Investigation of the presence of β-hydroxy-β-methylbutyric acid and α-hydroxyisocaproic acid in bovine whole milk and fermented dairy products by a validated liquid chromatography-mass spectrometry method

Molecular profiling of whey permeate reveals new insights into molecular affinities related to industrial unit operations during lactose production

Lactose powder production from whey permeate generates various side-streams. Molecular profiling of these side-streams and lactose powder can help to detect minor compounds affecting lactose crystallization, lactose powder properties and document the composition of the underutilized side-streams. In this study, whey permeate, lactose powder and intermediate streams from trial lactose productions were analyzed using gas chromatography-mass spectrometry (GC-MS) and proton nuclear magnetic resonance (¹H NMR) spectroscopy. In total, 110 compounds were identified and 49 were quantified. Linking the molecular profiles to in-process steps revealed differential compositional attenuation by the unit operations. Small molecules (e.g. methanol) and a few larger molecules (e.g. fatty acids) permeated reverse osmosis membrane, while twenty-three compounds (e.g. hydroxypyruvic acid, malonic acid, gluconic acid and ribonic acid) co-crystallized with lactose and ended up in lactose power. These results help to better understand and control lactose powder production and highlights possibilities to develop new food ingredients.

Gut microbiota and fermentation-derived branched chain hydroxy acids mediate health benefits of yogurt consumption in obese mice

Meta-analyses suggest that yogurt consumption reduces type 2 diabetes incidence in humans, but the molecular basis of these observations remains unknown. Here we show that dietary yogurt intake preserves whole-body glucose homeostasis and prevents hepatic insulin resistance and liver steatosis in a dietary mouse model of obesity-linked type 2 diabetes. Fecal microbiota transplantation studies reveal that these effects are partly linked to the gut microbiota. We further show that yogurt intake impacts the hepatic metabolome, notably maintaining the levels of branched chain hydroxy acids (BCHA) which correlate with improved metabolic parameters. These metabolites are generated upon milk fermentation and concentrated in yogurt. Remarkably, diet-induced obesity reduces plasma and tissue BCHA levels, and this is partly prevented by dietary yogurt intake. We further show that BCHA improve insulin action on glucose metabolism in liver and muscle cells, identifying BCHA as cell-autonomous metabolic regulators and potential mediators of yogurt's health effects.

Metabolomics of acid whey derived from Greek yogurt

Acid whey, a byproduct of Greek yogurt production, has little commercial value due to its low protein content and is also environmentally harmful when disposed of as waste. However, as a product of microbial fermentation, acid whey could be a rich source of beneficial metabolites associated with fermented foods. This study increases understanding of acid whey composition by providing a complete metabolomic profile of acid whey. Commercial and laboratory-made Greek yogurts, prepared with 3 different bacterial culture combinations, were evaluated. Samples of uncultured milk and cultured whey from each batch were analyzed. Ultra-high-performance liquid chromatography-tandem mass spectrometry metabolomics were used to separate and identify 477 metabolites. Compared with uncultured controls, acid whey from fermented yogurt showed decreases in some metabolites and increases in others, presumably due to the effects of microbial metabolism. Additional metabolites appeared in yogurt whey but not in the uncultured control. Therefore, the effect of microbial fermentation is complex, leading to increases or decreases in potentially bioactive bovine metabolites while generating new microbial compounds that may be beneficial. Metabolite production was significantly affected by combinations of culturing organisms and production location. Differences between laboratory-made and commercial samples could be caused by different starting ingredients, environmental factors, or both.

α-Hydroxyisocaproic Acid Decreases Protein Synthesis but Attenuates TNFα/IFNγ Co-Exposure-Induced Protein Degradation and Myotube Atrophy via Suppression of iNOS and IL-6 in Murine C2C12 Myotube

There is ongoing debate as to whether or not α-hydroxyisocaproic acid (HICA) positively regulates skeletal muscle protein synthesis resulting in the gain or maintenance of skeletal muscle. We investigated the effects of HICA on mouse C2C12 myotubes under normal conditions and during cachexia induced by co-exposure to TNFα and IFNγ. The phosphorylation of AMPK or ERK1/2 was significantly altered 30 min after HICA treatment under normal conditions. The basal protein synthesis rates measured by a deuterium-labeling method were significantly lowered by the HICA treatment under normal and cachexic conditions. Conversely, myotube atrophy induced by TNFα/IFNγ co-exposure was significantly improved by the HICA pretreatment, and this improvement was accompanied by the inhibition of iNOS expression and IL-6 production. Moreover, HICA also suppressed the TNFα/IFNγ co-exposure-induced secretion of 3-methylhistidine. These results demonstrated that HICA decreases basal protein synthesis under normal or cachexic conditions; however, HICA might attenuate skeletal muscle atrophy via maintaining a low level of protein degradation under cachexic conditions.

A Novel Fortified Dairy Product and Sarcopenia Measures in Sarcopenic Older Adults: A Double-Blind Randomized Controlled Trial

OBJECTIVES

To evaluate the efficacy of daily consumption of fortified yogurt with beta-Hydroxy beta-Methyl Butyrate (HMB) and vitamins D and C on measures of sarcopenia, inflammation, and quality of life in sarcopenic older adults.

DESIGN

In this 12-week randomized double-blind controlled trial, participants received either yogurt fortified with 3 g HMB, 1000 IU vitamin D, and 500 mg vitamin C in the intervention group (n = 33) or plain yogurt in the control group (n = 33).

SETTING AND PARTICIPANTS

A total of 66 older adults with sarcopenia recruited from the community in Shiraz, Iran.

MEASURES

Body composition, muscle strength, and functionality were measured using Dual-energy-X-ray Absorptiometry (DXA), hydraulic handgrip dynamometer, and usual gait speed, respectively. Serum concentrations of vitamin D, insulin-like growth factor-1 (IGF-1), C-reactive protein (hs-CRP), malondialdehyde, and insulin were measured at baseline and after 12 weeks. Health-related quality of life (HRQoL) was also evaluated using SF-12 questionnaire.

RESULTS

Consumption of fortified yogurt was associated with improvement in handgrip strength [mean change (95% confidence interval) 4.36 (3.35-5.37) vs. 0.97 (-0.04 to 1.99)] and gait speed [0.10 (0.07-0.13) vs. 0.01 (0.00-0.04)] in the intervention group compared with the control group (P < .001). In addition, the results revealed a significant increase in vitamin D and IGF-1 levels in the intervention group (P < .001). The nutritional intervention significantly prevented any increase in the serum concentration of hs-CRP compared with the control group (P = .033). The results also showed a more significant decrease in the malondialdehyde level in the intervention group compared with the control (P = .008). Moreover, there were significant differences between the 2 groups regarding physical aspects of HRQoL (P = .035).

CONCLUSIONS AND IMPLICATIONS

A novel dairy product fortified with HMB, vitamin D, and vitamin C not only could enhance muscle strength and functionality, but also modulate anabolic and inflammatory conditions as well as quality of life. This study suggested that specific nutritional interventions alone could be beneficial, especially for those who are unable to exercise.

Describing the fecal metabolome in cryogenically collected samples from healthy participants

The chemical composition of feces plays an important role in human metabolism. Metabolomics and lipidomics are valuable tools for screening the metabolite composition in feces. Here we set out to describe fecal metabolite composition in healthy participants in frozen stools. Frozen stool samples were collected from 10 healthy volunteers and cryogenically drilled in four areas along the specimen. Polar metabolites were analyzed using derivatization followed by two-dimensional gas chromatography and time of flight mass spectrometry. Lipids were detected using ultra high-performance liquid chromatography coupled with quadruple time-of-flight mass spectrometry. 2326 metabolic features were detected. Out of a total of 298 metabolites that were annotated we report here 185 that showed a technical variation of x < 30%. These metabolites included amino acids, fatty acid derivatives, carboxylic acids and phenolic compounds. Lipids predominantly belonged to the groups of diacylglycerols, triacylglycerols and ceramides. Metabolites varied between sampling areas, some were broadly homogeneous, others varied 80%. A LASSO-computed network using metabolites present in all areas showed two main clusters describing the system, DAG lipids and phenyllactic acid. In feces from healthy participants, the main groups detected were phenolic compounds, ceramides, diacylglycerols and triacylglycerols.

Transfer of β-hydroxy-β-methylbutyrate from sows to their offspring and its impact on muscle fiber type transformation and performance in pigs

Background

Previous studies suggested that supplementation of lactating sows with β-hydroxy-β-methylbutyrate (HMB) could improve the performance of weaning pigs, but there were little information in the muscle fiber type transformation of the offspring and the subsequent performance in pigs from weaning through finishing in response to maternal HMB consumption. The purpose of this study was to determine the effect of supplementing lactating sows with HMB on skeletal muscle fiber type transformation and growth of the offspring during d 28 and 180 after birth. A total of 20 sows according to their body weight were divided into the control (CON, n = 10) or HMB groups (HMB, n = 10). Sows in the HMB group were supplemented with β-hydroxy-β-methylbutyrate calcium (HMB-Ca) 2 g /kg feed during d 1 to 27 of lactation. After weaning, 48 mixed sex piglets were blocked by sow treatment and fed standard diets for post-weaning, growing, finishing periods. Growth performance was recorded during d 28 to 180 after birth. Pigs were slaughtered on d 28 (n = 6/treatment) and 180 (n = 6/treatment) postnatal, and the longissimus dorsi (LD) was collected, respectively.

Results

The HMB-fed sows during lactation showed increased HMB concentration (P < 0.05) in milk and LD of weaning piglets (P < 0.05). In addition, offsprings in HMB group had a higher finishing BW and lean percentage than did pigs in CON group (P < 0.05), meanwhile, compared with pigs from sows fed the CON diet, pigs from sows fed HMB diet showed higher type II muscle fiber cross-sectional area (CSA), elevated myosin heavy chain (MyHC) IIb and Sox6 mRNA, and fast-MyHC protein levels in LD (P < 0.05).

Conclusions

HMB supplemented to sow diets throughout lactation increases the levels of HMB in maternal milk and skeletal muscle of pigs during d 28 after birth and promotes subsequent performance of pigs between d 28 and 180 of age by enhancing glycolytic muscle fiber transformation.

Nontargeted LC-MSn Profiling of Compounds in Ileal Fluids That Decrease after Raspberry Intake Identifies Consistent Alterations in Bile Acid Composition

Ileostomy studies provide a unique insight into the digestion of foods, allowing identification of physiologically relevant dietary phytochemicals and their metabolites that are important to gut health. We previously reported an increase of components, including novel triterpenoids, in ileal fluids of 11 ileostomates following consumption of raspberries using nontargeted LC-MSⁿ techniques in combination with data deconvolution software. The current study focused on components that consistently decreased postsupplementation. After data deconvolution, 32 components were identified that met exclusion parameters of m/z signals and which decreased significantly in ileal fluids from eight of 11 participants post-raspberry supplementation. Two-thirds of these components were identified putatively from their MS properties. Consistent decreases were observed in components that possibly reflected "washing out" of presupplementation intake of common foods/drinks including (poly)phenol metabolites. Metabolites associated with fat metabolism such as hydroxylated fatty acids and cholate-type bile acids were specifically reduced. However, more directed re-examination of the data revealed that although some cholates were consistently reduced, the more polar glyco- and tauro-linked bile acid derivatives increased consistently, by as much as 100-fold over presupplementation levels. The possible reasons for these substantial alterations in bile acid composition in ileal fluids in response to raspberry intake are discussed.

Quantitation of α-hydroxy acids in complex prebiotic mixtures via liquid chromatography/tandem mass spectrometry

RATIONALE

Spark discharge experiments, like those performed by Stanley Miller in the 1950s, generate complex, analytically challenging mixtures that contain biopolymer building blocks. Recently, α-amino acids and α-hydroxy acids (AHAs) were subjected to environmental cycling to form simple depsipeptides (peptides with both amide and ester linkages). The synthesis of AHAs under possible primordial environments must be examined to better understand this chemistry.

METHODS

We report a direct, quantitative method for AHAs using ultrahigh-performance liquid chromatography and triple quadrupole mass spectrometry. Hexylamine ion-pairing chromatography and selected reaction monitoring detection were combined for the rapid analysis of ten AHAs in a single run. Additionally, prebiotic simulation experiments, including the first-ever reproduction of Miller's 1958 cyanamide spark discharge experiment, were performed to evaluate AHA synthesis over a wide range of possible primitive terrestrial environments.

RESULTS

The quantitating transition for each of the AHAs targeted in this study produced a limit of detection in the nanomolar concentration range. For most species, a linear response over a range spanning two orders of magnitude was found. The AHAs glycolic acid, lactic acid, malic acid, and α-hydroxyglutaric acid were detected in electric discharge experiments in the low micromolar concentration range.

CONCLUSIONS

The results of this work suggest that the most abundant building blocks available for prebiotic depsipeptide synthesis would have been glycolic, lactic, malic, and α-hydroxyglutaric acids, and their corresponding amino acids, glycine, alanine, and aspartic and glutamic acids. Copyright © 2016 John Wiley & Sons, Ltd.

Dietary supplementation with β-hydroxy-β-methylbutyrate calcium during the early postnatal period accelerates skeletal muscle fibre growth and maturity in intra-uterine growth-retarded and normal-birth-weight piglets

Intra-uterine growth restriction (IUGR) impairs postnatal growth and skeletal muscle development in neonatal infants. This study evaluated whether dietary β-hydroxy-β-methylbutyrate Ca (HMB-Ca) supplementation during the early postnatal period could improve muscle growth in IUGR neonates using piglets as a model. A total of twelve pairs of IUGR and normal-birth-weight (NBW) male piglets with average initial weights (1·85 (sem 0·36) and 2·51 (sem 0·39) kg, respectively) were randomly allotted to groups that received milk-based diets (CON) or milk-based diets supplemented with 800 mg/kg HMB-Ca (HMB) during days 7-28 after birth. Blood and longissimus dorsi (LD) samples were collected and analysed for plasma amino acid content, fibre morphology and the expression of genes related to muscle development. The results indicate that, regardless of diet, IUGR piglets had a significantly decreased average daily weight gain (ADG) compared with that of NBW piglets (P<0·05). However, IUGR piglets fed HMB-Ca had a net weight and ADG similar to that of NBW piglets fed the CON diet. Irrespective of body weight (BW), HMB-Ca supplementation markedly increased the type II fibre cross-sectional area and the mRNA expression of mammalian target of rapamycin (mTOR), insulin-like growth factor-1 and myosin heavy-chain isoform IIb in the LD of piglets (P<0·05). Moreover, there was a significant interaction between the effects of BW and HMB on mTOR expression in the LD (P<0·05). In conclusion, HMB-Ca supplementation during the early postnatal period could improve skeletal muscle growth and maturity by accelerating fast-twitch glycolytic fibre development in piglets.

Direct Analysis of Leucine and Its Metabolites β-Hydroxy-β-methylbutyric Acid, α-Ketoisocaproic Acid, and α-Hydroxyisocaproic Acid in Human Breast Milk by Liquid Chromatography-Mass Spectrometry

A direct, quantitative, and confirmatory method based on stable isotope dilution liquid chromatography-mass spectrometry was developed and validated for the analysis of leucine and metabolites β-hydroxy-β-methylbutyric acid (HMB), α-ketoisocaproic acid (KIC), and α-hydroxyisocaproic acid (HICA) in human breast milk. Chromatographic resolution was achieved between isobaric leucine and isoleucine. Accuracy and intermediate precision were 89-117% and <10% relative standard deviation (RSD) across three validation runs. Limits of quantitation for HMB, KIC, HICA, and leucine in human breast milk were 20 μg/L, 20 μg/L, 10 μg/L, and 1 mg/L. Measured concentrations of HMB, KIC, HICA, and free leucine in human breast milk from six donors at various stages of lactation were 42-164 μg/L, < 20-1057 μg/L, < 10 μg/L, and 2.1-88.5 mg/L. HMB and KIC were confirmed in human breast milk by orthogonal hydrophilic interaction chromatography (HILIC). This work provides a tool for further study of human breast milk composition and its effect on protein turnover in developing infants.