Polymeric diets

Fell, J. M., Paintin, M., Arnaud-Battandier, F., Beattie, R. M., Hollis, A., Kitching, P., Donnet-Hughes, A., MacDonald, T. T., and Walker-Smith, J. A. (2000). Mucosal healing and a fall in mucosal pro-inflammatory cytokine mRNA induced by a specific oral polymeric diet in paediatric Crohn s disease. Aliment. Pharmacol. Ther. 14, 281-289. 

In vitro culture isolated brain cells exposed for 20 h to graded concentrations of nickel chloride up to 116 mg Ni/L DOMESTIC DOG, Canis familiaris Diet Time- and dose-dependent effects on kinetics of brain microtubule polymerization effects reversed on removal of Ni2+ from culture media 4... 

Flavan-3-ols represent the most common flavonoid consumed in the American and, most probably, the Western diet and are regarded as functional ingredients in various beverages, whole and processed foods, herbal remedies, and supplements. Their presence in food affects quality parameters such as astringency, bitterness, sourness, sweetness, salivary viscosity, aroma, and color formation [Aron and Kennedy, 2007]. Flavan-3-ols are structurally the most complex subclass of flavonoids ranging from the simple monomers ( + )-catechin and its isomer (—)-epicatechin to the oligomeric and polymeric proanthocyanidins (Fig. 1.10), which are also known as condensed tannins [Crozier et al., 2006b]. 

Nowadays, there is a renewed interest for the preparation of fructose, for its food applications as a diet sugar[16] as well as for its nonfood applications as a starting material for the synthesis of furanic precursors of nonpetroleum derived polymeric materials. [17 19]... 

The products of oxidation affect the flavor of foods, either directly or by reacting with precursors. Their biological value depends generally on the degree of change due to scission, polymerization, and oxidation. Furthermore, essential a.a. in oxidized foods may become limiting in the diet. Formation of protein-protein and protein-lipid cross-links decreases the digestibility of proteins. 

Fig. 33.11. Regulation of acetyl Co A carboxylase. This enzyme is regulated allosterically, both positively and negatively, by phosphorylation (circled P) and dephosphorylation, and by diet-induced induction (circled t). It is active in the dephosphorylated state when citrate causes it to polymerize. Dephosphorylation is catalyzed by an insulin-stimulated phosphatase. Low energy levels, via activation of an AMP-dependent protein kinase, cause the enzyme to be phosphorylated and inactivated. The ultimate product of fatty acid synthesis, palmitate, is converted to its CoA derivative palmityl CoA, which inhibits the enzyme. A high-calorie diet increases the rate of transcription of the gene for acetyl CoA carboxylase, whereas a low-calorie diet reduces transcription of this gene.

Amino acids are the monomers which are polymerized to produce proteins. Amino acid synthesis is the set of biochemical processes which build the amino adds from carbon sources like glucose. Not all amino acids may be synthesized by every organism, for example adult humans have to obtain 8 of the 20 amino adds from their diet. 

It was generally assumed that oxidation products from oils and fats are poorly absorbed. Indeed, animals can be resistant to the effects of abused oils in their diet (29,30). Nevertheless, orally administered oxidized C-linoleic acid was incorporated into chylomicrons and very low density lipoprotein (VLDL) particles in rats. The absorbed oxidation products were subsequently identified as hydroxy fatty acids (31). Interestingly, dietary glutathione (GSH) reduced the absorption of peroxidized linoleate (32), presumably due to the activity of selenium-dependrait GSH peroxidase present in the intestinal epithelial cell (33). However, these absorption studies used free fatty adds, not triglycerides thus, they cannot address the role of pancreatic lipase and phospholipase. The fate of polymerized fatty adds has not been studied specifically. Whether the intestinal flora could degrade fliese polymers and hence allow their absorption remains to be seen. What is clear is that very little is known about the absorption of oxidized fat in animals and even less in humans. 

Glycerides are major components of edible oils. Those which contain fatty acids with a relatively high degree of unsaturation are thought to provide benefits in the diet. The ability of highly unsaturated oils to polymerize in the presence of air has made them useful for paints. Glycerides that contain a predominance of saturated fatty acids can be converted to salts by treatment with bases (saponification). Sodium and potassium salts are useful for soaps, whereas lithium salts are components of lubricants. Triglycerides from seed oils possibly represent the most likely substitute for petroleum in the future. 

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