1. Phase of menstrual cycle affects lysine requirement in healthy women
- Author
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Laksiri A. Goonewardene, Ronald O. Ball, Wantanee Kriengsinyos, Paul B. Pencharz, and Linda Wykes
- Subjects
Adult ,medicine.medical_specialty ,Physiology ,Endocrinology, Diabetes and Metabolism ,media_common.quotation_subject ,Phenylalanine ,Lysine ,Luteal phase ,Biology ,Luteal Phase ,Reference Values ,Physiology (medical) ,Internal medicine ,Follicular phase ,medicine ,Humans ,Amino Acids ,Menstrual cycle ,Progesterone ,media_common ,chemistry.chemical_classification ,Carbon Isotopes ,Estradiol ,Nutritional Requirements ,Oxidation reduction ,Fluorine ,Amino acid ,Endocrinology ,chemistry ,Breath Tests ,Follicular Phase ,Reference values ,Linear Models ,Female ,Oxidation-Reduction - Abstract
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 17β-estradiol and progesterone concentrations were measured on each IAAO study day. The rate of release of13CO2from [13C]phenylalanine oxidation (F13CO2) was measured, and a two-phase linear regression crossover model was applied to determine lysine requirement. F13CO2was higher during the luteal phase ( P < 0.001) and was positively associated with serum concentrations of 17β-estradiol and progesterone. The F13CO2data 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−1and 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.
- Published
- 2004