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NCT Number: NCT07234916

Multivitamin Impact on Micronutrient Status in GLP-1 Users: A Randomized 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.

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Key information

Conditions

Weight Loss Body Weight Body Weight Changes GLP - 1 Malnutrition Nutrition Disorders Nutritional Deficiencies Nutritional and Metabolic Diseases Obese Patients Obesity Overnutrition Overweight Pathological Conditions, Signs and Symptoms Signs and Symptoms

Age range

18 year–70 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

WeightWorks Clinics, Amersfoort, Netherlands

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Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Multivitamin Supplementation

Dietary Supplement

Multivitamin Supplementation

Placebo

Other

Placebo vitamine

Primary outcomes

  1. serum levels

    Time frame: 15 months

    • Vitamin B12 (Reference range: 200-500 pmol/L)
    • Vitamin D (Reference range: 50-200 nmol/L)
    • Ferritin (Reference range: 30-388 μg/L)
    • Folic acid (Reference range: 10-45 nmol/L)

Secondary outcomes

  1. 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

Other outcomes

  1. Weight loss

    Time frame: 12 months

    Weight and BMI changes throughout the study period

  2. GLP adherence

    Time frame: 12 months

    Adherence to GLP-1 therapy and study medication

  3. diet

    Time frame: 12 months

    Dietary intake patterns (assessed through food frequency questionnaires)

  4. QoL

    Time frame: 12 months

    Quality of life measures

  5. 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

  6. Resting Energy Expenditure (REE)

    Time frame: 12 months

    Measured via indirect calorimetry

Sponsors and collaborators

Lead sponsor

Erasmus Medical Center

Other

Collaborators

  • weightworks Clinic

Registry information

Official study title

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

Acronym: VITAGLP

Important dates

Study start
2025
Primary completion
2027
Study completion
2027
First posted
Nov 19, 2025
Registry last updated
Nov 19, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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