Nutritional Implications of Phenolic Monomers and Lignin: a Review

Abstract

Simple phenolic monomers and lignin are derived from the same biosynthetic pathway and occur in all vascular plants. p-Coumaric and ferulic acids appear to be the most common phenolic monomers in diets of animals. Free phenolics generally depress feed intake by animals. Several mammalian enzyme systems have been shown to be inhibited by phenolic monomers in vitro. Growth of both aerobic and anaerobic bacteria is inhibited by phenolic monomers. These monomers also are involved in cross-linking lignin with plant cell wall carbohydrates. The association of lignin with cell wall carbohydrates depresses extent of fiber digestion. Lignin is capable of binding nitrates, carcinogens, bile salts, amino acids and possibly minerals in the gastrointestinal tract. As with phenolic monomers, lignin inhibits microbial growth and enzymatic digestion. Soluble lignin-carbohydrate complexes are formed in the rumen and phenolic monomers bound to the cell wall are solubilized by bacterial action. The interrelationship of phenolic monomers and lignin requires that both groups be considered in discussing the effects of plant phenolics on nutrition. Copyright © 1983. American Society of Animal Science . Copyright 1983 by American Society of Animal Science