A mi no acid metabolism holds the key to understanding how and why nutrition is the answer lor treatment of chronic degenerative diseases. Knowledge of the biochemical processes involved with these vital compounds gives you a decided edge in dealing with acute immune problems as well. The many metabolic processes involved in protein metabolism form a fascinating array of complex activities that are intricately interwoven with those of carbohydrates and lipids. Before proceeding. I would like to point out that intestinal absorption of individual amino acids has been proven to be very poor compared to absorption of larger protein molecules, such as the dipeptide and polypeptide molecules provided by normal digestion of protein foods. The process of improving the body's ability to digest protein remains the most effective clinical method of restoring normal protein metabolism and utilization. Essential Ammo Acids All amino acids are essential for building our various body tissues. The label "essential" means that they are dietary essentials, and this includes nine or ten amino acids of the 20 or more amino acids. Whether or not an amino acid is considered to be essential depends on two factors: the body's ability to synthesize it's carbon skeleton, and the carbon skeleton's ability to accept nitrogen. It appears that some carbon skeletons accept nitrogen more readily than others. For example, glycine and ser-ine are considered to be "semi-essen- tial" because, while their carbon skeletons can be formed readily by the body, they do not accept nitrogen easily. The subject of essential is clouded even more because arginine and his-tidine have long been considered essential only for childhood growth. But, recent studies indicate that histidine may also be essential for adults. In addi- I tion, tyrosine is considered essential, j not because it fits the definition, but I because it is metabolized so rapidly in | the body. | Amphoteric Nature of Amino Acids j In chemistry, the word amino refers j to a base (alkaline) substance: so. we | are. at once, confronted by a paradox, j How can a material be both a base and | an acid at the same time, and why is | this important here? All amino acids I have the same general formula: a j chemical structure that combines acid j (COOH-) and base (NH,+) factors. | R stands for radical, or attached | side chains, found on every amino i acid. Each side chain is different, thus | making each amino acid different. | COOH—Carboxyl (acid) group. | This part of the molecule is the charac- I teristic acid group found in all acids. In I its ionic form, it carries the negative i charge. j NH2—Amino (alkaline) group. This part of the molecule carries the nitrogen and in its ionic form, the positive charge. As a result of this dual nature, an amino acid, in solution, can ionize (dissociate) to behave either as an acid or as a base, depending on the pH of the solution. This means that amino acids have a buffer capacity, which is an important clinical characteristic. Protein Buffering System The body has three primary buffering systems by which it maintains acid-base balance. Because of their high concentrations, the most plentiful of these are the plasma proteins and the protein within the cells. While the bicarbonate buffering system is the fastest responding of the three systems, it is estimated that the slower acting protein system performs about 75% of the work. The phosphate buffering system is found primarily within the tubular fluid of the kidneys. The Concept of Balance (Homeostasis) Many interdependent checks and balances exist throughout the body. There is a constant ebb-and-flow of materials, a building-up and breaking-down of parts, and a depositing and mobilizing of components. Many body mechanisms maintain internal physiological stability in a state of dynamic equilibrium. The body has NH2 COOH built-in controls that operate as finely tuned, coordinated responses to meet any situation that tends to disturb its normal condition or function. The resultant state of dynamic equilibrium is called Iwmeosiasis, and the various mechanisms designed to preserve it are called Iwmeostatic mechanisms. This sensitive balance between body parts and functions is life sustaining. Older ideas of a rigid body structure are giving way to this important balance concept of dynamic equilibrium, as more and more is learned about human nutrition and physiology. Protein Turnover and Dynamic Equilibrium All body constituents are in a constant state of flux, although some tissues are more actively engaged than others. This dynamic equilibrium is necessary to maintain homeostasis and meet the ever-changing stresses on the body. The body's protein tissues are continuously being broken down into amino acids and, then, resynthesized into tissue proteins. When "labeled" | amino acids are ingested, they are rapidly incorporated into various body tissue proteins. The rate of this protein turnover varies in different tissues. It is highest in the intestinal mucosa, liver, pancreas, kidney, and plasma. It is lower in muscle, brain, and skin tissues. There is slower protein turnover in structural tissues, such as collagen and bone matrix. The Body's Protein Storehouses Endogenous body protein exists in a balance between two compartments: the tissue protein compartment and the plasma protein compartment. These endogenous stores are further balanced with dietary protein intake. Protein from one compartment may be drawn to supply a need in the other. For example, during fasting, resources from the body protein stores may be used for tissue synthesis. But, the interesting fact is that, even when the intake of protein and other nutrients is adequate, the tissue proteins are still being constantly broken down and reformed. The adult body's state of stability, then, is the result of a balance between the rates of protein breakdown and resynthesis. In periods of growth, the synthesis (anabolic) rate is higher, so that new tissue can be formed. In conditions of starvation and wasting diseases and, more gradually, as the aging process continues in the elderly, the breakdown (catabolic) state exceeds that of synthesis, and the body gradually deteriorates. Metabolic Amino Acid Pool The term pool is used here in a collective sense. It refers to the total amount of a substance scattered in various parts of an organism's tissues and organs. In this case, it applies to the various sources of available amino acids for tissue protein synthesis. Amino acids derived from endogenous tissue break down and amino acids from dietary protein digestion and absorption: both comprise this common metabolic "pool" of aniino acids, and a balance ol amino acids is maintained to supply the body's constant needs. Shifts and balances between tissue breakdown and dietary protein intake ensure the constant availability of a balanced mixture of amino acids. From this reserve pool, specific amino acids can be supplied, as needed, for specific tissue protein synthesis, and to make up body losses. Metabolism of Amino Acids When energy levels are adequate, the amino acids derived from the diet are used first to synthesize tissue proteins. However, when energy levels are low. amino acids are deaminated and used for energy. This happens when: there are inadequate fat and carbohydrate levels to meet immediate needs: there are inadequate amounts of essential amino acids to synthesize required proteins: there are excessive amounts of amino acids—more than are needed: and the process of deamination releases ammonia (a poi son): but this is quickly converted to urea (Blood Urea Nitrogen), which is much less toxic and is excreted by the kidneys. The amino acids that are deaminated enter the same metabolic pathways as carbohydrate and lipids and arc converted to energy. About half of the amino acids, including alanine. serine. glycine. cysteine methionine. and tryptophan. are called tfliicoxenic aiiiino acids, because they serve as potential sources of glucose. Other amino acids, such as phenylalanine. tyrosine. leucine, isoleucine. and lysine. can be deaminated (lose their NH: group) and broken down like fat into the 2- carbon fragments that eventually form acetyl CoA. Like fat. these amino acids are able to form compounds called kcioncs. which can be used as a source of energy by the brain. They are. therefore, known as kcto^enic (imino micls. Of the remaining amino acids, all but aspartic acid are converted into glutamic acid, deaminaled, and used as an energy sources immediately. Aspartic acid that is not used in protein synthesis is deaminated and enters the metabolic cycle directly. A summary of the metabolism of amino acids is provided ill the Ibllinviiiii table. Summary In conclusion, allow me to reiterate that single amino acid supplementation is not the best course. Proper diet and enhanced digestion of protein, if needed, remains the best course. It is the author's opinion that poor protein digestion and assimilation are now major factors in the symptomatology seen in doctors' offices today. I have discussed that subject in several previous articles in The American Chiropractor. Howard F. Loomis, Jr.. DC. president of Enzyme Formulations. Inc.. has an extensive background in enzymes and enzyme formulations. As president of 21s' Century Nutrition. Inc.. for fifteen \ears. he has forged a remarkable career as an educator, having conducted over 400 seminars to date, in the United States. Canada. Germany, and Australia, on the diagnosis and treatment of enzyme deficiency syndromes. Call 2I-< Century Nutrition at I-H00-662-2630 for more information, o 1 IESTION °'"" / /ER AMINOACID - I POOL DIETARY PROTEIN TISSUE PROTEIN BOWEL A DIGESTION Syn'"es's a"dBreaMow" NhMREf < LIVER AMINOACID ► ENERGY NON.PROTBN URINE NITROGEN COMOPOUNDS UREA/CREATINE AMINO ACID CONVERSION TO ENERGY GLUCOGENIC AMINO ACIDS Glycine Alanine Serine Cysteine Methionine Tryptophan KETOGENIC AMINO ACIDS Leucine Isoleuclne Phenylalanine Tyrosine Lysine Glutamine OTHER AMINO ACIDS Valine Threonine Histidine Arginine Asparagine PYRUVATE ACETYL CoA GLUTAMIC ACID Deamlnated KREBS CYCLE ENERGY
