Human Protein and Amino Acid Requirements

Hoffer, L. John

doi:10.1177/0148607115624084

Cited by 86 publications

(69 citation statements)

References 105 publications

(141 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Figure 1 illustrates why—for the same reason that dextrose provides fewer calories than starch (3.4 versus 4.0 kcal/g)—free amino acids provide less energy and protein substrate than formed protein. For example, 100 g of hydrated mixed amino acids does not provide 400 kcal and 100 g protein, as widely taught, but only 340 kcal and 83 g of protein substrate [1,2]. …”

Section: Nutritional Biochemistry Of Amino Acids and Proteinsmentioning

confidence: 99%

“…The specific contribution of each NEAA to a parenteral amino acid mixture is less important than the total amount of non-essential N supplied. The amino acid mixtures used in parenteral nutrition (PN) compensate for their lack of glutamine (and sometimes glutamate or aspartate) by including sufficiently large amounts of glycine and other NEAAs [2]. …”

Section: Nutritional Biochemistry Of Amino Acids and Proteinsmentioning

confidence: 99%

“…This observation and some indirect clinical evidence, including hypercystathioninemia, suggest that cysteine could become an essential amino acid for premature infants [4]. There is no direct evidence that this temporary, incomplete metabolic blockade is clinically important [2], but some neonatal physicians nevertheless add cysteine hydrochloride to parenteral amino acid mixtures just prior to infusion [5]. The important intracellular reducing agent and reactive metabolic intermediate scavenger, glutathione, is a tripeptide of cysteine, glycine and glutamate.…”

Section: Nutritional Biochemistry Of Amino Acids and Proteinsmentioning

confidence: 99%

“…They are not further considered in this review, except to suggest that the claim that glutamine is a conditionally essential amino acid is questionable, given the lack of evidence that glutamine synthesis is impaired when its substrate (all other amino acids) is provided in a sufficient amount. What has been termed nutritional glutamine deficiency may, at least in part, represent inadequate total protein provision to protein-catabolic patients [2]. …”

Section: Standard and Specialized Amino Acid Mixturesmentioning

confidence: 99%

“…Regrettably, suitably-powered hard clinical outcome trials to confirm or refute this physiologically plausible conclusion have not yet been carried out [2]. Instead, until recently, large clinical nutrition trials in critical illness focused on the benefits of calorie supplementation, while largely ignoring or dismissing the importance of protein or amino acids.…”

Section: Effects Of Starvation and Disease On Protein Metabolism Amentioning

confidence: 99%

See 4 more Smart Citations

Parenteral Nutrition: Amino Acids

Hoffer

2017

Nutrients

View full text Add to dashboard Cite

There is growing interest in nutrition therapies that deliver a generous amount of protein, but not a toxic amount of energy, to protein-catabolic critically ill patients. Parenteral amino acids can achieve this goal. This article summarizes the biochemical and nutritional principles that guide parenteral amino acid therapy, explains how parenteral amino acid solutions are formulated, and compares the advantages and disadvantages of different parenteral amino acid products with enterally-delivered whole protein products in the context of protein-catabolic critical illness.

show abstract

Section: Nutritional Biochemistry Of Amino Acids and Proteinsmentioning

confidence: 99%

Section: Nutritional Biochemistry Of Amino Acids and Proteinsmentioning

confidence: 99%

Section: Nutritional Biochemistry Of Amino Acids and Proteinsmentioning

confidence: 99%

Section: Standard and Specialized Amino Acid Mixturesmentioning

confidence: 99%

Section: Effects Of Starvation and Disease On Protein Metabolism Amentioning

confidence: 99%

See 3 more Smart Citations

Parenteral Nutrition: Amino Acids

Hoffer

2017

Nutrients

View full text Add to dashboard Cite

show abstract

Amino Acid Biosynthesis

Picciotto¹,

Garibotto²

2020

Encyclopedia of Life Sciences

View full text Add to dashboard Cite

Amino acids are classically considered as the building blocks for the synthesis of proteins. The unique characteristics of amino acids are the presence of a free amino group in the α‐carbon and a free carboxyl group. The amino acids differ from each other with respect to their side‐chains and are classified into subgroups according to their similarity in carbon skeleton, substituent groups or a common metabolic pathway. The biosynthesis of amino acids involves several biochemical pathways in which amino acids are assembled from other precursors and is distinct from that involving lipids or carbohydrates because it includes the use of nitrogen. In addition to the 20 canonical amino acids that serve as the primary basis of protein structure and function, many noncanonical amino acids are either found in nature or are chemically created by man. Noncanonical amino acids are used as synthetic intermediates or therapeutics and may also be encoded directly into proteins to obtain useful new features, including better protein stability and increased activity. Key Concepts Amino acids are classically considered as the building blocks from which proteins are synthesised. In addition to their structural role in proteins, the amino acid sequence dictates protein tertiary structure and affects protein function, localisation, recognition and posttranslational modification. In addition, selected amino acids serve as regulators of gene expression and the protein phosphorylation cascade, and play a role in the regulation of protein turnover, signal transduction, transport of nitrogen and carbon across the organs, and neurotransmission. The biosynthesis of amino acids involves several biochemical pathways in which amino acids are assembled from other precursors and is distinct from that involving lipids or carbohydrates because it includes the use of nitrogen. The fixation of nitrogen is a process that converts atmospheric nitrogen to a form that can be used biologically. The pathways for the synthesis of essential amino acids are present only in microorganisms and plants. Nine of 12 nonessential amino acids are synthesised from amphibolic intermediates, whereas three amino acids (tyrosine, cysteine and hydroxylysine) derive from essential amino acids. Amino acid transaminases, glutamate dehydrogenase and glutamine synthetase play a central role in the synthesis of nonessential amino acids. In the human adult, as much as 200–250 g of proteins are degraded daily, and their constituent amino acids are in large part reutilised in protein synthesis. Amino acid deficiency states can result if any of the essential amino acid is present in inadequate amounts or omitted from the diet. Alanine, glutamate and glutamine are crucial links between energy and protein metabolism. Moreover, glutamine and alanine biosynthesis in muscle provides a means for the transport of carbon from peripheral tissues to the liver for gluconeogenesis and nitrogen for ureagenesis. Besides the 20 canonical amino acids, many noncanonical amino acids are either found in nature or are chemically created by man. Noncanonical amino acids are used as synthetic intermediates or therapeutics and may also be encoded directly into proteins to obtain useful new features, including better protein stability and increased activity.

show abstract