Protective effects of polyphenol-rich blackcurrant preparation on biochemical and metabolic biomarkers of rats fed a diet high in fructose.

The purpose of the study was to compare in vivo effects of dietary supplementation with blackcurrant pomaces containing variable level of phenolic compounds on blood and internal organ parameters in rats. Forty-eight growing Wistar rats were allocated to six treatment groups in which they were fed ad libitum for 4 weeks the following diets: standard chow (group S), high-fructose diet (group F), standard chow supplemented with 7.7% of either rich in polyphenols unprocessed blackcurrant pomace (UB) or polyphenol-deprived processed pomace (PB) (groups SUB and SPB respectively), and high-fructose diet with 7.7% of either UB or PB (groups FUB and FPB respectively). Blackcurrant pomace, irrespective of its phenolic content, selectively modulated the enzymatic activity of the colon microflora, reducing the activity of enzymes with potentially harmful properties and promoting activities of enzymes that might increase the use of carbohydrates that escaped digestion in the upper gastrointestinal tract. Although both pomaces increased antioxidant status of the liver and blood serum, the unprocessed pomace showed a greater ability to inhibit lipid peroxidation in heart and kidney than the pomace that was less abundant in polyphenols. Both of the examined pomaces had a positive influence on serum lipid profile, but better hypocholesterolemic effect was observed after supplementation of the diet with unprocessed preparation. The biochemical action of unprocessed pomace in the normalization of fructose-induced disturbances was more distinct than those of pomace remaining after extraction.