Intake and bioaccessibility of total polyphenols in a whole diet

The knowledge of dietary intake of polyphenols and their bioaccessibility in the human gut are key factors in assessing their significance in human health. The aim of this work was to estimate the amount of total polyphenols consumed in a whole diet (Spanish Mediterranean diet) and their intestinal bioaccessibility. Total polyphenols were determined, as the sum of the polyphenols present in methanol:acetone:water extracts (extractable polyphenols) of plant foods and condensed tannins and hydrolysable polyphenols (non-extractable polyphenols) in the corresponding residues. The polyphenols intestinal bioaccessibility was estimated by an in vitro gastrointestinal model where food polyphenols are released by enzyme digestion and colonic fermentation. The mean daily intake of polyphenols in the Spanish diet was estimated between 2590 and 3016 mg/person/day. The amount of non-extractable polyphenols was almost double that of extractable polyphenols. It was estimated that about 48% of dietary polyphenols are bioaccessible in the small intestine, while 42% become bioaccessible in the large intestine.