An intervention with selected dietary products affected inflammatory processes, oxidative stress, and metabolism in humans, as shown by large-scale profiling of genes, proteins, and metabolites in plasma, urine, and adipose tissue. This trial was registered at clinical trials.gov as NCT00655798.
We introduce the metabolomics and proteomics based Postprandial Challenge Test (PCT) to quantify the postprandial response of multiple metabolic processes in humans in a standardized manner. The PCT comprised consumption of a standardized 500 ml dairy shake containing respectively 59, 30 and 12 energy percent lipids, carbohydrates and protein. During a 6 h time course after PCT 145 plasma metabolites, 79 proteins and 7 clinical chemistry parameters were quantified. Multiple processes related to metabolism, oxidation and inflammation reacted to the PCT, as demonstrated by changes of 106 metabolites, 31 proteins and 5 clinical chemistry parameters. The PCT was applied in a dietary intervention study to evaluate if the PCT would reveal additional metabolic changes compared to non-perturbed conditions. The study consisted of a 5-week intervention with a supplement mix of anti-inflammatory compounds in a crossover design with 36 overweight subjects. Of the 231 quantified parameters, 31 had different responses over time between treated and control groups, revealing differences in amino acid metabolism, oxidative stress, inflammation and endocrine metabolism. The results showed that the acute, short term metabolic responses to the PCT were different in subjects on the supplement mix compared to the controls. The PCT provided additional metabolic changes related to the dietary intervention not observed in non-perturbed conditions. Thus, a metabolomics based quantification of a standardized perturbation of metabolic homeostasis is more informative on metabolic status and subtle health effects induced by (dietary) interventions than quantification of the homeostatic situation.Electronic supplementary materialThe online version of this article (doi:10.1007/s11306-011-0320-5) contains supplementary material, which is available to authorized users.
Background: A key feature of metabolic health is the ability to adapt upon dietary perturbations. Recently, it was shown that metabolic challenge tests in combination with the new generation biomarkers allow the simultaneous quantification of major metabolic health processes. Currently, applied challenge tests are largely non-standardized. A systematic review defined an optimal nutritional challenge test, the "PhenFlex test" (PFT). This study aimed to prove that PFT modulates all relevant processes governing metabolic health thereby allowing to distinguish subjects with different metabolic health status. Therefore, 20 healthy and 20 type 2 diabetic (T2D) male subjects were challenged both by PFT and oral glucose tolerance test (OGTT). During the 8-h response time course, 132 parameters were quantified that report on 26 metabolic processes distributed over 7 organs (gut, liver, adipose, pancreas, vasculature, muscle, kidney) and systemic stress.
We investigated the effects of dietary carbohydrates on the composition and pH of fecal material and on the ammonia emission from the slurry of growing pigs. Thirty-four barrows (BW approximately 40 kg) were randomly allotted to 1 of 10 diets. A basal diet was formulated to meet all requirements for protein, amino acids, minerals, and vitamins. The control diet was composed of the basal diet plus heat-treated cornstarch. In the other diets, the cornstarch in the control diet was replaced with three levels of either coconut expeller, soybean hulls, or dried sugar beet pulp. Feces were collected separately from urine in a balance experiment. Feces were mixed with a standardized urine (ratio of 1:2.5, wt/wt) to form a slurry. A sample of this slurry was placed in an in vitro system to determine the pH and the ammonia emission for 16 d at 20 degrees C. The fecal and slurry DM contents decreased (P < .001) and the total VFA concentrations increased (P < .001) when the level of dietary carbohydrates increased. The pH and the ammonia emission decreased as the level of carbohydrates increased (P < .001). The addition of soybean hulls to the diet had the greatest effect on reducing the pH and ammonia emission (P < .001), and the effects of sugar beet pulp and coconut expeller were approximately the same. A linear relationship was found between the intake of dietary nonstarch polysaccharides (NSP) and the ammonia emission (P < .001). For each 100-g increase in the intake of dietary NSP, the slurry pH decreased by approximately .12 unit and the ammonia emission from slurry decreased by 5.4%. We conclude that replacing cornstarch in the diet with components that have a high concentration of fermentable carbohydrates increases the VFA concentration of feces and slurry and reduces the pH and ammonia emission from the slurry of growing pigs.
BackgroundA key feature of metabolic health is the ability to adapt upon dietary perturbations. A systemic review defined an optimal nutritional challenge test, the “PhenFlex test” (PFT). Recently, it has been shown that the PFT enables the quantification of all relevant metabolic processes involved in maintaining or regaining homeostasis of metabolic health. Furthermore, it was demonstrated that quantification of PFT response was more sensitive as compared to fasting markers in demonstrating reduced phenotypic flexibility in metabolically impaired type 2 diabetes subjects.MethodsThis study aims to demonstrate that quantification of PFT response can discriminate between different states of health within the healthy range of the population. Therefore, 100 healthy subjects were enrolled (50 males, 50 females) ranging in age (young, middle, old) and body fat percentage (low, medium, high), assuming variation in phenotypic flexibility. Biomarkers were selected to quantify main processes which characterize phenotypic flexibility in response to PFT: flexibility in glucose, lipid, amino acid and vitamin metabolism, and metabolic stress. Individual phenotypic flexibility was visualized using the “health space” by representing the four processes on the health space axes. By quantifying and presenting the study subjects in this space, individual phenotypic flexibility was visualized.ResultsUsing the “health space” visualization, differences between groups as well as within groups from the healthy range of the population can be easily and intuitively assessed. The health space showed a different adaptation to the metabolic PhenFlex test in the extremes of the recruited population; persons of young age with low to normal fat percentage had a markedly different position in the health space as compared to persons from old age with normal to high fat percentage.ConclusionThe results of the metabolic PhenFlex test in conjunction with the health space reliably assessed health on an individual basis. This quantification can be used in the future for personalized health quantification and advice.Electronic supplementary materialThe online version of this article (10.1186/s12263-017-0589-8) contains supplementary material, which is available to authorized users.
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