Evaluation of the Bioavailability of Amino Acids From Purple Bacteria (PROTEBOOST_1)

Evaluation of the Consumption of Fresh Purple Bacteria Biomass in Healthy Humans: Safety Test and Monitoring of Metabolism

This interventional clinical study aims to evaluate the bioavailability of amino acids derived from purple bacteria in healthy adults. Participants will consume either a protein-enriched dairy product or a protein-enriched dairy product containing purple bacteria during two separate test periods in a randomized cross-over design. Blood amino acid concentrations will be measured over a 4-hour postprandial period to assess amino acid absorption and bioavailability.

Additional biological samples including saliva, exhaled air, and feces will be collected to evaluate gastrointestinal hormones, volatilome profiles, and related metabolic responses.

Study Overview

• Status: Completed
• Conditions: Healthy Volunteers
• Intervention / Treatment: Dietary supplement: Purple Bacteria-Enriched Dairy Product; Other: Protein-Enriched Dairy Product

Detailed Description

Purple bacteria are recognized for their high-quality protein content, including essential amino acids, as well as their vitamin and carotenoid composition. However, limited data are available regarding the bioavailability of amino acids derived from purple bacteria in humans.

This randomized, open-label, cross-over study will enroll approximately 12 healthy adult participants in Belgium. Each participant will receive two dairy-based formulations in randomized order:

Control formulation: protein-enriched dairy product. Test formulation: protein-enriched dairy product containing purple bacteria.

The two intervention periods will be separated by a washout period of at least one week.

Participants will undergo one screening visit and two test visits. During each test visit, serial blood samples will be collected over 240 minutes following ingestion of the assigned formulation to determine plasma amino acid concentrations. Additional saliva, exhaled air, and fecal samples will also be collected.

The primary objective is to determine whether amino acids present in purple bacteria are better absorbed than amino acids from other protein sources.

• Study Type: Interventional
• Enrollment (Actual): 12
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Belgium
  • Louvain-la-Neuve, Belgium, 1348
    • Center of Investigation in Clinical Nutrition (CICN)

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Adults aged 18 to 50 years
• Body mass index between 18 and 30 kg/m²
• Healthy participants
• Non-smokers
• Women of childbearing potential using effective contraception
• Able to understand and speak French
• Willing and able to comply with study procedures

Exclusion Criteria:

• Pregnancy or breastfeeding
• Use of medications or dietary supplements incompatible with study participation
• Any medical condition considered by the investigator to interfere with study participation or interpretation of results
• Vegan or vegetarian diets

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Purple Bacteria Formulation; Participants will consume a protein-enriched dairy product containing purple bacteria.	Dietary supplement: Purple Bacteria-Enriched Dairy Product; Approximately 50 g of purple bacteria incorporated into approximately 110 g of a protein-enriched dairy product.
Active Comparator: Control Formulation; Participants will consume a protein-enriched dairy product without purple bacteria.	Other: Protein-Enriched Dairy Product; 160 g of protein-enriched dairy product.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in postprandial plasma essential amino acid concentrations (µmol/L)	Plasma concentrations of essential amino acids (including leucine, isoleucine, valine, lysine, threonine, phenylalanine, methionine, tryptophan, and histidine) will be measured using LC-MS/MS at baseline and at multiple postprandial time points following ingestion of control and test formulations. Results will be reported as incremental area under the curve (iAUC, µmol/L·h) over the postprandial period.	Throughout the entire study, approxiamtely during 1 month

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in exhaled volatile organic compounds (VOCs) profile (relative abundance, arbitrary units)	Exhaled air samples will be analyzed using gas chromatography-mass spectrometry (GC-MS). Specific VOCs will be quantified and reported as relative abundance (arbitrary units) and/or multivariate profile changes (e.g., PCA scores) comparing test vs control formulations.	Throughout the entire study, approxiamtely during 1 month
Change in salivary gastrointestinal hormone concentrations (pg/mL)	Salivary concentrations of gastrointestinal hormones (e.g., ghrelin, GLP-1, PYY) will be measured using immunoassays. Results will be expressed as change from baseline and iAUC (pg/mL·h) over the postprandial period.	Throughout the entire study, approxiamtely during 1 month
Gastrointestinal symptom severity score assessed using a 5-point Likert scale (0-4)	Gastrointestinal tolerance will be assessed using a standardized symptom questionnaire evaluating the severity of gastrointestinal symptoms (including bloating, abdominal pain, flatulence, nausea, and diarrhea). Each symptom will be rated using a 5-point Likert scale, defined as: 0 = not at all; = slightly; = moderately; = severely; = very severely Results will be reported as: mean gastrointestinal symptom score (average across symptoms) and/or total symptom score (sum of all items; higher scores indicate worse symptoms) and change from baseline over the postprandial period following ingestion of study formulations.	Throughout the entire study, approxiamtely during 1 month
Number of participants with at least one adverse event	Adverse events will be collected throughout the study period and reported as the number and proportion of participants experiencing at least one adverse event, by condition.	Throughout the entire study, approxiamtely during 1 month

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Perceived stress score assessed using the Perceived Stress Scale (PSS-10; range 0-40)	Perceived stress will be assessed using the Perceived Stress Scale (10-item version, PSS-10), a validated questionnaire measuring the degree to which situations in one's life are appraised as stressful. The total score ranges from: 0 to 40, with higher scores indicating higher perceived stress Results will be reported as: mean total PSS score change from baseline over the study period and/or between-group differences following ingestion of the study formulations.	Throughout the entire study, approxiamtely during 1 month

Collaborators and Investigators

• Sponsor: Université Catholique de Louvain
• Collaborators: University of Liege; University of Mons
• Investigators: Principal Investigator: Sylvie Copine, Dr, Université Catholique de Louvain; Principal Investigator: Laurent Simar, Dr, Université Catholique de Louvain

Study record dates

Study Major Dates

• Study Start (Actual): April 13, 2026
• Primary Completion (Actual): May 8, 2026
• Study Completion (Actual): May 8, 2026

Study Registration Dates

• First Submitted: May 4, 2026
• First Submitted That Met QC Criteria: May 21, 2026
• First Posted (Actual): May 29, 2026

Study Record Updates

• Last Update Posted (Actual): May 29, 2026
• Last Update Submitted That Met QC Criteria: May 21, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Healthy adults; Postprandial metabolism; Functional foods; Amino acid bioavailability; Purple bacteria; Protein absorption; Dairy product
• Other Study ID Numbers: PROTEBOOST_BIODISPO1

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

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