Protein type and caloric density of protein supplements modulate postprandial amino acid profile through changes in gastrointestinal behaviour: A randomized trial (original) (raw)
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Rational Use of Protein Supplements in the Elderly—Relevance of Gastrointestinal Mechanisms
Nutrients, 2021
Protein supplements are increasingly used by older people to maintain nutrition and prevent or treat loss of muscle function. Daily protein requirements in older people are in the range of 1.2 gm/kg/day or higher. Many older adults do not consume this much protein and are likely to benefit from higher consumption. Protein supplements are probably best taken twice daily, if possible soon after exercise, in doses that achieve protein intakes of 30 gm or more per episode. It is probably not important to give these supplements between meals, as we have shown no suppressive effects of 30 gm whey drinks, and little if any suppression of 70 gm given to older subjects at varying time intervals from meals. Many gastrointestinal mechanisms controlling food intake change with age, but their contributions to changes in responses to protein are not yet well understood. There may be benefits in giving the supplement with rather than between meals, to achieve protein intakes above the effective an...
Nutrition Journal, 2014
Background: Decreased ability of muscles to respond to anabolic stimuli is part of the underlying mechanism for muscle loss with aging. Previous studies suggest that substantial amounts of essential amino acids (EAA), whey protein and leucine are beneficial for stimulation of acute muscle protein synthesis in older adults. However, these studies supplied only proteins, and no bolus studies have been done with dairy products or supplements that contained also fat and carbohydrates besides proteins. The aim of this study was to evaluate whether a specifically designed nutritional supplement in older adults stimulates muscle protein synthesis acutely to a greater extent than a conventional dairy product. Moreover, the combined effect with resistance exercise was studied by using a unilateral resistance exercise protocol.
Journal of Nutrition, 2009
Impaired digestion and/or absorption of dietary protein lowers postprandial plasma amino acid availability and, as such, could reduce the postprandial muscle protein synthetic response in the elderly. We aimed to compare in vivo dietary protein digestion and absorption and the subsequent postprandial muscle protein synthetic response between young and elderly men. Ten elderly (64 6 1 y) and 10 young (23 6 1 y) healthy males consumed a single bolus of 35 g specifically produced, intrinsically L-[1-13 C]phenylalanine-labeled micellar casein (CAS) protein. Furthermore, primed continuous infusions with L-[ring-2 H 5 ]phenylalanine, L-[1-13 C]leucine, and L-[ring-2 H 2 ]tyrosine were applied and blood and muscle tissue samples were collected to assess the appearance rate of dietary protein-derived phenylalanine in the circulation and the subsequent muscle protein fractional synthetic rate over a 6-h postprandial period. Protein ingestion resulted in a rapid increase in exogenous phenylalanine appearance in both the young and elderly men. Total exogenous phenylalanine appearance rates (expressed as area under the curve) were 39 6 3 mmol×6 h×kg 21 in the young men and 38 6 2 mmol×6 h×kg 21 in the elderly men (P = 0.73). In accordance, splanchnic amino acid extraction did not differ between young (72 6 2%) and elderly (73 6 1%) volunteers (P = 0.74). Muscle protein synthesis rates, calculated from the oral tracer, were 0.063 6 0.006 and 0.054 6 0.004%/h in the young and elderly men, respectively, and did not differ between groups (P = 0.27). We conclude that protein digestion and absorption kinetics and the subsequent muscle protein synthetic response following the ingestion of a large bolus of intact CAS are not substantially impaired in healthy, elderly men.
Nutrients, 2018
Protein-rich supplements are used widely for the prevention and management of malnutrition in older people. We have reported that healthy older, compared to younger, adults have less suppression of energy intake by whey-protein-effects on appetite-related hormones are unknown. The objective was to determine the effects of intraduodenally administered whey-protein on glucose, gut hormone, and amino acid concentrations, and their relation to subsequentenergy intake at a buffet meal, in healthy older and younger men. Hydrolyzed whey-protein (30 kcal, 90 kcal, and 180 kcal) and a saline control (~0 kcal) were infused intraduodenally for 60 min in 10 younger (19-29 years, 73 ± 2 kg, 22 ± 1 kg/m²) and 10 older (68-81 years, 79 ± 2 kg, 26 ± 1 kg/m²) healthy men in a randomized, double-blind fashion. Plasma insulin, glucagon, gastric inhibitory peptide (GIP), glucagon-like peptide-1 (GLP-1), peptide tyrosine-tyrosine (PYY), and amino acid concentrations, but not blood glucose, increased, wh...
Quality of meal protein determines anabolic response in older adults
Clinical nutrition (Edinburgh, Scotland), 2017
It has been demonstrated that the relative content and profile of essential amino acids (EAA) play a determining role for stimulation of muscle protein synthesis (MPS) following intake of pure EAA or protein alone. To test if this also holds in the context of mixed meals at both whole body and muscle levels, twelve older subjects (57-74 yrs) received primed continuous infusion of L-[ring-2H5]phenylalanine and L-[ring-2H2]tyrosine over a 9-h experimental period to determine whole body protein kinetics and MPS in the fasted state and following consumption of egg-based (EGG) or cereal-based (CEREAL) isocaloric and isonitrogenous breakfast. A standardized lunch, primarily consisting of beef protein was also consumed by each group. Whole body protein kinetics [protein synthesis (PS), breakdown (PB), and net balance (NB)] were expressed as changes from basal fasted period. We found that EGG breakfast resulted in a greater NB through a greater suppression of PB compared with the CEREAL bre...
Current Developments in Nutrition, 2021
Background Limited data are available examining dietary interventions for optimizing protein and leucine intake to stimulate muscle protein synthesis (MPS) in older humans. Objectives We aimed to investigate the aminoacidemia and appetite responses of older adults after consuming breakfast, a meal frequently consumed with high-carbohydrate and below-par amounts of protein and leucine for stimulating MPS. Methods Five men and 3 women (means ± SD; age: 74 ± 7 y, BMI: 25.7 ± 4.9 kg/m2, fat- and bone-free mass: 63 ± 7 kg) took part in this experiment in which they consumed breakfasts with low-protein (LP = 13 ± 2 g), high-protein (HP = 32 ± 5 g), and LP followed by a protein- and leucine-enriched bar formulation 2 h later (LP + Bar = 29 ± 2 g). The LP, HP, and LP + Bar breakfast conditions contained 519 ± 86 kcal, 535 ± 83 kcal, and 739 ± 86 kcal, respectively. Blood samples were drawn for 6 h and analyzed for amino acid, insulin, and glucose concentrations. Visual analog scales were as...
The Journal of clinical endocrinology and metabolism, 2015
An impaired muscle protein synthetic response to feeding likely contributes to muscle loss with aging. There are few data available on the effect of the macronutrient composition of clinical supplements on the postprandial muscle protein synthetic response in older subjects. To determine the impact of the macronutrient composition of a nutritional supplement on the postprandial muscle protein synthetic response in older men. A total of 45 non-sarcopenic older men (age: 69±1 y; BMI: 25.7±0.3 kg/m(2)) were randomly assigned to ingest 21 g of leucine-enriched whey protein with carbohydrate (9 g) and fat (3 g) (Pro-En), an isonitrogenous amount of 21 g of leucine-enriched whey protein without carbohydrate and fat (Pro), or an isocaloric mixture (628 kJ) containing carbohydrate and fat only (En). Stable isotope tracer methodology was applied to assess basal as well as postprandial muscle protein synthesis rates in the three groups. Ingestion of protein in the Pro-En and Pro groups signif...
Potential benefits of improved protein intake in older people
Nutrition & Dietetics, 2008
Ageing is associated with an increased incidence of diabetes, impaired immunity and numerous physiological, social and economic changes. Another under-recognised change to significantly impact on health outcomes and quality of life is the drastic loss of lean body mass. New concepts have recently emerged which indicate that different types of protein sources supply constituents differentially according to digestion rate, and that amino acids have roles additional to muscle synthesis. This review explores the benefits of higher protein intakes in older people and how the protein source may provide differential benefits. In particular, whey protein is more quickly digested than either casein or soy, and provides a faster and potentially greater net source of available nutrients and essential amino acids essential for maintaining better health. Figure 1 Body composition changes in normal male adults. Adapted from Phillips. 9 B. Dawson et al.
American journal of physiology. Endocrinology and metabolism, 2015
Dysregulated anabolic responses to nutrition/exercise may contribute to sarcopenia; however, these characteristics are poorly defined in female populations. We determined the effects of two-feeding regimes in older women (66±2.5y N=8/group): bolus-whey protein (WP-20 g) or novel low-dose leucine-enriched essential amino acids (EAA) (LEAA-3g [40% leucine]). Using (13)C6-Phenylalanine infusions, we quantified muscle (MPS) and albumin (APS) protein synthesis at baseline and both in response to feeding (FED) and feeding-plus-exercise (FED-EX; RE: 6×8 knee-extensions at 75%-1RM). We also quantified plasma insulin/AA concentrations, whole-leg (LBF)/muscle microvascular blood-flow (MBF), and muscle anabolic signaling by phospho-immunoblotting. Plasma insulinemia and EAA-aemia were markedly greater after WP than LEAA (P<0.001). Neither LEAA nor WP modified LBF in response to FED or FED-EX, while MBF increased to a similar extent in both groups, only after FED-EX (P<0.05). In response ...