British Journal of Nutrition

Full Papers

Berry flavonoids and phenolics: bioavailability and evidence of protective effects

Daniele Del Rioa1, Gina Borgesa2 and Alan Croziera2 c1

a1 Human Nutrition Unit, Department of Public Health, University of Parma, Via Volturno 39, 43100 Parma, Italy

a2 Plant Products and Human Nutrition Group, School of Medicine, College of Medical, Veterinary and Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, UK


Berries contain vitamin C and are also a rich source of phytochemicals, especially anthocyanins which occur along with other classes of phenolic compounds, including ellagitannins, flavan-3-ols, procyanidins, flavonols and hydroxybenzoate derivatives. This review examines studies with both human subjects and animals on the absorption of these compounds, and their glucuronide, sulphate and methylated metabolites, into the circulatory system from the gastrointestinal tract and the evidence for their localisation within the body in organs such as the brain and eyes. The involvement of the colonic microflora in catabolising dietary flavonoids that pass from the small to the large intestine is discussed along with the potential fate and role of the resultant phenolic acids that can be produced in substantial quantities. The in vitro and in vivo bioactivities of these polyphenol metabolites and catabolites are assessed, and the current evidence for their involvement in the protective effects of dietary polyphenols, within the gastrointestinal tract and other parts of the body to which they are transported by the circulatory system, is reviewed.

(Received January 25 2010)

(Accepted February 24 2010)


c1 Corresponding author: A. Crozier, fax +44 141 3305394, email


Abbreviations: Cmax, peak plasma concentration; Tmax, maximum time