Postprandial plasma betaine and other methyl donor-related responses after consumption of minimally processed wheat bran or wheat aleurone, or wheat aleurone incorporated into bread

Aleurone supplementation enhances the metabolic benefits of training in Standardbred mares: impacts on glucose-insulin dynamics and gut microbiome composition

Introduction

Aleurone, derived from the bran layer of grains like wheat and barley, has demonstrated positive effects on energy metabolism in pigs, mice, and untrained horses, influencing glucose-insulin dynamics and gut microbiome composition. Training itself enhances insulin sensitivity in horses, similar to the improvements in performance capacity observed in human athletes. This study aimed to investigate whether aleurone supplementation provides additional benefits to training by modulating insulin metabolism and gut microbiota in Standardbred mares.

Methods

Sixteen Standardbred mares (aged 3-5 years) participated in a cross-over study with two 8-week training periods separated by 8 weeks of detraining. Each horse received either 200 g/day aleurone supplementation or a control diet. Insulin metabolism was evaluated using oral (OGTT) and intravenous (FSIGTT) glucose tolerance tests, measuring parameters such as Maximumglucose, AUCglucose, Maximuminsulin, AUCinsulin, Time to peakinsulin (OGTT), Acute Insulin Response to Glucose (AIRg), glucose effectiveness (Sg), and disposition index (DI) (FSIGTT). Fecal samples underwent metagenomic analysis to assess alpha and beta diversity and microbial composition.

Results

Training alone: Training significantly improved OGTT parameters by decreasing Maximuminsulin (P = 0.005) and AUCinsulin (P = 0.001), while increasing Time to peakinsulin (P = 0.03), indicating enhanced insulin sensitivity. FSIGTT results also showed a decrease in logAIRg (P = 0.044). Training with Aleurone: Aleurone supplementation further reduced FSIGTT AIRg (P = 0.030), logAIRg (P = 0.021) while increasing glucose effectiveness (Sg; P = 0.031). These findings suggest aleurone improves insulin sensitivity, glucose disposal, and fasting glucose regulation beyond training. Microbiome analysis revealed training decreased Pseudomonas, associated with dysbiosis, while aleurone reduced inflammation-associated Desulfovibrio. Beta diversity metrics showed no significant changes.

Conclusion

Aleurone supplementation enhances training-induced improvements in glucose metabolism and fecal microbiota composition, which could offer potential benefits for equine athletes by optimizing metabolic flexibility. It also supports improvements in glucose and insulin dynamics, particularly by further enhancing insulin sensitivity and glucose-mediated disposal. Future studies should investigate the mechanisms of aleurone at the muscle and gut level and explore its potential applications for metabolic disorders such as Equine Metabolic Syndrome.

Plasma Metabolite Response to Simple, Refined and Unrefined Carbohydrate-Enriched Diets in Older Adults-Randomized Controlled Crossover Trial

Food intake data collected using subjective tools are prone to inaccuracies and biases. An objective assessment of food intake, such as metabolomic profiling, may offer a more accurate method if unique metabolites can be identified. To explore this option, we used samples generated from a randomized and controlled cross-over trial during which participants (N = 10; 65 ± 8 year, BMI, 29.8 ± 3.2 kg/m²) consumed each of the three diets enriched in different types of carbohydrate. Plasma metabolite concentrations were measured at the end of each diet phase using gas chromatography/time-of-flight mass spectrometry and ultra-high pressure liquid chromatography/quadrupole time-of-flight tandem mass spectrometry. Participants were provided, in random order, with diets enriched in three carbohydrate types (simple carbohydrate (SC), refined carbohydrate (RC) and unrefined carbohydrate (URC)) for 4.5 weeks per phase and separated by two-week washout periods. Data were analyzed using partial least square-discrimination analysis, receiver operating characteristics (ROC curve) and hierarchical analysis. Among the known metabolites, 3-methylhistidine, phenylethylamine, cysteine, betaine and pipecolic acid were identified as biomarkers in the URC diet compared to the RC diet, and the later three metabolites were differentiated and compared to SC diet. Hierarchical analysis indicated that the plasma metabolites at the end of each diet phase were more strongly clustered by the participant than the carbohydrate type. Hence, although differences in plasma metabolite concentrations were observed after participants consumed diets differing in carbohydrate type, individual variation was a stronger predictor of plasma metabolite concentrations than dietary carbohydrate type. These findings limited the potential of metabolic profiling to address this variable.

Effects of Aleurone Supplementation on Glucose-Insulin Metabolism and Gut Microbiome in Untrained Healthy Horses

Aleurone, a layer of the bran fraction, is deemed to be responsible for the positive health effects associated with the consumption of whole-grain products. Studies on rodents, pigs, and humans report beneficial effects of aleurone in five main areas: the reduction of oxidative stress, immunomodulatory effects, modulation of energy management, digestive health, and the storage of vitamins and minerals. Our study is the first aleurone supplementation study performed in horses. The aim of this study was to investigate the effect of an increase in the dose levels of aleurone on the postprandial glucose-insulin metabolism and the gut microbiome in untrained healthy horses. Seven adult Standardbred horses were supplemented with four different dose levels of aleurone (50, 100, 200, and 400 g/day for 1 week) by using a Latin square model with a 1-week wash out in between doses. On day 7 of each supplementation week, postprandial blood glucose-insulin was measured and fecal samples were collected. 16S ribosomal RNA (rRNA) gene sequencing was performed and QIIME2 software was used for microbiome analysis. Microbial community function was assessed by using the predictive metagenome analysis tool Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) and using the Metacyc database of metabolic pathways. The relative abundancies of a pathway were analyzed by using analysis of composition of microbiomes (ANCOM) in R. There was a significant dose-dependent increase in the postprandial time to peak of glucose (p = 0.030), a significant delay in the time to peak of insulin (p = 0.025), and a significant decrease in both the insulin peak level (p = 0.049) and insulin area under the curve (AUC) (p = 0.019) with increasing dose levels of aleurone, with a consideration of 200 g being the lowest significant dose. Alpha diversity and beta diversity of the fecal microbiome showed no significant changes. Aleurone significantly decreased the relative abundance of the genera Roseburia, Shuttleworthia, Anaerostipes, Faecalibacter, and Succinovibrionaceae. The most pronounced changes in the relative abundance at phyla level were seen in Firmicutes and Verrucomicrobia (downregulation) and Bacteroidetes and Spirochaetes (upregulation). The PICRUSt analysis shows that aleurone induces a downregulation of the degradation of L-glutamate and taurine and an upregulation of the three consecutive pathways of the phospholipid membrane synthesis of the Archaea domain. The results of this study suggest a multimodal effect of aleurone on glucose-insulin metabolism, which is most likely to be caused by its effect on feed texture and subsequent digestive processing; and a synergistic effect of individual aleurone components on the glucose-insulin metabolism and microbiome composition and function.

Plant-Based Food By-Products: Prospects for Valorisation in Functional Bread Development

The industrial and small-scale processing of plant-based food materials is associated with by-products that may have a negative impact on the environment but could add value to bread-based products. The bioactivity of plant-based food by-products, their impact on the properties of functional bread, and their bioavailability/bioaccessibility leading to potential health effects when consumed was reviewed. Plant-based food by-products which may be added to bread include rice bran, wheat bran, corn bran, grape pomace/seed extract, tomato seed/skin, and artichoke stems/leaves. These by-products contain high concentrations of bioactive compounds, including phenolics, bioactive peptides, and arabinoxylan. Pre-treatment procedures, including fermentation and thermal processing, impact the properties of plant-based by-products. In most cases, bread formulated with flour from plant-based by-products demonstrated increased fibre and bioactive compound contents. In terms of the sensory and nutritional acceptability of bread, formulations with an average of 5% flour from plant-based by-products produced bread with acceptable sensory properties. Bread enriched with plant-based by-products demonstrated enhanced bioavailability and bioaccessibility and favourable bioactive properties in human blood, although long-term studies are warranted. There is a need to investigate the bioactive properties of other underutilised plant-based by-products and their potential application in bread as a sustainable approach towards improving food and nutrition security.

Diets rich in whole grains increase betainized compounds associated with glucose metabolism

Background

Epidemiologic evidence suggests that diets rich in whole grains are associated with a reduced risk of developing chronic diseases and all-cause mortality. However, the molecular mechanisms behind these beneficial metabolic effects are poorly understood.

Objective

Our aim was to investigate novel trimethylated (betainized) compounds from mice and humans, and their association with whole grain-rich diets and insulin resistance and insulin secretion.

Design

Fasting plasma samples were obtained in a mouse (C57BL/6J male) feeding trial and a controlled dietary intervention. The mouse trial involved feeding the mice a rye and wheat bran-enriched feed which was compared with a high-fat diet. In the human trial, participants recruited from Kuopio, Finland (n = 69) and Naples, Italy (n = 54) with characteristics of the metabolic syndrome were randomly assigned to either a whole grain-enriched diet or a control diet for 12 wk. Plasma concentrations of betainized compounds were analyzed with the use of liquid chromatography-tandem mass spectrometry. Insulin resistance and insulin secretion were assessed in an oral-glucose-tolerance test and a meal-glucose-tolerance test.

Results

The betaines that were increased in mouse plasma after bran-enriched feeding were identified de novo via chemical synthesis and liquid chromatography-tandem mass spectrometry, and confirmed to be associated with an increased intake of whole-grain products in humans. In particular, the concentrations of pipecolic acid betaine were increased at the end of the whole-grain intervention in both the Kuopio cohort (P < 0.001) and the Naples cohort (P < 0.05), and these concentrations inversely correlated with the postprandial glucose concentration. Furthermore, the concentration of valine betaine was substantially increased during the intervention in Naples (P < 0.001) with an inverse correlation with the postprandial insulin concentration. In addition, the concentrations of other betaines, e.g., glycine betaine and proline betaine, correlated with glucose and insulin concentrations at the end of the intervention.

Conclusions

Novel betainized compounds in humans are associated with diets rich in whole grains, and they improve insulin resistance and insulin secretion. These results suggest that these novel compounds may contribute to the beneficial effects of whole grain-rich diets. The studies were registered at clinicaltrials.gov as NCT00945854 (Naples) and NCT00573781 (Kuopio).

Enhancing mineral bioavailability from cereals: Current strategies and future perspectives

Inadequate intake of essential minerals such as iron and zinc is a public health concern in the UK, particularly for girls and young women. Approximately 30% and 50% of the zinc and iron, respectively, in the UK diet is provided by cereals. In wheat, most of the iron and zinc is contained within the aleurone cell layer; however, aleurone is removed during processing of wheat into white flour. While elemental iron powder is added back into white flour at the milling stage, there is no restoration of zinc. Elemental iron powder has very low bioavailability, and therefore, in our current Biotechnology and Biological Sciences Research Council Diet and Health Research Industry Club-funded project, we are investigating the potential use of aleurone as a bioavailable source of minerals that could be added to wheat-based foods. This work has relevance for the food industry and may establish the use of aleurone as a functional food ingredient for fortification of a range of cereal-based food products.

Diurnal variation of NMR based blood metabolites in calves fed a high plane of milk replacer: a pilot study

BACKGROUND

Blood profiles have been used to monitor herd health status, diagnose disorders, and predict the risk of diseases in cattle and calves. Characterizing plasma metabolites in dairy calves could provide further insight into daily metabolic variations and the mechanisms that lead to metabolic diseases. In addition, by understanding physiological ranges of plasma metabolites relative to meal and the time of feeding in healthy animals, veterinarians can accurately diagnose abnormalities with a blood test. For diagnostic purposes, nuclear magnetic resonance (NMR) spectroscopy shows promise as a new and reliable method to determine a large number of blood metabolites simultaneously.

RESULTS

Results demonstrated that the concentration of specific metabolites in plasma (i.e., lysine, isoleucine, leucine, tyrosine, glutamine, creatine, and 1-methylhistidine) fluctuated around meal times, while others (i.e., glutamic acid, methanol, formic acid, and acetic acid) maintained a stable temporal concentration. In addition to temporal changes in concentration, results also characterized differences for overall plasma metabolite concentrations; for example, methionine had the lowest (38 μM) while glutamine had the highest concentration (239 μM) amongst plasma AA. This is the first report describing how the plasma metabolome changes during 24-h period in young calves fed an elevated plane of milk replacer twice daily.

CONCLUSIONS

Data from this pilot study will help to establish reference standards for future metabolic diagnostics in dairy calves. In addition, this pilot study illustrated that feeding milk replacer may influence plasma metabolite concentrations. With the rapid implementation of blood metabolomics in monitoring animal health, it is then important to consider the time of feeding during the day when interpreting metabolomics analysis results.

Defining genetic and chemical diversity in wheat grain by 1H-NMR spectroscopy of polar metabolites

SCOPE

The application of high-throughput 1H nuclear magnetic resonance (1H-NMR) of unpurified extracts to determine genetic diversity and the contents of polar components in grain of wheat.

METHODS AND RESULTS

Milled whole wheat grain was extracted with 80:20 D2 O:CD3 OD containing 0.05% d4 -trimethylsilylpropionate. 1H-NMR spectra were acquired under automation at 300°K using an Avance Spectrometer operating at 600.0528 MHz. Regions for individual metabolites were identified by comparison to a library of known standards run under identical conditions. The individual 1H-NMR peaks or levels of known metabolites were then compared by Principal Component Analysis using SIMCA-P software.

CONCLUSIONS

High-throughput 1H-NMR is an excellent tool to compare the extent of genetic diversity within and between wheat species, and to quantify specific components (including glycine betaine, choline, and asparagine) in individual genotypes. It can also be used to monitor changes in composition related to environmental factors and to support comparisons of the substantial equivalence of transgenic lines.

Using NMR-Based Metabolomics to Evaluate Postprandial Urinary Responses Following Consumption of Minimally Processed Wheat Bran or Wheat Aleurone by Men and Women

Wheat bran, and especially wheat aleurone fraction, are concentrated sources of a wide range of components which may contribute to the health benefits associated with higher consumption of whole-grain foods. This study used NMR metabolomics to evaluate urine samples from baseline at one and two hours postprandially, following the consumption of minimally processed bran, aleurone or control by 14 participants (7 Females; 7 Males) in a randomized crossover trial. The methodology discriminated between the urinary responses of control, and bran and aleurone, but not between the two fractions. Compared to control, consumption of aleurone or bran led to significantly and substantially higher urinary concentrations of lactate, alanine, N-acetylaspartate acid and N-acetylaspartylglutamate and significantly and substantially lower urinary betaine concentrations at one and two hours postprandially. There were sex related differences in urinary metabolite profiles with generally higher hippurate and citrate and lower betaine in females compared to males. Overall, this postprandial study suggests that acute consumption of bran or aleurone is associated with a number of physiological effects that may impact on energy metabolism and which are consistent with longer term human and animal metabolomic studies that used whole-grain wheat diets or wheat fractions.

Plasma Concentrations of Trimethylamine-N-oxide Are Directly Associated with Dairy Food Consumption and Low-Grade Inflammation in a German Adult Population

BACKGROUND

Trimethylamine-N-oxide (TMAO) is a metabolite of carnitine, choline, and phosphatidylcholine, which is inversely associated with survival of cardiovascular disease (CVD) patients.

OBJECTIVE

We examined the associations of diet with plasma concentrations of TMAO, choline, and betaine and the associations of TMAO with plasma concentrations of various cytokines.

METHODS

Plasma TMAO, choline, and betaine concentrations were measured using LC-high resolution mass spectrometry in 271 participants, ≥18 y old, of the Second Bavarian Food Consumption Survey, conducted in 2002 and 2003. Food consumption was assessed using at least two 24-h dietary recalls. Cytokines were measured in plasma with enzyme-linked immunosorbent assays. Geometric mean concentrations of TMAO, choline, and betaine by categories of meat, dairy food, egg, and fish consumption were computed, adjusted for sex, age, and BMI. Multivariable-adjusted geometric mean concentrations of cytokines [tumor necrosis factor-α (TNF-α), soluble TNF receptors (sTNF-R) p55, sTNF-R p75, interleukin-6 (IL-6), and C-reactive protein (CRP)] were computed by quartiles of TMAO concentration using general linear models.

RESULTS

Meat, egg, or fish consumption was not associated with TMAO, choline, or betaine concentrations (all P-trend ≥ 0.05). With increases in milk and other dairy food consumption, the plasma TMAO concentration increased [geometric mean bottom quartile of milk consumption: 2.08 μM (95% CI: 1.69, 2.57 μM); compared with top quartile: 3.13 μM (95% CI: 2.56, 3.84 μM); P-trend = 0.008]. Participants in the top TMAO quartile had higher plasma concentrations of TNF-α, sTNF-R p55, and sTNF-R p75 than participants in the bottom quartile (percentage difference ranging between 14.4% and 17.3%; all P-trend < 0.05), but there were no differences in plasma concentrations of CRP and IL-6 (all P-trend ≥ 0.05).

CONCLUSIONS

Results of this study conducted among healthy adults from the general population do not indicate a strong effect of diet on plasma concentrations of TMAO, choline, or betaine, with the exception of a positive association between dairy food consumption and plasma TMAO concentrations. Also, plasma TMAO concentrations were positively associated with inflammation. Whether habitual diet is strongly linked to the plasma TMAO concentration, a potential marker of CVD risk, needs to be determined in further studies.

In Vitro Bioaccessibility of Phenolic Acids from a Commercial Aleurone-Enriched Bread Compared to a Whole Grain Bread

Wheat aleurone, due to its potentially higher bioaccessibility and bioavailability of micronutrients and phenolic acids, could represent a useful ingredient in the production of commonly consumed cereal-based food. The aim of the present study was to investigate the in vitro bioaccessibility of phenolic acids both from an aleurone-enriched bread and from a whole grain bread. The two bread samples were firstly characterized for the phenolic acid content. An in vitro digestion was then performed in order to evaluate the release of phenolic acids. The results obtained suggest that the bioaccessibility of the phenolic acids in the aleurone-enriched bread is higher than in the whole grain bread. These in vitro results suggest the potential use of aleurone in the production of foods, and this may represent an attractive possibility to vehicle nutritionally interesting components to consumers.

The contribution of wheat to human diet and health

Wheat is the most important staple crop in temperate zones and is in increasing demand in countries undergoing urbanization and industrialization. In addition to being a major source of starch and energy, wheat also provides substantial amounts of a number of components which are essential or beneficial for health, notably protein, vitamins (notably B vitamins), dietary fiber, and phytochemicals. Of these, wheat is a particularly important source of dietary fiber, with bread alone providing 20% of the daily intake in the UK, and well-established relationships between the consumption of cereal dietary fiber and reduced risk of cardio-vascular disease, type 2 diabetes, and forms of cancer (notably colo-rectal cancer). Wheat shows high variability in the contents and compositions of beneficial components, with some (including dietary fiber) showing high heritability. Hence, plant breeders should be able to select for enhanced health benefits in addition to increased crop yield.