Lysine requirements of healthy adult Indian subjects, measured by an indicator amino acid balance technique.
BACKGROUND
In an earlier study, using a modification of the indicator amino acid oxidation approach, we concluded that the 1985 FAO/WHO/UNU-proposed lysine requirement of 12 mg x kg(-1) x d(-1) is likely inadequate to maintain body amino acid homeostasis in apparently healthy south Asian subjects and that our proposed requirement of 30 mg x kg(-1) x d(-1) is more appropriate.


OBJECTIVE
We assessed the lysine requirement in a similar population by using 4 test lysine intakes (12, 20, 28, and 36 mg x kg(-1) x d(-1)) with an indicator amino acid balance approach.


METHODS
Sixteen healthy male Indians were studied during each of 2 randomly assigned 8-d L-amino acid diets that supplied either 12 and 28 or 20 and 36 mg lysine. At 1800 on day 8, a 24-h intravenous [(13)C]leucine tracer-infusion protocol was conducted to assess leucine oxidation and daily leucine balance at each lysine intake.


RESULTS
Mean 24-h leucine oxidation rates decreased significantly (P = 0.005) across different lysine intakes and were 104.1, 97.8, 87.3, and 87.3 mg x kg(-1) x d(-1) at intakes of 12, 20, 28, and 36 mg x kg(-1) x d(-1), respectively; mean 24-h leucine balances were 3.3, 9.1, 19.7, and 20.7 mg x kg(-1) x d(-1), respectively (P = 0.015, mixed-model analysis of variance). Oxidation and balances differed significantly between the lower and higher lysine intakes but were not significantly different between the 12- and 20-mg and 28- and 36-mg test intakes. Two-phase regression analysis indicated a mean breakpoint at 29 mg lysine x kg(-1) x d(-1) in the relation between lysine intake and leucine oxidation or balance.


CONCLUSIONS
We propose a mean lysine requirement of 30 mg x kg(-1) x d(-1) for healthy Indian adults, which is the same amount we proposed previously for Western populations.
Kurpad
A V
AV
Department of Physiology and Nutrition Research Center, St John's Medical College, Bangalore, India. vryoung@mit.edu
Raj
T
T
El-Khoury
A
A
Beaumier
L
L
Kuriyan
R
R
Srivatsa
A
A
Borgonha
S
S
Selvaraj
A
A
Regan
M M
MM
Young
V R
VR
D000328:Adult; D000596:Amino Acids / Q000378:metabolism*; D001944:Breath Tests; D002245:Carbon Dioxide / Q000032:analysis; D002247:Carbon Isotopes; D006801:Humans; D007194:India; D007262:Infusions, Intravenous; D008239:Lysine / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism*; D008297:Male; D009751:Nutritional Requirements; D010084:Oxidation-Reduction; D012016:Reference Values; D012044:Regression Analysis; D044465:White People
D000596:Amino Acids; D002247:Carbon Isotopes; D002245:Carbon Dioxide; D008239:Lysine