QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Ingenbleek, Y. Search for Related Content PubMed PubMed Citation Articles by Ingenbleek, Y.

---

Supplement: 5th Amino Acid Assessment Workshop: Session I

The Nutritional Relationship Linking Sulfur to Nitrogen in Living Organisms¹

Laboratory of Nutrition, Faculty of Pharmacy, University Louis-Pasteur, Strasbourg, France

² To whom correspondence should be addressed. E-mail: ingen{at}pharma.u-strasbg.fr.

Nitrogen (N) and sulfur (S) coexist in the biosphere as free elements or in the form of simple inorganic NO₃^– and SO₄^2– oxyanions, which must be reduced before undergoing anabolic processes leading to the production of methionine (Met) and other S-containing molecules. Both N and S pathways are tightly regulated in plant tissues so as to maintain S:N ratios ranging from 1:20 to 1:35. As a result, plant products do not adequately fulfill human tissue requirements, whose mean S:N ratios amount to 1:14.5. The evolutionary patterns of total body N (TBN) and of total body S (TBS) offer from birth to death sex- and age-related specificities well identified by the serial measurement of plasma transthyretin (TTR). Met is regarded as the most limiting of all indispensable amino acids (IAAs) because of its participation in a myriad of molecular, structural, and metabolic activities of survival importance. Met homeostasis is regulated by subtle competitive interactions between transsulfuration and remethylation pathways of homocysteine (Hcy) and by the actual level of TBN reserves working as a direct sensor of cystathionine-ß-synthase activity. Under steady-state conditions, the dietary intake of SO₄^2– is essentially equal to total sulfaturia. The recommended dietary allowances for both S-containing AAs allotted to replace the minimal obligatory losses resulting from endogenous catabolism is largely covered by Western customary diets. By contrast, strict vegans and low-income populations living in plant-eating countries incur the risk of chronic N and Met dietary deficiencies causing undesirable hyperhomocysteinemia best explained by the downsizing of their TBN resources and documented by declining TTR plasma values.

KEY WORDS: • sulfur biology • S-containing compounds • food composition • sulfate balance • hyperhomocysteinemia • protein nutritional status • transthyretin

This article has been cited by other articles:

				R. O. Ball, G. Courtney-Martin, and P. B. Pencharz The In Vivo Sparing of Methionine by Cysteine in Sulfur Amino Acid Requirements in Animal Models and Adult Humans J. Nutr., June 1, 2006; 136(6): 1682S - 1693S. [Abstract] [Full Text] [PDF]