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Synergistic Responses of Tibetan Sheep Rumen Microbiota, Metabolites, and the Host to the Plateau Environment.
(MDPI (Basel, Switzerland), 2023-10-03) Sha Y; Guo X; He Y; Li W; Liu X; Zhao S; Hu J; Wang J; Li S; Zhao Z; Hao Z; Miccheli A; Docea AO; Fukui H
Plateau adaptation in animals involves genetic mechanisms as well as coevolutionary mechanisms of the microbiota and metabolome of the animal. Therefore, the characteristics of the rumen microbiome and metabolome, transcriptome, and serum metabolome of Tibetan sheep at different altitudes (4500 m, 3500 m, and 2500 m) were analyzed. The results showed that the rumen differential metabolites at 3500 m and 4500 m were mainly enriched in amino acid metabolism, lipid metabolism, and carbohydrate metabolism, and there was a significant correlation with microbiota. The differentially expressed genes and metabolites at middle and high altitudes were coenriched in asthma, arachidonic acid metabolism, and butanoate and propanoate metabolism. In addition, the serum differential metabolites at 3500 m and 4500 m were mainly enriched in amino acid metabolism, lipid metabolism, and metabolism of xenobiotics by cytochrome P450, and they were also related to microbiota. Further analysis revealed that rumen metabolites accounted for 7.65% of serum metabolites. These common metabolites were mainly enriched in metabolic pathways and were significantly correlated with host genes (p < 0.05). This study found that microbiota, metabolites, and epithelial genes were coenriched in pathways related to lipid metabolism, energy metabolism, and immune metabolism, which may be involved in the regulation of Tibetan sheep adaptation to plateau environmental changes.
The kinetics of amino acid disappearance in the small intestine is related to the extent of amino acids absorbed in growing pigs
(Cambridge University Press on behalf of The Nutrition Society, 2024-03-14) Montoya CA; van Bemmel M; Kreutz K; Hodgkinson SM; Stroebinger N; Moughan PJ
This study evaluated the importance of a correction for amino acids (AA) released into the hindgut on a measure of AA absorption kinetics and tested whether AA absorption kinetics are related to the extent of AA absorption using the growing pig as a model for humans. Thirty-six nine-week-old pigs (22·3 kg) received a diet containing whey protein as the sole protein source for 8 d. Pigs received their last meal containing the indigestible marker titanium dioxide before being euthanised at 1, 2, 3, 4, 6 and 12 h post-feeding. The entire content of each gastrointestinal tract (GIT) region was collected to determine AA released into the hindgut, and the kinetics and extent of AA absorption (uncorrected and corrected for AA entering the hindgut). Amounts of AA released into the hindgut increased over time (e.g. 33 and 180 mg of Glu for 4 and 6 h post-feeding). The corrected apparent amount of each AA absorbed from the GIT lumen after 4 h post-feeding was generally lower (P ≤ 0·05) than the uncorrected counterpart. Differences in both the kinetics and extent of AA absorption were observed across AA. For example, the time to reach half of the apparent AA absorption (T50) was 1·5 and 3·4 h for Met and Arg, respectively, whereas their extent of apparent absorption was 93 and 73 %. Negative correlations between parameters related to kinetics and the extent of apparent absorption were observed (e.g. for T50 r = -0·81; P < 0·001). The kinetics of AA absorption is related to the extent of AA absorption.
The impact of heat-set milk protein gel textures modified by pH on circulating amino acid appearance and gastric function in healthy female adults: a randomised controlled trial.
(Royal Society of Chemistry, 2024-05-21) Milan AM; Menting GGA; Barnett MPG; Liu Y; McNabb WC; Roy NC; Hutchings SC; Mungure T; Weeks M; Li S; Hort J; Calder S; O'Grady G; Mithen RF
Modification of dairy proteins during processing impacts structural assemblies, influencing textural and nutritional properties of dairy products, and release and availability of amino acids during digestion. By modifying only pH, acid heat-set bovine dairy gels with divergent textural properties were developed to alter protein digestion. In vitro assay confirmed faster digestion of protein from a firm gel (pH 5.65) versus a soft gel (pH 6.55). We hypothesised that firm gel (FIRM-G; pH 5.6) would result in greater indispensable amino acid (IAA) appearance in circulation over 5 h and corresponding differences in gastric myoelectrical activity relative to soft gel (SOFT-G; pH 6.2). In a randomised, single-blind cross-over trial, healthy females (n = 20) consumed 150 g of each gel; plasma amino acid appearance was assessed over 5 hours. Iso-nitrogenous, iso-caloric gels were prepared from identical mixtures of bovine milk and whey protein concentrates; providing 17.7 g (FIRM-G) and 18.9 g (SOFT-G) of protein per serving. Secondary outcomes included gastric myoelectrical activity measured by body surface gastric mapping, glycaemic, triglyceridaemic, and subjective appetite and digestive responses. Overall plasma IAA (area under the curve) did not differ between gels. However, plasma IAA concentrations were higher, and increased more rapidly over time after SOFT-G compared with FIRM-G (1455 ± 53 versus 1350 ± 62 μmol L-1 at 30 min, p = 0.024). Similarly, total, branched-chain and dispensable amino acids were higher at 30 min with SOFT-G than FIRM-G (total: 3939 ± 97 versus 3702 ± 127 μmol L-1, p = 0.014; branched-chain: 677 ± 30 versus 619 ± 34 μmol L-1, p = 0.047; dispensable: 2334 ± 53 versus 2210 ± 76 μmol L-1, p = 0.032). All other measured parameters were similar between gels. Peak postprandial aminoacidaemia was higher and faster following ingestion of SOFT-G. Customised plasma amino acid appearance from dairy is achievable by altering gel coagulum structure using pH during processing and may have minimal influence on related postprandial responses, with implications for targeting food design for optimal health. The Clinical Trial Registry number is ACTRN12622001418763 (https://www.anzctr.org.au) registered November 7, 2022.
Ileal Digestibility of Nitrogen and Amino Acids in Human Milk and an Infant Formula as Determined in Neonatal Minipiglets
(Elsevier Inc. on behalf of American Society for Nutrition, 2023-04) Charton E; Henry G; Cahu A; Le Gouar Y; Dahirel P; Moughan PJ; Montoya CA; Bellanger A; Dupont D; Le Huërou-Luron I; Deglaire A
BACKGROUND: Infant formula (IF) has to provide at least the same amount of amino acids (AAs) as human milk (HM). AA digestibility in HM and IF was not studied extensively, with no data available for tryptophan digestibility. OBJECTIVES: The present study aimed to measure the true ileal digestibility (TID) of total nitrogen and AAs in HM and IF to estimate AA bioavailability using Yucatan mini-piglets as an infant model. METHODS: Twenty-four 19-day-old piglets (males and females) received either HM or IF for 6 days or a protein-free diet for 3 days, with cobalt-EDTA as an indigestible marker. Diets were fed hourly over 6 h before euthanasia and digesta collection. Total N, AA, and marker contents in diets and digesta were measured to determine the TID. Unidimensional statistical analyses were conducted. RESULTS: Dietary N content was not different between HM and IF, while true protein was lower in HM (-4 g/L) due to a 7-fold higher non-protein N content in HM. The TID of total N was lower (P < 0.001) for HM (91.3 ± 1.24%) than for IF (98.0 ± 0.810%), while the TID of amino acid nitrogen (AAN) was not different (average of 97.4 ± 0.655%, P = 0.272). HM and IF had similar (P > 0.05) TID for most of the AAs including tryptophan (96.7 ± 0.950%, P = 0.079), except for some AAs (lysine, phenylalanine, threonine, valine, alanine, proline, and serine), with small significant difference (P < 0.05). The first limiting AA was the aromatic AAs, and the digestible indispensable AA score (DIAAS) was higher for HM (DIAASHM = 101) than for IF (DIAASIF = 83). CONCLUSION: HM, compared to IF, had a lower TID for total N only, whereas the TID of AAN and most AAs, including Trp, was high and similar. A larger proportion of non-protein N is transferred to the microbiota with HM, which is of physiological relevance, although this fraction is poorly considered for IF manufacturing.
Evaluation of Protein Adequacy From Plant-Based Dietary Scenarios in Simulation Studies: A Narrative Review
(Elsevier Inc on behalf of the American Society for Nutrition, 2024-02) Soh BXP; Smith NW; R von Hurst P; McNabb WC
Although a diet high in plant foods can provide beneficial nutritional outcomes, unbalanced and restrictive plant-based diets may cause nutrient deficiencies. Protein intake from these diets is widely discussed, but the comparison of animal and plant proteins often disregards amino acid composition and digestibility as measurements of protein quality. Poor provision of high-quality protein may result in adverse outcomes, especially for individuals with increased nutrient requirements. Several dietary modeling studies have examined protein adequacy when animal-sourced proteins are replaced with traditional and novel plant proteins, but no review consolidating these findings are available. This narrative review aimed to summarize the approaches of modeling studies for protein intake and protein quality when animal-sourced proteins are replaced with plant foods in diet simulations and examine how these factors vary across age groups. A total of 23 studies using dietary models to predict protein contribution from plant proteins were consolidated and categorized into the following themes-protein intake, protein quality, novel plant-based alternatives, and plant-based diets in special populations. Protein intake from plant-based diet simulations was lower than from diets with animal-sourced foods but met country-specific nutrient requirements. However, protein adequacy from some plant-sourced foods were not met for simulated diets of children and older adults. Reduced amino acid adequacy was observed with increasing intake of plant foods in some scenarios. Protein adequacy was generally dependent on the choice of substitution with legumes, nuts, and seeds providing greater protein intake and quality than cereals. Complete replacement of animal to plant-sourced foods reduced protein adequacy when compared with baseline diets and partial replacements.
Presence of Unabsorbed Free Amino Acids at the End of the Small Intestine Indicates the Potential for an Increase in Amino Acid Uptake in Humans and Pigs
(Elsevier Inc on behalf of American Society for Nutrition, 2023-03) van der Wielen N; de Vries S; Gerrits WJ; Lammers-Jannink K; Moughan PJ; Mensink M; Hendriks W
BACKGROUND: Unabsorbed free amino acids (AAs) at the end of the small intestine result in a potential preventable nutritional loss. OBJECTIVES: This study aimed to quantify free AAs in terminal ileal digesta of both humans and pigs to investigate its relevance for the nutritional value of food proteins. METHODS: Two studies with three diets were performed: a human study-ileal digesta from eight adult ileostomates were collected over 9 h after ingestion of a single meal unsupplemented or supplemented with 30 g zein or whey; pig study-12 cannulated pigs were fed for 7 d with a diet containing whey or zein or no-protein diet, and ileal digesta were collected on the last 2 d. Digesta were analyzed for total and 13 free AAs. True ileal digestibility (TID) of AAs was compared with and without free AAs. RESULTS: All terminal ileal digesta samples contained free AAs. The TID of AAs in whey was 97% ± 2.4% (mean ± SD) in human ileostomates and 97% ± 1.9% in growing pigs. If the analyzed free AAs would have been absorbed, TID of whey would increase by 0.4%-units in humans and 0.1%-units in pigs. The TID of AAs in zein was 70% ± 16.4% in humans and 77% ± 20.6% in pigs and would increase by 2.3%-units and 3.5%-units, respectively, if the analyzed free AAs would have been fully absorbed. The largest difference was observed for threonine from zein: if free threonine was absorbed, the TID would increase by 6.6%-units in both species (P < 0.05). CONCLUSIONS: Free AAs are present at the end of the small intestine and can potentially have a nutritionally relevant effect for poorly digestible protein sources, whereas the effect is negligible for highly digestible protein sources. This result provides insight into the room for improvement of a protein's nutritional value if all free AAs are to be absorbed. J Nutr 2023;xx:xx-xx. This trial was registered at clinicaltrials.gov as NCT04207372.
In vitro digestibility of dietary proteins and in vitro DIAAS analytical workflow based on the INFOGEST static protocol and its validation with in vivo data
(Elsevier Ltd, 2023-03-15) Sousa R; Recio I; Heimo D; Dubois S; Moughan PJ; Hodgkinson SM; Portmann R; Egger L
The FAO recommends the digestible indispensable amino acid score (DIAAS) to determine protein quality in foods, preferably tested in vivo. Here, the INFOGESTin vitrodigestion protocol was applied and supplemented with an analytical workflow allowing the assessment of protein digestibility and DIAAS calculation. The protocol was applied to selected samples WPI, zein, collagen, black beans, pigeon peas, All-Bran®, and peanuts. The total protein digestibility, digestibility of individual amino acids (AA), and DIAAS values were established and compared with in vivo data for the same substrates. Total protein digestibility (total Nitrogen, r = 0.7, P < 0.05; primary amines (OPA), r = 0.6, P < 0.02; total AA, r = 0.6, P < 0.02) and digestibility of individual AA (r = 0.6, P < 0.0001) were in good agreement, between in vitro and in vivo, with a mean difference of 1.2 %. In vitro DIAAS was highly correlated with DIAAS obtained from in vivo true ileal digestibility values (r = 0.96, R2 = 0.89, P < 0.0001) with a mean difference of 0.1 %.
Comparison of True Ileal Amino Acid Digestibility between Adult Humans and Growing Pigs
(Oxford University Press on behalf of the American Society for Nutrition, 2022-07) Hodgkinson SM; Stroebinger N; van der Wielen N; Mensink M; Montoya C; Hendriks WH; de Vries S; Stein HH; Moughan PJ
BACKGROUND: It is not feasible to determine the true ileal amino acid (AA) digestibility of protein sources in humans on a routine basis, and the growing pig has been recommended as an animal model for this purpose but requires further validation. OBJECTIVES: To determine and compare true ileal AA digestibility between adult human ileostomates and growing cannulated pigs for a range of food proteins. METHODS: Seven protein sources (black beans, bread, collagen, pigeon peas, wheat bran, whey protein isolate, and zein) that spanned the range of digestibilities typically seen in foods were evaluated. Six female growing pigs received each of the protein sources, as well as a protein-free diet, and digesta were collected via ileal T-cannula. Adult human ileostomates consumed the same protein sources (5-8 ileostomates, depending on the protein source), as well as a protein-free diet, and digesta were collected. Titanium dioxide and celite were included in the diets as indigestible markers. True ileal AA digestibility coefficients were determined. RESULTS: There was a significant effect of protein source (P ≤ 0.001) for all AAs. The effect of species was not significant (P > 0.05) except for total lysine (but not for available lysine). When analyzed within diets, the statistically significant species effect for true lysine digestibility was found for black beans only. Pig and human digestibility values were generally highly and significantly (P ≤ 0.05) correlated. A linear regression equation derived for true ileal AA digestibility (given as coefficients) determined in the human and pig for the overall mean of all AAs was (y = human, x = pig) y = 1.00x - 0.010, with the slope not statistically significant (P > 0.05) from unity and the intercept not different (P > 0.05) from zero. CONCLUSIONS: True ileal AA digestibility values determined in the growing pig can be directly used for predicting digestibility in adult humans.
Plasma metabolomic response to high-carbohydrate meals of differing glycaemic load in overweight women.
(Springer Nature, 2023-04-21) Durainayagam B; Mitchell CJ; Milan AM; Kruger MC; Roy NC; Fraser K; Cameron-Smith D
BACKGROUND: Metabolomic dysregulation following a meal in overweight individuals with the Metabolic Syndrome (MetS) involves multiple pathways of nutrient storage and oxidation. OBJECTIVE: The aim of the current study was to perform an acute cross-over intervention to examine the interactive actions of meal glycaemic load (GL) on the dynamic responses of the plasma metabolome in overweight females. METHODS: Postmenopausal women [63 ± 1.23y; Healthy (n = 20) and MetS (n = 20)] ingested two differing high-carbohydrate test meals (73 g carbohydrate; 51% energy) composed of either low glycemic index (LGI) or high (HGI) foods in a randomised sequence. Plasma metabolome was analysed using liquid chromatography-mass spectrometry (LC-MS). RESULTS: In the overweight women with MetS, there were suppressed postprandial responses for several amino acids (AAs), including phenylalanine, leucine, valine, and tryptophan, p < 0.05), irrespective of the meal type. Meal GL exerted a limited impact on the overall metabolomic response, although the postprandial levels of alanine were higher with the low GL meal and uric acid was greater following the high GL meal (p < 0.05). CONCLUSIONS: MetS participants exhibited reduced differences in the concentrations of a small set of AAs and a limited group of metabolites implicated in energy metabolism following the meals. However, the manipulation of meal GL had minimal impact on the postprandial metabolome. This study suggests that the GL of a meal is not a major determinant of postprandial response, with a greater impact exerted by the metabolic health of the individual. Trial registration Australia New Zealand Clinical Trials Registry: ACTRN12615001108505 (21/10/2015).
Effect of Amino Acid Supplementation on Iron Regulation after Endurance Exercise.
(MDPI (Basel, Switzerland), 2023-11-25) Lin C-A; Hayashi N; Badenhorst CE; Goto K; Rowlands D
The purpose of this study was to determine the effects of pre-exercise amino acid (AA) supplementation on post-exercise iron regulation. Ten healthy males participated under two different sets of conditions in a randomized, double-blind, crossover design with a washout period of at least 21 days. Participants received either an AA supplement or placebo (PLA) for five consecutive days (4 g/dose, 3 doses/day). On the sixth day, participants ran on a treadmill for 60 min at 70% of maximal oxygen consumption (V˙O2max). Venous blood samples were collected before (baseline), immediately after, and 1 and 3 h after exercise. The serum hepcidin levels increased significantly 3 h post-exercise in both trials when compared to the baseline (p < 0.001), but the levels were not different between trials. The plasma interleukin-6 (IL-6) level significantly increased immediately after exercise compared to the baseline (p < 0.001) and was significantly higher in the AA trial than in the PLA trial (p = 0.014). Moreover, the exercise-induced increase in serum glycerol level was significantly higher in the AA trial (21.20 ± 3.98 mg/L) than in the PLA trial (17.28 ± 4.47 mg/L, p = 0.017). No significant differences were observed between the AA and PLA trials for serum iron, ferritin, and total ketone body levels (p > 0.05). In conclusion, five days of AA supplementation augmented exercise-induced increases in IL-6 and glycerol in healthy males. However, it did not affect post-exercise iron status or regulation.

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