Nutritional availability

Many pharmaceutical compounds are weak acids or bases that can be analyzed by an aqueous or nonaqueous acid-base titration examples include salicylic acid, phenobarbital, caffeine, and sulfanilamide. Amino acids and proteins can be analyzed in glacial acetic acid, using HCIO4 as the titrant. For example, a procedure for determining the amount of nutritionally available protein has been developed that is based on an acid-base titration of lysine residues. ... 

Cobalt. Cobalt is nutritionally available only as vitamin 2 ( )- Although Co " can function as a replacement in vitro for other divalent cations, in particular Zn ", no in vivo function for inorganic cobalt is known for humans (149). In mminant animals, B22 is synthesi2ed by bacteria in the mmen. 

Howard, A (1942) Medical testament , in Grant, D, Feeding the Family in War-time, Based on the New Knowledge of Nutrition. Available as a web-publication on http // joumeytoforever.org/farm library/medtest/medtest howard.html... 

Prolonged heating of protein-rich foods in alkaline conditions may decrease the nutritional availability of proteins by loss of essential amino... 

While the determination of total lysine is rather straightforward, the determination of free or available lysine is more problematic. In this situation, the term free is meant to imply that the e-amine of the lysine side chain has not reacted with various components of the sample matrix (most commonly carbohydrates via Maillard browning). This is important because reaction of the e-amine can render lysine nutritionally unavailable and the nutritive value for that protein is then diminished if lysine is the limiting amino acid (which is often the situation with soy proteins). While enzymatic digestion in the human gut may not release the modified lysine in a nutritionally available state, often these lysine adducts are labile to the standard acid hydrolysis in 6N HC1 at 110°C. This results in total lysine values that overestimate the amount of nutritionally available lysine. 

Of the eight amino acids essential for man and other animals, lysine is the most easily damaged by processing and/or storage of food. This damage or modification results in a reduction in nutritional availability of lysine. Available lysine can be... 

The nutritional availability of lysine in foods of plant and animal origin may be significantly decreased by the ready involvement of the C-NH2 group of lysine in intra- and intermolecular... 

In addition to cytochrome P-450 induction, other diet induced metabolic effects are likely to be involved in carcinogenesis. High temperature processing or long-term storage of foods with attendant exposure to oxygen can lead to the formation of lipid peroxides and oxidized sulfur amino acids in the food. The partially oxidized S-amino acids cystine monoxide (CMO) and methionine sulfoxide (MSO) are nutritionally available, but require in vivo conversion to the reduced amino acids at the... 

Lysine locked up as e-glycosylamine appears to be nutritionally available.7... 

Because of the partial recovery of lysine, the interpretation of the results of the analysis is complicated. It is important to bear in mind that lysine locked up in the Amadori compound, although partially recoverable by amino acid analysis, is no longer nutritionally available. 

The determination of nutritionally available lysine was dealt in Chapter 2. 

During the processing of foods, several chemical reactions affect the structure of some amino acids reactions with reducing sugars and polyphenols, interaction of the side chains of the amino acids, oxidation, etc. In some cases, these chemical modifications do not seem to change the nutritional availability of the amino acids involved, while in other cases, they do. In all cases, the presence of the newly formed molecules induces biochemical and physiological changes. 

Nutritional Availability of Acylated Lysine and Proteins. The successful use of chemically derivatized proteins as food ingredients requires that they be digestible and nontoxic, and that the modified amino acid residues should be available nutritionally. Nutritional studies using modified food proteins are limited. The nutritional availability of several acylated lysines were studied by Bjarnason and Carpenter (105) and Mauron (106) and the results are summarized in Table III. The bioavailability of the acylated lysine varied significantly with the type of the acyl groups (see Table III). In addition acylated proteins (acetylated and succinylated) gave lower responses to the growth activity for the rats than equivalent supplements of unmodified proteins... 

Table III. Nutritional Availability of Acylated Lysine Percent Utilization as a Source Derivatives ...

Acidic pH conditions caused the removal of dtraconyl groups from the citraconylated yeast proteins, so the environmental conditions of the stomach, i.e., pH and temperature, may cause the deacylation to occur following consumption of citraconylated proteins. This then would make lysine nutritionally available. The peptic digestibility of the citraconylated and decitraconylated yeast proteins was determined soy proteins and egg albumin were studied also for comparison. In a typical experi-... 

The total amount of a given element in the diet is not always the measure of its nutritional availability. Many trace metals... 

These categories are nseful for understanding the kinetics of exchange reactions (less acidic cations tend to exchange water or other hgands more rapidly), enviromnental persistence, and nutritional availability (see Nutritional Aspects of Metals Trace Elements). Thus, natural waters polluted by acid rain may have pHs as low as 2 or 3 in such waters and only in such waters do moderately acidic cations such as Fe + and... 

Ascorbyl palmitate and ascorbyl stearate are synthetic derivatives of ascorbic acid. Ascorbic palmitate is soluble in lipid-containing foods because of its relatively good hydrophobicity (88). Ascorbyl palmitate is hydrolyzed by the digestive system to provide nutritionally available ascorbic acid and palmitic acid, but health claims cannot be made for its vitamin C contribution. 

Coral-roots are saprophytic orchids of forests. These plants lack chlorophyll and depend on nutrition available from the decomposer food web of the forest floor to supply their needs. These plants and their flowers are reddish purple in color. The most widespread species is the spotted coral-root (Corallorhiza maculata). 

This observation seems to run directly counter to common assumptions (4) that, over the normal range of hemoglobin levels, the concentration of hemoglobin in the blood is directly related to the body iron stores (and to the amount and nutritional availability of iron in the diet). As such, this situation seemed worthy of further experimental study. 

The final point is perhaps the most critical as well as the most overlooked. Even under normal circumstances the fish thyroid cascade responds to a wide array of environmental variables and changes in whole-animal physiologic state. In fact, much fish thyroid literature (unrelated to ecotoxicants) documents thyroidal responses to variables such as temperature, stressors, nutritional availability and sexual state. The thyroidal system is also pivotal in the total endocrine network. Consequently,... 

Mutanen M, Koivistoinen P, Morris VC, et al. 1987. Relative nutritional availability to rats of selenium in Finnish spring wheat (Triticum aestivum L.) fertilized or sprayed with sodium selenate and in an American winter bread wheat naturally high in Se. Br J Nutr 57 319-329. 

The encrusting of cellulose fibrils by lignin-carbohydrate complexes within the cell wall is still a possible mechanism for lowered cellulose availability. The nutritive availability of the different fractions of hemicellulose and cellulose is quite different as shown by the data of Gaillard (26) in Table IV. Xylan is generally less digestible than other fractions (26, 30), and Lyford et ah (36) have shown that the micellular pentosans have a low digestibility. 

FA distribution in TAG as well as in phospholipids affects the physical properties, lipolitic and oxidative stability, and nutritional availability of lipids. In many TAG, the FA are arranged in a nonrandom distribution. In plants, monoenoic FA and PUFA are dominant at a sn-2 position (Orthoefer, 1996). In pig depot fat and in cow s milk, the TAG sn-2 position is occupied by palmitic acid. The distribution is also different in cattle and sheep depot fats (Love, 1996). In blubber seals, long-chain n-3 PUFA are esterified rather in sn-l,3 positions, whereas, in muscle, TAG in the sn-2 position that is typical for the lipid muscles of nearly all fish (Ackman, 1994). Enzymatic syntheses of structured TAG containing dY-5,8,ll,14,17-eicosapentaenoic acid (EPA) and dY-4,7,10,13,16,19-docosahexaenoic acid (DHA) in the sn-2 position with medium-chain FA at the end positions are particularly interesting (Halldorsson... 

Sources. Niacin and substances that are convertible to niacin are found naturally in meat (especially red meat), poultry, fish, legumes, and yeast. In addition to preformed niacin, some L-tryptophan found in the proteins of these foods is metabolized to niacin. Niacin is also present in cereal grains, such as corn and wheat. However, consumption of corn-rich diets has resulted in niacin deficiency in certain populations. The reason for this is that niacin exists in cereal grains in bound forms, such as the glycoside niacytin, which exhibit little or no nutritional availability. Interestingly, niacin deficiency is not common in Mexico and Central America even though the diets of those in these countries are based on com. Alkaline treatment, such as soaking corn in a lime solution—the process used by the populations of Mexico and Central America in the production of com tortillas—yields release of bound niacin and increased availability of the vitamin. 

The term fat can refer to a wide array of substances—oil, tallow, lard, fatty acids, all the glycerides (tri-, di-, and mono-), etc. All of these are nutritionally available, and all contain the same high level of energy, of about 9cal/g, while carbohydrates and protein only contain 4cal/g. 

From this, it should be clear that what an animal is fed influences the composition of its waste. If any closed-cycle BU, such as a biome is to be formed, then the normal cycle of wastes from some biome constituents feeding other constituents may be disrupted without proper nutritional availability. 

Essential nutrient elements snch as Cu, Fe and Mn can be successfully incorporated into slowly soluble phosphate glass pellets, and fed to ruminant animals (Section 12.9). The glass pellet stays lodged in the rumen for several months where it supplies the nutrient elements [12]. Phospholipids are incorporated in some formnlations to improve animal metabolism. Phosphorus compounds are sometimes added to commercial prodncts for anti-microbial action or to increase their stability. Grains and seeds generally contain more P than hays and grasses, but in the former case much is present as phytic acid salts which are not easily nutritionally available. In some cases appropriate enzymes can be added to rectify this. 

Faure, G.C. Dynamics of the main immunologically and nutritionally available proteins of human milk during lacta- 40. 

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