HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science 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 ISI Web of Science (6) Citing Articles via Google Scholar Google Scholar Articles by Kriengsinyos, W. Articles by Pencharz, P. B. Search for Related Content PubMed PubMed Citation Articles by Kriengsinyos, W. Articles by Pencharz, P. B.

Phase of menstrual cycle affects lysine requirement in healthy women

Departments of ¹Nutritional Sciences and ²Paediatrics, University of Toronto, Toronto M5S 3E2; ³The Research Institute, The Hospital for Sick Children, Toronto, Ontario M5G 1X8; ⁴School of Dietetics and Human Nutrition, McGill University, Montreal, Quebec H9X 3V9; and ⁵Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta T6G 2P5, Canada

Submitted 12 June 2003 ; accepted in final form 1 April 2004

The aim of this study was to investigate whether the phases of the menstrual cycle affect lysine requirement in healthy adult females, as determined by the indicator amino acid oxidation (IAAO) method. Five healthy females with regular menstrual cycles were studied at seven graded levels of lysine intake, in random order, with an oral [¹³C]phenylalanine tracer protocol in both the follicular and luteal phases. A total of 14 studies were conducted for each subject. Breath and plasma samples were collected according to the standard IAAO protocol. Serum 17-estradiol and progesterone concentrations were measured on each IAAO study day. The rate of release of ¹³CO₂ from [¹³C]phenylalanine oxidation (F¹³CO₂) was measured, and a two-phase linear regression crossover model was applied to determine lysine requirement. F¹³CO₂ was higher during the luteal phase (P < 0.001) and was positively associated with serum concentrations of 17-estradiol and progesterone. The F¹³CO₂ data were adjusted for subjects and sex hormones and used to define breakpoints for lysine requirements. The lysine requirement of healthy females in the luteal phase was 37.7 mg·kg^–1·day^–1 and higher (P = 0.025) than that of females in the follicular phase (35.0 mg·kg^–1·day^–1). At all lysine intake levels, plasma amino acids were lower and phenylalanine oxidation was higher in the luteal relative to the follicular phase. Therefore, we reason that the higher lysine requirement observed in the luteal phase is probably due to higher amino acid catabolism.

indicator amino acid oxidation

This article has been cited by other articles:

				M. A. Humayun, R. Elango, S. Moehn, R. O. Ball, and P. B. Pencharz Application of the Indicator Amino Acid Oxidation Technique for the Determination of Metabolic Availability of Sulfur Amino Acids from Casein versus Soy Protein Isolate in Adult Men J. Nutr., August 1, 2007; 137(8): 1874 - 1879. [Abstract] [Full Text] [PDF]

				D. Tome and C. Bos Lysine Requirement through the Human Life Cycle J. Nutr., June 1, 2007; 137(6): 1642S - 1645S. [Abstract] [Full Text] [PDF]

				M. J. Toth, C. K. Sites, D. E. Matthews, and P. R. Casson Ovarian suppression with gonadotropin-releasing hormone agonist reduces whole body protein turnover in women Am J Physiol Endocrinol Metab, September 1, 2006; 291(3): E483 - E490. [Abstract] [Full Text] [PDF]

				M. J. Toth, C. K. Sites, and D. E. Matthews Role of ovarian hormones in the regulation of protein metabolism in women: effects of menopausal status and hormone replacement therapy Am J Physiol Endocrinol Metab, September 1, 2006; 291(3): E639 - E646. [Abstract] [Full Text] [PDF]