Lysine requirements of chronically undernourished adult Indian men, measured by a 24-h indicator amino acid oxidation and balance technique.
BACKGROUND
In earlier studies with well-nourished subjects that used a 24-h indicator amino acid oxidation or balance approach, we concluded that the 1985 FAO/WHO/UNU requirement for lysine (12 mg x kg(-1) x d(-1)) was inadequate for healthy South Asian subjects and proposed a tentative requirement of 30 mg x kg(-1) x d(-1).


OBJECTIVE
We assessed whether chronic undernutrition, with low habitual dietary protein and lysine intakes, leads to changed lysine requirements.


METHODS
Twenty-seven otherwise clinically healthy, chronically undernourished Indian men were studied during 2 randomly assigned 7-d diet periods supplying 12 and 30, 18 and 36, or 24 and 42 mg lysine x kg(-1) x d(-1), based on an L-amino acid diet. The subjects' leucine intake was 40 mg x kg(-1) x d(-1). At 1800 on day 6, a 24-h intravenous [(13)C]leucine tracer-infusion protocol was conducted to assess leucine oxidation and daily leucine balance at each test lysine intake.


RESULTS
A breakpoint was not identified in the lysine intake-leucine oxidation or balance response over the range of intakes studied. Mixed-models linear regression analysis indicated a mean requirement of 44 mg lysine x kg(-1) x d(-1) (95% CI: 36, 63) for the lysine intake-leucine balance relation.


CONCLUSIONS
The mean lysine requirement in chronically undernourished men is estimated to be higher than the value of 30 mg x kg(-1) x d(-1) proposed for well-nourished individuals. This may be related to body-composition differences. It also suggests that these subjects have not elicited a metabolic adaptation in response to their habitually low lysine intakes by substantially improving their efficiency of dietary lysine utilization.
Kurpad
Anura V
AV
Department of Physiology and Division of Nutrition, St John's Medical College, Bangalore India. a.kurpad@divnut.net
Regan
Meredith M
MM
Raj
Tony
T
Vasudevan
Jahnavi
J
Kuriyan
Rebecca
R
Gnanou
Justin
J
Young
Vernon R
VR
D000328:Adult; D000886:Anthropometry; D002153:Calorimetry, Indirect; D002908:Chronic Disease; D004032:Diet; D006801:Humans; D007194:India; D008239:Lysine / Q000008:administration & dosage / Q000378:metabolism*; D008297:Male; D009748:Nutrition Disorders / Q000178:diet therapy* / Q000378:metabolism; D009751:Nutritional Requirements; D009752:Nutritional Status; D010084:Oxidation-Reduction; D011203:Poverty
D008239:Lysine