Berries are a rich dietary source of bioactive polyphenols, including flavonoids, such as anthocyanins(1). Dietary flavonoids are known to decrease the expression of the facilitative GLUT2 and the sodium-glucose cotransporter (SGLT1) genes, the two main glucose transporters in human subjects' intestinal Caco-2 cells(2). Acute inhibitory effects on glucose absorption have previously been observed in the presence of flavonoids, however, little is known regarding genomic effects on uptake(3). The present study investigated the influence of a flavonoid-rich berry-extract on glucose uptake in human subject's intestinal Caco-2 cell monolayers.
Human subject’s intestinal Caco-2 cells, cultured for 19 d, were treated, acutely (15 min) or chronically (16 h) with a flavonoid-rich berry-extract (OptiBerry; InterHealth Nutraceuticals, Benicia, CA, USA) at a final concentration of 0.125% (w/v) then subjected to radiolabelled glucose for 2 min, in the presence or absence of Na. Uptake was determined by liquid scintillation counting of cell lysate. Data were normalised to cell protein concentration and presented as uptake as a percentage of control. Statistical significance was determined by Student's t-test (P⩽0.05; n 12).
Results indicated that berry flavonoids significantly decrease glucose uptake in human subject's intestinal Caco-2 cells both acutely and chronically. These inhibitory effects are evident in both Na -dependent and Na -independent glucose uptake pathways. Studies are in progress to investigate the biological relevance of the observed effects in relation to berry consumption and glucose metabolism. Potentially, such berry-extracts may be useful in the dietary modulation of postprandial glucose homeostasis.