Selective bio-availability of phenolic acids from Scottish strawberries

Scottish strawberries were found to be a rich source of phenolic acids, namely benzoic (1287.95 +/- 279.98 mg/kg) and cinnamic (1159.40 +/- 233.96 mg/kg) acids, both free and attached to other plant components. Studies suggest a chemopreventative role for such compounds in several major clinical conditions, but the anticipated benefits are likely to be affected by their bio-availability and metabolic fate. In this pilot study, strawberries (750 g) was consumed by four healthy human volunteers (32 +/- 6 years). Only the benzoic acids were detected in the plasma. Of these, the major free ( gentisic, protocatechuic and p-hydroxybenzoic acid) and conjugated (syringic acid) benzoic acids were 26-27% recovered in the urine within 5 h. Cinnamic acids were completely undetected in plasma and only trace amounts were found in the urine. Since, the cinnamic acids escaped absorption early in the gastrointestinal tract, their release and/or metabolism is dependant on the host colonic microbiota. Results indicate that there is a high degree of selective absorption of strawberry phenolic acids into the systemic circulation. If selective absorption of phenolic acids is observed with consumption of other plant-based foods, this is likely to have implications for the bioactive role of these compounds in chronic disease prevention.