Dietary lignin

Begum, A.N., Nicolle, C., Mila, I., Lapierre, C., Nagano, K., Fukushima, K., Heinonen, S.-M., Adlercreutz, H., Remesy, C. and Scalbert, A. (2004) Dietary lignins are precursors of mammalian lignans in rats. Journal of Nutrition 134,120-127. 

Lignins, three-dimensional networks built of units of phenylpropane (Figure 3.5), are components of the tough or woodlike portions of plants and seeds. Bran and other cereal products are the main sources of dietary lignin. This fiber is distinguished by the fact that it is not degraded by enzymes produced by the human or by the gut microflora (Adlercreutz, 1984). 

Dietary lignin was somewhat more beneficial. Rats exposed to T-2 toxin again had depressed final body weight and feed consumption although 2.5 or 5% lignin lessened this effect when compared to animals fed the control diet. Feed efficiency decreased in response to T-2 toxin only with the feeding of 0 or 7.5% lignin. 

Historically, dietary fiber referred to iasoluble plant cell wall material, primarily polysaccharides, not digested by the endogenous enzymes of the human digestive tract. This definition has been extended to iaclude other nondigestible polysaccharides, from plants and other sources, that are iacorporated iato processed foods. Cellulose [9004-34-6] (qv) is fibrous however, lignin [9005-53-2] (qv) and many other polysaccharides ia food do not have fiberlike stmctures (see also Carbohydrates). 

The variation ia water solubiUty among polysaccharides results ia varied physiological roles. Plant ceU-waH polysaccharides and lignin provide iasoluble dietary fiber (IDF) nondigestible storage polysaccharides, some pectic polysaccharides, and most of the functional additives contribute soluble dietary fiber (SDF). 

Dietary fiber is a mixture of simple and complex polysaccharides and lignin. In intact plant tissue these components are organized into a complex matrix, which is not completely understood. The physical and chemical interactions that sustain this matrix affect its physicochemical properties and probably its physiological effects. Several of the polysaccharides classified as soluble fiber are soluble only after they have been extracted under fairly rigorous conditions. 

Dietary fiber and fiber-rich food fractions bind bile acids and bile salts in vitro. This interaction is more pronounced for the lignin component. 

Dietary fibre, which comprises all the non-digestible structural carbohydrates of plant cell walls and any associate lignin, provides a further example of a complex food-borne factor which cannot be classified as a nutrient, and which continues to generate debate over such issues as definition and analytical techniques. However, whatever the unresolved complexities, dietary fibre has a lengthy history and had proved itself eminently suitable as a component of functional food products long before the term was even coined. 

DF dietary fiber Cel cellulose Rha rhamnose Fuc fucose Ara arabinose Xyl xylose Man mannose Gal galactose Glu glucose U. ac. uronic acids KL Klason lignin n.d. not determined t traces Source Englyst and Cummings 1988 Englyst and others 1988 Marlett and Vollendorf 1994. 

Bunzel M, Seiler A and Steinhart H. 2005. Characterization of dietary fiber lignins from fruits and vegetables using the DCFR method. J Agric Food Chem 53 9553-9559. 

Dietary Fibre. An area of some contention is what should be included as dietary fibre. There are several different methods of measuring dietary fibre and all of them will give different results on the same sample. The EU favours the Association of Analytical Chemists (AOAC) method, which includes lignin and resistant starch, while the UK has preferred the Englyst method and has defined fibre as nonstarch polysaccharides from cell walls as the only substances that count as fibre. 

Bile acids and salts have been found to enhance the absorption of both calcium and vitamin D hence, to increase calcium absorption both directly and indirectly (3,37). However, the ability of some dietary fibers such as lignin and pectin to absorb conjugated and deconjugated bile salts onto their surfaces to be excreted in the feces (a mechanism credited to the hypocholesterolemic effect of some dietary fibers) may result in an overall decrease in calcium absorption from the gastrointestinal tract (7,33,38-40). 

Dietary fibre was defined by Hugh TroweU as the plant polysaccharides and lignin which are resistant to hydrolysis by the digestive enzymes of humans . This definition lacks chemical precision, because non-flbrous pectins and gums are also present. The term nonstarch polysaccharide (NSP) is often preferred, although the term dietary fibre still persists. Unfortunately, NSP is also not satisfactory since some starch, known as resistant or par-... 

The plant precursors of mammalian lignans include secoisolaricinol, laricresinol, matair-esinol, 7-hydroxymatairesinol, pinoresinol, and lignin. ° ° Flaxseed and whole cereal grains are considered the most important dietary sources, but many others are known, for example, strawberry achenes, berries, coffee beans, tea leaves, etc. ... 

Fiber Dietary fiber is defined as the nondigestible carbohydrates and lignin (a complex polymer of phenylpropanoid subunits) pres ent in plants. Several different terms are used to described this complex group of compounds. For example, functional fiber is the... 

Lignin [9005-53-2] - [CHEMURGY] (Vol 5) -as dietary fiber [DIETARY FIBER] (Vol 8) -as food additive pOOD ADDITIVES] (Vol 11) -as fuel pUELS FROM WASTE] (Vol 12) -removal by bleaching pLEACHING AGENTS - PULP AND PAPER] (Vol 4) -m whiskey pEVERAGE SPIRITS DISTILLED] (Vol 4)... 

Dietary Fiber. Dietary fiber is a broad term that encompasses the indigestible carbohydrate and carbohydrate-like components of foods that are found predominantly in plant cell walls (see Carbohydrates). It includes cellulose lignin, hemicelluloses. pentosans, gums, and pectins. 

Animal feeds as well as human diets vary considerably in the type and quantity of dietary fiber. Wise and Gilbert (9) using modified detergent methods analyzed fourteen commercial rodent diets and found that the total dietary fiber content varied from 8.3 to 22.4%. In fact, it is not unusual for commercially available cereal-based rodent diets to contain 20% dietary fiber on a dry weight basis (10). In general, the fermentable fibers constitute more than half of the total dietary fiber the remainder composed of the fibers more resistant to fermentation, such as cellulose and lignin (9). Thus, a significant portion of rodent diets has the potential to be fermented in the intestinal tract. 

Lignin polymers are often found in most plant structures in association with cellulose. The structure of lignin is not well defined, but lignin appears to be made up of polymers of propylbenzene with hydroxy and methoxy groups attached. Lignin is primarily hydrocarbon in nature and makes up a major portion of insoluble dietary fiber. 

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