RESUMO
BACKGROUND: A 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. METHODS: This 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. RESULTS: Using 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. CONCLUSION: The 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.
RESUMO
A number of studies have shown that tea catechins can inhibit intestinal iron absorption, mostly iron in the nonhaem form. This randomized, double-blind, placebo-controlled, 3-periods cross-over study examined the degree of inhibition of nonhaem iron absorption by pure crystalline epigallocatechin gallate (EGCG). The study was designed to show the maximum inhibitory action of EGCG by selecting 30 healthy women with low iron stores. Treatments were 150 mg, 300 mg EGCG and placebo each for 8 consecutive study days with a wash-out period of 14 days between treatments. Iron incorporation was assessed by supplying 57Fe orally and 58Fe intravenously. Differences in fractional nonhaem iron absorption between the treatments were evaluated by using two-sided ANOVA. Results showed a relative nonhaem iron absorption reduction of 14% with 150mg EGCG and 27% for 300mg EGCG treatment compared to placebo. Differences were statistically significant (p < or = 0.05) between the placebo and the 300mg EGCG treatments and between the 150 and 300 mg EGCG treatments. The inverse relation between EGCG dose and fractional nonhaem iron absorption was linear (p = 0.0002). In this study the magnitude of the inhibitory action of EGCG on nonhaem iron absorption was found to be much lower than that reported in the literature for black tea and similar compounds. The doses of EGCG in supplements, which will be lower than those used in this study, are not expected to have any health relevant effects on iron absorption in subjects with normal iron stores.
