Individual variation in macronutrient regulation measured by proton magnetic resonance spectroscopy of human plasma

Abstract

DP. Individual variation in macronutrient regulation measured by proton magnetic resonance spectroscopy of human plasma. Am J Physiol Regul Integr Comp Physiol 297: R202-R209, 2009. First published May 20, 2009 doi:10.1152/ajpregu.90757.2008.-Proton nuclear magnetic resonance ( 1 H-NMR) spectroscopy of plasma provides a global metabolic profiling method that shows promise for clinical diagnostics. However, cross-sectional studies are complicated by a lack of understanding of intraindividual variation, and this limits experimental design and interpretation of data. The present study determined the diurnal variation detected by 1 H NMR spectroscopy of human plasma. Data reduction methods revealed three time-of-day metabolic patterns, which were associated with morning, afternoon, and night. Major discriminatory regions for these time-of-day patterns included the various kinds of lipid signals , and the region between 3 and 4 ppm heavily overlapped with amino acids that had ␣-CH and ␣-CH2. The phasing and duration of time-of-day patterns were variable among individuals, apparently because of individual difference in food processing/digestion and absorption and clearance of macronutrient energy sources (fat, protein, carbohydrate). The times of day that were most consistent among individuals, and therefore most useful for cross-sectional studies, were fasting morning (0830 -0930), postprandial afternoon (1430 -1630), and nighttime samples (0430 -0530). Importantly, the integrated picture of metabolism provided by 1 H-NMR spectroscopy of plasma suggests that this approach is suitable to study complex regulatory processes, including eating patterns/eating disorders, upper gastrointestinal functions (gastric emptying, pancreatic, biliary functions), and absorption/clearance of macronutrients. Hence, 1 H-NMR spectroscopy of plasma could provide a global metabolic tolerance test to assess complex processes involved in disease, including eating disorders and the range of physiological processes causing dysregulation of energy homeostasis. metabolomics; diurnal variation; eating disorders; gastrointestinal regulation GLOBAL METABOLIC PROFILING coupled with bioinformatic methods offers an approach to study the integration of macronutrient energy metabolism and can be useful to detect disease, toxicity, and nutritional deficiency (11,23,30,36). A variety of metabolic profiling methods are available, including gas chromatography-mass spectrometry, liquid chromatographymass spectrometry, and NMR spectroscopy (10,31,39). In view of its capability to handle multiple specimens in a high-throughput, semiautomated system, 1 H-NMR may offer unique insight into the in vivo metabolism of macronutrients (1, 2, 9). Dysfunction in macronutrient metabolism, i.e., carbohydrate, fat, protein, and alcohol, is relevant to obesity, metabolic syndrome, diabetes, cardiovascular disease and other common pathological conditions (19,25).Pioneering studies by Nicholson and coworkers (3, 24, 27, 35) established the utility of 1 H NMR spectroscopy f...

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