title: Supplementing a low-protein diet with dibasic amino acids increases urinary calcium excretion in young women.
abstract: Increasing dietary protein within a physiologic range stimulates intestinal calcium absorption, but it is not known if specific amino acids or dietary protein as a whole are responsible for this effect. Therefore, we selectively supplemented a low-protein (0.7 g/kg) diet with either the calcium-sensing receptor-activating amino acids (CaSR-AAAs) L-tryptophan, L-phenylalanine, and L-histidine, or the dibasic amino acids (DAAs) L-arginine and L-lysine, to achieve intakes comparable to the content of a high-protein diet (2.1 g/kg) and measured intestinal calcium absorption. Fourteen young women took part in a placebo-controlled, double-blind, crossover feeding trial in which each participant ingested a 6-d low-protein diet supplemented with CaSR-AAAs, DAAs, or methylcellulose capsules (control) after an 11-d adjustment period. All participants ingested all 3 diets in random order. Intestinal calcium absorption was measured between days 5 and 6 using dual-stable calcium isotopes ((42)Ca, (43)Ca, and (44)Ca). There was no difference in calcium absorption between the diet supplemented with CaSR-AAAs (22.9 ± 2.0%) and the control diet (22.3 ± 1.4%) (P = 0.64). However, calcium absorption tended to be greater during the DAA supplementation period (25.2 ± 1.4%) compared with the control diet period (22.3 ± 1.4%) (P < 0.10). Larger and longer clinical trials are needed to clarify the possible benefit of arginine and lysine on calcium absorption.
authors.affiliation: Department of Nutritional Sciences and.
authors.forename: Jessica D
authors.initials: JD
authors.lastname: Bihuniak
authors.forename: Rebecca R
authors.initials: RR
authors.lastname: Sullivan
authors.forename: Christine A
authors.initials: CA
authors.lastname: Simpson
authors.forename: Donna M
authors.initials: DM
authors.lastname: Caseria
authors.forename: Tania B
authors.initials: TB
authors.lastname: Huedo-Medina
authors.forename: Kimberly O
authors.initials: KO
authors.lastname: O'Brien
authors.forename: Jane E
authors.initials: JE
authors.lastname: Kerstetter
authors.forename: Karl L
authors.initials: KL
authors.lastname: Insogna
mesh_terms: D000328:Adult; D000599:Amino Acids, Diamino / Q000008:administration & dosage*; D001120:Arginine / Q000008:administration & dosage; D015992:Body Mass Index; D002136:Calcium, Dietary / Q000493:pharmacokinetics / Q000652:urine*; D003404:Creatinine / Q000097:blood; D018592:Cross-Over Studies; D018753:Diet, Protein-Restricted; D004044:Dietary Proteins / Q000008:administration & dosage; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007408:Intestinal Absorption; D008239:Lysine / Q000008:administration & dosage; D010649:Phenylalanine / Q000008:administration & dosage; D044169:Receptors, Calcium-Sensing / Q000378:metabolism; D014364:Tryptophan / Q000008:administration & dosage; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D055815:Young Adult
chemical_list: D000599:Amino Acids, Diamino; D002136:Calcium, Dietary; D004044:Dietary Proteins; D044169:Receptors, Calcium-Sensing; D014807:Vitamin D; D010649:Phenylalanine; D014364:Tryptophan; D001120:Arginine; C104450:25-hydroxyvitamin D; D003404:Creatinine; D008239:Lysine