Tannins digestion effects

LONGSTAFF M, MCNAB J M (1991) The inhibitory effects of hull polysaccharides and tannins of field beans (Vida faba L.) on the digestion of amino acids, starch and hpid and on digestive enzyme activities in young chicks. Br. TNutr. 65 199-216. 

Herbivores that commonly feed on tannin-rich plants have evolved interesting methods to lessen the effect of ingested tannins on their digestive systems. For example, the salivary proteins of rabbits and other rodents are high in the amino acid proline, which has a very high affinity for tannins. Eating food high in tannins stimulates the secretion of these proteins and diminishes the toxic effect of the tannins. 

The flavonoid quercetin suppresses growth somewhat in prairie voles, M. ochrogaster, while tannic acid, a hydrolyzable tannin, has an even stronger effect (Lindroth and Batzli, 1984). Quercetin is toxic, but does not bind with protein and, therefore, does not affect protein digestibility. Tannic acid has some effect on protein digestibility but is also toxic. 

Blytt, H. J., Guscar, T. K., and Butler, L. G. (1988). Antinutritional effects and ecological significance of dietary condensed tannins may not be due to binding and inhibiting digestive enzymes. Journal ofChemicalEcology 14,1455. 

Tannins have have been widely considered to reduce the digestibility and thus nutritional value of plant imterial to herbivores. Evidence from vivo studies exploring the potential allelochemical effects of tannins is reviewed together with infonnation regarding the probable irechanisms leading to observed effects. 

Recent publications on tannins and their effects on herbivores liave tended to deal specifically with only vertebrate (2,3) or invertebrate (, ) herbivores, and have drawn slightly different conclusions for the two groups. Sirtplistically, these are tliat tannins do not act as effective digestibility - reducers in insects, and that they have sotb, but not completely effective, deterrent action against maitmals. 

Feeny (13) attempted to resolve this dilemma by proposing that forest trees may have developed a particularly recalcitrant defense, one which even insects could not overcome in hundreds of generations. His suggestion was that protein-complexing polyphenols, or tannins, could provide such protection. However, there are many insects which feed preferentially on high-tannin content tissues (14, ), and specific adaptations exist which can nullify or reduce the digestion inhibition effects of tannins (16). ... 

N.A. Iridoid glycosides, verbenalin, saponins, tannins.100 102 123 Mild effect on the involuntary nervous system, which governs the digestive system. 

Folklore Kola is traditionally used in tonics for exhaustion and poor appetite. The tannins have an astringent effect in cases of diarrhoea. In the countries of origin the seed is ground as a condiment for food and chewed before meals to promote good digestion (Bown, 2003 British Herbal Medicine Association, 1983 Gruenwald et al., 2002 Tierra, 1998). 

McAllister TA, Martinez T, Bae FID, Muir AD, Yanke LJ, Jones GA. 2005. Characterization of condensed tannins purified from legume forages Chromophore production, protein precipitation, and inhibitory effects on cellulose digestion. J Chem Ecol 31 2049-2068. 

Ortiz, L.T., Centeno, C. and Trevino, J. (1993) Tannins in faba bean seeds effects on the digestion of protein and amino acids in growing chicks. Animal Feed Science and Technology 41, 271-278. 

Bhatta, R., Krishnamoorthy, U. and Mohammed, F. (2000) Effect of feeding tamarind (Tamarindus indica) seed husk as a source of tannin on dry matter intake, digestibility of nutrients and production performance of crossbred dairy cows in mid-lactation. Animal Teed Science and Technology 83(1), 67-74. 

Interactions between tannins and proteins have been extensively studied (Hager-man 1989 Haslam and Lilley 1988 Haslam et al. 1992), owing to their role in haze formation, astringency perception, and nutritional and anti-nutritional effects resulting from inhibition of various enzymes and reduction of dietary protein digestion. Other effects include reduced adsorption of /3-casein at the air-liquid interface in the presence of epigallocatechin gallate with potential consequences on foam properties (Sausse et al. 2003). 

Koenig WD (1991) The effects of tannins and hpids on digestion of acorns by acorn woodpeckers. Auk 108 79-88... 

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