Multivitamin Impact on Micronutrient Status in GLP-1 Users: A Randomized Trial (VITAGLP)

November 14, 2025 updated by: Bart Torensma, Erasmus Medical Center

The Impact of Multivitamin Supplementation on Micronutrient Levels in GLP-1 Users: A Randomized, Double-Blind, Placebo-Controlled Trial

Rationale: Glucagon-Like Peptide-1 (GLP-1) receptor agonists have emerged as effective treatments for obesity and associated medical conditions. However, patients may be at risk of micronutrient deficiencies during therapy due to reduced appetite, altered gastrointestinal physiology, and weight loss. Multivitamin supplementation is commonly prescribed to mitigate these risks, but the necessity and efficacy of multivitamin use in GLP-1 users remain debatable, as some clinicians advocate for routine supplementation while others do not.

Objective: To assess the differences in micronutrient levels between patients who use multivitamin supplements while on GLP-1 therapy and those who do not, to provide evidence on the necessity and benefits of supplementation.

Study Design: Randomized, double-blind, placebo-controlled trial. Study Population: Adults with obesity (BMI ≥30 kg/m² or ≥27 kg/m² with obesity-associated medical problems) currently using GLP-1 receptor agonists for at least 3 months with stable dosing.

Intervention:

  • Group A (Intervention): Multivitamin supplementation while on GLP-1 therapy
  • Group B (Control): Matching placebo while on GLP-1 therapy Main Study Parameters/Endpoints: The primary outcomes are the differences in serum levels of Vitamin B12, Vitamin D, and Ferritin between the multivitamin and placebo groups after 12 months of supplementation while on GLP-1 therapy.

Nature and Extent of the Burden and Risks: Participants will undergo blood sampling at four timepoints: baseline (before starting GLP-1 therapy), at randomization (3 months of stable GLP-1 therapy), and at 6 and 12 months post-randomization. The risks associated with the study are minimal and primarily related to blood sampling and potential side effects of multivitamin supplementation. The burden includes time commitment for study visits and daily supplement intake.

Study Overview

Status

Enrolling by invitation

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

246

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Netherlands
      • Amersfoort, Netherlands
        • WeightWorks Clinics
      • Rotterdam, Netherlands
        • Erasmus MC

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Age ≥18 to 70 years.
  • Start with the use of Tirzepatide GLP-1 receptor agonists and for at least 3 months with stable dosing before randomization.
  • BMI ≥30 kg/m² or ≥27 kg/m² with obesity-associated medical problems (such as type 2 diabetes, hypertension, or dyslipidemia) at the start of GLP-1 therapy
  • Willing and able to provide informed consent
  • Able to comply with study procedures and follow-up visits
  • Own vitamins should be completely discontinued 2 weeks before the start

Exclusion Criteria:

  • Known allergy or hypersensitivity to any components of the multivitamin supplement
  • Current use of other vitamin or mineral supplements
  • Pregnancy or planning pregnancy during the study period
  • Patients who follow a vegan diet.
  • Active malignancy or ongoing cancer treatment
  • Severe kidney disease (eGFR <30 mL/min/1.73m²)
  • Severe liver disease (Child-Pugh C)
  • History of metabolic bariatric surgery
  • Participation in other clinical trials within the past 3 months
  • Any condition that, in the investigator's opinion, would interfere with study participation or compromise patient safety

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Group A (Multivitamin Supplementation)
Participants in this group will receive a daily multivitamin supplement formulated to provide comprehensive micronutrient support. The supplement will be taken once daily with a meal for the 12-month intervention period following randomization.
Dietary supplement: Multivitamin Supplementation
Multivitamin Supplementation
Placebo Comparator: Group B (Placebo)
Participants in this group will receive a matching placebo that is identical in appearance, taste, and packaging to the active multivitamin supplement. The placebo will be taken once daily with a meal for the 12-month intervention period following randomization.
Other: Placebo
Placebo vitamine

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
serum levels
Time Frame: 15 months
  1. Vitamin B12 (Reference range: 200-500 pmol/L)
  2. Vitamin D (Reference range: 50-200 nmol/L)
  3. Ferritin (Reference range: 30-388 μg/L)
  4. Folic acid (Reference range: 10-45 nmol/L)
15 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
other micronutrient levels
Time Frame: 12 months

Changes in other micronutrient levels from baseline to 12 months, including:

  • Iron (10-30 μmol/L)
  • Vitamin B1 (70-180 nmol/L)
  • Vitamin B6 (35-110 nmol/L)
  • Zinc (10-18 μmol/L)
  • Magnesium (0.70-1.05 mmol/L)
  • Calcium:

Total serum calcium: 2.15-2.55 mmol/L) Ionized calcium: 1.16-1.32 mmol/L PTH (Parathyroid Hormone) (1.6-6.9 pmol/L)

Changes in additional iron-related functional markers:

  • Transferrin (2.0-3.6 g/L)
  • Transferrin saturation (20-45%)
  • Total iron binding capacity 2. Changes in hematological parameters:
  • Hemoglobin (Female: 7.5-10.0 mmol/L; Male: 8.5-11.0 mmol/L)
  • Mean Corpuscular Volume (MCV) (80-100 fL)
  • HbA1c (4.0-6.0% (20-42 mmol/mol)) Inflammation and protein status
  • C-reactive protein (CRP): <10 mg/L
  • Albumin: 35-50 g/L Incidence of clinically significant deficiencies requiring intervention Correlation between weight loss parameters (%TWL, %EWL) and changes in micronutrient levels
12 months

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
Weight loss
Time Frame: 12 months
Weight and BMI changes throughout the study period
12 months
GLP adherence
Time Frame: 12 months
Adherence to GLP-1 therapy and study medication
12 months
diet
Time Frame: 12 months
Dietary intake patterns (assessed through food frequency questionnaires)
12 months
QoL
Time Frame: 12 months
Quality of life measures
12 months
Body composition assessment
Time Frame: 12 months
  • Measured at baseline, 6 months, and 12 months
  • Parameters: fat mass, fat-free mass, muscle mass, visceral fat
12 months
Resting Energy Expenditure (REE)
Time Frame: 12 months
Measured via indirect calorimetry
12 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Erasmus Medical Center

Collaborators

weightworks Clinic

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

December 16, 2025

Primary Completion (Estimated)

March 16, 2027

Study Completion (Estimated)

April 30, 2027

Study Registration Dates

First Submitted

April 25, 2025

First Submitted That Met QC Criteria

November 14, 2025

First Posted (Actual)

November 19, 2025

Study Record Updates

Last Update Posted (Actual)

November 19, 2025

Last Update Submitted That Met QC Criteria

November 14, 2025

Last Verified

November 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • GLP-1-RCT-2025
  • ABR 2025 GLP (Other Identifier: The Netherlands Medical Research Portal (CCMO))

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

The investigator will be responsible for the data analysis. The analysis will be performed on a blinded data set after medical/scientific review has been completed, all protocol violations have been identified, and the data set has been declared complete. All data will be collected in a data management system (Castor EDC, Amsterdam, The Netherlands; https://www.castoredc.com) and performed according to Good Clinical Practice guidelines, Data Protection Directive certificate and complies with Title 21 CFR Part 11. Furthermore, the datacenter where all the research data is stored is ISO27001, ISO9001 certified and the Dutch NEN7510 certified.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • ICF
  • ANALYTIC_CODE
  • CSR

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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