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=563d3d34-a547-471e-aecd-f4a4a57cbf1d. Retrieved 8 November 2019.
13. ↑ Catalkaya, Gizem; Venema, Koen; Lucini, Luigi; Rocchetti, Gabriele; Delmas, Dominique; Daglia, Maria; Filippis, Anna De; Xiao, Hang et al. (2020). "Interaction of dietary polyphenols and gut microbiota: Microbial metabolism of polyphenols, influence on the gut microbiota, and implications on host health" (in en). Food Frontiers 1 (2): 109–133. doi:10.1002/fft2.25. ISSN 2643-8429. https://onlinelibrary.wiley.com/doi/abs/10.1002/fft2.25.

## Further reading

* Fraga, Cesar G., ed (2010). Plant Phenolics and Human Health: Biochemistry, Nutrition and Pharmacology. Wiley. ISBN 978-0-470-28721-7.

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