Ellen Blaak

Ellen Blaak
Maastricht University | UM · Department of Human Biology

PhD

About

430
Publications
60,890
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
19,035
Citations
Introduction
Ellen Blaak currently works at the Department of Human Biology, Maastricht University. Ellen does research in Human Biology

Publications

Publications (430)
Article
Full-text available
Detrimental consequences of antibiotic treatment may include long-lasting disruption of the gut microbiota. Previous studies found no negative effects of antibiotics on metabolic health, although individualized responses were observed. Here, we aimed to investigate the subject-specific response to vancomycin use in tissue-specific insulin sensitivi...
Article
Background and aims: Body fat distribution is closely associated with the risk for developing obesity-related cardiometabolic diseases. Rodent and human studies suggest that mitochondrial dysfunction in adipose tissue (AT) contributes to obesity-related metabolic complications. However, whether mitochondrial function differs between AT depots remai...
Article
Maintaining good glycemic control to prevent complications is crucial in people with type 2 diabetes and in people with prediabetes and in the general population. Different strategies to improve glycemic control involve the prescription of blood glucose‐lowering drugs and the modulation of physical activity and diet. Interestingly, lifestyle interv...
Article
Background: Abdominal obesity is associated with insulin resistance and increased cardiometabolic disease risk, whereas lower-body fat accumulation seems protective against metabolic derangements. Differences in upper-body and lower-body adipose tissue (AT) function seem to underlie these opposing associations. Here, we investigated the inflammator...
Article
Full-text available
p>In the version of this article initially published, a composition error appeared in the second sentence of the Fig. 1 caption. In the text now reading “Microbial pathways related to short-chain fatty acid (SCFA) metabolism are already reduced and those related to branched-chain amino acid (BCAA) metabolism increased in metabolically matched contr...
Article
Growing evidence indicates an important link between gut microbiota, obesity, and metabolic syndrome. Alterations in exocrine pancreatic function are also widely present in patients with diabetes and obesity. To examine this interaction, C57BL/6J mice were fed either a chow diet, high-fat diet (HFD) or HFD plus oral vancomycin or metronidazole to m...
Article
Full-text available
Accumulating evidence indicates that the gut microbiome is an important regulator of body weight, glucose and lipid metabolism, and inflammatory processes, and may thereby play a key role in the aetiology of obesity, insulin resistance and type 2 diabetes. Interindividual responsiveness to specific dietary interventions may be partially determined...
Article
Integrated analysis of microbiome and metabolome profiles in unique cohorts reveals early and late markers of the transition towards ischemic heart disease.
Article
Adipose tissue of metabolically compromised humans with obesity is often characterized by impaired regulation of autophagy pathway. However, data on the role of autophagy in human adipocyte lipid catabolism is scarce. Therefore, we investigated the effect of pharmacological agents (including 3-methyladenine (3MA), bafilomycin A1 (BAF), chloroquine...
Article
Full-text available
Low total energy expenditure (TEE, MJ/d) has been a hypothesized risk factor for weight gain, but repeatability of TEE, a critical variable in longitudinal studies of energy balance, is understudied. We examine repeated doubly labeled water (DLW) measurements of TEE in 348 adults and 47 children from the IAEA DLW Database (mean ± SD time interval:...
Article
Full-text available
Adipose tissue (AT) oxygen tension (pO 2 ) has been implicated in AT dysfunction and metabolic perturbations in both rodents and humans. Compelling evidence suggests that hypoxia exposure alters metabolism, at least partly through effects on AT. However, it remains to be elucidated whether mild intermittent hypoxia (MIH) exposure impacts the AT pro...
Article
Full-text available
Infusions of the short-chain fatty acid (SCFA) acetate in the distal colon improved metabolic parameters in men. Here, we hypothesized that combining rapidly and slowly fermentable fibers will enhance distal colonic acetate production and improve metabolic health. In vitro cultivation studies in a validated model of the colon were used to identify...
Article
Full-text available
Background Family-based approaches have been reported to be effective in improving overweight or obesity in children. Objectives To investigate the relationship of changes in body mass index and metabolic parameters between adults with overweight or obesity and their children during a weight-maintenance family-based dietary intervention. Methods...
Article
Full-text available
Angiotensin converting enzyme-2 (ACE2) is the cell-surface receptor enabling cellular entry of SARS-CoV-2. ACE2 is highly expressed in adipose tissue (AT), rendering AT a potential SARS-CoV-2 reservoir contributing to massive viral spread in COVID-19 patients with obesity. Although rodent and cell studies suggest that the polyphenol resveratrol alt...
Article
Full-text available
Background Worldwide, the prevalence of obesity and insulin resistance has grown dramatically. Gene expression profiling in blood represents a powerful means to explore disease pathogenesis, but the potential impact of inter-individual differences in a cell-type profile is not always taken into account. The objective of this project was to investig...
Article
Whether older adults need more protein than younger adults is debated. The population reference intake for adults set by the European Food Safety Authority is 0.83 g/kg body weight (BW)/d based primarily on nitrogen balance studies, but the underlying data on health outcomes are outdated. An expert committee of the Health Council of the Netherlands...
Article
Full-text available
Dietary interventions to delay carbohydrate digestion or absorption can effectively prevent hyperglycemia in the early postprandial phase. L-arabinose can specifically inhibit sucrase. It remains to be assessed whether co-ingestion of L-arabinose with sucrose delays sucrose digestion, attenuates subsequent glucose absorption, and impacts hepatic gl...
Article
Full-text available
Individuals with hepatic steatosis often display several metabolic abnormalities including insulin resistance and muscle atrophy. Previously, we found that hepatic steatosis results in an altered hepatokine secretion profile, thereby inducing skeletal muscle insulin resistance via inter-organ crosstalk. In this study, we aimed to investigate whethe...
Article
Full-text available
Background: Physical activity may be a way to increase and maintain fat-free mass (FFM) in later life, similar to the prevention of fractures by increasing peak bone mass. Objectives: A study is presented of the association between FFM and physical activity in relation to age. Methods: In a cross-sectional study, FFM was analyzed in relation t...
Article
Background This study aimed to investigate the putative role of the Triglyceride-glucose index (TyG index) computed as ln[TG (mg/dL) × glucose (mg/dL)/2] and derived proxies as predictors of adiposity and weight loss changes after a low calorie diet (LCD) intervention. Methods A total of 744 adult participants from the multicenter DIOGenes interve...
Article
Full-text available
Total daily energy expenditure (“total expenditure”) reflects daily energy needs and is a critical variable in human health and physiology, but its trajectory over the life course is poorly studied. We analyzed a large, diverse database of total expenditure measured by the doubly labeled water method for males and females aged 8 days to 95 years. T...
Article
Full-text available
Understanding the impacts of activity on energy balance is crucial. Increasing levels of activity may bring diminishing returns in energy expenditure because of compensatory responses in non-activity energy expenditures.1, 2, 3 This suggestion has profound implications for both the evolution of metabolism and human health. It implies that a long-te...
Article
Background High postprandial lipemia is associated with increased risk of cardiovascular disease, independently of fasting lipid concentrations. Abdominal and gluteofemoral fat depots handle lipoproteins differently, which could affect postprandial lipemia and contribute to the relation between abdominal fat distribution and cardiovascular disease...
Article
Full-text available
Objective: Recent studies suggest that hypoxia exposure may improve glucose homeostasis, but well-controlled human studies are lacking. We hypothesized that mild intermittent hypoxia (MIH) exposure decreases tissue oxygen partial pressure (pO2) and induces metabolic improvements in people who are overweight/obese. Methods: In a randomized, contr...
Article
Full-text available
Our recent in vivo human studies showed that colonic administration of sodium acetate (SA) resulted in increased circulating acetate levels, which was accompanied by increments in whole-body fat oxidation in overweight-obese men. Since skeletal muscle has a major role in whole-body fat oxidation, we aimed to investigate effects of SA on fat oxidati...
Article
Full-text available
Background: It is well-established that the etiology of type 2 diabetes differs between individuals. Insulin resistance (IR) may develop in different tissues, but the severity of IR may differ in key metabolic organs such as the liver and skeletal muscle. Recent evidence suggests that these distinct tissue-specific IR phenotypes may also respond di...
Article
Full-text available
Context Inhibitors of the protease neprilysin (NEP) are used for treating heart failure, but are also linked to improvements in metabolism. NEP may cleave proglucagon-derived peptides, including the glucose and amino acid (AA)-regulating hormone glucagon. Studies investigating NEP inhibition on glucagon metabolism are warranted. Objective To inves...
Chapter
This chapter reviews how dietary fibers can be used to prevent Type 2 diabetes mellitus. Dietary fibers are a heterogenous group of food compounds. The physicochemical properties of dietary fibers determine their effects on gastrointestinal and metabolic health, including effect on gastro-intestinal transit, glycemic response, microbial composition...
Article
Full-text available
A low-calorie diet (LCD) is an effective strategy to lose weight and improve cardiometabolic risk factors, however, sexual dimorphism may be present. This study aims to investigate sexual dimorphism in cardiometabolic risk factors following weight loss and after weight maintenance. 782 overweight/obese participants (65% women) of the DiOGenes trial...
Article
Full-text available
Objective SARS‐CoV‐2 uses the hosts angiotensin‐converting enzyme 2 (ACE2) as cellular entry point. Hence, modulating ACE2 might impact SARS‐CoV‐2 viral replication, shedding and COVID‐19 severity. Here, we investigated if the angiotensin II type 1 receptor (AT1R) blocker valsartan alters the expression of renin‐angiotensin system (RAS) components,...
Article
Full-text available
Background: Macrophages play an important role in regulating adipose tissue function, while their frequencies in adipose tissue vary between individuals. Adipose tissue infiltration by high frequencies of macrophages has been linked to changes in adipokine levels and low-grade inflammation, frequently associated with the progression of obesity. The...
Article
Full-text available
The gut microbiota may affect host metabolic health through microbial metabolites. The balance between the production of microbial metabolites by saccharolytic and proteolytic fermentation may be an important determinant of metabolic health. Amongst the best-studied saccharolytic microbial metabolites are the short-chain fatty acids acetate, propio...
Article
Full-text available
To investigate (1) the association of four VDR polymorphisms (TaqI/rs731236, ApaI/rs7975232, FokI/rs10735810, and Bsml/rs1544410) with markers of adiposity and tissue-specific insulin resistance at baseline, after weight loss and weight maintenance; (2) the effect of the VDR polymorphisms in the SAT transcriptome in overweight/obese Caucasians of t...
Article
Full-text available
Plasma glucose and insulin responses following an oral glucose challenge are representative of glucose tolerance and insulin resistance, key indicators of type 2 diabetes mellitus pathophysiology. A large heterogeneity in individuals’ challenge test responses has been shown to underlie the effectiveness of lifestyle intervention. Currently, this he...
Article
Full-text available
Background/objectives Despite considerable literature supporting the potential health benefits of reducing postprandial glucose (PPG), and insulin (PPI) exposures, the size of a clinically relevant reduction is currently unknown. We performed a systematic review and meta-analysis to quantify effects of alpha-glucosidase-inhibiting (AGI) drugs on ac...
Article
The role of carbohydrate in a healthy diet has been controversial. The confusion over carbohydrate has come from the long standing limitation of dietary recall studies as well as inability in many of these studies to delineate between the different types of carbohydrates. It is the aim of this paper, to understand and review the data on the role of...
Article
Full-text available
Context: Mitochondria are essential for cellular energy homeostasis, yet their role in subcutaneous adipose tissue (SAT) during different types of weight-loss interventions remains unknown. Objective: Investigate how SAT mitochondria change following diet-induced and bariatric surgery-induced weight-loss interventions in four independent weight-...
Article
Full-text available
Five years ago, with the editorial board of Frontiers in Nutrition, we took a leap of faith to outline the Goals for Nutrition Science – the way we see it ( 1 ). Now, in 2020, we can put ourselves to the test and take a look back. Without a doubt we got it right with several of the key directions. To name a few, Sustainable Development Goals (SDGs)...
Article
Full-text available
PurposeReducing postprandial hyperglycemia has beneficial effects on diabetes-related risk factors, but the magnitude of the reduction needed to achieve such an effect is unknown. The purpose of the study was to quantify the relationship of acute glucose and insulin postprandial responses with longer-term effects on diabetes-related risk factors by...
Article
Numerous strategies have been investigated to overcome the excessive weight gain that accompanies a chronic positive energy balance. Most approaches focus on a reduction of energy intake and the improvement of lifestyle habits. The use of high intensity artificial sweeteners, also known as non-caloric sweeteners (NCS), as sugar substitutes in foods...
Article
Full-text available
The doubly labeled water (DLW) method measures total energy expenditure (TEE) in free-living subjects. Several equations are used to convert isotopic data into TEE. Using the International Atomic Energy Agency (IAEA) DLW database (5,756 measurements of adults and children), we show considerable variability is introduced by different equations. The...
Article
Full-text available
A poor diet is one of the leading causes for non-communicable diseases. Due to the increasing prevalence of overweight and obesity, there is a strong focus on dietary overconsumption and energy restriction. Many strategies focus on improving energy balance to achieve successful weight loss. One of the strategies to lower energy intake is refraining...
Article
Obesity is associated with many adverse health effects, such as an increased cardiometabolic risk. Despite higher adiposity for a given BMI, premenopausal women are at lower risk of cardiometabolic disease than men of the same age. This cardiometabolic advantage in women seems to disappear after the menopause or when type 2 diabetes mellitus develo...
Article
The human gut microbiome is a complex ecosystem, densely colonised by thousands of microbial species. It varies among individuals and depends on host genotype and environmental factors, such as diet and antibiotics. In this review, we focus on stability and resilience as essential ecological characteristics of the gut microbiome and its relevance f...
Article
In 2019, we published a Review on the relevance of gut microbial metabolites in obesity, non-alcoholic fatty liver disease and type 2 diabetes mellitus. Here, we highlight the importance of the balance between colonic proteolytic and saccharolytic metabolite production for metabolic health and the need to focus on more subgroup-based or personalize...
Article
Full-text available
Evidence is accumulating that short chain fatty acids (SCFA) play an important role in the maintenance of gut and metabolic health. The SCFA acetate, propionate and butyrate are produced from the microbial fermentation of indigestible carbohydrates and appear to be key mediators of the beneficial effects elicited by the gut microbiome. Microbial SC...
Article
Background: Vitamin D has been suggested to affect peripheral insulin sensitivity. Evidence regarding the effect of vitamin D supplementation on insulin sensitivity is still conflicting. Purpose: This meta-analysis aimed to assess the effect of vitamin D supplementation on insulin sensitivity in humans with or at risk for insulin resistance. Da...
Article
Full-text available
Non‐Alcoholic fatty liver disease (NAFLD) is the most common form of liver disease and is characterized by fat accumulation in the liver. Hypercaloric diets generally increase hepatic fat accumulation, whereas hypocaloric diets decrease liver fat content. In addition, there is evidence to suggest that moderate amounts of unsaturated fatty acids see...
Article
Full-text available
Als voorbereiding op het VoedingNLcongres 'Koolhydraten en insulinegevoeligheid' (10 maart 2020) hebben we een expertsessie georganiseerd met professionals afkom stig uit wetenschap en praktijk. We hebben deze experts uitgenodigd om hun visie te geven op verschillende deelvragen omtrent koolhydraten en insulinegevoeligheid, en hen gevraagd om onder...
Article
Full-text available
Weight loss aims to improve glycemic control in obese but strong variability is observed. Using a multi-omics approach, we investigated differences between 174 responders and 201 non-responders, that had lost >8% body weight following a low-caloric diet (LCD, 800 kcal/d for 8 weeks). The two groups were comparable at baseline for body composition,...
Article
Full-text available
Recent evidence indicates that insulin resistance (IR) in obesity may develop independently in different organs, representing different etiologies toward type 2 diabetes and other cardiometabolic diseases. The aim of this study was to investigate whether IR in the liver and IR in skeletal muscle are associated with distinct metabolic profiles. This...
Article
Full-text available
A growing body of evidence suggests that the human gut microbiota plays a role in the development of obesity and related metabolic diseases. However, there is little consensus between studies, which could be due to biological as well as technical variation. In addition, little human data are available to investigate whether tissue-specific insulin...
Article
Full-text available
Lifestyle intervention may be effective in reducing type 2 diabetes mellitus incidence and cardiometabolic risk. A more personalised nutritional approach based on an individual or subgroup-based metabolic profile may optimise intervention outcome. Whole body insulin resistance (IR) reflects defective insulin action in tissues such as muscle, liver,...
Article
Full-text available
Aims/hypothesis Insulin resistance in skeletal muscle and liver plays a major role in the pathophysiology of type 2 diabetes. The hyperinsulinaemic–euglycaemic clamp is considered the gold standard for assessing peripheral and hepatic insulin sensitivity, yet it is a costly and labour-intensive procedure. Therefore, easy-to-measure, cost-effective...
Article
Full-text available
Microbially-produced acetate has been reported to beneficially affect metabolic health through effects on satiety, energy expenditure, insulin sensitivity, and substrate utilization. Here, we investigate the association between sex-specific concentrations of acetate and insulin sensitivity/resistance indices (Homeostatic Model Assessment of Insulin...
Article
Full-text available
Acute intake of the wheat bran extract Arabinoxylan-Oligosaccharide (AXOS) modulates the gut microbiota, improves stool characteristics and postprandial glycemia in healthy humans. Yet, little is known on how long-term AXOS intake influences gastrointestinal (GI) functioning, gut microbiota, and metabolic health. In this randomized, placebo-control...
Article
Full-text available
Heterogeneity of interindividual and intraindividual responses to interventions is often observed in randomized, controlled trials for obesity. To address the global epidemic of obesity and move toward more personalized treatment regimens, the global research community must come together to identify factors that may drive these heterogeneous respon...
Article
Full-text available
Cathepsin L1 (CTSL1) and B (CTSB) are lysosomal proteases, of which the expression and activity are impaired in adipose tissue (AT) of obese rodents, indicating AT lysosomal dysfunction. Here we assess the relation between abdominal subcutaneous AT (SCAT) CTSL1 and CTSB gene expression (qRT-PCR), body composition and tissue-specific insulin resista...
Article
Full-text available
Longer colonic transit time and hard stools are associated with increased gut microbiota diversity. Here, we investigate to what extent quantitative measures of (segmental) colonic transit time were related to gut microbiota composition, microbial metabolites and gut-related parameters in a human cross-sectional study. Using radio-opaque markers, (...
Article
Full-text available
Obesity is characterized by a blunted lipolytic response in abdominal subcutaneous adipose tissue (SAT) and low circulating vitamin D levels. Here we investigated whether an impaired SAT lipolytic response coincides with an impaired SAT vitamin D release in eight lean and six obese men. 25-hydroxyvitamin D3 [25(OH)D3 ] and 1,25-dihydroxyvitamin D3...
Article
Obesity-related insulin resistance (IR) may develop in multiple organs, representing various etiologies for cardiometabolic diseases. We identified abdominal subcutaneous adipose tissue (ScAT) transcriptome profiles in liver or muscle IR by means of RNA sequencing in overweight or obese participants of the Diet, Obesity, and Genes (DiOGenes) (NCT00...