Elango Rajavel, Humayun Mohammad A, Ball Ronald O, Pencharz Paul B
Research Institute, The Hospital for Sick Children, Toronto, Canada.
Am J Clin Nutr. 2007 Aug;86(2):360-5. doi: 10.1093/ajcn/86.2.360.
The current Dietary Reference Intake (DRI) recommendations for lysine requirements in children are based on a factorial estimate.
The objective of the current study was to determine the lysine requirement in healthy school-age children by measuring the oxidation of l-[1-(13)C]phenylalanine to (13)CO(2) (F(13)CO(2)) in response to graded intakes of lysine.
Five healthy school-age children randomly received each of 7 lysine intakes (5, 15, 25, 35 50, 65, and 80 mg x kg(-1) x d(-1)) along with an amino acid mixture to give a final calculated protein intake of 1.5 g x kg(-1) x d(-1) and an energy intake of 1.7 x resting energy expenditure (REE). The mean lysine requirement was determined by applying 2-phase linear regression crossover analysis on F(13)CO(2) data, which identified a breakpoint (requirement) at minimal F(13)CO(2) in response to graded lysine intakes.
The mean and population-safe (upper 95% CI) lysine requirements were determined to be 35 and 58 mg x kg(-1) x d(-1), respectively.
The mean and population-safe lysine requirements for children are similar to those for adults (36 and 52 mg x kg(-1) x d(-1), respectively), which suggests that the findings from the current study reflect predominantly the maintenance lysine requirements in children and not all requirements for growth. Therefore, to ensure age-appropriate growth in school-age children, we propose the addition of the requirement of lysine for growth (approximately 6 mg x kg(-1) x d(-1)) to the mean estimate. The new mean and population-safe lysine requirements are 41 and 58 mg x kg(-1) x d(-1), respectively; these values are significantly higher than the current DRIs of 37 and 46 mg x kg(-1) x d(-1), respectively.
目前儿童赖氨酸需求量的膳食参考摄入量（DRI）建议是基于因子估计得出的。
本研究的目的是通过测量l-[1-(13)C]苯丙氨酸氧化为(13)CO₂（F(13)CO₂）对不同剂量赖氨酸摄入的反应，来确定健康学龄儿童的赖氨酸需求量。
五名健康学龄儿童随机接受七种赖氨酸摄入量（5、15、25、35、50、65和80mg·kg⁻¹·d⁻¹）中的每一种，同时摄入氨基酸混合物，以使最终计算的蛋白质摄入量为1.5g·kg⁻¹·d⁻¹，能量摄入量为1.7×静息能量消耗（REE）。通过对F(13)CO₂数据应用两阶段线性回归交叉分析来确定平均赖氨酸需求量，该分析在对不同剂量赖氨酸摄入的反应中，于最低F(13)CO₂处确定了一个断点（需求量）。
平均赖氨酸需求量和人群安全（95%CI上限）赖氨酸需求量分别确定为35和58mg·kg⁻¹·d⁻¹。
儿童的平均赖氨酸需求量和人群安全赖氨酸需求量与成人相似（分别为36和52mg·kg⁻¹·d⁻¹），这表明本研究结果主要反映了儿童的维持性赖氨酸需求量，而非所有生长所需的需求量。因此，为确保学龄儿童适宜年龄的生长，我们建议在平均估计值中增加生长所需的赖氨酸需求量（约6mg·kg⁻¹·d⁻¹）。新的平均赖氨酸需求量和人群安全赖氨酸需求量分别为41和58mg·kg⁻¹·d⁻¹；这些值显著高于目前分别为37和46mg·kg⁻¹·d⁻¹的DRI值。
