Daily requirement for and splanchnic uptake of leucine in healthy adult Indians

Background: The 1985 FAO/WHO/UNU requirement for leucine is too low accordi ng to tracer-derived estimates of leucine oxidation and balance in adults f rom developed regions. Objective: The leucine requirement in populations in developing countries w as assessed with use of the 24-h tracer balance method and on the basis of nitrogen balances. Design: Twenty healthy Indian men were studied during their consumption for 6 d of 2 L-amino acid diets that supplied either 14 and 30 (n = 10) or 22 and 40 (n = 10) mg leucine.kg(-1).d(-1) in random order. At 1800 on day 7, a 24-h constant intravenous [C-13]leucine tracer-infusion protocol was cond ucted to determine leucine oxidation and daily leucine balance. During the intake of 40 mg leucine/d, [H-2(3)]leucine was given orally to assess the s planchnic uptake of leucine. Results: Mean 24-h leucine oxidation rates were 29.8, 30.6, 33.6, and 39.3 mg.kg(-1).d(-1) at leucine intakes of 14, 22, 30, and 40 mg.kg(-1).d(-1), r espectively; daily leucine balances were -16.5, -9.0, -3.3, and 0.5 mg.kg(- 1).d(-1), respectively. Mixed-models linear regression of balance against l eucine intake resulted in a zero balance at a leucine intake of 37.3 mg.kg( -1).d(-1). Nitrogen balances were -12.7, -17.9, -3.9, and 1.0 mg.kg(-1).d(- 1) at leucine intakes of 14,22,30, and 40 mg.kg(-1).d(-1). Regression of ni trogen balance against intake resulted in a zero balance at a leucine intak e of 37.6 mg.kg(-1.)d(-1). The first-pass splanchnic uptake of leucine was 45.7% and 33.9% in the fasted and fed periods, respectively. Conclusion: A tentative mean leucine requirement of 40 mg.kg(-1).d(-1) is p roposed for healthy Indian adults, as it is for Western subjects.