| The problem of nitrogen disposal in the obese. | |
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MedLine Citation:
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PMID: 22309896 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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Amino-N is preserved because of the scarcity and nutritional importance of protein. Excretion requires its conversion to ammonia, later incorporated into urea. Under conditions of excess dietary energy, the body cannot easily dispose of the excess amino-N against the evolutively adapted schemes that prevent its wastage; thus ammonia and glutamine formation (and urea excretion) are decreased. High lipid (and energy) availability limits the utilisation of glucose, and high glucose spares the production of ammonium from amino acids, limiting the synthesis of glutamine and its utilisation by the intestine and kidney. The amino acid composition of the diet affects the production of ammonium depending on its composition and the individual amino acid catabolic pathways. Surplus amino acids enhance protein synthesis and growth, and the synthesis of non-protein-N-containing compounds. But these outlets are not enough; consequently, less-conventional mechanisms are activated, such as increased synthesis of NO∙ followed by higher nitrite (and nitrate) excretion and changes in the microbiota. There is also a significant production of N2 gas, through unknown mechanisms. Health consequences of amino-N surplus are difficult to fathom because of the sparse data available, but it can be speculated that the effects may be negative, largely because the fundamental N homeostasis is stretched out of normalcy, forcing the N removal through pathways unprepared for that task. The unreliable results of hyperproteic diets, and part of the dysregulation found in the metabolic syndrome may be an unwanted consequence of this N disposal conflict. |
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Authors:
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Marià Alemany |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2012-2-6 |
Journal Detail:
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Title: Nutrition research reviews Volume: - ISSN: 1475-2700 ISO Abbreviation: - Publication Date: 2012 Feb |
Date Detail:
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Created Date: 2012-2-7 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9113797 Medline TA: Nutr Res Rev Country: - |
Other Details:
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Languages: ENG Pagination: 1-11 Citation Subset: - |
Affiliation:
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Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, Barcelona, Spain. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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