[Role of polyphenols in the low nutritive value of Vicia faba]

The inclusion of field bean (Vicia faba) in diets for growing experimental animals, reduced their growth performance in a similar way as compared with controls fed a casein diet, with 0.2% tannic acid. Hydroalcoholic extracts or isolated tannins obtained from Vicia faba seeds, decreased the intestinal transport of D-glucose. The addition of 0.05, 0.1 or 0.2% of tannic acid to the perfusion solutions containing D-glucose proportionally diminished the intestinal uptake of sugar according to its poliphenolic content. It has been postulated that polyphenols reduce, at least partially, the nutritive value of legumes, by altering monosaccharide absorption. Other constituents, however, could also be involved.