Hans-Peter Helfrich

Epicatechin ingested via cocoa products reduces blood pressure in humans: a nonlinear regression model with a Bayesian approach

BACKGROUND Four meta-analyses of randomized controlled trials (RCTs) based on the classical random-effects model showed that cocoa consumption can reduce systolic blood pressure (SBP) and diastolic blood pressure (DBP). Because epicatechin is suggested to be responsible for the treatment effect, changes in blood pressure should depend on the dose of ingested epicatechin, which may explain the between-study differences. OBJECTIVE The objective was to quantify the effect of epicatechin ingested via cocoa products on changes in SBP and DBP. DESIGN A nonlinear meta-regression model was chosen to investigate the impact of the epicatechin dose on changes in SBP and DBP. A Bayesian approach using Markov chain Monte Carlo methods was applied for an appropriate treatment of the nonlinearity. RESULTS Data from 16 RCTs on SBP and 15 RCTs on DBP were included. The dose of epicatechin ingested via cocoa products influenced the changes in SBP and DBP. The asymptotic limit for the reduction was estimated at -4.6 mm Hg (95% CI: -5.4, -3.9 mm Hg) for SBP and at -2.1 mm Hg (95% CI: -2.7, -1.6 mm Hg) for DBP. An intake of 25 mg epicatechin/d led to a mean reduction of -4.1 mm Hg (95% CI: -4.6, -3.6 mm Hg) in SBP and of -2.0 mm Hg (95% CI: -2.4, -1.5 mm Hg) in DBP. CONCLUSIONS Blood pressure reduction by consumption of cocoa products depends on the dose of ingested epicatechin, which explains most of the between-study differences in classical meta-analyses. Similar effects may be achieved by consumption of other foods that are also rich in epicatechin.

Kinetics of l-Theanine Uptake and Metabolism in Healthy Participants Are Comparable after Ingestion of l-Theanine via Capsules and Green Tea

L-Theanine, an amino acid in green tea, is suggested to improve cognition and mood. Therefore, L-theanine is available as a supplement and is now used as an ingredient in functional drinks. Because data on the metabolic fate of L-theanine from human studies are lacking, we investigated the kinetics of L-theanine uptake and its metabolites, ethylamine and glutamic acid, in healthy participants. Within a randomized crossover study, 12 participants ingested a bolus of 100 mg L-theanine via capsules or green tea. On further occasions, 3 participants received 50 and 200 mg L-theanine via capsules. Blood and urine were collected before and up to 24 h postconsumption to determine the concentrations of L-theanine, proteinogenic amino acids, and ethylamine in plasma, erythrocytes, and urine by HPLC. L-Theanine increased in plasma, erythrocytes, and urine with comparable results after both treatments. The maximum plasma concentration of L-theanine occurred 0.8 h after intake of 100 mg L-theanine via capsules (24.3 ± 5.7 μmol/L) and tea (26.5 ± 5.2 μmol/L), respectively. The AUC of L-theanine in plasma increased dose dependently after intake of 50, 100, and 200 mg L-theanine via capsules. Moreover, ethylamine and glutamic acid increased in plasma and were excreted by urine after intake of capsules and tea. In conclusion, L-theanine is rapidly absorbed and seems to be hydrolyzed to ethylamine and glutamic acid. A minor part of L-theanine is retained in erythrocytes. Kinetics and urinary excretion of L-theanine, ethylamine, and glutamic acid are comparable after both treatments. Thus, functional effects of L-theanine intake may result from L-theanine, ethylamine, or glutamic acid.

Wavelet Analysis of Geoscientific Data

Wavelets have shown to be an indispensable tool for a scale-sensitive representation and analysis of spatial or temporal data. In this chapter we illustrate the basic mathematical background for wavelets as well as fast algorithms for multivariate wavelet constructions on bounded domains. Finally, we will show an application of wavelets to analysis and compression of precipitation data.

Diffusion Methods for Form Generalisation

In this section we focus our interest on techniques originating in computer vision. There we have the problem of distinguishing fine scale structures from coarse scale structures in digital images. A major step in solving this problem is related to the concept of a scale space. The classical example is the Gaussian scale space, which gives a linear method for the transition from fine to coarse scales. We demonstrate relations of this scale space to smoothing and averaging procedures. We show that the concept of a scale space is also applicable to form generalisations of digital elevation models (DEM). Anisotropy and inhomogeneity of DEM demand an application of nonlinear diffusion methods that have to be customised by steering parameters, which have to be interpretable in the context of DEM form generalisation. An example is given for elevation data from the Broeltal near Bonn.

A nutritive dose of pure (–)-epicatechin does not beneficially affect increased cardiometabolic risk factors in overweight-to-obese adults—a randomized, placebo-controlled, double-blind crossover study

Background Regular cocoa consumption has been shown to reduce blood pressure, improve lipid profiles, and increase insulin sensitivity and flow-mediated dilatation in healthy adults. It is assumed that these effects can be attributed to polyphenolic cocoa ingredients such as flavanols, especially to (-)-epicatechin. Nutritive intervention studies to prove this hypothesis are scarce. Objective We aimed to evaluate whether regular consumption of 25 mg of pure (-)-epicatechin can affect increased cardiometabolic risk factors [blood pressure, glucose and lipid metabolism, low-density lipoprotein (LDL) oxidation] in overweight-to-obese subjects. Design Forty-eight overweight or obese nonsmokers [body mass index (kg/m2) ≥25.0, ages 20-65 y] with clear signs of metabolic syndrome (blood pressure ≥130/85 mm Hg, glucose >5.55 mmol/L, or triglycerides >1.69 mmol/L or cholesterol >5.2 mmol/L in fasting blood) and without chronic diseases were included in a randomized, placebo-controlled, double-blind crossover study. Participants ingested daily 25 mg (-)-epicatechin (encapsulated) or placebo for 2-wk in random order (2-wk washout). After an overnight fast, blood pressure was monitored and blood samples were collected before and after both treatments. Anthropometric data were determined at each visit. Dietary intake was assessed by 3-d food records during both treatments and during run-in and washout phase. Results Supplementation of pure (-)-epicatechin did not significantly affect blood pressure, glucose, insulin, homeostasis model assessment of insulin resistance, triglycerides, or total, LDL, or HDL cholesterol. Oxidized LDL, vitamins C and E, and β-carotene in plasma were not modulated. Body weight, fat mass, fat distribution, and the intake of energy, nutrients, and (-)-epicatechin from food remained stable throughout the study. Conclusions Daily intake of 25 mg of pure (-)-epicatechin for 2 wk does not reduce cardiometabolic risk factors in overweight-to-obese adults. Thus, the hypothesis that the cardioprotective effects of regular cocoa consumption are exclusively ascribed to (-)-epicatechin should be reconsidered. The study was registered at the German Clinical Trial Register as DRKS-ID: DRKS00009846.

Regular Intake of a Usual Serving Size of Flavanol-Rich Cocoa Powder Does Not Affect Cardiometabolic Parameters in Stably Treated Patients with Type 2 Diabetes and Hypertension—A Double-Blinded, Randomized, Placebo-Controlled Trial

Regular cocoa consumption has been shown to improve blood pressure (BP), insulin sensitivity, and lipid levels in patients with type 2 diabetes (T2D), using up to 100 g of chocolate or 54 g of cocoa. These effects, attributed to cocoa flavanols, would be beneficial for patients with T2D if they could be achieved by a usual serving size of flavanol-rich cocoa. Forty-two hypertensive patients with T2D (stable pharmacological treatment, with good adjustment for glucose metabolism, lipids, and BP) ingested capsules with 2.5 g/day of a flavanol-rich cocoa or cocoa-free capsules for 12 weeks in a double-blinded, randomized, placebo-controlled study with parallel group design. Participants had to maintain diet, lifestyle, and medication. Before and after intervention, fasting blood samples were collected; BP and nutritional status were investigated. Cocoa treatment did not affect BP, nor glucose metabolism (glucose, HbA1c, insulin, HOMA-IR) and lipids (triglycerides, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol). Body weight, fat mass, and nutrient supply remained unchanged. Changes in the placebo group did not occur. Regular intake of a usual serving size of flavanol-rich cocoa does not improve cardiometabolic parameters in stably treated patients with T2D and hypertension. As the medication modulates partly the same targets as cocoa flavanols, future studies should focus on the preventive effect of cocoa against diabetes and other cardiometabolic diseases in individuals with preexisting abnormalities that do not require any pharmacological treatment.

Analytical Coupling of Scales — Transport of Water and Solutes in Porous Media

In almost all phenomena in the natural sciences many scales are present. Each of these scales contains specific information about the underlying physical process. Upscaling techniques allow the transfer of information, i. e., laws which are given on a micro-scale to laws valid on a higher scale. This means that the laws valid on the micro-scale are generalised to a higher scale, but does not mean that the laws are of the same type. By some typical examples, we describe the results of mathematical homogenisation. As an application, we consider the problem of fluid flow in porous media involving strong capillary forces as well as water uptake by roots.