Kurpad Anura V, Regan Meredith M, Raj Tony, Vasudevan Jahnavi, Kuriyan Rebecca, Gnanou Justin, Young Vernon R
Department of Physiology and Division of Nutrition, St John's Medical College, Bangalore India.
Am J Clin Nutr. 2003 Jan;77(1):101-8. doi: 10.1093/ajcn/77.1.101.
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).
We assessed whether chronic undernutrition, with low habitual dietary protein and lysine intakes, leads to changed lysine requirements.
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.
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.
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.
在早期针对营养良好受试者的研究中，我们采用24小时指示性氨基酸氧化或平衡法得出结论，即1985年粮农组织/世界卫生组织/联合国大学提出的赖氨酸需求量（12毫克×千克⁻¹×天⁻¹）对于健康的南亚受试者而言并不充足，并提出了30毫克×千克⁻¹×天⁻¹的暂定需求量。
我们评估了长期营养不良、日常膳食蛋白质和赖氨酸摄入量较低的情况是否会导致赖氨酸需求量发生变化。
27名在其他方面临床健康的慢性营养不良印度男性参与了研究，研究为期2个随机分配的7天饮食期，基于L-氨基酸饮食，分别提供12和30、18和36或24和42毫克赖氨酸×千克⁻¹×天⁻¹。受试者的亮氨酸摄入量为40毫克×千克⁻¹×天⁻¹。在第6天的18:00，进行了一项24小时静脉注射[¹³C]亮氨酸示踪剂输注方案，以评估每种测试赖氨酸摄入量下的亮氨酸氧化和每日亮氨酸平衡。
在所研究的摄入量范围内，未在赖氨酸摄入量-亮氨酸氧化或平衡反应中确定转折点。混合模型线性回归分析表明，赖氨酸摄入量-亮氨酸平衡关系的平均需求量为44毫克赖氨酸×千克⁻¹×天⁻¹（95%置信区间：36, 63）。
据估计，慢性营养不良男性的平均赖氨酸需求量高于为营养良好个体提出的30毫克×千克⁻¹×天⁻¹的值。这可能与身体成分差异有关。这也表明，这些受试者并未通过大幅提高膳食赖氨酸利用率来对其习惯性低赖氨酸摄入量产生代谢适应性反应。
