Health enhancing properties of berries

A group of recently published papers in the ASAP section of the Journal of Agricultural and Food Chemistry (JAFC) highlight how the dietary intake of berry fruits can have an important impact on human health, performance and disease. Several of the authors were also contributors to the 2007 International Berry Health Benefits Symposium held in Oregon, US in June 2007. Dr Navindra P Seeram, who co-authors several articles, is Assistant Director of the University of California-LA (UCLA) Center for Human Nutrition and Adjunct Assistant Professor at the David Geffen School of Medicine at UCLA.
Alongside well known raspberries, blackberries, cranberries and blueberries, Seeram introduces an extraordinary list of lesser known berries such as the chokeberry, the crowberry, the silver buffalo berry, the serviceberry, the Chilean maqui berry and the Brazilian acai berry. Huge strides, he says, have been made in identifying the phytochemicals present in berries and in elucidating the cellular and molecular mechanisms of action of some of these compounds.  Although berries contain both micro-and macronutrients including vitamins, minerals, folate and fibre, their various biological properties have been linked to their content of polyphenolic compounds. Amongst these, it is thought that it is the hydrophilic compounds which play the most important role in the bioactivities of berries.  In addition, it appears that complementary, additive or synergistic effects of several berry components are responsible for the observed biological properties rather than individual compounds.
Berry phenolics include flavonoids (anthocyanins, flavonols and flavanols), condensed tannins (proanthocyanidins) and hydrolysable tannins (ellagitannins and gallotannins), stilbenoids and phenolic acids.  Anthocyanins, which give berries their distinctive colours, have been the best studied of the berry phenolics and are thought to have anti-cancer, anti-inflammatory and antioxidant properties. The levels of a particular type of tannin can vary considerably between commonly consumed berries.  Blueberries and cranberries, for instance contain mainly proanthocyanidins while blackberries, red raspberries and strawberries contain predominantly ellagitannins. Therefore the type and specific chemical structure of tannins may contribute significantly to its unique biological properties. For example, the bacterial anti-adhesive properties of the cranberry is accounted for by its possession of specific A-type oligomeric proanthocyanidins. In the case of strawberries and blueberries, aging rats fed a strawberry diet had better protection against spatial deficits while animals fed on blueberries had improved reversal learning, a behaviour more dependent on intact striatal function  in the brain. Although best known for their ability to act as antioxidants, the biological activities of berry phytochemicals are now being shown to encompass the regulation of metabolising enzymes, the modulation of nuclear receptors, gene expression and subcellular signalling pathways, and the repair of oxidative damage to DNA. 
Individual papers on berries appearing in JAFC cover: the anti-proliferative properties of strawberry phenolics; ellagitannins in blackberries; anthocyanins and dietary fats; how processing and storage affect monomeric anthocyanins in blackberry products; berry fruits for cancer prevention; biological activity affected by strawberry genotype; cranberry proanthocyanidins and apoptosis; the composition and properties of wild berries used by native North Americans; the bioavailability of pelargonidin-3-O-glucoside from strawberries consumed with and without cream;  antimicrobial and antioxidant activity of the bilberry; berry fruits and the aging brain; anti-cancer properties of strawberry phenolics. 
A related article co-authored by Dr Seeram compares the antioxidant potency, the ability to inhibit LDL oxidation and the total polyphenol content of commonly consumed polyphenol-rich beverages in the United States. In descending order of potency the beverages were found to be pomegranate juice, red wine, Concorde grape juice, blueberry juice, black cherry juice, acai juice, cranberry juice, orange juice, iced tea and apple juice.