Advancing human gut microbiota research by considering gut transit time.

Accumulating evidence indicates that gut transit time is a key factor in shaping the gut microbiota composition and activity, which are linked to human health. Both population-wide and small-scale studies have identified transit time as a top covariate contributing to the large interindividual variation in the faecal microbiota composition. Despite this, transit time is still rarely being considered in the field of the human gut microbiome. Here, we review the latest research describing how and why whole gut and segmental transit times vary substantially between and within individuals, and how variations in gut transit time impact the gut microbiota composition, diversity and metabolism. Furthermore, we discuss the mechanisms by which the gut microbiota may causally affect gut motility. We argue that by taking into account the interindividual and intraindividual differences in gut transit time, we can advance our understanding of diet-microbiota interactions and disease-related microbiome signatures, since these may often be confounded by transient or persistent alterations in transit time. Altogether, a better understanding of the complex, bidirectional interactions between the gut microbiota and transit time is required to better understand gut microbiome variations in health and disease.

Associations between sheep meat intake frequency and blood plasma levels of metabolites and lipoproteins in healthy Uzbek adults.

INTRODUCTION: Uzbekistan is one of the countries with the highest number of diet-related chronic diseases, which is believed to be associated with high animal fat intake. Sheep meat is high in fats (~ 5% in muscle), including saturated and monounsaturated fatty acids, and it contains nearly twice the higher amounts of n-3 polyunsaturated fatty acids and conjugated linoleic acids compared to beef. Nevertheless, sheep meat is considered health promoting by the locals in Uzbekistan and it accounts for around 1/3 of red meat intake in the country. OBJECTIVES: The aim of this study was to apply a metabolomics approach to investigate if sheep meat intake frequency (SMIF) is associated with alterations in fasting blood plasma metabolites and lipoproteins in healthy Uzbek adults. METHODS: The study included 263 subjects, 149 females and 114 males. For each subject a food intake questionnaire, including SMIF, was recorded and fasting blood plasma samples were collected for metabolomics. Blood plasma metabolites and lipoprotein concentrations were determined using 1H NMR spectroscopy. RESULTS AND CONCLUSION: The results showed that SMIF was confounded by nationality, sex, body mass index (BMI), age, intake frequency of total meat and fish in ascending order (p < 0.01). Multivariate and univariate data analyses showed differences in the levels of plasma metabolites and lipoproteins with respect to SMIF. The effect of SMIF after statistical adjustment by nationality, sex, BMI, age, intake frequency of total meat and fish decreased but remained significant. Pyruvic acid, phenylalanine, ornithine, and acetic acid remained significantly lower in the high SMIF group, whereas choline, asparagine, and dimethylglycine showed an increasing trend. Levels of cholesterol, apolipoprotein A1, as well as low- and high-density lipoprotein subfractions all displayed a decreasing trend with increased SMIF although the difference were not significant after FDR correction.

Effects of changing from a diet with saturated fat to a diet with n-6 polyunsaturated fat on the serum metabolome in relation to cardiovascular disease risk factors.

PURPOSE: Replacing saturated fatty acids (SFA) with polyunsaturated fatty acids (PUFA) is associated with a reduced risk of cardiovascular disease. Yet, the changes in the serum metabolome after this replacement is not well known. Therefore, the present study aims to identify the metabolites differentiating diets where six energy percentage SFA is replaced with PUFA and to elucidate the association of dietary metabolites with cardiometabolic risk markers. METHODS: In an 8-week, double-blind, randomized, controlled trial, 99 moderately hyper-cholesterolemic adults (25-70 years) were assigned to a control diet (C-diet) or an experimental diet (Ex-diet). Both groups received commercially available food items with different fatty acid compositions. In the Ex-diet group, products were given where SFA was replaced mostly with n-6 PUFA. Fasting serum samples were analysed by untargeted ultra-performance liquid chromatography high-resolution mass spectrometry (UPLC-HRMS). Pre-processed data were analysed by double cross-validated Partial Least-Squares Discriminant Analysis (PLS-DA) to detect features differentiating the two diet groups. RESULTS: PLS-DA differentiated the metabolic profiles of the Ex-diet and the C-diet groups with an area under the curve of 0.83. The Ex-diet group showed higher levels of unsaturated phosphatidylcholine plasmalogens, an unsaturated acylcarnitine, and a secondary bile acid. The C-diet group was characterized by odd-numbered phospholipids and a saturated acylcarnitine. The Principal Component analysis scores of the serum metabolic profiles characterizing the diets were significantly associated with low-density lipoprotein cholesterol, total cholesterol, and triglyceride levels but not with glycaemia. CONCLUSION: The serum metabolic profiles confirmed the compliance of the participants based on their diet-specific metabolome after replacing SFA with mostly n-6 PUFA. The participants' metabolic profiles in response to the change in diet were associated with cardiovascular disease risk markers. This study was registered at clinicaltrials.gov as NCT01679496 on September 6th 2012.

Mediterranean diet intervention in overweight and obese subjects lowers plasma cholesterol and causes changes in the gut microbiome and metabolome independently of energy intake.

OBJECTIVES: This study aimed to explore the effects of an isocaloric Mediterranean diet (MD) intervention on metabolic health, gut microbiome and systemic metabolome in subjects with lifestyle risk factors for metabolic disease. DESIGN: Eighty-two healthy overweight and obese subjects with a habitually low intake of fruit and vegetables and a sedentary lifestyle participated in a parallel 8-week randomised controlled trial. Forty-three participants consumed an MD tailored to their habitual energy intakes (MedD), and 39 maintained their regular diets (ConD). Dietary adherence, metabolic parameters, gut microbiome and systemic metabolome were monitored over the study period. RESULTS: Increased MD adherence in the MedD group successfully reprogrammed subjects' intake of fibre and animal proteins. Compliance was confirmed by lowered levels of carnitine in plasma and urine. Significant reductions in plasma cholesterol (primary outcome) and faecal bile acids occurred in the MedD compared with the ConD group. Shotgun metagenomics showed gut microbiome changes that reflected individual MD adherence and increase in gene richness in participants who reduced systemic inflammation over the intervention. The MD intervention led to increased levels of the fibre-degrading Faecalibacterium prausnitzii and of genes for microbial carbohydrate degradation linked to butyrate metabolism. The dietary changes in the MedD group led to increased urinary urolithins, faecal bile acid degradation and insulin sensitivity that co-varied with specific microbial taxa. CONCLUSION: Switching subjects to an MD while maintaining their energy intake reduced their blood cholesterol and caused multiple changes in their microbiome and metabolome that are relevant in future strategies for the improvement of metabolic health.

Pre- and post-diagnostic intake of whole grain and dairy products and breast cancer prognosis: the Danish Diet, Cancer and Health cohort.

PURPOSE: Fiber rich foods and dairy products have been suggested to be associated with breast cancer prognosis, though existing research is limited and either report on pre- or post-diagnostic dietary intake in relation to breast cancer prognosis. We investigated the associations between intake of whole grain (WG) and dairy products assessed both pre- and post-diagnostically in relation to breast cancer prognosis. METHODS: A total of 1965 women from the Diet, Cancer and Health cohort who were diagnosed with breast cancer between baseline (1993-1997) and December 2013 were included and followed for a median of 7 years after diagnosis. During follow-up, 309 women experienced breast cancer recurrence and 460 women died, of whom 301 died from breast cancer. Dietary assessment by food frequency questionnaires was obtained up to three times, pre- and post-diagnostic, over a period of 18 years. Cox proportional hazard models were used to estimate hazard ratios. RESULTS: No associations were observed between pre- or post-diagnostic intake of total WG or total dairy products and breast cancer prognosis. A high pre-diagnostic intake of oatmeal/muesli was associated with lower all-cause mortality (HR 0.76, 95% CI 0.59-0.99), whereas high post-diagnostic intake of rye bread was associated with higher breast cancer-specific mortality (HR 1.29, 95% CI 1.02-1.63). A generally high intake of cheese was associated with a higher recurrence rate. CONCLUSION: Pre-diagnostic intake of oatmeal/muesli was associated with lower all-cause mortality, and post-diagnostic intake of rye bread was associated with higher breast cancer specific mortality.

Pre-meal protein intake alters postprandial plasma metabolome in subjects with metabolic syndrome.

PURPOSE: We examined the effect on the postprandial plasma metabolome of protein pre-meals before a fat-rich main meal. METHODS: Two randomized, cross-over meal studies were conducted to test the dose-response effect (0 g, 10 g, 20 g) of a pre-meal with whey protein (WP) (PREMEAL I), and the effect of protein quality (10 g WP, casein, or gluten) and timing (- 15 min vs - 30 min) of the pre-meal (PREMEAL II). Participants with metabolic syndrome received one of the test meals on each test day, - 15 min (or - 30 min) prior to a standardized fat-rich breakfast. Plasma samples were collected at - 15 min (or - 30 min), 0, 120, 240 a nd 360 min and analyzed using liquid chromatography-mass spectrometry with an untargeted method. RESULTS: Pre-meal WP intake elevated plasma branched-chain amino acids (BCAA), aromatic amino acids and methionine and decreased plasma LPC (16:0) and PC (32:1) levels before the main meal. Early (- 15 to 0 min) aromatic amino acids and BCAA in response to pre-meal WP partially predict the glucose and insulin response after the main meal. A pre-meal with WP altered the postprandial plasma metabolic pattern of acyl-carnitines, specific PCs, LPCs and LPEs, betaine, citric acid, linoleic acid, and ß-hydroxypalmitic acid compared to no pre-meal. The casein and WP pre-meals exhibited similar postprandial amino acid responses whereas a pre-meal with gluten resulted in lower levels of plasma amino acids and its metabolites. CONCLUSION: A pre-meal with protein affects the postprandial metabolic pattern indicating facilitated glucose and lipid disposal from plasma in participants with metabolic syndrome.

Discovery and Validation of Banana Intake Biomarkers Using Untargeted Metabolomics in Human Intervention and Cross-sectional Studies.

BACKGROUND: Banana is one of the most widely consumed fruits in the world. However, information regarding its health effects is scarce. Biomarkers of banana intake would allow a more accurate assessment of its consumption in nutrition studies. OBJECTIVES: Using an untargeted metabolomics approach, we aimed to identify the banana-derived metabolites present in urine after consumption, including new candidate biomarkers of banana intake. METHODS: A randomized controlled study with a crossover design was performed on 12 healthy subjects (6 men, 6 women, mean ± SD age: 30.0 ± 4.9 y; mean ± SD BMI: 22.5 ± 2.3 kg/m2). Subjects underwent 2 dietary interventions: 1) 250 mL control drink (Fresubin 2 kcal fiber, neutral flavor; Fresenius Kabi), and 2) 240 g banana + 150 mL control drink. Twenty-four-hour urine samples were collected and analyzed with ultra-performance liquid chromatography coupled to a quadrupole time-of-flight MS and 2-dimensional GC-MS. The discovered biomarkers were confirmed in a cross-sectional study [KarMeN (Karlsruhe Metabolomics and Nutrition study)] in which 78 subjects (mean BMI: 22.8; mean age: 47 y) were selected reflecting high intake (126-378 g/d), low intake (47.3-94.5 g/d), and nonconsumption of banana. The confirmed biomarkers were examined singly or in combinations, for established criteria of validation for biomarkers of food intake. RESULTS: We identified 33 potentially bioactive banana metabolites, of which 5 metabolites, methoxyeugenol glucuronide (MEUG-GLUC), dopamine sulfate (DOP-S), salsolinol sulfate, xanthurenic acid, and 6-hydroxy-1-methyl-1,2,3,4-tetrahydro-ß-carboline sulfate, were confirmed as candidate intake biomarkers. We demonstrated that the combination of MEUG-GLUC and DOP-S performed best in predicting banana intake in high (AUCtest = 0.92) and low (AUCtest = 0.87) consumers. The new biomarkers met key criteria establishing their current applicability in nutrition and health research for assessing the occurrence of banana intake. CONCLUSIONS: Our metabolomics study in healthy men and women revealed new putative bioactive metabolites of banana and a combined biomarker of intake. These findings will help to better decipher the health effects of banana in future focused studies. This study was registered at clinicaltrials.gov as NCT03581955 and with the Ethical Committee for the Protection of Human Subjects Sud-Est 6 as CPP AU 1251, IDRCB 2016-A0013-48; the KarMeN study was registered with the German Clinical Trials Register (DRKS00004890). Details about the study can be obtained from https://www.drks.de.

The impact of short-chain fatty acids on GLP-1 and PYY secretion from the isolated perfused rat colon.

The colonic epithelium harbors a large number of endocrine cells, but little is known about the endocrine functions of the colon. However, the high density of glucagon like peptide-1 (GLP-1)- and peptide-YY (PYY)-secreting L cells is of great interest because of the potential antidiabetic and antiobesity effects of GLP-1 and PYY. Short-chain fatty acids (SCFAs) produced by local bacterial fermentation are suggested to activate the colonic free fatty acid receptors FFAR2 (GPR43) and FFAR3 (GPR41), stimulating the colonic L cells. We used the isolated perfused rat colon as a model of colonic endocrine secretion and studied the effects of the predominant SCFAs formed: acetate, propionate, and butyrate. We show that luminal and especially vascular infusion of acetate and butyrate significantly increases colonic GLP-1 secretion, and to a minor extent also PYY secretion, but only after enhancement of intracellular cAMP. Propionate neither affected GLP-1 nor PYY secretion whether administered luminally or vascularly. A FFAR2- and FFAR3-specific agonist [( S)-2-(4-chlorophenyl)-3,3-dimethyl- N-(5-phenylthiazol-2-yl)butamide (CFMB)/ AR420626 ] had no effect on colonic GLP-1 output, and a FFAR3 antagonist ( AR399519 ) did not decrease the SCFA-induced GLP-1 response. However, the voltage-gated Ca2+-channel blocker nifedipine, the KATP-channel opener diazoxide, and the ATP synthesis inhibitor 2,4-dinitrophenol completely abolished the responses. FFAR2 receptor studies confirmed low-potent partial agonism of acetate, propionate, and butyrate, compared with CFMB, which is a full agonist with ~750-fold higher potency than the SCFAs. In conclusion, SCFAs may increase colonic GLP-1/PYY secretion, but FFAR2/FFAR3 do not seem to be involved. Rather, SCFAs are metabolized and appear to function as a colonocyte energy source. NEW & NOTEWORTHY By the use of in situ isolated perfused rat colon we show that short-chain fatty acids (SCFAs) primarily are used as a colonocyte energy source in the rat, subsequently triggering glucagon like peptide-1 (GLP-1) secretion independent of the free fatty acid receptors FFAR2 and FFAR3. Opposite many previous studies on SCFAs and FFAR2/FFAR3 and GLP-1 secretion, this experimental model allows investigation of the physiological interactions between luminal nutrients and secretion from cells whose function depend critically on their blood supply as well as nerve and paracrine interactions.

Sea buckthorn decreases and delays insulin response and improves glycaemic profile following a sucrose-containing berry meal: a randomised, controlled, crossover study of Danish sea buckthorn and strawberries in overweight and obese male subjects.

PURPOSE: Berries and mixed berry products exert acute effects on postprandial glycaemia and insulinemia, but very few berries have been studied, and primarily in normal weight subjects. Sea buckthorn and strawberry are compositionally widely different berries and may likely produce different responses. The effects of strawberry and sea buckthorn on postprandial glycaemia and insulinemia were examined in overweight or obese male subjects. Subjective appetite sensations and ad libitum intake were also examined. METHODS: The study was conducted as a randomised, controlled, single-blinded, three-way crossover study. Eighteen subjects were studied in three 2-h meal tests followed by a subsequent ad libitum meal. Test meals contained added sucrose and either sea buckthorn, strawberry or no berries with added fructose (control). Blood samples were collected at t = 0, 30, 45, 60, 90 and 120 min. Subjective appetite sensations were recorded at t = 0, 15, 30, 45, 60, 90, 120, and 140 min and subsequent ad libitum intake was recorded. Statistical differences in all continuous measures were evaluated based on the existence of a meal or a time-meal interaction by repeated measures linear model analyses or by differences in AUC by linear mixed models. RESULTS: None of the berries affected postprandial glucose. However, sea buckthorn improved glycaemic profile (44.7%, p < 0.01) compared to control. Sea buckthorn also resulted in a decrease in plasma insulin concentration at 30 min (39.6%, p < 0.01) and at 45 min (16.5%, p < 0.05) compared to control and the maximal increase in plasma insulin was lower following sea buckthorn compared with control (23.6%, p < 0.01). Strawberry did not affect postprandial insulin concentrations compared to control. No differences between control and each of the two berries were observed for any of the appetite parameters, except for desire for something sweet, which was increased following the sea buckthorn meal compared to control. CONCLUSIONS: There was no effect on postprandial glucose response to a sugar challenge given together with purees of strawberry or sea buckthorn. Sea buckthorn decreased and delayed the insulin response and improved glycaemic profile compared with control. Strawberry had no such effects. No important differences were seen for the appetite measures. Sea buckthorn might be useful as a culinary tool for lowering meal insulin response.

Antibiotic Treatment Preventing Necrotising Enterocolitis Alters Urinary and Plasma Metabolomes in Preterm Pigs.

Necrotising enterocolitis (NEC) is a serious gut inflammatory condition in premature neonates, onset and development of which depend on the gut microbiome. Attenuation of the gut microbiome by antibiotics can reduce NEC incidence and severity. However, how the antibiotics-suppressed gut microbiome affects the whole-body metabolism in NEC-sensitive premature neonates is unknown. In formula-fed preterm pigs, used as a model for preterm infants, plasma and urinary metabolomes were investigated by LC-MS and 1H NMR, with and without antibiotic treatment immediately after birth. While it reduced the gut microbiome density and NEC lesions as previously reported, the antibiotic treatment employed in the current study affected the abundance of 44 metabolites in different metabolic pathways. In antibiotics-treated pigs, tryptophan metabolism favored the kynurenine pathway, relative to the serotonin pathway, as shown by specific metabolites. Metabolites associated with the gut microbiome, including 3-phenyllactic acid, 4-hydroxyphenylacetic acid, and phenylacetylglycine, all from phenylalanine, and three bile acids showed lower levels in the antibiotics-treated pigs where the gut microbiome was extensively attenuated. Findings in the current study warrant further investigation of metabolic and developmental consequences of antibiotic treatment in preterm neonates.

Forecasting Chronic Diseases Using Data Fusion.

Data fusion, that is, extracting information through the fusion of complementary data sets, is a topic of great interest in metabolomics because analytical platforms such as liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR) spectroscopy commonly used for chemical profiling of biofluids provide complementary information. In this study, with a goal of forecasting acute coronary syndrome (ACS), breast cancer, and colon cancer, we jointly analyzed LC-MS, NMR measurements of plasma samples, and the metadata corresponding to the lifestyle of participants. We used supervised data fusion based on multiple kernel learning and exploited the linearity of the models to identify significant metabolites/features for the separation of healthy referents and the cases developing a disease. We demonstrated that (i) fusing LC-MS, NMR, and metadata provided better separation of ACS cases and referents compared with individual data sets, (ii) NMR data performed the best in terms of forecasting breast cancer, while fusion degraded the performance, and (iii) neither the individual data sets nor their fusion performed well for colon cancer. Furthermore, we showed the strengths and limitations of the fusion models by discussing their performance in terms of capturing known biomarkers for smoking and coffee. While fusion may improve performance in terms of separating certain conditions by jointly analyzing metabolomics and metadata sets, it is not necessarily always the best approach as in the case of breast cancer.

Progressive Changes in the Plasma Metabolome during Malnutrition in Juvenile Pigs.

Severe acute malnutrition (SAM) is one of the leading nutrition-related causes of death in children under five years of age. The clinical features of SAM are well documented, but a comprehensive understanding of the development from a normal physiological state to SAM is lacking. Characterizing the temporal metabolomic change may help to understand the disease progression and to define nutritional rehabilitation strategies. Using a piglet model we hypothesized that a progressing degree of malnutrition induces marked plasma metabolite changes. Four-week-old weaned pigs were fed a nutrient-deficient maize diet (MAL) or nutritionally optimized reference diet (REF) for 7 weeks. Plasma collected weekly was subjected to LC-MS for a nontargeted profiling of metabolites with abundance differentiation. The MAL pigs showed markedly reduced body-weight gain and lean-mass proportion relative to the REF pigs. Levels of eight essential and four nonessential amino acids showed a time-dependent deviation in the MAL pigs from that in the REF. Choline metabolites and gut microbiomic metabolites generally showed higher abundance in the MAL pigs. The results demonstrated that young malnourished pigs had a profoundly perturbed metabolism, and this provides basic knowledge about metabolic changes during malnourishment, which may be of help in designing targeted therapeutic foods for refeeding malnourished children.

Detecting Beer Intake by Unique Metabolite Patterns.

Evaluation of the health related effects of beer intake is hampered by the lack of accurate tools for assessing intakes (biomarkers). Therefore, we identified plasma and urine metabolites associated with recent beer intake by untargeted metabolomics and established a characteristic metabolite pattern representing raw materials and beer production as a qualitative biomarker of beer intake. In a randomized, crossover, single-blinded meal study (MSt1), 18 participants were given, one at a time, four different test beverages: strong, regular, and nonalcoholic beers and a soft drink. Four participants were assigned to have two additional beers (MSt2). In addition to plasma and urine samples, test beverages, wort, and hops extract were analyzed by UPLC-QTOF. A unique metabolite pattern reflecting beer metabolome, including metabolites derived from beer raw material (i.e., N-methyl tyramine sulfate and the sum of iso-α-acids and tricyclohumols) and the production process (i.e., pyro-glutamyl proline and 2-ethyl malate), was selected to establish a compliance biomarker model for detection of beer intake based on MSt1. The model predicted the MSt2 samples collected before and up to 12 h after beer intake correctly (AUC = 1). A biomarker model including four metabolites representing both beer raw materials and production steps provided a specific and accurate tool for measurement of beer consumption.

Alcohol-related breast cancer in postmenopausal women - effect of CYP19A1, PPARG and PPARGC1A polymorphisms on female sex-hormone levels and interaction with alcohol consumption and NSAID usage in a nested case-control study and a randomised controlled trial.

BACKGROUND: Alcohol consumption is associated with increased risk of breast cancer (BC), and the underlying mechanism is thought to be sex-hormone driven. In vitro and observational studies suggest a mechanism involving peroxisome proliferator-activated receptor gamma (PPARγ) in a complex with peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC-1α) and interaction with aromatase (encoded by CYP19A1). Use of non-steroidal anti-inflammatory drugs (NSAID) may also affect circulating sex-hormone levels by modifying PPARγ activity. METHODS: In the present study we assessed whether genetic variation in CYP19A1 is associated with risk of BC in a case-control study group nested within the Danish "Diet, Cancer and Health" cohort (ncases = 687 and ncontrols = 687) and searched for gene-gene interaction between CYP19A1 and PPARGC1A, and CYP19A1 and PPARG, and gene-alcohol and gene-NSAID interactions. Association between the CYP19A1 polymorphisms and hormone levels was also examined among 339 non-HRT users. Incidence rate ratios were calculated based on Cox' proportional hazards model. Furthermore, we performed a pilot randomised controlled trial to determine the effect of the PPARG Pro(12)Ala polymorphism and the PPARγ stimulator Ibuprofen on sex-hormone levels following alcohol intake in postmenopausal women (n = 25) using linear regression. RESULTS: Genetic variations in CYP19A1 were associated with hormone levels (estrone: P rs11070844 = 0.009, estrone sulphate: P rs11070844 = 0.01, P rs749292 = 0.004, P rs1062033 = 0.007 and P rs10519297 = 0.03, and sex hormone-binding globulin (SHBG): P rs3751591 = 0.03) and interacted with alcohol intake in relation to hormone levels (estrone sulphate: P interaction/rs2008691 = 0.02 and P interaction/rs1062033= 0.03, and SHBG: P interaction/rs11070844 = 0.03). CYP19A1/rs3751591 was both associated with SHBG levels (P = 0.03) and with risk of BC (Incidence Rate Ratio = 2.12; 95 % Confidence Interval: 1.02-4.43) such that homozygous variant allele carriers had increased levels of serum SHBG and were at increased risk of BC. Acute intake of alcohol decreased blood estrone (P = <0.0001), estrone sulphate (P = <0.0001), and SHBG (P = 0.009) levels, whereas Ibuprofen intake and PPARG Pro(12)Ala genotype had no effect on hormone levels. CONCLUSIONS: Our results suggest that genetically determined variation in CYP19A1 is associated with differences in sex hormone levels. However, the genetically determined differences in sex hormone levels were not convincingly associated with BC risk. The results therefore indicate that the genetically determined variation in CYP19A1 contributes little to BC risk and to alcohol-mediated BC risk. TRIAL REGISTRATION: NCT02463383, June 3, 2015.

Acute effects of light and dark roasted coffee on glucose tolerance: a randomized, controlled crossover trial in healthy volunteers.

PURPOSE: Epidemiological evidence suggests that coffee consumption is associated with a lower risk of type 2 diabetes. Coffee contains caffeine and several other components that may modulate glucose regulation. The chlorogenic acids (CGA) in coffee have been indicated as constituents that may help to normalize the acute glucose response after a carbohydrate challenge. The aim of this study was to investigate whether two coffee beverages that differ in CGA content due to different roasting degrees will differentially affect glucose regulation. METHODS: In a controlled crossover trial, 11 healthy fasted volunteers consumed 300 mL of either light (LIR) or dark (DAR) roasted coffee, or water, followed 30 min later by a 75-g oral glucose tolerance test (OGTT). Blood samples were drawn at baseline, 30, 60, and 120 min. Differences in glucose and insulin responses and insulin sensitivity index (ISI) were analyzed. The CGA and caffeine contents in the coffees were analyzed using UPLC-MS/MS. RESULTS: No differences in glucose area under the curve (AUC) were found between treatments. Glucose concentrations were higher at 60 min after ingestion of DAR compared with water, while ingestion of LIR showed similar glucose concentrations as ingestion of water. Insulin AUC was higher after ingestion of DAR compared with water, and both coffees raised insulin concentrations and reduced ISI compared with water, with no difference between the two coffees. CONCLUSION: Two coffees with different CGA contents did not differentially affect glucose or insulin responses during an OGTT, but both increased the insulin response compared with water.

A Healthy Nordic Diet Alters the Plasma Lipidomic Profile in Adults with Features of Metabolic Syndrome in a Multicenter Randomized Dietary Intervention.

BACKGROUND: A healthy Nordic diet is associated with improvements in cardiometabolic risk factors, but the effect on lipidomic profile is not known. OBJECTIVE: The aim was to investigate how a healthy Nordic diet affects the fasting plasma lipidomic profile in subjects with metabolic syndrome. METHODS: Men and women (n = 200) with features of metabolic syndrome [mean age: 55 y; body mass index (in kg/m2): 31.6] were randomly assigned to either a healthy Nordic (n = 104) or a control (n = 96) diet for 18 or 24 wk at 6 centers. Of the participants, 156 completed the study with plasma lipidomic measurements. The healthy Nordic diet consisted of whole grains, fruits, vegetables, berries, vegetable oils and margarines, fish, low-fat milk products, and low-fat meat. An average Nordic diet served as the control diet and included low-fiber cereal products, dairy fat-based spreads, regular-fat milk products, and a limited amount of fruits, vegetables, and berries. Lipidomic profiles were measured at baseline, week 12, and the end of the intervention (18 or 24 wk) by using ultraperformance liquid chromatography mass spectrometry. The effects of the diets on the lipid variables were analyzed with linear mixed-effects models. Data from centers with 18- or 24-wk duration were also analyzed separately. RESULTS: Changes in 21 plasma lipids differed significantly between the groups at week 12 (false discovery rate P < 0.05), including increases in plasmalogens and decreases in ceramides in the healthy Nordic diet group compared with the control group. At the end of the study, changes in lipidomic profiles did not differ between the groups. However, when the intervention lasted 24 wk, changes in 8 plasma lipids that had been identified at 12 wk, including plasmalogens, were sustained. There were no differences in changes in plasma lipids between groups with an intervention of 18 wk. By the dietary biomarker score, adherence to diet did not explain the difference in the results related to the duration of the study. CONCLUSIONS: A healthy Nordic diet transiently modified the plasma lipidomic profile, specifically by increasing the concentrations of antioxidative plasmalogens and decreasing insulin resistance-inducing ceramides. This trial was registered at clinicaltrials.gov as NCT00992641.

Comparative nontargeted profiling of metabolic changes in tissues and biofluids in high-fat diet-fed Ossabaw pig.

Typical clinical biomarker analyses on urine and plasma samples from human dietary interventions do not provide adequate information about diet-induced metabolic changes taking place in tissues. The aim of this study was to show how a large-scale nontargeted metabolomic approach can be used to reveal metabolite groups for generating new hypotheses of obesity-related metabolic disturbances produced in an animal model. A large spectrum of metabolites in the semipolar region, including small water-soluble molecules like betaine and dihydroxyindole, and a wide range of bile acids as well as various lipid species were detected. The high-fat diet influenced metabolic homeostasis of Ossabaw pigs, especially the lipid metabolome, throughout all the analyzed sample types, including plasma, urine, bile, liver, pancreas, brain cortex, intestinal jejunum and proximal colon. However, even dramatic metabolic changes in tissues were not necessarily observed in plasma and urine. Metabolite profiling involving multiple sample types was shown to be a feasible method for the examination of a wide spectrum of metabolic species extending from small water-soluble metabolites to an array of bile acids and lipids, thus pointing to the pathways of metabolism affected by the dietary treatment.

Extracted oat and barley ß-glucans do not affect cholesterol metabolism in young healthy adults.

ß-Glucans are known to exhibit hypocholesterolemic effects. Increased intestinal viscosity is thought to be crucial for cholesterol lowering. It is suggested that concentration, molecular mass, and structure, including the ratio of (1→3) to (1→4) glucan bonds in the molecule, are of importance for ß-glucan functionality. This study investigated the effects of 3 different ß-glucan sources, incorporated into a beverage and yogurt, on blood lipids and fecal endpoints. Fourteen participants completed this randomized, crossover, single-blinded study with four 3-wk periods: control and 3.3 g/d oat, barley, and barley mutant ß-glucans of similar molecular mass. Before and after each period, fasting and postprandial blood samples were drawn and 3-d fecal samples were collected. Treatment did not affect changes in total, LDL, and HDL cholesterol compared with control; however, consumption of 3.3 g/d of oat ß-glucans for 3 wk resulted in greater decreases in total (-0.29 ± 0.09 mmol/L, P < 0.01), LDL (-0.23 ± 0.07 mmol/L, P < 0.01), and HDL (-0.05 ± 0.03 mmol/L, P < 0.05) cholesterol compared with baseline. Changes in LDL in the ß-glucan treatments were not related to ß-glucan structure (cellotriosyl:cellotetraosyl). Decreases in fasting triacylglycerol were substantially greater after oat ß-glucan treatment compared with control (P = 0.03). Fecal dry and wet weight, stool frequency, fecal pH, and energy excretion were unaffected. The results do not fully support the hypocholesterolemic effects by differently structured oat and barley ß-glucans. However, substantial differences compared with baseline suggest a potential for oat ß-glucan, presumably due to its higher solubility and viscosity. This underlines the importance of elusive structural ß-glucan features for beneficial physiologic effects.

Metabolite profiling and beyond: approaches for the rapid processing and annotation of human blood serum mass spectrometry data.

In this paper, we describe data processing and metabolite identification approaches which lead to a rapid and semi-automated interpretation of metabolomics experiments. Data from metabolite fingerprinting using LC-ESI-Q-TOF/MS were processed with several open-source software packages, including XCMS and CAMERA to detect features and group features into compound spectra. Next, we describe the automatic scheduling of tandem mass spectrometry (MS) acquisitions to acquire a large number of MS/MS spectra, and the subsequent processing and computer-assisted annotation towards identification using the R packages MetShot, Rdisop, and the MetFusion application. We also implement a simple retention time prediction model using predicted lipophilicity logD, which predicts retention times within 42 s (6 min gradient) for most compounds in our setup. We putatively identified 44 common metabolites including several amino acids and phospholipids at metabolomics standards initiative (MSI) levels two and three and confirmed the majority of them by comparison with authentic standards at MSI level one. To aid both data integration within and data sharing between laboratories, we integrated data from two labs and mapped retention times between the chromatographic systems. Despite the different MS instrumentation and different chromatographic gradient programs, the mapped retention times agree within 26 s (20 min gradient) for 90% of the mapped features.

LC-QTOF/MS metabolomic profiles in human plasma after a 5-week high dietary fiber intake.

The objective was to investigate the alterations of plasma metabolome profiles to identify exposure and effect markers of dietary fiber intake. Subjects (n = 25) aged 58.6 (1.1) years (mean and SD) with a body mass index of 26.6 (0.5) kg/m(2) were given a high fiber (HF) and a low fiber (LF) diet, in a 5-week randomized controlled crossover intervention. The HF diet consisted of oat bran, rye bran, and sugar beet fiber incorporated into test food products, whereas the LF diet was made of equivalent food products to the HF diet, but without adding fibers. Blood plasma samples were collected at the start and end of each intervention period and analyzed by LC-QTOF/MS. In total, 6 features in positive mode and 14 features in negative mode were significantly different between the HF and the LF diet (p < 0.01, q < 0.05). Two markers, 2,6-dihydroxybenzoic acid and 2-aminophenol sulfate, were increased after HF diet, along with a tentatively identified saponin derived from oat avenacosides. The untargeted metabolomics approach enabled the identification of two new markers of dietary fiber intake in human plasma. Further studies will be needed to verify if these markers could serve as compliance markers of fiber intake.