Effects of Protein Type and Mineral Form on Amino Acid Availability (ProMin)

Effects of Protein Type and Mineral Form on Postprandial Amino Acid Availability in Healthy Young Adults: a Randomized Cross-over Study

To compare postprandial plasma amino acid availability, expressed as incremental area under the curve (iAUC), over a 6 hour period following ingestion of 25 g of different protein isolates in healthy, young adults. The primary objective is divided into the following 2 sub-studies, each with 3 comparisons:

• Sub-study 1: whey protein, calcium caseinate, sodium caseinate.
• Sub-study 2: calcium caseinate, magnesium caseinate, potassium caseinate.

Study Overview

• Status: Not yet recruiting
• Conditions: Protein Metabolism
• Intervention / Treatment: Dietary supplement: Protein beverage

Detailed Description

All living tissues are in a constant state of protein turnover, with synthesis and breakdown processes ensuring structural integrity, metabolic flexibility and the capacity for repair. Amino acids are the building blocks of proteins and must be supplied through the diet to maintain a positive protein balance. Ingestion of high-quality protein sources (e.g. meat, dairy) leads to a postprandial increase in circulating amino acids, and as such can facilitate tissue protein synthesis. The magnitude and the kinetics of the amino acid response largely depend on the amino acid composition combined with protein digestion and amino acid absorption rate.

Beyond their structural role, amino acids also function as signalling molecules involved in gastrointestinal hormone secretion and appetite control. One such key hormone is glucagon-like peptide 1 (GLP-1), a gut-derived hormone that plays an essential role in metabolic regulation such as insulin secretion and appetite suppression. Given its role in metabolic health, particularly in the context of obesity and type 2 diabetes, increasing GLP-1 availability has become a target for support in metabolic care. However, many pharmacological approaches to elevate GLP-1 are costly and carry risks of harmful side-effects.

Nutritional strategies that modulate GLP-1 secretion and availability therefore offer an attractive alternative. Emerging evidence suggests that not only protein ingestion itself, but also the matrix in which the protein is delivered can modulate GLP-1 secretion. For example, co- ingestion of specific minerals, especially calcium, has been shown to enhance GLP-1 secretion beyond the effects of protein ingestion alone. These data indicate that mineral-protein interactions may play a meaningful role in appetite regulation and metabolic signalling, warranting further investigation.

Bovine milk contains two primary high-quality protein fractions: whey (~20%) and casein (~80 %). Whey protein is rapidly digested, resulting in fast but transient increases in circulating amino acids, whereas casein protein is digested more slowly, leading to more prolonged but sustained amino acid availability (13-15). To optimize the functional properties of casein, various processing techniques can be applied, including the formation of caseinate salts through binding casein with different minerals such as calcium, sodium, magnesium, and potassium. These caseinate forms differ in mineral composition, which may influence not only digestion and absorption kinetics, but also GLP-1 secretion capacity. Although the differences in digestion kinetics between whey and casein are well-established, a direct comparison of postprandial amino acid and GLP-1 responses following ingestion of whey versus various mineral-bound caseinates has not yet been performed.

• Study Type: Interventional
• Enrollment (Estimated): 16
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Noortje Boot, MSc; Phone Number: 088-3887246; Email: noortje.boot@maastrichtuniversity.nl
• Study Contact Backup: Name: Luc van Loon, Prof., PhD; Phone Number: 043-3881397; Email: l.vanloon@maastrichtuniversity.nl

Study Locations

• Netherlands
  • Limburg
    • Maastricht, Limburg, Netherlands, 6200
      • Maastricht University Medical Centre
      • Contact: Luc van Loon, PhD; Phone Number: 043-3881397; Email: l.vanloon@maastrichtuniversity.nl

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

To be eligible to participate in this study, a participant must meet all of the following criteria:

• Male or female sex
• Aged between 18 - 35 years inclusive
• BMI between 18 - 30 kg/m2
• Healthy, recreationally active (exercise at least once per two weeks and a maximum of four days per week)
• No physical limitations (i.e., able to perform all activities associated with daily living independently)

A potential participant who meets any of the following criteria will be excluded from participation in this study:

• Intolerant to milk protein and/or dairy-based products
• Smoking regularly
• Diagnosed with gastro-intestinal disorders
• Diagnosed with metabolic disorders (e.g. diabetes)
• Diagnosed with musculoskeletal disorders
• Blood donation in the past 2 months
• Females: pregnancy
• Use of any medication known to affect protein metabolism (e.g. corticosteroids, non-steroidal anti-inflammatories or prescribed acne medications)
• Chronic use of gastric acid suppressing drugs (e.g. proton pump inhibitors, H2-antagonists)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

5

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Whey protein; 25 g whey protein isolate	Dietary supplement: Protein beverage; 25 g protein isolate, dissolved in 500 mL water
Experimental: Sodium caseinate; 25 g sodium caseinate protein	Dietary supplement: Protein beverage; 25 g protein isolate, dissolved in 500 mL water
Experimental: Calcium caseinate; 25 g calcium caseinate protein	Dietary supplement: Protein beverage; 25 g protein isolate, dissolved in 500 mL water
Experimental: Magnesium caseinate; 25 g magnesium caseinate protein	Dietary supplement: Protein beverage; 25 g protein isolate, dissolved in 500 mL water
Experimental: Potassium caseinate; 25 g potassium caseinate protein	Dietary supplement: Protein beverage; 25 g protein isolate, dissolved in 500 mL water

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Six-hour postprandial plasma total amino acid availability following ingestion of 25 grams of different protein isolates in healthy, young adults	Plasma total amino acid availability is expressed as the incremental area under the curve (iAUC) and compared between whey protein, calcium caseinate and sodium caseinate (sub-study 1) and between calcium caseinate, magnesium caseinate and potassium caseinate (sub-study 2).	Six hours

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Plasma essential amino acid concentrations	The summed measurement of histidine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine concentrations	Essential amino acid concentrations are derived from blood samples taken before beverage ingestion and during the six-hour postprandial time-period (at 15, 30, 45, 60, 75, 90, 120, 150, 180, 210, 240, 300 and 360 minutes following beverage ingestion).
Non-essential amino acid concentrations	The summed measurement of alanine, arginine, aspartic acid, cysteine, glutamic acid, glycine, serine, tyrosine and valine concentrations	Nonssential amino acid concentrations are derived from blood samples taken before beverage ingestion and during the six-hour postprandial time-period (at 15, 30, 45, 60, 75, 90, 120, 150, 180, 210, 240, 300 and 360 minutes following beverage ingestion).
Plasma amino acid kinetics	Compare peak plasma amino acid concentrations and the time to reach these peak concentrations of all individually measured amino acids	During the six-hour postprandial period
Circulating mineral concentrations	Calcium, magnesium, sodium, potassium and parathyroid hormone concentrations	During the six-hour postprandial period
Glucagon-like peptide-1 concentrations	Postprandial glucacon-like peptide-1 (GLP-1) concentrations	During the six-hour postprandial period

Collaborators and Investigators

• Sponsor: Maastricht University Medical Center
• Collaborators: Friesland Campina

Study record dates

Study Major Dates

• Study Start (Estimated): September 15, 2026
• Primary Completion (Estimated): July 15, 2027
• Study Completion (Estimated): July 15, 2027

Study Registration Dates

• First Submitted: June 24, 2026
• First Submitted That Met QC Criteria: June 24, 2026
• First Posted (Actual): June 30, 2026

Study Record Updates

• Last Update Posted (Actual): June 30, 2026
• Last Update Submitted That Met QC Criteria: June 24, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Amino acid; Minerals; Satiety hormone; Protein kinetics
• Other Study ID Numbers: METC 26-007; NL-011398 (Other Identifier: CCMO)

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No