Scallop protein with endogenous high taurine and glycine content prevents high-fat, high-sucrose-induced obesity and improves plasma lipid profile in male C57BL/6J mice

The Food Sources in Western Diets Modulate Obesity Development, Insulin Sensitivity, and the Plasma and Cecal Metabolome in Mice

SCOPE

Dietary constituents modulate development of obesity and type 2 diabetes. The metabolic impact from different food sources in western diets (WD) on obesity development is not fully elucidated. This study aims to identify dietary sources that differentially affect obesity development and the metabolic processes involved.

METHODS AND RESULTS

Mice were fed isocaloric WDs with protein and fat from different food groups, including egg and dairy, terrestrial meat, game meat, marine, vegetarian, and a mixture of all. This study evaluates development of obesity, glucose tolerance, insulin sensitivity, and plasma and cecal metabolome. WD based on marine or vegetarian food sources protects male mice from obesity development and insulin resistance, whereas meat-based diets promote obesity. The intake of different food sources induces marked differences in the lipid-related plasma metabolome, particularly impacting phosphatidylcholines. Fifty-nine lipid-related plasma metabolites are positively associated with adiposity and a distinct cecal metabolome is found in mice fed a marine diet.

CONCLUSION

This study demonstrates differences in obesity development between the food groups. Diet specific metabolomic signatures in plasma and cecum associated with adiposity, where a marine based diet modulates the level of plasma and cecal phosphatidylcholines in addition to preventing obesity development.

Association between dietary glycine intake and the prevalence of hypertension, hyperlipidemia, overweight or obesity in rural northern China: a cross-sectional study

Objective

The objective of this research is to investigate the relationship between dietary glycine consumption and the prevalence of hypertension, hyperlipidemia, and overweight or obesity in economically disadvantaged areas of northern China using a cross-sectional study design.

Methods

A cross-sectional study involving 774 participants utilized a web-based dietary questionnaire (IDQC) and underwent physical measurements. Data analysis was conducted using IBM SPSS Statistics software (Version 21). Participants were stratified into four groups based on quartiles of their dietary glycine intake: Q1 (<1.32), Q2 (1.32-1.82), Q3 (1.82-2.26), and Q4 (>2.26). Continuous variables were reported as mean ± standard deviation and compared using ANOVA or the Kruskal-Wallis test, while categorical variables were presented as frequencies (%) and compared using the chi-square test. Finally, multivariable logistic regression with p-value of less than 0.05 was considered statistically significant.

Results

Significant differences in dietary glycine intake were observed between the highest quartile group (Q4) and the lowest quartile group (Q1), with corresponding dominance ratios of 0.590 (95% CI, 0.360-0.966), 0.547 (95% CI, 0.327-0.913), and 0.547 (95% CI, 0.353-0.850) for the risk of hypertension, hyperlipidemia, and overweight/obesity, respectively. Furthermore, no significant correlation was found between dietary glycine intake and hypertension or hyperlipidemia within each sex and age subgroup.

Conclusion

There exists a potential correlation between increased dietary glycine intake and reduced prevalence of hypertension, hyperlipidemia, and overweight/obesity. However, additional research is necessary to validate this finding through larger-scale studies conducted at a population level.

Macronutrient-differential dietary pattern impacts on body weight, hepatic inflammation, and metabolism

Introduction

Obesity is a multi-factorial disease frequently associated with poor nutritional habits and linked to many detrimental health outcomes. Individuals with obesity are more likely to have increased levels of persistent inflammatory and metabolic dysregulation. The goal of this study was to compare four dietary patterns differentiated by macronutrient content in a postmenopausal model. Dietary patterns were high carbohydrate (HC), high fat (HF), high carbohydrate plus high fat (HCHF), and high protein (HP) with higher fiber.

Methods

Changes in body weight and glucose levels were measured in female, ovariectomized C57BL/6 mice after 15 weeks of feeding. One group of five mice fed the HCHF diet was crossed over to the HP diet on day 84, modeling a 21-day intervention. In a follow-up study comparing the HCHF versus HP dietary patterns, systemic changes in inflammation, using an 80-cytokine array and metabolism, by untargeted liquid chromatography-mass spectrometry (LCMS)-based metabolomics were evaluated.

Results

Only the HF and HCHF diets resulted in obesity, shown by significant differences in body weights compared to the HP diet. Body weight gains during the two-diet follow-up study were consistent with the four-diet study. On Day 105 of the 4-diet study, glucose levels were significantly lower for mice fed the HP diet than for those fed the HC and HF diets. Mice switched from the HCHF to the HP diet lost an average of 3.7 grams by the end of the 21-day intervention, but this corresponded with decreased food consumption. The HCHF pattern resulted in dramatic inflammatory dysregulation, as all 80 cytokines were elevated significantly in the livers of these mice after 15 weeks of HCHF diet exposure. Comparatively, only 32 markers changed significantly on the HP diet (24 up, 8 down). Metabolic perturbations in several endogenous biological pathways were also observed based on macronutrient differences and revealed dysfunction in several nutritionally relevant biosynthetic pathways.

Conclusion

Overall, the HCHF diet promoted detrimental impacts and changes linked to several diseases, including arthritis or breast neoplasms. Identification of dietary pattern-specific impacts in this model provides a means to monitor the effects of disease risk and test interventions to prevent poor health outcomes through nutritional modification.

Intake of different types of seafood and meat and risk of type 2 diabetes in women: a prospective study supported by a dietary intervention in mice

Detailed knowledge regarding the associations between intake of different types of seafood and meat and the risk of type 2 diabetes (T2D), and insight into possible mechanisms are warranted. In this study we aimed to evaluate the associations between intake of different types of seafood and meat and the subsequent risk of T2D using the Norwegian Mother, Father, and Child Cohort Study (MoBa), and furthermore, by using a mouse model to gain further insight into possible molecular mechanisms contributing to the associated metabolic changes. Women in MoBa who were free of pharmacologically treated diabetes at baseline (n = 60,777) were prospectively evaluated for incident T2D, identified on the basis of medication usages > 90 days after delivery, ascertained by the Norwegian Prescription Database. Dietary intake was obtained with a validated 255-item food frequency questionnaire which assessed habitual diet during the first 4-5 months of pregnancy. Metabolic phenotypes and plasma metabolome were investigated in female mice fed isocaloric diets with different types of seafood and meat mimicking the dietary intake in the human cohort. During maximum 10-year and mean (SD) 7.2 (1.6) years follow-up time, 681 (1.1%) women developed pharmacologically treated T2D. All statistical models identified a higher risk of T2D with increased shellfish intake, whereas no associations were observed for total seafood, fatty fish, total meat and red meat in the adjusted models. In mice, the shellfish-based western diet induced reduced glucose tolerance and insulin secretion compared to the diet based on lean fish, and we identified a number of metabolites elevated in plasma from shellfish-fed mice that correlated with glucose intolerance. Mice fed a western diet based on meat also exhibited reduced glucose tolerance in comparison to lean fish fed mice, whereas mice fed fatty fish, total seafood or red meat did not differ from lean fish fed mice. We observed a diet-specific metabolic signature in plasma demonstrating five distinct metabolite profiles in mice fed shellfish, fatty fish, total seafood/lean fish, a mixed diet and meat. In conclusion, these findings demonstrate that different types of seafood have different outcome on T2D risk. In women, intake of shellfish was associated with higher risk of T2D. In female mice, a shellfish enriched diet reduced glucose tolerance and altered the abundance of several distinct plasma metabolites correlating with glucose tolerance.

Host-gut microbiota interactions shape parasite infections in farmed Atlantic salmon

Animals and their associated microbiota share long evolutionary histories. However, it is not always clear how host genotype and microbiota interact to affect phenotype. We applied a hologenomic approach to explore how host-microbiota interactions shape lifetime growth and parasite infection in farmed Atlantic salmon (Salmo salar). Multi-omics data sets were generated from the guts of 460 salmon, 82% of which were naturally infected with an intestinal cestode. A single Mycoplasma bacterial strain, MAG01, dominated the gut metagenome of large, non-parasitized fish, consistent with previous studies showing high levels of Mycoplasma in the gut microbiota of healthy salmon. While small and/or parasitized salmon also had high abundance of MAG01, we observed increased alpha diversity in these individuals, driven by increased frequency of low-abundance Vibrionaceae and other Mycoplasma species that carried known virulence genes. Colonization by one of these cestode-associated Mycoplasma strains was associated with host individual genomic variation in long non-coding RNAs. Integrating the multi-omic data sets revealed coordinated changes in the salmon gut mRNA transcriptome and metabolome that correlated with shifts in the microbiota of smaller, parasitized fish. Our results suggest that the gut microbiota of small and/or parasitized fish is in a state of dysbiosis that partly depends on the host genotype, highlighting the value of using a hologenomic approach to incorporate the microbiota into the study of host-parasite dynamics.IMPORTANCEStudying host-microbiota interactions through the perspective of the hologenome is gaining interest across all life sciences. Intestinal parasite infections are a huge burden on human and animal health; however, there are few studies investigating the role of the hologenome during parasite infections. We address this gap in the largest multi-omics fish microbiota study to date using natural cestode infection of farmed Atlantic salmon. We find a clear association between cestode infection, salmon lifetime growth, and perturbation of the salmon gut microbiota. Furthermore, we provide the first evidence that the genetic background of the host may partly determine how the gut microbiota changes during parasite-associated dysbiosis. Our study therefore highlights the value of a hologenomic approach for gaining a more in-depth understanding of parasitism.

Amino Acid Composition in Different Tissues of Iceland Scallop from the Barents Sea

The Iceland scallop from the Barents Sea is a commercially important species with promising aquaculture potential, but information on the biochemical properties of its tissues is limited. Our analysis of the adductor muscle, gonad, and mantle of this bivalve mollusk from coastal waters provided insight into its amino acid composition. Biochemical analysis revealed predominant levels of glycine (11.8, 11.5, and 9.6 mg g-1, respectively) and arginine (11.2, 8.3, and 5.8 mg g-1, respectively). While multivariate comparisons did not reveal significant differences in amino acid composition between the tissues, single comparisons showed significantly higher levels of arginine and leucine in the adductor muscle compared to those of the mantle. The abundant presence of glycine and arginine underscores their importance in maintaining basic physiological processes, consistent with other scallop species. Redundancy analysis identified water depth and scallop gonad index as influential factors shaping the amino acid profile in the adductor muscle. In the case of the mantle, water temperature emerged as the main driver of amino acid content. Our results confirm the richness of essential amino acids in scallop by-products and highlight their potential for human consumption, production of feed ingredients for farmed animals, and nutraceuticals.

Metabolic effects of diet containing blue mussel (Mytilus edulis) and blue mussel-fed salmon in a mouse model of obesity

Alternative feed ingredients for farmed salmon are warranted due to increasing pressure on wild fish stocks. As locally farmed blue mussels may represent an environmentally sustainable substitute with a lower carbon footprint, we aimed to test the potential and safety of substituting fish meal with blue mussel meal in feed for Atlantic salmon. Salmon were fed diets in which fish meal was partially replaced with blue mussel meal in increments, accounting for up to 13.1 % of the ingredients. Fillets from the salmon were subsequently used to prepare obesity-promoting western diets for a 13-weeks mouse feeding trial. In a second mouse trial, we tested the effects of inclusion of up to 8% blue mussel meal directly in a meat-based western diet. Partial replacement of fish meal with blue mussel meal in fish feed preserved the n-3 polyunsaturated fatty acid (PUFA) content in salmon fillets. The observed blue mussel-induced changes in the fatty acid profiles in salmon fillets did not translate into similar changes in the livers of mice that consumed the salmon, and no clear dose-dependent responses were found. The relative levels of the marine n-3 fatty acids, EPA, and DHA were not reduced, and the n-3/n-6 PUFA ratios in livers from all salmon-fed mice were unchanged. The inclusion of blue mussel meal in a meat-based western diet led to a small, but dose-dependent increase in the n-3/n-6 PUFA ratios in mice livers. Diet-induced obesity, glucose intolerance, and hepatic steatosis were unaffected in both mice trials and no blue mussel-induced adverse effects were observed. In conclusion, our results suggest that replacing fish meal with blue mussel meal in salmon feed will not cause adverse effects in those who consume the salmon fillets.

Recent insights into the molecular regulators and mechanisms of taurine to modulate lipid metabolism: a review

Lipid metabolism disorders such as hypertriglyceridemia and hypercholesterolemia are risk factors for cardiovascular diseases and atherosclerosis that are grave public health issues. Taurine, a sulfur-containing non-essential amino acid exerts a wide range of physiological effects that regulate lipid metabolic disorders. Although the effects of taurine on lipid-lowering have been reported in animals and humans, mechanisms elucidating the lipid-lowering action of taurine remain unclear. A series of molecular regulators associated with lipid metabolism have been identified in the past few decades. These include nuclear receptors, transcription factors, and enzymes that undergo important changes during taurine treatment. In this review, we focus on the role of taurine in lipid metabolism and discuss taurine-related interventions in combating lipid disorders.

Taurine prevents high-fat diet-induced-hepatic steatosis in rats by direct inhibition of hepatic sterol regulatory element-binding proteins and activation of AMPK

This study investigated if the protective effect of taurine against high fat diet-induced hepatic steatosis involves modulating the hepatic activity of 5' AMP-activated protein kinase (AMPK) and levels/activity of the sterol regulatory element-binding proteins-1/2 (SREBP1/2). Rats were divided into four groups (n = 12/group) as (a) STD, fed standard diet (3.85 kcal/g); (b) STD + taurine (500 mg/kg); (c) HFD, fed HFD (4.73 kcal/g); and (d) HFD + taurine. All treatments were conducted for 12 weeks. Independent of food intake or modulating glucose or insulin levels, taurine administration to STD and HFD-fed rats significantly lowered weekly weight gain and the accumulation of the retroperitoneal, visceral and subcutaneous fats. In both groups, taurine also reduced serum and hepatic levels of triglycerides and cholesterol and reduced hepatic mRNA and protein levels of fatty acid synthase (FAS), acetyl CoA carboxylase-1 (ACC-1), HMG-CoA-reductase and HMG-CoA synthetase. In control rats only, taurine reduced hepatic levels of mature forms of sterol regulatory element-binding proteins (SREBP)-1/2. In HFD-fed rats, taurine reduced SREBP-1/2 precursor and mature forms in the livers of HFD-fed rats. Besides, taurine significantly increased levels of glutathione (GSH), the activity of superoxide dismutase (SOD), and the activity of AMPK and its downstream β-oxidation genes including peroxisome proliferator-activated receptor-α (PPAR-α) and carnitine palmitoyltransferase (CPT-1) in the livers of both the control and HFD-fed rats. In conclusion, taurine protects against HFD-induced hepatic steatosis stimulating antioxidant levels, and concomitant stimulating hepatic β-oxidation and suppressing lipid synthesis, mediated by activation of AMPK and suppression of SREBP-1.

The Anti-Obesogenic Effect of Lean Fish Species is Influenced by the Fatty Acid Composition in Fish Fillets

Fillets from marine fish species contain n-3 polyunsaturated fatty acids (PUFAs) in the form of phospholipids (PLs). To investigate the importance of PL-bound n-3 PUFAs in mediating the anti-obesogenic effect of lean seafood, we compared the anti-obesogenic properties of fillets from cod with fillets from pangasius, a fresh water fish with a very low content of PL-bound n-3 PUFAs. We prepared high-fat/high-protein diets using chicken, cod and pangasius as the protein sources, and fed male C57BL/6J mice these diets for 12 weeks. Mice fed the diet containing cod gained less adipose tissue mass and had smaller white adipocytes than mice fed the chicken-containing diet, whereas mice fed the pangasius-containing diet were in between mice fed the chicken-containing diet and mice fed the cod-containing diet. Of note, mice fed the pangasius-containing diet exhibited reduced glucose tolerance compared to mice fed the cod-containing diet. Although the sum of marine n-3 PUFAs comprised less than 2% of the total fatty acids in the cod-containing diet, this was sufficient to significantly increase the levels of eicosapentaenoic acid (EPA) and docosahexaenoic acids (DHA) in mouse tissues and enhance production of n-3 PUFA-derived lipid mediators as compared with mice fed pangasius or chicken.

Belly flap from Norwegian spring-spawning herring (Clupea harengus L.): A potentially new product with high content of vitamin D, EPA and DHA

Processing Norwegian spring-spawning herring (NSSH) yields large amounts of rest raw material which currently is used mainly for production of fish oil and fish meal for feed in aquaculture. However, belly flaps from NSSH might be a profitable resource as a food product. This study investigates the nutritional composition of the belly flaps.

NSSH was harvested in the main season between September and February. Chemical analyses of fatty acids, protein and vitamin A and D in belly flaps were conducted.

Belly flaps from NSSH had a mean fat and protein content of 32.3 ± 6.9 g/100 g and 12.6 ± 0.9 g/100g, respectively. Mean vitamin D level was 53.5 ± 8.5 μg/100 g and mean eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels were 2.0 ± 0.8 g/100g and 2.3 ± 1.0 g/100g, respectively. Belly flap from NSSH contains twice the amount of vitamin D, EPA and DHA compared to NSSH fillet. There were large seasonal variations in the amount of both vitamin D, EPA and DHA. Mean level of vitamin A was 45.0 ± 8.9 μg/100 g. Belly flap from NSSH is a potential product for human consumption with a high nutritional value.

Metabolic Fingerprint of Turner Syndrome

Girls with Turner syndrome (TS) are at increased risk of developing insulin resistance and coronary artery disease as a result of hypertension and obesity frequently seen in these patients. On the other hand, it is known that obesity is associated with increased serum levels of branched-chain amino acids (BCAAs: valine; leucine and isoleucine) and aromatic amino acids. The aim of the study is to compare the metabolic fingerprint of girls with TS to the metabolic fingerprint of girls with obesity. Metabolic fingerprinting using an untargeted metabolomic approach was examined in plasma from 46 girls with TS (study group) and 22 age-matched girls with obesity (control group). The mean values of BCAAs, methionine, phenylalanine, lysine, tryptophan, histidine, tyrosine, alanine and ornithine were significantly lower in the study group than in the control (p from 0.0025 to <0.000001). Strong significant correlation between BCAAs, phenylalanine, arginine, tyrosine, glutamic acid, citrulline and alanine, and body mass index expressed as standard deviation score BMI-SDS in the patients with obesity (p from 0.049 to 0.0005) was found. In contrast; there was no correlation between these amino acids and BMI-SDS in the girls with TS. It is suggested that obesity in patients with TS is not associated with altered amino acids metabolism.

Fish-derived proteins and their potential to improve human health

Emerging evidence from studies evaluating the effect of lean fish consumption in humans suggests that proteins from fish have several beneficial metabolic effects. Rest, or waste, material from the fishing industry contains high-quality proteins, and utilization of this material offers novel possibilities for the development of protein-containing products that might be beneficial for human consumption. Fish-derived peptides containing bioactive amino acid sequences suggested to beneficially influence pathways involved in body composition, hypertension, lipid profile, and regulation of glucose metabolism are of particular interest, although the results of published studies are conflicting. This review aims to summarize current knowledge from animal studies and clinical interventions in humans evaluating the effects of lean fish, fish proteins, and fish-derived peptides on outcomes related to metabolic health. Fish proteins have a high content of taurine, and animal trials suggest that taurine mediates some of the beneficial effects observed thus far, although the mechanisms by which fish peptides exert their action are not yet elucidated. At this time, the literature is inconsistent, and there is insufficient mechanistic evidence to support a beneficial effect of fish-derived peptides on metabolic health.

Novel Markers of the Metabolic Impact of Exogenous Retinoic Acid with A Focus on Acylcarnitines and Amino Acids

Treatment with all-trans retinoic acid (ATRA), the carboxylic form of vitamin A, lowers body weight in rodents by promoting oxidative metabolism in multiple tissues including white and brown adipose tissues. We aimed to identify novel markers of the metabolic impact of ATRA through targeted blood metabolomics analyses, with a focus on acylcarnitines and amino acids. Blood was obtained from mice treated with a high ATRA dose (50 mg/kg body weight/day, subcutaneous injection) or placebo (controls) during the 4 days preceding collection. LC-MS/MS analyses with a focus on acylcarnitines and amino acids were conducted on plasma and PBMC. Main results showed that, relative to controls, ATRA-treated mice had in plasma: increased levels of carnitine, acetylcarnitine, and longer acylcarnitine species; decreased levels of citrulline, and increased global arginine bioavailability ratio for nitric oxide synthesis; increased levels of creatine, taurine and docosahexaenoic acid; and a decreased n-6/n-3 polyunsaturated fatty acids ratio. While some of these features likely reflect the stimulation of lipid mobilization and oxidation promoted by ATRA treatment systemically, other may also play a causal role underlying ATRA actions. The results connect ATRA to specific nutrition-modulated biochemical pathways, and suggest novel mechanisms of action of vitamin A-derived retinoic acid on metabolic health.

The Impact of Different Animal-Derived Protein Sources on Adiposity and Glucose Homeostasis during Ad Libitum Feeding and Energy Restriction in Already Obese Mice

Low-fat diets and energy restriction are recommended to prevent obesity and to induce weight loss, but high-protein diets are popular alternatives. However, the importance of the protein source in obesity prevention and weight loss is unclear. The aim of this study was to investigate the ability of different animal protein sources to prevent or reverse obesity by using lean or obese C57BL/6J mice fed high-fat/high-protein or low-fat diets with casein, cod or pork as protein sources. Only the high-fat/high-protein casein-based diet completely prevented obesity development when fed to lean mice. In obese mice, ad libitum intake of a casein-based high-fat/high-protein diet modestly reduced body mass, whereas a pork-based high-fat/high-protein diet aggravated the obese state and reduced lean body mass. Caloric restriction of obese mice fed high-fat/high-protein diets reduced body weight and fat mass and improved glucose tolerance and insulin sensitivity, irrespective of the protein source. Finally, in obese mice, ad libitum intake of a low-fat diet stabilized body weight, reduced fat mass and increased lean body mass, with the highest loss of fat mass found in mice fed the casein-based diet. Combined with caloric restriction, the casein-based low-fat diet resulted in the highest loss of fat mass. Overall, the dietary protein source has greater impact in obesity prevention than obesity reversal.

Salmon in Combination with High Glycemic Index Carbohydrates Increases Diet-Induced Thermogenesis Compared with Salmon with Low Glycemic Index Carbohydrates⁻An Acute Randomized Cross-Over Meal Test Study

The study investigated the acute effects of meals containing either salmon or veal in combination with carbohydrates with high or low glycemic index (GI) on diet-induced thermogenesis (DIT) (primary endpoint), appetite sensations, and energy intake (EI). Twenty-five overweight men and women ingested four iso-caloric test meals: salmon with mashed potatoes (high GI) (SM), salmon with wholegrain pasta (low GI) (SP), veal with mashed potatoes (VM) and veal with wholegrain pasta (VP). Energy expenditure was measured in the fasting state and six times postprandially for 25 min with 5-min breaks between each measurement. Appetite sensations were measured every 30 min. Blood samples, from arterialized venous blood, were drawn every 20 min until an ad libitum buffet-style lunch was served 3.5 h later. DIT was 40% higher after the SM meal compared to the SP meal (p = 0.002). Prospective food consumption was lower after the SM meal compared with the VP meal (p = 0.01). There were no differences in satiety, hunger, fullness, or ad libitum EI between the test meals (all p > 0.05). In conclusion, salmon with high GI carbohydrates increased DIT compared to salmon with low GI carbohydrates. This indicates that DIT is sensitive to the GI of the carbohydrates after intake of salmon but not veal.

Seafood intake and the development of obesity, insulin resistance and type 2 diabetes

We provide an overview of studies on seafood intake in relation to obesity, insulin resistance and type 2 diabetes. Overweight and obesity development is for most individuals the result of years of positive energy balance. Evidence from intervention trials and animal studies suggests that frequent intake of lean seafood, as compared with intake of terrestrial meats, reduces energy intake by 4–9 %, sufficient to prevent a positive energy balance and obesity. At equal energy intake, lean seafood reduces fasting and postprandial risk markers of insulin resistance, and improves insulin sensitivity in insulin-resistant adults. Energy restriction combined with intake of lean and fatty seafood seems to increase weight loss. Marine n-3 PUFA are probably of importance through n-3 PUFA-derived lipid mediators such as endocannabinoids and oxylipins, but other constituents of seafood such as the fish protein per se, trace elements or vitamins also seem to play a largely neglected role. A high intake of fatty seafood increases circulating levels of the insulin-sensitising hormone adiponectin. As compared with a high meat intake, high intake of seafood has been reported to reduce plasma levels of the hepatic acute-phase protein C-reactive protein level in some, but not all studies. More studies are needed to confirm the dietary effects on energy intake, obesity and insulin resistance. Future studies should be designed to elucidate the potential contribution of trace elements, vitamins and undesirables present in seafood, and we argue that stratification into responders and non-responders in randomised controlled trials may improve the understanding of health effects from intake of seafood.

Effects of exercise and dietary protein sources on adiposity and insulin sensitivity in obese mice

Low-fat diets and exercise are generally assumed to ameliorate obesity-related metabolic dysfunctions, but the importance of exercise vs. dietary changes is debated. Male C57BL/6J mice were fed a high-fat/high-sucrose (HF/HS) diet to induce obesity and then either maintained on the HF/HS or shifted to low-fat (LF) diets containing either salmon or entrecote. For each diet, half of the animals exercised voluntarily for 8 weeks. We determined body composition, glucose tolerance, insulin sensitivity and hepatic triacylglycerol levels. The microbiota composition in cecal and fecal samples was analyzed using 16S ribosomal RNA gene amplicon sequencing. Voluntary exercise improved insulin sensitivity but did not improve glucose tolerance. Voluntary exercise did not reduce adiposity in mice maintained on an HF/HS diet but enhanced LF-induced reduction in adiposity. Hepatic triacylglycerol levels were reduced by voluntary exercise in LF- but not HF/HS-fed mice. Voluntary exercise induced shifts in the cecal and fecal microbiota composition and functional potential in mice fed LF or HF/HS diets. Whereas voluntary exercise improved insulin sensitivity, a switch to an LF diet was the most important factor related to body weight and fat mass reduction.

Dietary Proteins, Brown Fat, and Adiposity

High protein diets have become popular for body weight maintenance and weight loss despite controversies regarding efficacy and safety. Although both weight gain and weight loss are determined by energy consumption and expenditure, data from rodent trials consistently demonstrate that the protein:carbohydrate ratio in high fat diets strongly influences body and fat mass gain per calorie eaten. Here, we review data from rodent trials examining how high protein diets may modulate energy metabolism and the mechanisms by which energy may be dissipated. We discuss the possible role of activating brown and so-called beige/BRITE adipocytes including non-canonical UCP1-independent thermogenesis and futile cycles, where two opposing metabolic pathways are operating simultaneously. We further review data on how the gut microbiota may affect energy expenditure. Results from human and rodent trials demonstrate that human trials are less consistent than rodent trials, where casein is used almost exclusively as the protein source. The lack of consistency in results from human trials may relate to the specific design of human trials, the possible distinct impact of different protein sources, and/or the differences in the efficiency of high protein diets to attenuate obesity development in lean subjects vs. promoting weight loss in obese subjects.

Comparative Rice Bran Metabolomics across Diverse Cultivars and Functional Rice Gene⁻Bran Metabolite Relationships

Rice (Oryza sativa L.) processing yields ~60 million metric tons of bran annually. Rice genes producing bran metabolites of nutritional and human health importance were assessed across 17 diverse cultivars from seven countries using non-targeted metabolomics, and resulted in 378–430 metabolites. Gambiaka cultivar had the highest number and Njavara had the lowest number of metabolites. The 71 rice bran compounds of significant variation by cultivar included 21 amino acids, seven carbohydrates, two metabolites from cofactors and vitamins, 33 lipids, six nucleotides, and two secondary metabolites. Tryptophan, α-ketoglutarate, γ-tocopherol/β-tocopherol, and γ-tocotrienol are examples of bran metabolites with extensive cultivar variation and genetic information. Thirty-four rice bran components that varied between cultivars linked to 535 putative biosynthetic genes using to the OryzaCyc 4.0, Plant Metabolic Network database. Rice genes responsible for bran composition with animal and human health importance is available for rice breeding programs to utilize in crop improvement.

Effects of Frozen Storage on Phospholipid Content in Atlantic Cod Fillets and the Influence on Diet-Induced Obesity in Mice

A large fraction of the n-3 polyunsaturated fatty acids (PUFAs) in cod fillet is present in the form of phospholipids (PLs). Freezing initiates hydrolysis of the PLs present in the fillet. Here, we compared the effects of Western diets based on frozen cod, fresh cod or pork with a diet based on casein in male C57BL/6J mice fed for 12 weeks at thermoneutrality. Diets based on fresh cod contained more PL-bound n-3 PUFAs (3.12 mg/g diet) than diets based on frozen cod (1.9 mg/g diet). Mice fed diets containing pork and fresh cod, but not frozen cod, gained more body and fat mass than casein-fed mice. Additionally, the bioavailability of n-3 PUFAs present in the cod fillets was not influenced by storage conditions. In a second experiment, diets with pork as the protein source were supplemented with n-3 PUFAs in the form of PL or triacylglycerol (TAG) to match the levels of the diet containing fresh cod. Adding PL-bound, but not TAG-bound, n-3 PUFAs, to the pork-based diet increased body and fat mass gain. Thus, supplementation with PL-bound n-3 PUFAs did not protect against, but rather promoted, obesity development in mice fed a pork-based diet.

Amino acid profiles of young adults differ by sex, body mass index and insulin resistance

BACKGROUND AND AIMS

An increase in plasma branched-chain amino acids is associated with a higher risk of developing type 2 diabetes and cardiovascular diseases. However, little is known about the basal plasma amino acid concentrations in young adults. Our aim was to determine the plasma amino acid profiles of young adults and to evaluate how these profiles were modified by sex, body mass index (BMI) and insulin resistance (IR).

METHODS AND RESULTS

We performed a transversal study with 608 Mexican young adults aged 19.9 ± 2.4 years who were applicants to the Universidad Autónoma de San Luis Potosí. The subjects underwent a physical examination and provided a clinical history and a blood sample for biochemical, hormonal and amino acid analyses. The women had higher levels of arginine, aspartate and serine and lower levels of α-aminoadipic acid, cysteine, isoleucine, leucine, methionine, proline, tryptophan, tyrosine, urea and valine than the men. The obese subjects had higher levels of alanine, aspartate, cysteine, ornithine, phenylalanine, proline and tyrosine and lower levels of glycine, ornithine and serine than the normal weight subjects. Subjects with IR (defined as HOMA > 2.5) had higher levels of arginine, alanine, aspartate, isoleucine, leucine, phenylalanine, proline, tyrosine, taurine and valine than the subjects without IR. Furthermore, we identified two main groups in the subjects with obesity and/or IR; one group was composed of amino acids that positively correlated with the clinical, biochemical and hormonal parameters, whereas the second group exhibited negative correlations.

CONCLUSION

This study demonstrates that young adults with obesity or IR have altered amino acid profiles characterized by an increase in alanine, aspartate, proline and tyrosine and a decrease in glycine.

Arsenic Exposure from Drinking Water and Urinary Metabolomics: Associations and Long-Term Reproducibility in Bangladesh Adults

BACKGROUND

Chronic exposure to inorganic arsenic from drinking water has been associated with a host of cancer and noncancer diseases. The application of metabolomics in epidemiologic studies may allow researchers to identify biomarkers associated with arsenic exposure and its health effects.

OBJECTIVE

Our goal was to evaluate the long-term reproducibility of urinary metabolites and associations between reproducible metabolites and arsenic exposure.

METHODS

We studied samples and data from 112 nonsmoking participants (58 men and 54 women) who were free of any major chronic diseases and who were enrolled in the Health Effects of Arsenic Longitudinal Study (HEALS), a large prospective cohort study in Bangladesh. Using a global gas chromatography-mass spectrometry platform, we measured metabolites in their urine samples, which were collected at baseline and again 2 y apart, and estimated intraclass correlation coefficients (ICCs). Linear regression was used to assess the association between arsenic exposure at baseline and metabolite levels in baseline urine samples.

RESULTS

We identified 2,519 molecular features that were present in all 224 urine samples from the 112 participants, of which 301 had an ICC of ≥0.60. Of the 301 molecular features, water arsenic was significantly related to 31 molecular features and urinary arsenic was significantly related to 74 molecular features after adjusting for multiple comparisons. Six metabolites with a confirmed identity were identified from the 82 molecular features that were significantly associated with either water arsenic or urinary arsenic after adjustment for multiple comparisons.

CONCLUSIONS

Our study identified urinary metabolites with long-term reproducibility that were associated with arsenic exposure. The data established the feasibility of using metabolomics in future larger studies. https://doi.org/10.1289/EHP1992.

Links between Dietary Protein Sources, the Gut Microbiota, and Obesity

The association between the gut microbiota and obesity is well documented in both humans and in animal models. It is also demonstrated that dietary factors can change the gut microbiota composition and obesity development. However, knowledge of how diet, metabolism and gut microbiota mutually interact and modulate energy metabolism and obesity development is still limited. Epidemiological studies indicate an association between intake of certain dietary protein sources and obesity. Animal studies confirm that different protein sources vary in their ability to either prevent or induce obesity. Different sources of protein such as beans, vegetables, dairy, seafood, and meat differ in amino acid composition. Further, the type and level of other factors, such as fatty acids and persistent organic pollutants (POPs) vary between dietary protein sources. All these factors can modulate the composition of the gut microbiota and may thereby influence their obesogenic properties. This review summarizes evidence of how different protein sources affect energy efficiency, obesity development, and the gut microbiota, linking protein-dependent changes in the gut microbiota with obesity.

Quantitative Metabolomic Profiling of Plasma, Urine, and Liver Extracts by 1H NMR Spectroscopy Characterizes Different Stages of Atherosclerosis in Hamsters

Atherosclerosis (AS) is a progressive disease that contributes to cardiovascular disease and shows a complex etiology, including genetic and environmental factors. To understand systemic metabolic changes and to identify potential biomarkers correlated with the occurrence and perpetuation of diet-induced AS, we applied ¹H NMR-based metabolomics to detect the time-related metabolic profiles of plasma, urine, and liver extracts from male hamsters fed a high fat and high cholesterol (HFHC) diet. Conventional biochemical assays and histopathological examinations as well as protein expression analyses were performed to provide complementary information. We found that diet treatment caused obvious aortic lesions, lipid accumulation, and inflammatory infiltration in hamsters. Downregulation of proteins related to cholesterol metabolism, including hepatic SREBP2, LDL-R, CYP7A1, SR-BI, HMGCR, LCAT, and SOAT1 was detected, which elucidated the perturbation of cholesterol homeostasis during the HFHC diet challenge. Using "targeted analysis", we quantified 40 plasma, 80 urine, and 60 liver hydrophilic extract metabolites. Multivariate analyses of the identified metabolites elucidated sophisticated metabolic disturbances in multiple matrices, including energy homeostasis, intestinal microbiota functions, inflammation, and oxidative stress coupled with the metabolisms of cholesterol, fatty acids, saccharides, choline, amino acids, and nucleotides. For the first time, our results demonstrate a time-dependent metabolic progression of multiple biological matrices in hamsters from physiological status to early AS and further to late-stage AS, demonstrating that ¹H NMR-based metabolomics is a reliable tool for early diagnosis and monitoring of the process of AS.

The role of glycine in regulated cell death

The cytoprotective effects of glycine against cell death have been recognized for over 28 years. They are expressed in multiple cell types and injury settings that lead to necrosis, but are still not widely appreciated or considered in the conceptualization of cell death pathways. In this paper, we review the available data on the expression of this phenomenon, its relationship to major pathophysiologic pathways that lead to cell death and immunomodulatory effects, the hypothesis that it involves suppression by glycine of the development of a hydrophilic death channel of molecular dimensions in the plasma membrane, and evidence for its impact on disease processes in vivo.

The protein source determines the potential of high protein diets to attenuate obesity development in C57BL/6J mice

The notion that the obesogenic potential of high fat diets in rodents is attenuated when the protein:carbohydrate ratio is increased is largely based on studies using casein or whey as the protein source. We fed C57BL/6J mice high fat-high protein diets using casein, soy, cod, beef, chicken or pork as protein sources. Casein stood out as the most efficient in preventing weight gain and accretion of adipose mass. By contrast, mice fed diets based on pork or chicken, and to a lesser extent mice fed cod or beef protein, had increased adipose tissue mass gain relative to casein fed mice. Decreasing the protein:carbohydrate ratio in diets with casein or pork as protein sources led to accentuated fat mass accumulation. Pork fed mice were more obese than casein fed mice, and relative to casein, the pork-based feed induced substantial accumulation of fat in classic interscapular brown adipose tissue accompanied by decreased UCP1 expression. Furthermore, intake of a low fat diet with casein, but not pork, as a protein source reversed diet-induced obesity. Compared to pork, casein seems unique in maintaining the classical brown morphology in interscapular brown adipose tissue with high UCP1 expression. This was accompanied by increased expression of genes involved in a futile cycling of fatty acids. Our results demonstrate that intake of high protein diets based on other protein sources may not have similar effects, and hence, the obesity protective effect of high protein diets is clearly modulated by protein source.

Intake of a Western diet containing cod instead of pork alters fatty acid composition in tissue phospholipids and attenuates obesity and hepatic lipid accumulation in mice

The content of the marine n-3 polyunsaturated fatty acids (PUFAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is far lower in lean than in fatty seafood. Cod filets contain less than 2g fat per kg, whereof approximately 50% is EPA and DHA. However, a large fraction of these n-3 PUFAs is present in the phospholipid (PL) fraction and may have high bioavailability and capacity to change the endocannabinoid profile. Here we investigated whether exchanging meat from a lean terrestrial animal with cod in a background Western diet would alter the endocannabinoid tone in mice and thereby attenuate obesity development and hepatic lipid accumulation. Accordingly, we prepared iso-caloric diets with 15.1 energy (e) % protein, 39.1 e% fat and 45.8 e% carbohydrates using freeze-dried meat from cod filets or pork sirloins, and using a combination of soybean oil, corn oil, margarine, milk fat, and lard as the fat source. Compared with mice receiving diets containing pork, mice fed cod gained less adipose tissue mass and had a lower content of hepatic lipids. This was accompanied by a lower n-6 to n-3 ratio in liver PLs and in red blood cells (RBCs) in the mice. Furthermore, mice receiving the cod-containing diet had lower circulating levels of the two major endocannabinoids, N-arachidonoylethanolamine and 2-arachidonoylglycerol. Together, our data demonstrate that despite the relatively low content of n-3 PUFAs in cod fillets, the cod-containing diet could exert beneficial metabolic effects.

Dietary intake of cod and scallop reduces atherosclerotic burden in female apolipoprotein E-deficient mice fed a Western-type high fat diet for 13 weeks

Background

It is now increasingly recognized that the beneficial effects of seafood consumption is not limited to lipids and fatty acid, but that the protein part, i.e., peptides and amino acids, together with vitamins and even unknown bioactive constituents also are important for disease prevention. This study was designed to evaluate the putative anti-atherogenic effects of different protein sources (a lean seafood and a nonseafood) in apolipoprotein E-deficient (apoE^−/−) mice.

Methods

Twenty-four 5-week-old female apoE^−/− mice were fed Western type diets containing chicken or a combination of cod and scallops as dietary protein sources for 13 weeks. Atherosclerotic plaque burden, weight, serum levels of leptin, glucose and LDL cholesterol as well as gene expressions from liver and heart were evaluated. Statistical analyses were performed using SPSS. Differences between the variables were evaluated using independent t-test or Mann–Whitney U test for normally and non-normally distributed variables, respectively. Normality was defined by the Shapiro-Wilk test.

Results

The mice fed cod-scallop had a 24 % (p < 0.05) reduced total aorta atherosclerotic plaque burden compared to the chicken fed group, whereas the reduction in plaque in the less lesion prone thoracic and abdominal parts of the descending aorta were 46 % (p < 0.05) and 56 % (p < 0.05), respectively. In addition, mice fed cod-scallop gained less weight, and had lower serum levels of leptin, glucose and LDL cholesterol, compared to those fed chicken. Analysis of expression of the genes from liver and heart showed that hepatic endogenous antioxidant paraoxonase 2 (Pon2 gene) and the vascular cell adhesion molecule VCAM-1 (Vcam1 gene) were down regulated in mice fed cod-scallop compared to mice fed chicken.

Conclusion

The present study revealed a metabolic beneficial effect of lean seafood compared to chicken, as atherosclerotic plaque burden, serum glucose, leptin and LDL cholesterol levels were reduced in mice fed cod-scallop.

Electronic supplementary material

The online version of this article (doi:10.1186/s12986-016-0068-z) contains supplementary material, which is available to authorized users.

Plasma Glycine and Risk of Acute Myocardial Infarction in Patients With Suspected Stable Angina Pectoris

Background

Glycine is an amino acid involved in antioxidative reactions, purine synthesis, and collagen formation. Several studies demonstrate inverse associations of glycine with obesity, hypertension, and diabetes mellitus. Recently, glycine‐dependent reactions have also been linked to lipid metabolism and cholesterol transport. However, little evidence is available on the association between glycine and coronary heart disease. Therefore, we assessed the association between plasma glycine and acute myocardial infarction (AMI).

Methods and Results

A total of 4109 participants undergoing coronary angiography for suspected stable angina pectoris were studied. Cox regression was used to estimate the association between plasma glycine and AMI, obtained via linkage to the CVDNOR project. During a median follow‐up of 7.4 years, 616 patients (15.0%) experienced an AMI. Plasma glycine was higher in women than in men and was associated with a more favorable baseline lipid profile and lower prevalence of obesity, hypertension, and diabetes mellitus (all P<0.001). After multivariate adjustment for traditional coronary heart disease risk factors, plasma glycine was inversely associated with risk of AMI (hazard ratio per SD: 0.89; 95% CI, 0.82–0.98; P=0.017). The inverse association was generally stronger in those with apolipoprotein B, low‐density lipoprotein cholesterol, or apolipoprotein A‐1 above the median (all P_interaction≤0.037).

Conclusions

Plasma glycine was inversely associated with risk of AMI in patients with suspected stable angina pectoris. The associations were stronger in patients with apolipoprotein B, low‐density lipoprotein cholesterol, or apolipoprotein A‐1 levels above the median. These results motivate further studies to elucidate the relationship between glycine and lipid metabolism, in particular in relation to cholesterol transport and atherosclerosis.

Clinical Trial Registration

URL: https://www.clinicaltrials.gov. Unique identifier: NCT00354081.

Effects of yam dioscorin interventions on improvements of the metabolic syndrome in high-fat diet-induced obese rats

BACKGROUND

The metabolic syndrome (MS) is termed a cluster of multiple metabolic risk criteria which is positively correlated with cardiovascular disease and type 2 diabetes mellitus (DM). Yam dioscorins have been reported to exhibit biological activities, however, little is known their preventive effects on the MS. Therefore, a high-fat (HF) diet was used to induce Wistar rat obesity and then yam dioscorin (50 mg/kg, dio50) was intervened daily concurrent HF diet (HF diet + dio50) for five weeks to check the changes of weights of body and tissues, blood pressures, and impaired glucose tolerances. The in vitro peptic hydrolysates of dioscorin with molecular mass between 3 kDa and 10 kDa and less than 3 kDa were used to determine dipeptidyl peptidase IV (DPP IV) inhibitory activities which DPP IV inhibitor has been reported to prevent and treat type 2 DM.

RESULTS

There were no significant difference in body weights, feed intakes, feed conversion, and weights of adipose tissues of obese rats in groups of HF and (HF diet + dio50). However, the systolic blood pressures in obese rats of 2-, 3- and 4-week dioscorin interventions were showed significantly lower (P < 0.05) compared to the HF group. The dioscorin intervention (HF+ dio50) was showed significantly different (P < 0.05) and improved the impaired glucose tolerances compared to HF group in obese rats by the oral glucose tolerance tests. It was also found that the fraction with different molecular mass of dioscorin peptic hydrolysates (5 mg/ml) showed inhibitory activities against DPP IV using sitagliptin phosphate as positive controls.

CONCLUSIONS

Yam dioscorins exhibit improved MS activities in obese rats which the related mechanisms may need further investigations.

Role of taurine in the pathogenesis of obesity

Taurine is a sulfur-containing amino acid that is present in mammalian tissues in millimolar concentrations. Taurine is involved in a diverse array of biological and physiological functions, including bile salt conjugation, osmoregulation, membrane stabilization, calcium modulation, anti-oxidation, and immunomodulation. The prevalence of obesity and being overweight continues to rise worldwide at an alarming rate. Obesity is associated with a higher risk of metabolic and cardiovascular diseases, cancer, and other clinical conditions. Ingestion of taurine has been shown to alleviate metabolic diseases such as hyperlipidemia, diabetes, hypertension, and obesity in animal models. A global epidemiological survey showed that 24-h urinary taurine excretion, as a marker of dietary taurine intake, was inversely associated with BMI, blood pressure, and plasma cholesterol in humans. In addition, taurine chloramine, an endogenous product derived from activated neutrophils, has been reported to suppress obesity-induced oxidative stress and inflammation in adipocytes. Synthetic activity and concentration of taurine in adipose tissues and plasma have been shown to decrease in humans and animals during the development of obesity, suggesting a relationship between taurine deficiency and obesity. In this review, I summarize the effects of taurine on the progression of obesity in animal models and humans. Furthermore, I discuss possible mechanisms underlying the antiobesity effects of taurine.

A mixture of cod and scallop protein reduces adiposity and improves glucose tolerance in high-fat fed male C57BL/6J mice

Low-protein and high-protein diets regulate energy metabolism in animals and humans. To evaluate whether different dietary protein sources modulate energy balance when ingested at average levels obesity-prone male C57BL/6J mice were pair-fed high-fat diets (67 energy percent fat, 18 energy percent sucrose and 15 energy percent protein) with either casein, chicken filet or a mixture of cod and scallop (1∶1 on amino acid content) as protein sources. At equal energy intake, casein and cod/scallop fed mice had lower feed efficiency than chicken fed mice, which translated into reduced adipose tissue masses after seven weeks of feeding. Chicken fed mice had elevated hepatic triglyceride relative to casein and cod/scallop fed mice and elevated 4 h fasted plasma cholesterol concentrations compared to low-fat and casein fed mice. In casein fed mice the reduced adiposity was likely related to the observed three percent lower apparent fat digestibility compared to low-fat, chicken and cod/scallop fed mice. After six weeks of feeding an oral glucose tolerance test revealed that despite their lean phenotype, casein fed mice had reduced glucose tolerance compared to low-fat, chicken and cod/scallop fed mice. In a separate set of mice, effects on metabolism were evaluated by indirect calorimetry before onset of diet-induced obesity. Spontaneous locomotor activity decreased in casein and chicken fed mice when shifting from low-fat to high-fat diets, but cod/scallop feeding tended (P = 0.06) to attenuate this decrease. Moreover, at this shift, energy expenditure decreased in all groups, but was decreased to a greater extent in casein fed than in cod/scallop fed mice, indicating that protein sources regulated energy expenditure differently. In conclusion, protein from different sources modulates energy balance in C57BL/6J mice when given at normal levels. Ingestion of a cod/scallop-mixture prevented diet-induced obesity compared to intake of chicken filet and preserved glucose tolerance compared to casein intake.

Urinary loss of tricarboxylic acid cycle intermediates as revealed by metabolomics studies: an underlying mechanism to reduce lipid accretion by whey protein ingestion?

Whey protein intake is associated with the modulation of energy metabolism and altered body composition both in human subjects and in animals, but the underlying mechanisms are not yet elucidated. We fed obesity-prone C57BL/6J mice high-fat diets with either casein (HF casein) or whey (HF whey) for 6 weeks. At equal energy intake and apparent fat and nitrogen digestibility, mice fed HF whey stored less energy as lipids, evident both as lower white adipose tissue mass and as reduced liver lipids, compared with HF-casein-fed mice. Explorative analyses of 48 h urine, both by ¹H NMR and LC–MS metabolomic platforms, demonstrated higher urinary excretion of tricarboxylic acid (TCA) cycle intermediates citric acid and succinic acid (identified by both platforms), and cis-aconitic acid and isocitric acid (identified by LC–MS platform) in the HF whey, relative to in the HF-casein-fed mice. Targeted LC–MS analyses revealed higher citric acid and cis-aconitic acid concentrations in fed state plasma, but not in liver of HF-whey-fed mice. We propose that enhanced urinary loss of TCA cycle metabolites drain available substrates for anabolic processes, such as lipogenesis, thereby leading to reduced lipid accretion in HF-whey-fed compared to HF-casein-fed mice.