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True Ileal Amino Acid Digestibility of Human Foods Classified According to Food Type as Determined in the Growing Pig
(Elsevier Inc on behalf of the American Society for Nutrition, 2025-10-18) Hodgkinson SM; Stroebinger N; Stein HH; Fanelli NS; de Vries S; van der Wielen N; Hendriks WH; Moughan PJ
Background: A Food and Agriculture Organization Expert Consultation recommended the use of digestible indispensable amino acid score (DIAAS) to evaluate protein quality of foods for humans. Calculation of DIAAS requires true ileal digestibility (TID) of amino acid (AA) values but currently insufficient data are available. Objectives: This study aims to generate in pigs TID of AA for a wide range of foods commonly consumed by humans and determine the range of differences in TID of AA among food types. Methods: A standardized protocol was followed to determine TID of AA in 97 foods across 3 laboratories. Female pigs (25–100 kg during study, n ≥ 6) received foods for 7 d following a Youden Square design with ileal digesta collected via T-cannula on days 6–7. Endogenous AA losses were determined by feeding a protein-free diet. Foods, diets, and digesta were analyzed for nitrogen, AA, reactive lysine, titanium and dry matter. Foods were categorized into food types with the degree of variation within each food type evaluated using descriptive statistics. Results: The TID (mean of AA) ranged from 0.247 (apples) to 0.988 (beef tenderloin). The median TID of AA was high (mean of AA > 0.90) for foods categorized as dairy products, eggs, fish and seafood, isolates and concentrates, meat, nuts, plant-based burgers, soy products and wheat products. Food categories with median TID < 0.80 were baked products, fruit, pulses and seeds, and wheat bran cereal, yeast, and zein. Food categories with low variations between foods were fish and seafood (1% units), dairy products (3% units), and eggs (5% units), whereas categories with the greatest variation were grains (18% units), vegetables (16% units), seeds (14% units), and fruit (12% units). There was considerable variation in TID for individual AA both within and among foods. Conclusions: The database with TID of AA of 97 foods generated by 3 laboratories using a standardized methodology can be utilized for protein quality evaluation.
The Hypoglycaemic Effects of the New Zealand Pine Bark Extract on Sucrose Uptake and Glycaemic Responses in Healthy Adults—A Single-Blind, Randomised, Placebo-Controlled, Crossover Trial
(MDPI (Basel, Switzerland), 2025-07-09) Lim WXJ; Page RA; Gammon CS; Moughan PJ; Novoa DMA; Silva FRMB
Background: The New Zealand pine bark has been demonstrated in vitro to inhibit digestive enzymes involved in carbohydrate digestion (alpha-amylase, alpha-glucosidase, and dipeptidyl-peptidase 4 (DPP-4)). Objective: This study aims to investigate the inhibitory effects of the New Zealand pine bark on sucrose uptake and glycaemic responses in humans. Methods: A single-blind, randomised, placebo-controlled, crossover trial was carried out involving healthy adults (n = 40 (M: 12, F: 28), 30.1 ± 1.3 years, BMI 23.4 ± 0.5 kg/m2, HbA1c 32.5 ± 0.6 mmol/mol, FBG 4.7 ± 0.1 mmol/L). A control (75 g of sucrose powder only), and two doses of the pine bark extract (50 and 400 mg) were provided on separate occasions, with 75 g of sucrose mixed in 250 mL of water. Blood samples were collected at −10, 0, 15, 30, 45, 60, 90, and 120 min via a finger prick test. A linear mixed model for repeated measures (SPSS v30, IBM) was applied, and data presented as model-adjusted mean ± SEM. Results: Compared to control (247.5 ± 14.0 mmol/L⋅min), the iAUCglucose was significantly reduced with the 400 mg dose (211.8 ± 13.9 mmol/L⋅min, 14.4% reduction, and p = 0.037), but not with 50 mg dose (220.8 ± 14.2 mmol/L⋅min, 10.8% reduction, and p = 0.184). Compared to control (9.1 ± 0.2 mmol/L), glucose peak value was significantly reduced with the 50 mg dose (8.6 ± 0.2 mmol/L, 5.5% reduction, and p = 0.016) but not with the 400 mg dose (8.7 ± 0.2 mmol/L, 4.4% reduction, and p = 0.093). There were no statistically significant changes in postprandial insulin levels with the pine bark extract compared to control. Conclusions: The New Zealand pine bark extract attenuated sucrose uptake with improved glycaemic responses, and may therefore be useful as a hypoglycaemic adjunct to the diet.
Bioaccessibility and associated concepts: Terminology in the context of in vitro food digestion studies
(Elsevier Ltd, 2025-09-01) Grundy MM-L; Deglaire A; Le Feunteun S; Reboul E; Moughan PJ; Wilde PJ; McClements DJ; Marze S
In vitro gastrointestinal models are widely used to study food digestion, in combination with analytical methods to determine the physicochemical and biochemical fate of food compounds. The in vitro bioaccessibility determined with these models is often used as an indicator of the in vivo bioavailability. However, the bioaccessibility concept is not used consistently within the scientific literature, leading to confusion and making it difficult to compare the results from different studies. The aim of this article is to provide standardized definitions of in vitro digestibility and bioaccessibility, detailing the main processes involved, including physical release, solubilization, and biochemical/metabolic reactions. The terminology of complementary cellular, ex vivo, and animal/human in vivo experiments is also given. Application of the in vitro terminology to different nutrients is discussed, including lipids, proteins, carbohydrates, vitamins, and other bioactive compounds. The proposed definitions unify most concepts related to the gastrointestinal fate of ingested food compounds.
Gastric protein digestion of cow, goat, and sheep milk is not reflected in the amino acid appearance in the blood of suckling piglets
(Elsevier Inc on behalf of the American Dairy Science Association, 2025-06) Roy D; Montoya CA; Stroebinger N; Hodgkinson SM; Ye A; McNabb WC; Moughan PJ; Singh H
Structural changes in milk during gastric digestion are a key driving factor for the rate of digestion of nutrients in the gastrointestinal tract. Thus, the influence of gastric coagulation behavior on the kinetics of protein digestion of raw cow, goat, and sheep whole milk in the stomach was investigated using the 3-wk-old suckled male piglet as an animal model for human infants. Piglets received a single meal of fresh raw milk normalized for protein content, and were slaughtered at 0, 30, 90, 150, or 210 min postprandially. Gastric chyme and cardiac blood samples were collected. Gastric pepsin activity, rate of protein hydrolysis, and gastric emptying of AA were determined along with how these changes influence the appearance of AA in the plasma. The disappearance rates of individual proteins (especially β-LG and αS-CN), total digested proteins entering the small intestine, as well as the gastric emptying of some AA (proline, leucine) were (or tended to be) greater for goat and sheep milk than for cow milk. Differences in plasma concentrations for some AA (e.g., leucine) were observed across milk types, but they did not directly reflect changes in gastric protein digestion and the gastric emptying of AA. In conclusion, a combination of protein (and AA) composition, susceptibility of specific proteins to hydrolysis, and the nature of the curd structure formed influenced the digestion behavior of milk proteins in the stomach and their subsequent release into the small intestine.
Editorial: Dietary protein for human health.
(Frontiers Media S.A., 2025-01-15) Moughan PJ; Hendriks WH; Hodgkinson SM; Chungchunlam SMS; Lim WXJ; Mensink M; Stroebinger N; van der Wielen N; Pivovarova-Ramich O
Toward a Dynamic Model of Indispensable Amino Acid Requirements of the Adult Human: A Factorial Estimate of Oxidative Amino Acid Losses.
(Elsevier B.V., 2024-11-02) Starck CS; Wolfe RR; Moughan PJ
Background Consensus regarding the required intake of indispensable amino acids (IDAAs) and protein [representing total amino acids (AAs)] in the adult is lacking. Oxidation is a major, although not exclusive, source of IDAA loss in humans body and a primary factor determining requirements; a quantitative understanding of oxidative IDAA losses is required. Objectives This study aimed to develop a factorial diurnal model of total oxidative IDAA and protein losses in the adult human. Methods A factorial diurnal model of oxidative losses of protein and each IDAA at maintenance was developed by estimating the magnitude and variability of sources of oxidative loss from existing literature: inevitable catabolism (constitutive oxidation of each absorbed dietary AA), and protein turnover in the postprandial and postabsorptive states. Total oxidative losses were calculated by summing individual losses, validated against published independent nitrogen balance data and compared with current IDAA requirements. Results The factorial model predicted minimum oxidative total AA losses of 390 ± 60 mg/kg BW/d, 59% of the estimated average requirement for protein. Inevitable AA oxidation and oxidation associated with postabsorptive protein turnover were the major sources of the oxidative loss for protein, at 40% and 44%, respectively. Summed oxidative IDAA losses ranged from 64% (isoleucine) to 91% (tryptophan) of current requirements. Total oxidative losses predicted by the model were significant predictors of actual experimental oxidative losses obtained by nitrogen balance (R2 = 0.66; P = 0.049). Conclusions The use of a factorial model for estimation of minimum IDAA and protein oxidative losses in the adult human provides an essential starting point for an updated understanding of protein and IDAA requirements. Further iterations of the model will estimate total protein and IDAA requirements, and account for variations in dietary protein quantity and quality, as well as different populations and physiologic states. Additional data, especially for inevitable oxidation in humans, and particularly with respect to individual IDAAs, are needed.
Consideration of the role of protein quality in determining dietary protein recommendations
(Frontiers Media S.A., 2024-11-13) Wolfe RR; Church DD; Ferrando AA; Moughan PJ; Grootswagers P
The quality of a dietary protein refers to its ability to provide the EAAs necessary to meet dietary requirements. There are 9 dietary amino acids that cannot be metabolically produced in the body and therefore must be consumed as part of the diet to avoid adverse metabolic consequences. These essential amino acids (EAAs) serve a variety of roles in the body. The amount and profile of the dietary EAAs relative to the individual EAA requirements and the digestibility of the dietary protein are the key factors that determine its quality. Currently the Digestible Indispensable Amino Acid Score (DIAAS) is the best available approach to quantifying protein quality. The most prominent metabolic role of dietary EAAs is to stimulate protein synthesis by serving as signals to activate molecular mechanisms responsible for the initiation of protein synthesis and, most importantly, to provide the necessary precursors for the synthesis of complete proteins. Current dietary recommendations generally do not consider protein quality. Accounting for protein quality in dietary patterns can be accomplished while staying within established ranges for dietary protein consumption. Poor protein quality can be compensated for to some extent by eating more low-quality protein, but to be effective (“complementary”) the limiting EAA must differ between the low-quality protein and the base diet to which it is being supplemented. Adding a high-quality protein to a dietary pattern based on low-quality protein is more effective in meeting EAA goals than increasing the amount of low-quality protein, even if the low-quality proteins are complementary. Further, reliance entirely on low-quality protein food sources, particularly in circumstances that may benefit from a level of dietary EAAs greater than minimal requirements, is likely to include excessive caloric consumption. While protein consumption in high-income nations is generally perceived to be adequate or even excessive, assessment of dietary patterns indicates that a significant percentage of individuals may fall short of meeting optimal levels of EAA consumption, especially in circumstances such as aging in which the optimal EAA consumption is greater than basal values for healthy young individuals. The case is made that protein quality is an important consideration in meeting EAA requirements.
Human milk vs. Infant formula digestive fate: In vitro dynamic digestion and in vivo mini-piglet models lead to similar conclusions
(Elsevier Ltd, 2024-11-01) Charton E; Menard O; Cochet M-F; Le Gouar Y; Jardin J; Henry G; Ossemond J; Bellanger A; Montoya CA; Moughan PJ; Dupont D; Le Huërou-Luron I; Deglaire A
Infant formula (IF), the only nutritionally adequate substitute for human milk (HM), still needs to be improved to be more biomimetic with HM, including in terms of digestive fate. The latter can be explored using different digestion models. The present study aimed to compare IF and HM digestion using in vivo (mini-piglet) and in vitro (dynamic system, DIDGI®) models. Fresh mature HM was collected and compared with a standard bovine IF. In vivo, 18 Yucatan mini-piglets (24-day-old) received HM or IF and were euthanized 30 min after the last meal. The entire digestive content was collected from the stomach to the colon. In vitro, the same meals were fed to an in vitro dynamic digestion model simulating the term infant at four weeks of age. Digesta were sampled regularly in the gastric and intestinal compartments. Structure (confocal microscopy and laser light scattering) and proteolysis (SDS-PAGE for residual intact proteins, OPA for hydrolysis degree, LC-MS/MS for peptides) were investigated along digestion. The digesta microstructure differed between HM and IF in a similar way between in vitro and in vivo digestion. In vitro gastric proteolysis of caseins and α-lactalbumin was significantly slower for HM than for IF, such as for the early intestinal proteolysis degree. In vitro bioaccessibility of free AAs explained only 30 % of the true ileal digestibility of AAs. Peptide mapping of caseins differed between HM and IF along their digestion. The relative peptide mapping data over six proteins from HM and IF were highly correlated between in vitro and in vivo digestion, particularly at 80 and 120 min of in vitro gastric digestion vs. in vivo stomach data and at 20 and 40 min of in vitro intestinal digestion vs. in vivo proximal jejunum data (r = 0.7–0.9, p < 0.0001, n = 1604). 40 to 50 % of the bioactive peptides identified in vivo were also found in vitro, with a good correlation of their abundances (r = 0.5, p < 0.0001, n = 61). Overall, in vitro and in vivo digestion were in good agreement, both indicating a different digestive fate for HM and IF.
Diet affordability: a key dimension in the assessment of sustainable food systems and healthy diets
(Frontiers Media S.A., 2024-08-12) Chungchunlam SMS; Moughan PJ; Raubenheimer D
A promulgated global shift toward a plant-based diet is largely in response to a perceived negative environmental impact of animal food production, but the nutritional adequacy and economic implications of plant-sourced sustainable healthy dietary patterns need to be considered. This paper reviews recent modeling studies using Linear Programming to determine the respective roles of animal- and plant-sourced foods in developing a least-cost diet in the United States and New Zealand. In both economies, least-cost diets were found to include animal-based foods, such as milk, eggs, fish, and seafood, to meet the energy and nutrient requirements of healthy adults at the lowest retail cost. To model a solely plant-based least-cost diet, the prevailing costs of all animal-sourced foods had to be increased by 1.1 to 11.5 times their original retail prices. This led to the inclusion of fortified plant-based foods, such as fortified soymilk, and a plant-based diet that was considerably (34–45%) more costly. The first-limiting essential nutrients were mostly the vitamins and minerals, with special focus on pantothenic acid, zinc, and vitamin B-12, when transitioning from an animal- and plant-containing least-cost diet to a plant-only based least-cost diet. Modeled least-cost diets based on contemporary food costs include animal-sourced foods, at least for developed high-income US and NZ food economies, and potentially for developing low- and middle-income countries, such as Indonesia. Modeling of least-cost diets that consist exclusively of plant-based foods is feasible, but at a higher daily diet cost, and these diets are often close to limiting for several key nutrients. Diet affordability, as a key dimension of sustainable healthy diets, and the respective economic roles of animal- and plant-sourced foods need to be considered.
The Importance of Dietary Protein Quality in Mid- to High-Income Countries
(Elsevier Inc on behalf of American Society for Nutrition, 2024-03) Moughan PJ; Fulgoni VL; Wolfe RR
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.

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