Essential Amino Acid Supplementation Research Articles

Free Amino Acids in Citrullus vulgaris (Watermelon)

To the Editor.— Currently accepted dietary management of citrullinemia and other urea cycle disorders includes protein restriction, sodium benzoate, and dietary supplements of keto acids or essential amino acids with postblock intermediates such as arginine in citrullinemia and arginino-succinic aciduria. When a child survives the neonatal period on such a regimen and solid foods are introduced into the diet, there is at least one fruit that should be avoided, Citrullus Vulgaris, commonly known as watermelon. Quantitation of free amino acids extracted from 1 g wet weight of watermelon fruit yielded the following (in mmoles per gram wet weight): Phenylalanine, 1.25; histidine, 0.24; tryptophan, 0.35; lysine, 0.82; ornithine, 0.32; arginine, 11.36; aspartic acid, 0.97; threonine, 0.74; serine, 1.05; glutamine, 3.86; glutamic acid, 1.38; citrulline, 23.68; alanine, 1.15; valine, 0.17; isoleucine, 1.24; leucine, 0.24.

Quantitative digestion by sheep of carbohydrates, nitrogen and S-methyl-L-cysteine sulphoxide in diets of fresh kale (Brassica oleracea)

SummaryApparent digestibility of forage kale (cv. Maris Kestrel) was compared with that of mixed perennial ryegrass (0·85) and clover (0·15) herbage in two experiments. In a third experiment measurements were made of the partition of digestion between the reticulo-rumen and post-ruminal regions of the digestive tract in sheep fed kale, using intra-ruminal infusion of inert ruthenium phenanthroline and chromium-EDTA markers and time sequence sampling from the duodenum. Results in Expt 3 were compared with predicted values for a range of ruminant diets, including digestion of fresh perennial ryegrass and white clover.In Expts 1 and 2 the ratio of readily fermentable to structural carbohydrate (CHO) was much higher in kale (2·6–3·2) than in mixed ryegrass and clover herbage (0·6), and showed little difference between kale leaf and stem components. Apparent digestibilities of organic matter (OM), cellulose and hemicellulose were 80–90% for kale diets, varied little with changes in leaf/stem ratio, and were generally slightly higher than for mixed ryegrass and clover herbage. Calculated metabolizable energy (ME) concentrations were 12·0 and 11·7 MJ ME/kg D.M. for kale and mixed ryegrass and clover respectively.Despite large intakes of water-soluble CHO and pectins in kale-fed sheep in Expt 3, duodenal flows were small and respectively 92 and 98% of the total amounts digested were digested in the rumen. Ruminal cellulose digestion (95% total digested) was as predicted for normal ruminant diets, but less hemicellulose was digested in the rumen (71% total digested) than predicted. Total N flow at the duodenum was 5 g/day less than N intake, and respectively 27 and 66% of the N apparently digested was accounted for as total N absorption from the rumen and post-ruminal absorption of NAN. Calculated absorption of amino acids from the small intestine was less for the kale diet (14% ME intake) than for diets of fresh perennial ryegrass and white clover (20% ME intake). Possible reasons are that 10% more of the OM ingested was digested in the rumens of sheep fed kale than was predicted, that the ratio of dietary total N/100 g digestible OM was much less for kale (3·7) than for perennial ryegrass and white clover (5·6) diets, and that protein formed a lower proportion of the total N in kale diets (75%) than in diets of ryegrass and clover (90%). Despite 3·3 g of S-methyl-L-cysteine sulphoxide (SMCO) being consumed per day, none was detected in either rumen or duodenal contents or in faeces.In was concluded that complete conversion of SMCO to dimethyl disulphide occurred in the rumen, that dimethyl disulphide may have caused the depression in ruminal digestion of hemicellulose, and that the digestion products of kale are deficient in absorbed amino acids relative to other forms of energy, thus explaining responses to essential amino acid supplementation in lambs grazing kale.

Catabolic stress to nitrogen (N) metabolism and essential amino acid (EAA) supplementation in hemodialysis (HD)

Catabolic stress to nitrogen (N) metabolism and essential amino acid (EAA) supplementation in hemodialysis (HD)

Loss of Amino Acids during Hemodialysis: Effect of Oral Essential Amino Acid Supplementation

The aim of this study was to investigate the effect of amino acid (AA) supplementation on the loss and its time course of free AA, during hemodialysis. 2 uremic patients on regular hemodialysis received an increasing number of essential AA tablets during the dialysis. The loss and its time course of 6 essential and 7 nonessential free AA during dialysis was assayed in the dialysate. The loss per dialysis treatment of the administered essential AA increased almost proportionally with the doses of AA tablets. For the nonessential AA, no definite relationship between doses of AA tablets and losses was observed. At all levels of supplementation, methionine was retained best: 90% of the amount present in the tablets. Threonine showed the lowest retention: 15-55%.

Nutritional therapy in children with chronic renal failure

Children grow most during the first 2 years of life; growth retardation at this time has a major effect on the height of a child. Dietary therapy to maximize growth during the first few years before dialysis and transplantation are generally recommended as important. Energy and protein requirements for children in relation to their body weights are greater than for adults. In addition, the metabolic rate may be increased in uremia. Malnutrition and the metabolic disturbances of uremia appear to be more severe in prepubertal children than in adults and growth in such children is generally poor. This may be related to the lower anabolic drive of the prepuberal child; anabolic steroids may improve growth. Severely limited protein diets are difficult to achieve in children without reducing energy intake. It may be easier to give babies diets high in energy and low in protein with essential amino acid supplements to ensure an adequate essential amino acid intake. Fat intake should be increased to provide sufficient energy without causing hypertriglyceridemia. It is hoped that ketoacids may allow sufficient protein to be consumed as that an adequate energy intake is ensured while reducing nitrogen toxicity.

Oral essential amino acid supplements in children with advanced chronic renal failure

The effects on growth, nitrogen balance, and body composition of a protein-restricted diet supplemented with oral essential amino acids (EAA) were studied in seven children with advanced chronic renal failure. The diet was designed to provide minimum protein requirements for height-age, half in unselected form and half as an EAA supplement. Energy from carbohydrate and fat were increased to give a protein/energy ratio of 1.25 G:100 kcal. Nitrogen balance, studied in five children before and after 6 to 8 months of EAA treatment, was improved in each case. intracellular water (total body water minus bromide space) increased in four children but fell in three children during treatment. No significant improvement in growth, expressed as height or height velocity standard deviation scores in relation to bone age, was observed. Serum urea and urea/creatinine ratio fell after institution of EAA treatment, but the fall was not sustained. Although the EAA preparation proved acceptable to the children, dietary assessments indicated that the desired dietary aims were rarely achieved. It is concluded that, in this pediatric age group, the long-term application of a protein restricted diet with EAA supplements is of limited value.

Effects of Supplementation and Depletion of a Single Essential Amino Acid on Hepatic Polyribosome Profile in Rats

The effects of supplementation and depletion of one essential amino acid on hepatic polysome profile of rats were investigated in the meal-feeding condition. Only methionine supplementation to a protein-free diet reduced the population of monosomes and disomes per total profile. The single supplementation of other essential amino acids did not change the polysome profile as compared with the protein-free diet group. The results suggested that, when rats were fed a protein-free diet, methionine is the first limiting amino acid for liver protein synthesis. In the case of depletion of one essential amino acid (tryptophan, methionine-cystine, threonine, phenylalanine-tyrosine, leucine, isoleucine, valine, lysine), the values of monosomes and disomes per total ribosomes of rats were significantly higher than that of rats fed a complete amino acid mixture diet. In rats tube-fed the threonone-deficient diet three times a day for 3 or 5 days, the polysomes in liver were aggregated heavier than those of rats that received a complete diet. These results indicated that, under meal-feeding condition which may be considered more a physiological condition than force-feeding, the deficiency of single essential amino acid generally causes the disaggregation of hepatic polysomes leading the decreased synthesis of hepatic proteins.

Effect of low protein diet and surplus of essential amino acids on the serum concentration and the urinary excretion of methylguanidine and guanidinosuccinic acid in chronic renal failure.

20 patients with moderate renal failure (serum creatinine 4.5--12.0 mg/dl) and some uremic symptoms on a diet ad libitum were treated with a high caloric diet containing 0.5--0.7 g/kg/day protein, supplemented with eight essential amino acids and histidine in the form of solution and/or granules. During the treatment uremic symptoms subsided or diminished without the signs of malnutrition, SUN and the ratio SUN/S-creatinine fell and the nitrogen balance and the ratio N-balance/intake N improved. The serum concentration and the urinary excretion of MG and GSA of the 12 patients were determined by Stein's method using the modified Sakaguchi reaction. In all patients, the serum concentration and the urinary excretion of MG and GSA diminished remarkably during the treatment with a low protein diet alone and furthermore with a low protein diet and essential amino acid supply. We concluded that conservative treatment -- low nitrogen diet supplemented with sufficient calories and essential amino acids -- improved the nutritional state of uremic subjects, and decreased the metabolic production of MG and GSA. The results show that the supplementation of essential amino acids to uremic patients may be a useful treatment.

The effects of calorie and essential amino acid supplementation on plasma proteins in patients with chronic renal failure ,

Ten plasma proteins, the packed cell volume and serum urea were determined in 12 patients with chronic renal failure who were receiving 30 g of dietary protein plus 2000 cal per day for 4 weeks and in 12 normal individuals. Seven patients received an additional 400 cal during a 2nd month and also during the 3rd month when oral essential amino acids plus tyrosine (1 g of nitrogen per day) were added to the diet. Calorie supplementation alone did not produce any consistent changes, but when combined with essential amino acids there was a significant increase in plasma transferrin, prealbumin, and albumin and, for five patients, in β-lipoprotein and cholinesterase. During the month after the supplements were stopped, concentrations of most proteins were maintained above the presupplementation values. Dietary changes had no significant effect on α2-macroglobulin, α1-antitrypsin, α1-antichymotrypsin, ceruloplasmin, packed cell volume, or urea. An evaluation of 20 proteins measured in this and previous investigations shows that several proteins, and particularly transferrin, are useful for the assessment of nutritional status. In addition, certain proteins, such as prealbumin, β-lipoprotein, and cholinesterase, can be used for monitoring the effect of changes in dietary therapy. It is concluded that essential amino acid supplements are utilized for protein synthesis in most patients on low protein diets with a minimal increase in urea production.

Comparison of the effects of keto acid analogues and essential amino acids on nitrogen homeostasis in uremic patients on moderately protein-restricted diets ,

Comparisons of isonitrogenous supplements (1.2 g N) of essential amino acids and five keto acid analogues with four essential amino acids were made in seven patients with stable chronic renal failure (creatinine clearance, 4.6 to 16 ml/min) on moderately protein-restricted diets (4.60 to 7.8 g N per day). Full nitrogen balance data on the four patients who have already completed studies lasting 24 weeks are presented. No benefits of keto acid over amino acid supplements were observed. Two transient episodes of hypercalcemia occurred during keto acid treatment. There was no improvement of renal function with keto acids. Also, no carry-over effects were seen after keto acid treatment. It is concluded that any beneficial effects of keto acids in patients with chronic renal failure are only likely to occur in those taking a diet of less than 30 g protein daily.

Effect of essential amino acid supplementation on muscle and plasma free amino acids in chronic uremia

In chronic uremia patients on an 18-g protein diet for 2 to 3 weeks, the intracellular free amino acid pattern in muscle was grossly abnormal, with low concentrations of threonine, valine, carnosine, and high concentrations of aspartate, glutamine, glycine, alanine, and taurine. When the protein-poor diet was supplemented with essential amino acids (2 to 3 times that for minimum requirements) and histidine, these abnormalities were partly corrected. Other abnormalities, however, were observed, such as low intracellular concentrations of phenylalanine and tyrosine, and high concentrations of lysine, histidine, ornithine, and citrulline.

Protein restriction in the conservative management of uremia

Protein-restricted diets are widely used in the dietary management of uremia. These diets are undoubtedly effective in ameliorating many aspects of the uremic syndrome. However, there is no consensus as to whether diets providing less than 0.6 g/kg per day of protein are nutritionally adequate and capable of preventing the wasting syndrome. Wasting is common in the adult patient with renal insufficiency as is growth failure in the uremic child. There is some evidence that wasted patients do less well on hemodialysis and are more prone to infection. Experimental studies in uremic animals point to diminished efficiency of utilization of protein, increased gluconeogenesis from amino acids, and increased catabolism of protein in the fasting state; in addition, the metabolism of a number of individual amino acids is altered in uremia. In view of these multiple abnormalities, it would seem unwise to routinely provide less than the Recommended Daily Allowances of protein. More recent developments, i.e., supplementation of essential amino acids and perhaps α keto acids, may provide useful alternatives. One important aspect of dietary management, i.e., prevention of hyperlipidemia, has attracted surprisingly little attention so far. Therapy with protein restricted diets in nondialyzed uremic patients has to compete with other modalities of treatment currently available, i.e., hemodialysis and transplantation, in providing optimal medical rehabilitation of the patient.

Production and Utilization of Amino Acids

AbstractThe amino acid industry has been steadily expanding since monosodium glutamate was first marketed as a flavoring material in 1909. Its production has recently reached almost the 1 billion dollar level. Amino acids are produced by extraction from protein hydrolyzates, by fermentation with the aid of microorganisms, by enzymatic processes, and by chemical synthesis. To obtain natural L‐amino acid, chemical synthesis generally requires two additional steps, i.e. optical resolution and racemization of the D isomer. The most important applications of amino acids include the fortification of plant food and feeds by supplementation of the deficient essential amino acid(s). Apart from their uses in the food industry, medical applications of amino acids (nutritional preparations and therapeutic agents) are becoming increasingly important.

Effects of oral neomycin and kanamycin in chronic uremic patients: II. Nitrogen balance

Nitrogen balance was studied for five to seven days before and during oral administration of neomycin or kanamycin to 14 patients with severe chronic renal failure who were receiving long-term nutritional therapy consisting of protein restriction and supplements of essential amino acids or their nitrogen-free analogues. There was a significant improvement in nitrogen balance during the antibiotic period when compared to the control period, averaging +0.80 g of N per day (P less than 0.005). There was no significant change in average dietary nitrogen, fecal nitrogen, the excretion of non-urea urinary nitrogen, or urea appearance (defined as the sum of urinary urea and the change in the urea pool) during the antibiotic period. However, total nitrogen intake increased by 0.47 g per day owing to nitrogen contained in the drugs. The lack of a change in fecal nitrogen implies that fecal nitrogen not attributable to the drug must have fallen substantially. We conclude that oral neomycin and kanamycin may improve nitrogen balance in patients with severe chronic renal failure by diminishing endogenous fecal nitrogen.

Loss of Amino Acid During Hemodialysis and Essential Amino Acid Supplementation in Patients on Regular Dialysis Treatment

Loss of Amino Acid During Hemodialysis and Essential Amino Acid Supplementation in Patients on Regular Dialysis Treatment

Plasma amino acids and protein levels in chronic renal failure and changes caused by oral supplements of essential amino acids

1. 1. Plasma amino acids and six proteins have been measured in patients with chronic renal failure receiving low protein diets before and after oral supplementation with essential amino acids. 2. 2. All the patients on low protein diets had a lower percentage of essential amino acids in their plasma than normal subjects but after supplementation, plasma levels increased significantly with minimal increase in non-essential amino acids or urea nitrogen. 3. 3. Mean levels of plasma transferrin, complement C3 and globulin Gc were lower and plasma prealbumin higher in patients than in normal subjects. Plasma complement C4 and albumin were not different from normal. 4. 4. Seven out of nine patients who tolerated the supplementation showed a significant increase in plasma transferrin, prealbumin and complement C3 but not in complement C4, globulin Gc or albumin. 5. 5. Correlations between the percentage of essential amino acids and each of plasma transferrin, prealbumin and complement C3 and also between several of the plasma proteins further substantiate their value in the assessment of dietary intake in chronic renal failure. 6. 6. The value of amino acid supplementation on low protein diets in chronic renal failure is discussed in relation to these observations.

Utilization of Enzymatically Hydrolyzed Soybean Protein and Crystalline Amino Acid Diets by Rats with Exocrine Pancreatic Insufficiency

Exocrine pancreatic-deficient rats (PD) were prepared by cannulation and ligation of the common duct in a way which permitted bile, but not pancreatic juice, to enter the intestine. After surgery the PD rats were fed purified diets containing a high quality nitrogen source in the form of crystalline amino acids (AA), an enzymatic hydrolysate of soybean protein supplemented with essential amino acids (EH) or intact soybean protein with an essential amino acid supplement (SP). PD rats fed SP failed to regain any of their surgically-induced weight loss during the 10-day postoperative period. PD rats fed AA did not resume weight gains until after the sixth postoperative day while those fed diet EH resumed growth by the third postoperative day and grew at a rate which was nearly identical to that observed in sham-operated controls. The three diets afforded almost identical growth rates in weanling rats and in sham-operated rats used as controls for the PD rats. The amino acid compositions of AA and EH were nearly identical. Thus, the better utilization of diet EH in the PD rats was attributed to the fact that approximately 85% of the nitrogen in EH was in the form of oligopeptides. The results indicate that pancreatic enzymes are not required for the terminal stages of protein digestion and suggest that enzymatically hydrolyzed proteins are utilized more efficiently than mixtures of amino acids in the absence of exocrine pancreatic function.

The Use of Non-Protein Nitrogen by Laying Hens for Egg Production

Experiments were conducted to investigate the possibility of laying hens utilizing sources of non-protein nitrogen for egg production. Sources of non-protein nitrogen were added to low protein diets composed of practical feed ingredients and to a semipurified diet composed mainly of glucose, starch, isolated soybean protein, and blood meal. Essential amino acid supplementation was used to achieve a better amino acid balance of the diets.When the nitrogen supplements were added to a diet containing 12.5% protein, and with levels of essential amino acids that approximated those recommended by the National Research Council, a graded response in egg production was obtained to two levels of supplemental urea. A similar supplementation with monosodium glutamate had no effect on egg production. A low level of diammonium citrate supplementation produced a small increase in egg production and a higher level depressed egg production and feed intake. When the level of protein in the basal diet was reduced to 11.5%, and diammonium phosphate was used as source of non-protein nitrogen there was a depression in egg production but not in feed intake or nitrogen retention.Diammonium phosphate had the same effect when supplemented to a semipurified diet that contained all essential amino acids at a level equal to or higher than that recommended by the National Research Council. When glycine was supplemented to the semipurified diet, an increase in egg production was obtained.

ESSENTIAL AMINO ACID SUPPLEMENTATION OF INTACT PROTEINS FED TO THE GRAVID GILT.

ESSENTIAL AMINO ACID SUPPLEMENTATION OF INTACT PROTEINS FED TO THE GRAVID GILT.

Daily output of pancreatic juice and some dietary factors which influence it.

Evidence is presented that the chronic pancreatic fistula dogs can be used effectively to study pancreatic physiology on a daily output basis. By increasing the amount of a mixed diet fed or by adding fat to the diet the volume and protease and lipase activities can be increased. Additions of cellulose, milk, casein hydrolysate were ineffective. On the basal mixed diet neither volume, amylase nor protease increased independently of each other. Changes in one enzyme activity without the other or in volume without enzymes were seen with supplements of essential amino acids or soy flour. The possible mechanism of these effects is discussed.