Effects of Fasting on Blood Non-Protein Amino Acids in Humans1
L. W. Charkey,
Adeline K. Kano and
Duane F. Hougham
Department of Chemistry, Colorado Agricultural and Mechanical College, Fort Collins
1. Fasting in adult humans led in 48 hours to increased bloodlevels of leucine and valine. Blood levels of 5 other aminoacids, namely lysine, threonine, methionine, arginine and tryptophanwere simultaneously reduced by fasting.
2. The response ofadult humans to fasting, in terms of bloodnon-protein aminoacid levels, was entirely different from thatfound in chicksup to 6 weeks of age, in that the blood levelsof differentamino acids were increased as a result of fasting.
3. Examinationof the literature revealed a correspondence,for the human species,between amino acids exhibiting a bloodlevel rise during fastingand those not metabolically availableby tissue conversion ofstructural analogues. A similar relationshiphad been foundearlier in chicks. Hence it is suggested thata correspondence,between amino acids exhibiting increased bloodlevels due tofasting and those metabolically unavailable byprecursor amination,may hold true for a variety of species.
1 Scientific Series Paper no. 432, Colorado Agricultural ExperimentStation.