Clinical Biomarkers Laboratory, Emory University, Atlanta, GA 30322, USA.
J Nutr. 2011 Aug;141(8):1424-31. doi: 10.3945/jn.111.138875. Epub 2011 Jun 15.
The content of sulfur amino acid (SAA) in a meal affects postprandial plasma cysteine concentrations and the redox potential of cysteine/cystine. Because such changes can affect enzyme, transporter, and receptor activities, meal content of SAA could have unrecognized effects on metabolism during the postprandial period. This pilot study used proton NMR ((1)H-NMR) spectroscopy of human plasma to test the hypothesis that dietary SAA content changes macronutrient metabolism. Healthy participants (18-36 y, 5 males and 3 females) were equilibrated for 3 d to adequate SAA, fed chemically defined meals without SAA for 5 d (depletion), and then fed isoenergetic, isonitrogenous meals containing 56 mg·kg(-1)·d(-1) SAA for 4.5 d (repletion). On the first and last day of consuming the chemically defined meals, a morning meal containing 60% of the daily food intake was given and plasma samples were collected over an 8-h postprandial time course for characterization of metabolic changes by (1)H-NMR spectroscopy. SAA-free food increased peak intensity in the plasma (1)H-NMR spectra in the postprandial period. Orthogonal signal correction/partial least squares-discriminant analysis showed changes in signals associated with lipids, some amino acids, and lactate, with notable increases in plasma lipid signals (TG, unsaturated lipid, cholesterol). Conventional lipid analyses confirmed higher plasma TG and showed an increase in plasma concentration of the lipoprotein lipase inhibitor, apoC-III. The results show that plasma (1)H-NMR spectra can provide useful macronutrient profiling following a meal challenge protocol and that a single meal with imbalanced SAA content alters postprandial lipid metabolism.
膳食中含硫氨基酸（SAA）的含量会影响餐后血浆半胱氨酸浓度和半胱氨酸/胱氨酸的氧化还原电位。由于这些变化可能会影响酶、转运体和受体的活性，因此膳食 SAA 的含量可能会对餐后代谢产生未被认识到的影响。本研究使用质子磁共振波谱（1H-NMR）分析人类血浆，以检验饮食 SAA 含量改变宏量营养素代谢的假说。健康参与者（18-36 岁，5 名男性和 3 名女性）先进行 3 天的 SAA 均衡饮食，然后连续 5 天不摄入 SAA 的化学定义膳食（消耗阶段），接着再摄入 4.5 天含有 56mg·kg-1·d-1 SAA 的等能量、等氮的膳食（补充阶段）。在摄入化学定义膳食的第 1 天和最后 1 天，给予 60%日总热量的早餐，在餐后 8 小时内采集血浆样本，通过 1H-NMR 波谱分析代谢变化。无 SAA 的食物增加了餐后血浆 1H-NMR 图谱的峰强度。正交信号校正/偏最小二乘法判别分析显示，与脂质、一些氨基酸和乳酸相关的信号发生变化，血浆脂质信号显著增加（甘油三酯、不饱和脂质、胆固醇）。常规脂质分析证实了更高的血浆甘油三酯，并显示载脂蛋白 C-III 抑制剂，即 apoC-III 的血浆浓度增加。结果表明，血浆 1H-NMR 图谱可提供有用的宏量营养素谱分析，而单一含有不平衡 SAA 含量的膳食会改变餐后脂质代谢。
