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1.
J Nutr ; 154(3): 804-814, 2024 03.
Artigo em Inglês | MEDLINE | ID: mdl-38253225

RESUMO

In wealthy countries, the protein intake of adults is usually considered to be adequate, and considerations of protein quality are often deemed irrelevant. The objective was to examine dietary protein intakes of adults in developed countries in the context of dietary protein quality. An analysis of NHANES population data on actual protein intakes in the United States (a developed country) demonstrated that for a dietary Digestible Indispensable Amino Acid Score (DIAAS) of 100%, 11% of the adult (19-50 y) population had habitual protein intakes below the Estimated Average Requirement (EAR) and 22% below the Recommended Dietary Allowance. The percentage of the population with utilizable protein intakes potentially falling below the EAR increased as the assumed DIAAS declined. Analysis of the NHANES data and several other datasets also indicated that total protein intakes can be limiting or close to limiting for the elderly and some vegetarians and vegans. Here, lower dietary protein quality can potentially lead to inadequate utilizable protein intakes. For many people in specific physiological states (e.g., weight loss, endurance sports, resistance exercise) attempting to meet higher dietary protein targets often with accompanying lowered energy intakes, low dietary protein quality can lead to protein calories expressed as a proportion of total calories, falling outside what may be acceptable limits (maximum of 30% protein calories from total calories). In general, individuals within the adult population may be susceptible to macronutrient imbalance (whenever total protein intakes are high, daily energy intakes low) and for diets with lower protein quality (DIAAS <100%). Our analysis shows that dietary protein quality is relevant in mid- to high-income countries.


Assuntos
Dieta , Ingestão de Energia , Humanos , Adulto , Estados Unidos , Idoso , Países Desenvolvidos , Inquéritos Nutricionais , Proteínas Alimentares/metabolismo , Dieta com Restrição de Proteínas
2.
J Nutr ; 154(4): 1461-1471, 2024 04.
Artigo em Inglês | MEDLINE | ID: mdl-38432560

RESUMO

BACKGROUND: An in vivo/in vitro ileal fermentation assay using growing pigs has been developed but not yet formally validated. OBJECTIVES: This study aimed to validate the in vivo/in vitro ileal fermentation assay by comparing in vitro fermentation values with those obtained in vivo in growing pigs. The effect of raising pigs under different environmental conditions was also investigated. METHODS: Thirty piglets (1.59 ± 0.31 kg body weight, mean ± standard deviation) were subjected to 1 of 3 treatments: artificially reared (AR) (nonfarm, laboratory housing conditions) from postnatal day (PND) 7 (AR group), inoculated orally with human infant fecal extracts from birth until PND 8 and AR (AR+ group), or conventionally reared on a farm (control group). Starting at PND 7, the AR and AR+ pigs received human infant formula for 3 wk, followed by a human-type diet for 5 wk. Control pigs were weaned on the farm and, on PND 63, relocated to the laboratory animal facility. From PND 63, all pigs received a human-type diet. On PND 78, pigs were killed, after which ileal digesta were collected to perform an in vitro ileal fermentation (in vitro organic matter [OM] fermentability and organic acid production) and to determine digesta microbial composition and dietary OM fermentability in vivo. RESULTS: The rearing regimen resulted in only a few differences in ileal microbial taxonomic composition. The rearing regimen generally did not affect the in vitro production of individual organic acids. The in vivo and in vitro OM fermentability of proximal ileal digesta (19.7 ± 2.04%; mean ± SEM) was similar (P > 0.05) for the AR and control pigs but not for the AR+ pigs. CONCLUSIONS: The control-rearing regimen was preferred over AR or AR+ because of ease of implementation. The in vitro ileal fermentation assay accurately predicted the in vivo OM fermentability.


Assuntos
Dieta , Íleo , Humanos , Suínos , Animais , Fermentação , Íleo/metabolismo , Fezes , Dieta/veterinária , Projetos de Pesquisa , Ração Animal/análise , Digestão
3.
J Nutr ; 2024 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-39019158

RESUMO

BACKGROUND: Absorption of tryptophan (TRP) across the gut epithelium is potentially modulated by competing large neutral amino acids (LNAAs), which could affect the appearance of TRP and its metabolites in the bloodstream. OBJECTIVES: This study aimed to determine, in a growing pig model of an adult human, the absorption of TRP and other LNAAs from the gastrointestinal tract, and plasma appearance of TRP, LNAAs and TRP metabolites , in response to dietary proteins varying in TRP content. METHODS: Pigs were adapted for seven days to each of four diets that differed in their protein source and TRP content: 1) alpha-lactalbumin (AL; 9.95mg TRP/g diet DM), 2) whey protein (6.59mg TRP/g), 3) casein (3.73mg TRP/g), or 4) zein (0.14mg TRP/g). On day 8, after a 12h fast, pigs received a test meal consisting of 45g protein, or a protein-free meal, and were euthanized 0 (baseline), 1, 2, 3, 4, or 6h later (n=6 pigs at each time in each meal group). Tryptophan and LNAA absorption from the small intestine, and appearance of TRP, LNAAs and TRP metabolites (melatonin, serotonin, kynurenine pathway metabolites), in the portal vein and systemic circulation, were determined. RESULTS: AL intake resulted in sustained elevated plasma TRP concentrations after an overnight fast. The amount of TRP absorbed was dose-dependently related to protein TRP content (p=0.028), with fastest rates for pigs fed AL (371mg/h). Portal and systemic plasma TRP, TRP/LNAA and the TRP metabolites were highest (p≤0.05) after AL intake , and remained above baseline levels for ∼4h postprandially. Absorption rates of TRP correlated with postprandial plasma TRP and TRP metabolites(p≤0.05). CONCLUSIONS: In adult humans, postprandial plasma TRP and TRP metabolite concentrations can likely be modulated by the TRP content of the meal.

4.
Br J Nutr ; 131(5): 762-772, 2024 03 14.
Artigo em Inglês | MEDLINE | ID: mdl-37881009

RESUMO

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.


Assuntos
Aminoácidos , Digestão , Humanos , Suínos , Animais , Aminoácidos/metabolismo , Intestino Delgado/metabolismo , Trato Gastrointestinal/metabolismo , Dieta/veterinária , Ração Animal/análise , Íleo/metabolismo , Fenômenos Fisiológicos da Nutrição Animal
5.
J Nutr ; 153(7): 1858-1865, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37207803

RESUMO

Amino acid (AA) digestibility in humans has been determined conventionally based on oro-ileal AA disappearance. With this approach, it is necessary to account for undigested AAs of body origin (endogenous AAs) found in the ileal digesta. Determination of the endogenous AAs under physiological conditions is not straightforward, and the use of isotopes (labeled foods or body tissues) has been pivotal to advancing our understanding. The application of isotopes for determining gut endogenous AAs and AA digestibility is discussed as well as the types of digestibility coefficient generated (apparent, true, real) dependent upon methodology. Recently a new dual isotope-based method for determining ileal AA digestibility in humans has been developed that obviates the collection of ileal digesta. The dual isotope method, which awaits full validation, offers considerable promise for making noninvasive measures of AA digestibility in humans of different ages and physiological states.


Assuntos
Proteínas Alimentares , Digestão , Humanos , Digestão/fisiologia , Proteínas Alimentares/metabolismo , Aminoácidos/metabolismo , Dieta , Isótopos/metabolismo , Íleo/metabolismo , Ração Animal
6.
J Nutr ; 153(10): 2868-2877, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37604383

RESUMO

BACKGROUND: Organic acid synthesis by the hindgut microbiota is commonly believed to be mainly of fermentable material of dietary origin. OBJECTIVE: This study aimed to determine the hindgut organic acid synthesis from fermentable material of dietary (mainly fiber) or nondietary origin for different types and amounts of dietary fiber in growing pigs used as a model for adult humans. METHOD: Seven fiber-containing diets were formulated: 4 fiber types (cellulose, gum acacia, oligofructose, and pectin) at 6% of the diet and 3 (gum acacia, oligofructose, and pectin) at 3% as the sole fiber source. Ileal cannulated female pigs (n = 14; Landrace/Large white) were fed the fiber-containing diets (n = 6 pigs/diet) for 11 days (fiber phase) followed by 3 days on a fiber-free diet (fiber-free phase), using a replicated Youden square. Ileal digesta for each phase were collected and fermented in vitro with a pooled fecal microbial inoculum prepared from feces collected during the fiber phase to determine the organic acids synthesized from fermentable material of dietary (fiber phase) and nondietary (fiber-free phase) origins. RESULTS: The total amount of each individual organic acid synthesized during in vitro hindgut fermentation differed (P ≤ 0.05) across the types and amounts of dietary fiber intake. For example, the amount of acetate was 3.6-fold higher (P ≤ 0.05) for pigs fed the 6% pectin-containing diet than those fed the 6% oligofructose-containing diet. The nondietary substrate contributed between 36% (hexanoate) and 70% (succinate) to the total hindgut organic acid synthesis. The adaptation to the different fiber-containing diets led to different amounts of some organic acids of nondietary origin. CONCLUSIONS: The total amount of organic acids synthesized in the hindgut by the resident microbes is influenced by the type and amount of dietary fiber consumed. This study quantifies the interaction between both dietary and nondietary fermentable materials in hindgut fermentation.

7.
J Nutr ; 153(2): 505-510, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36894242

RESUMO

BACKGROUND: When foods are subjected to heat and pressure, a proportion of lysine is structurally altered and some will revert to lysine because of acid hydrolysis during amino acid analysis. Altered lysine molecules may be partly absorbed but are not utilized post-absorption. OBJECTIVES: A guanidination-based bioassay has been developed to determine true ileal digestible reactive lysine but it was only used in animal models (pig and rat). The objective of this study was to apply the assay and determine whether there is a difference between true ileal digestible total lysine and true ileal digestible reactive lysine in adult human ileostomates. METHODS: Six cooked or processed foods were analyzed for total lysine and reactive lysine. Six adults with a fully functioning ileostomy (4 women and 2 men; age range: 41-70 y; BMI: 20.8-28.1) participated. Foods for which total lysine > reactive lysine (cooked black beans, toasted wheat bread, and processed wheat bran), as well as a protein-free diet, were consumed by the ileostomates (n = 5 to 8; test food meals contained 25 g protein) and ileal digesta was collected. Each food was ingested twice by each participant, and the digesta was pooled. The order of foods for each participant was determined according to a Youden square. True ileal digestible total lysine and true ileal digestible reactive lysine were determined and a 2-way ANOVA model was used to analyze data. RESULTS: True ileal digestible reactive lysine was significantly lower than true ileal digestible total lysine for cooked black beans, toasted wheat bread, and processed wheat bran by 89%, 55%, and 85%, respectively (P< 0.05). CONCLUSIONS: True ileal digestible reactive lysine was lower than true ileal digestible total lysine, similar to that previously reported in pigs and rats, demonstrating the importance of determining the true ileal digestible reactive lysine contents of processed foods.


Assuntos
Digestão , Lisina , Masculino , Humanos , Adulto , Feminino , Ratos , Animais , Suínos , Pessoa de Meia-Idade , Idoso , Lisina/metabolismo , Aminoácidos/metabolismo , Íleo/metabolismo , Grão Comestível/química , Fibras na Dieta/análise , Ração Animal/análise
8.
J Nutr ; 153(3): 673-682, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36809852

RESUMO

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.


Assuntos
Aminoácidos , Zeína , Animais , Humanos , Aminoácidos/metabolismo , Ração Animal/análise , Fenômenos Fisiológicos da Nutrição Animal , Dieta/veterinária , Digestão , Íleo/metabolismo , Suínos , Treonina , Zeína/metabolismo
9.
J Nutr ; 153(4): 1063-1074, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36868512

RESUMO

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.


Assuntos
Aminoácidos , Leite Humano , Masculino , Recém-Nascido , Lactente , Feminino , Humanos , Animais , Suínos , Aminoácidos/metabolismo , Leite Humano/química , Fórmulas Infantis/química , Triptofano/metabolismo , Nitrogênio/metabolismo , Digestão/fisiologia , Íleo/metabolismo , Dieta , Dieta com Restrição de Proteínas , Ração Animal/análise
10.
J Nutr ; 153(12): 3439-3447, 2023 12.
Artigo em Inglês | MEDLINE | ID: mdl-37863267

RESUMO

BACKGROUND: The amino acid (AA) composition of human milk is used to define the AA requirements of the infant. Thus, it is important that estimates of composition be as complete and accurate as possible. When determining AA composition using standard hydrolysis methods, some AAs are progressively destroyed while others are incompletely released. For accuracy, AA composition needs to be determined using multiple hydrolysis times. The true ileal digestibility of AAs also needs to be taken into consideration. OBJECTIVE: The objective was to bring together AA compositional (determined using multiple hydrolysis intervals) and digestibility data determined using the piglet to give an estimate of the absorbed AA profile of human milk with reference in particular to Asian females. METHODS: Mature milk was collected from Chinese females. AA analysis using multiple hydrolysis intervals and a nonlinear regression model was used to accurately estimate AA composition. Human milk, as well as a protein-free diet, were fed to piglets (n = 6), and ileal digesta were collected (piglet age, 21 d) to determine the true ileal AA digestibility of AAs in human milk. RESULTS: True ileal AA digestibility coefficients ranged from (mean ± standard error of the mean) 0.61 ± 0.081 for tyrosine to 1.01 ± 0.030 for tryptophan, with a digestibility for total nitrogen of 0.90 ± 0.013. Convergence criteria were met for the modeling for each AA, and the model had a level of significance of P < 0.0001 for each AA. The amount of available AAs (total AA content as per the model prediction multiplied by the true ileal AA digestibility coefficient determined in the piglet) are reported. CONCLUSIONS: An estimate of the absorbed AA profile of mature milk collected from Chinese females is provided. For the first time, data is presented for cysteine.


Assuntos
Aminoácidos , Leite Humano , Humanos , Animais , Feminino , Suínos , Adulto Jovem , Adulto , Leite Humano/química , Aminoácidos/metabolismo , Digestão , Proteínas Alimentares/metabolismo , Íleo/metabolismo , China , Ração Animal/análise , Dieta , Fenômenos Fisiológicos da Nutrição Animal
11.
Crit Rev Food Sci Nutr ; : 1-36, 2023 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-37522617

RESUMO

Vitamins are essential components of enzyme systems involved in normal growth and function. The quantitative estimation of the proportion of dietary vitamins, that is in a form available for utilization by the human body, is limited and fragmentary. This review provides the current state of knowledge on the bioavailability of thirteen vitamins and choline, to evaluate whether there are differences in vitamin bioavailability when human foods are sourced from animals or plants. The bioavailability of naturally occurring choline, vitamin D, vitamin E, and vitamin K in food awaits further studies. Animal-sourced foods are the almost exclusive natural sources of dietary vitamin B-12 (65% bioavailable) and preformed vitamin A retinol (74% bioavailable), and contain highly bioavailable biotin (89%), folate (67%), niacin (67%), pantothenic acid (80%), riboflavin (61%), thiamin (82%), and vitamin B-6 (83%). Plant-based foods are the main natural sources of vitamin C (76% bioavailable), provitamin A carotenoid ß-carotene (15.6% bioavailable), riboflavin (65% bioavailable), thiamin (81% bioavailable), and vitamin K (16.5% bioavailable). The overview of studies showed that in general, vitamins in foods originating from animals are more bioavailable than vitamins in foods sourced from plants.

12.
Appetite ; 180: 106339, 2023 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-36216216

RESUMO

Protein is considered to be the most satiating food macronutrient and the satiating effect may be dependent on the source of the protein. The maize-derived protein zein and milk protein casein have been shown previously to lower stomach emptying rate more than dairy whey protein, but the effect of zein on satiety has not been evaluated. The objective was to compare the satiating effects of zein and casein, with whey protein and its protein component α-lactalbumin. The study was a randomised crossover design with thirteen normal-weight men (mean age 27.8 years and mean BMI 24.4 kg/m2) consuming isoenergetic (∼4000 kJ, ∼990 kcal) preload mixed meals enriched with Zein, Casein, whey protein isolate (Whey), α-lactalbumin (ALac), or maltodextrin carbohydrate (Carb). Consumption of an ad libitum standardised test meal of chicken fried rice and water provided 360 min following ingestion of the preload meal was measured, and subjective feelings of appetite (hunger, fullness, desire to eat, and prospective food consumption) were assessed using 100-mm visual analogue scales (VAS). There were no differences among the five preload mixed meals in the amount of chicken fried rice consumed at the ad libitum test meal (mean ± sem: 531.6 ± 35.0 g, p = 0.47) or total (preload + test meal) energy intakes (mean ± sem: 5780.5 ± 146.0 kJ, p = 0.29). The subjective VAS appetite ratings and total area under the curve responses for hunger, fullness, desire to eat, and prospective food consumption, were not different following consumption of all five preload mixed meals (p > 0.05). The findings indicate that the effects of zein and casein on satiety were not different from the satiating effects of whey protein and α-lactalbumin.


Assuntos
Ingestão de Alimentos , Proteínas do Leite , Saciação , Proteínas do Soro do Leite , Zeína , Caseínas/farmacologia , Lactalbumina/farmacologia , Proteínas do Soro do Leite/farmacologia , Zea mays , Estudos Cross-Over , Humanos , Masculino , Adulto
13.
J Nutr ; 152(7): 1635-1646, 2022 07 06.
Artigo em Inglês | MEDLINE | ID: mdl-35349701

RESUMO

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.


Assuntos
Aminoácidos , Digestão , Aminoácidos/metabolismo , Ração Animal/análise , Fenômenos Fisiológicos da Nutrição Animal , Animais , Dieta/veterinária , Feminino , Humanos , Íleo/metabolismo , Lisina/metabolismo , Suínos
14.
J Dairy Sci ; 105(5): 3810-3831, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35221062

RESUMO

This study investigated the structural and physicochemical changes that occur in milk, a naturally designed complex structured emulsion, during gastric digestion using the bottle-fed piglet as an animal model. The gastric digestions of cow, goat, and sheep milk were compared in male piglets euthanized at different postfeeding times to collect the stomach chyme. The cow and noncow milks separated into curd (aggregated caseins) and liquid (mostly soluble whey) phases in the piglet's stomach. For milk from all the species, the curd remained longer in the stomach because of its slow disintegration, whereas the liquid phase emptied readily. The majority of the fat globules were found to be entrapped within the protein network of the curd. The rate of release of fat globules was strongly dependent on the breakdown of the surrounding protein network of the curd. The consistency of the gastric curds changed as digestion progressed, with goat and sheep milk curds having relatively softer curd consistency and less fused protein networks, especially toward the end of digestion. This might have led to the lower protein and fat retention in the goat and sheep milk curds and relatively faster gastric emptying of these nutrients from goat and sheep milk in comparison to cow milk. This in vivo study provided new and enhanced understanding of the mechanisms of the gastric digestion of milk from different species. It may have implications for developing bioinspired structures for the controlled digestion and delivery of nutrients.


Assuntos
Digestão , Leite , Animais , Bovinos , Eutanásia Animal , Feminino , Cabras , Masculino , Leite/química , Ovinos , Estômago , Suínos
15.
J Anim Physiol Anim Nutr (Berl) ; 106(3): 545-551, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-34169581

RESUMO

The oxygen (O2 ) concentration of gastrointestinal tract (GIT) contents decreases distally, but little is known about how O2 concentrations are influenced by ingestion of a meal. The O2 concentration in luminal contents at different GIT locations (stomach [cardia and pylorus], proximal, mid- and distal small intestine and caecum) and how these concentrations changed post-prandially were determined. Fifty entire male pigs (22 kg bodyweight at the start of study) were fed semi-synthetic diets containing casein, α-lactalbumin, whey protein isolate or zein as the sole source of protein for 8 days. A further group of pigs received the casein diet for six days and a semi-synthetic protein-free diet for a further 2 days. On day 8, pigs (n = 2 per diet and time point) were euthanized post-prandially (0, 1, 2, 4 and 6 h), and the stomach, small intestine and caecum were isolated and O2 determined in the GIT contents. Observations at each time point were averaged across the diets (n = 10). The mean O2 concentration was markedly higher (p ≤ 0.05) in the stomach compared with the rest of the GIT. The O2 concentration was similar in the small intestinal regions (p > 0.05; 1.0%-1.1%) and the caecum (0.9%), apart for the proximal small intestine which had a 24% higher (p ≤ 0.05) O2 concentration than the caecum. The mean O2 concentration in the GIT varied post-prandially (p ≤ 0.05). The O2 concentration in the cardia decreased 1.8%/h over the first two hours post-feeding and thereafter increased 0.3%/h (p ≤ 0.05). In the caecum, the O2 concentration was constant during the first 4 h and thereafter increased slightly (p ≤ 0.05). The flow of food through the GIT influenced both the concentration and amount of O2 in GIT luminal contents.


Assuntos
Ração Animal , Trato Gastrointestinal , Ração Animal/análise , Animais , Caseínas/metabolismo , Dieta/veterinária , Conteúdo Gastrointestinal , Trato Gastrointestinal/metabolismo , Masculino , Oxigênio/metabolismo , Suínos
16.
J Nutr ; 151(5): 1102-1110, 2021 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-33880549

RESUMO

BACKGROUND: Calcium (Ca) can complex with free fatty acids in the gastrointestinal tract (GIT), leading to the formation of insoluble unabsorbable Ca-fatty acid soaps, contributing to the proposed effect of Ca on weight loss in humans. OBJECTIVES: We determined the effect of dietary Ca concentration and the individual long-chain fatty acids on Ca-fatty acid soap formation and fatty acid digestibility. METHODS: Nine-week-old crossbreed male pigs (n = 144; mean ± SD body weight: 21.7 ± 0.15 kg) were used as an animal model for digestion in the adult human. The animals received purified diets containing 4 Ca concentrations (0, 2, 4, and 6 g/kg diet) and 4 fat sources (tallow, palmolein oil, soybean oil, and olive oil) in a completely randomized design. Fatty acids, Ca, and Ca-fatty acid soaps were determined in feces (n = 9 per diet). RESULTS: Increasing dietary Ca led to a 4-fold increase (P ≤ 0.05) in excreted palmitic and stearic acid when diets contained tallow or palmolein oil as the major fat source. More than 80% of these excreted fatty acids were present as soaps. For the tallow-based diets, increasing dietary Ca led to a decrease in stearic acid digestibility from 91% to 66% (P ≤ 0.01) and in palmitic acid digestibility from 96% to 83% (P ≤ 0.01). For the olive oil- and soybean oil-based diets dietary Ca did not (P > 0.05) influence fatty acid excretion. CONCLUSIONS: Ca-fatty acid soap formation led to decreased fat absorption in the GIT of growing pigs, which supports the hypothesis that higher dietary Ca concentrations reduce fat absorption.


Assuntos
Cálcio da Dieta/administração & dosagem , Cálcio/química , Ácidos Graxos/química , Ácidos Graxos/metabolismo , Fezes/química , Ração Animal/análise , Fenômenos Fisiológicos da Nutrição Animal , Animais , Dieta , Digestão/fisiologia , Metabolismo dos Lipídeos , Masculino , Modelos Animais , Azeite de Oliva/química , Óleo de Palmeira/química , Óleo de Soja/química , Suínos , Titânio/química
17.
J Nutr ; 151(10): 2976-2985, 2021 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-34320183

RESUMO

BACKGROUND: The degree of ileal organic matter (OM) fermentation appears to be comparable to hindgut fermentation in growing pigs. OBJECTIVES: This study aimed to determine if dietary fiber sources with known different total gastrointestinal tract (GIT) fermentability in humans affect ileal and hindgut microbial communities and ileal fermentation in growing pigs used as an animal model for human adults. METHODS: Male pigs (21 kg bodyweight; 9 wk old; PIC Camborough 46 × PIC boar 356L; n = 8/diet) were fed for 42 d a diet containing cellulose (CEL, low fermentability) as the sole fiber source (4.5%) or diets in which half of the CEL was replaced by moderately fermentable fiber, psyllium (PSY), or kiwifruit (KF) fiber. For each diet, terminal jejunal (substrate) and ileal (inoculum) digesta were collected from euthanized animals for in vitro ileal fermentation (2 h). Terminal ileal (substrate) and cecal (inoculum) digesta were used for in vitro hindgut fermentation (24 h). After in vitro fermentations, OM fermentation and short-chain fatty acid (SCFA) production were determined. Ileal digesta and feces were collected for microbial analysis. Data were analyzed by 2-factor ANOVA (diet × GIT region). RESULTS: In vitro ileal OM fermentation was on average 22% and comparable to hindgut OM fermentation. Ileal and hindgut OM fermentation, SCFA production, and microbial community composition changed (P < 0.05) when CEL was partially replaced by KF or PSY. For instance, pigs fed the PSY diet had 3-fold higher (P ≤ 0.05) number of ileal and fecal bacteria than pigs fed the CEL and KF diets. Pigs fed the CEL diet had 4-fold higher (P ≤ 0.05) hindgut valeric acid production than pigs fed the other diets. CONCLUSIONS: Ileal fermentation is quantitatively significant. Partial substitution of CEL with more fermentable fibers influences both ileal and hindgut microbial communities and the fermentation in growing pigs.


Assuntos
Fibras na Dieta , Microbiota , Ração Animal/análise , Animais , Dieta/veterinária , Fibras na Dieta/análise , Digestão , Ácidos Graxos Voláteis/metabolismo , Fezes/química , Fermentação , Íleo/metabolismo , Masculino , Suínos
18.
Br J Nutr ; 125(9): 998-1006, 2021 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-32912366

RESUMO

This study characterised the in vitro ileal fermentability of different substrates in the growing pig, adopted as an animal model for the adult human, and compared in vitro ileal and caecal fermentation in the pig. Substrates (arabinogalactan (AG), cellulose, fructo-oligosaccharide (FOS), inulin, mucin, citrus pectin and resistant starch) were fermented in vitro (ileal 2 h and caecal 24 h) with an ileal or caecal inoculum prepared from ileal or caecal digesta collected from growing pigs (n 5) fed a human-type diet for 15 d. The organic matter (OM) fermentability and production of organic acids were determined. In general, there was considerable in vitro ileal fermentation of fibre, and the substrates differed (P < 0·001) for both in vitro ileal and caecal OM fermentability and for organic acid production. Pectin had the greatest in vitro ileal OM fermentability (26 %) followed by AG, FOS and resistant starch (15 % on average), and cellulose, inulin and mucin (3 % on average). The fermentation of FOS, inulin and mucin was greater for in vitro caecal fermentation compared with the ileal counterpart (P ≤ 0·05). In general, the organic acid production was higher for in vitro caecal fermentation (P ≤ 0·05). For instance, the in vitro ileal acetic acid production represented 4-46 % of in vitro caecal production. Energy from fibre fermentation of 0·6-11 kJ/g substrate fermented could be expected in the ileum of the pig. In conclusion, substrates are fermented in both the ileum and caecum. The degree of fermentation varies among substrates, especially for in vitro ileal fermentation.


Assuntos
Bactérias/metabolismo , Ceco/microbiologia , Dieta Ocidental , Fibras na Dieta/metabolismo , Fermentação , Íleo/microbiologia , Animais , Ceco/metabolismo , Celulose/metabolismo , Fibras na Dieta/administração & dosagem , Digestão , Galactanos/metabolismo , Humanos , Íleo/metabolismo , Masculino , Modelos Animais , Mucinas/metabolismo , Oligossacarídeos/metabolismo , Pectinas/metabolismo , Amido/metabolismo , Suínos
19.
Eur J Nutr ; 60(2): 1141-1148, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32970234

RESUMO

PURPOSE: The purpose of the study was to determine if an actinidin protease aids gastric digestion and the protein anabolic response to dietary protein. METHODS: Hayward green kiwifruit (containing an actinidin protease) and Hort 16A gold kiwifruit (devoid of actinidin protease) were given in conjunction with a beef meal to healthy older subjects. Twelve healthy older males (N = 6) and females (N = 6) were studied with a randomized, double-blinded, crossover design to assess muscle and whole-body protein metabolism before and after ingestion of kiwifruit and 100 g of ground beef. Subjects consumed 2 of each variety of kiwifruit daily for 14 d prior to each metabolic study, and again during each study with beef intake. RESULTS: Hayward green kiwifruit consumption with beef resulted in a more rapid increase in peripheral plasma essential amino acid concentrations. There were significant time by kiwifruit intake interactions for plasma concentrations of EAAs, branched chain amino acids (BCAAs), and leucine (P < 0.01). However, there was no difference in the total amount of EAAs absorbed. As a result, there were no differences between kiwifruit in any of the measured parameters of protein kinetics. CONCLUSION: Consumption of Hayward green kiwifruit, with a beef meal facilitates protein digestion and absorption of the constituent amino acids as compared to Hort 16A gold kiwifruit. CLINICAL TRIAL: NCT04356573, April 21, 2020 "retrospectively registered".


Assuntos
Actinidia , Digestão , Estudos Cross-Over , Proteínas Alimentares/metabolismo , Método Duplo-Cego , Feminino , Frutas , Humanos , Masculino , Proteólise , Carne Vermelha
20.
J Dairy Sci ; 104(2): 1394-1411, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33309366

RESUMO

Coagulation of milk in the stomach is the first crucial step in its digestion. Using a human gastric simulator, the dynamic gastric digestion of goat and sheep skim milk were compared with that of cow skim milk, focusing particularly on their physical characteristics. The gastric contents were analyzed for changes in dry matter and microstructure, and the extent of protein digestion. The study revealed that the skim milk from all species formed a curd within the first 15 min of gastric digestion, at which time the pH was ~6.1 to 6.3. Compared with cow skim milk, the dry matter contents of the clots formed from goat and sheep skim milk were lower and higher, respectively, which was due to the differences in their total solids and protein contents. Microstructural analysis showed that, as digestion progressed, the clot structure became more cohesive, along with a decrease in moisture content, which in turn affected the breakdown and hydrolysis of caseins by pepsin; this phenomenon was similar for milk from all species. However, the extent of moisture retained in the sheep skim milk clot appeared to be lower than those of the cow and goat skim milk clots. In addition, the relative firmness of the sheep milk clot was higher than those of the cow and goat milk clots at the end of gastric digestion. The pattern of protein hydrolysis by pepsin was similar for the milk of all species, despite the differences in the proportions of different proteins. The study provided insight into the coagulation kinetics of goat and sheep skim milk under in vitro gastric digestion conditions.


Assuntos
Bovinos , Digestão , Cabras , Leite/química , Leite/metabolismo , Ovinos , Animais , Caseínas/metabolismo , Feminino , Mucosa Gástrica/enzimologia , Cabras/metabolismo , Humanos , Proteínas do Leite/análise , Pepsina A/metabolismo
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