The vitaglp trial is finally testing if multivitamins work for GLP-1 patients

You take your GLP-1 medication for weight loss or blood sugar control. You eat less, lose weight, and feel in control. But there's a trade-off no one warned you about: nutrient gaps. The VITAGLP trial (NCT07234916) is the first real study testing whether a daily multivitamin can fix what your reduced diet leaves behind. Here's what we know so far.

What the vitaglp trial is investigating

The VITAGLP trial is a randomised, placebo-controlled study led by researchers at Erasmus Medical Center in the Netherlands. It's the first of its kind to measure whether a standard daily multivitamin can improve micronutrient status in people actively using GLP-1 medications like Ozempic, Wegovy, or Mounjaro. Enrollment started in December 2025, and results are expected by April 2027.

This matters because until now, most advice about GLP-1 supplements has been guesswork. You've probably heard someone say "just take a multivitamin" without any evidence it works for your specific situation. The VITAGLP trial changes that. It asks a direct question: can a daily multivitamin correct the nutrient deficits caused by reduced food intake and slower digestion?

Why this trial matters for you

If you're on a GLP-1 medication, you're eating less - sometimes 500 to 1,000 fewer calories per day. That means fewer vitamins and minerals coming in. At the same time, these drugs slow gastric emptying, which can reduce how much you absorb from the food you do eat. The combination creates a perfect storm for deficiencies.

Early findings from a 2026 review by Urbina et al. in Clinical Obesity show that common deficiencies in GLP-1 patients include vitamin B12, folate, iron, vitamin D, and calcium. The review notes that routine supplementation may help, but robust clinical trials have been lacking. The VITAGLP trial is designed to fill that gap.

Why GLP-1 patients are at risk for nutrient gaps

GLP-1 receptor agonists work by mimicking a hormone that signals fullness and slows gastric emptying. That's great for appetite control, but it creates specific challenges for nutrient absorption.

Here's what happens inside your body:

• Reduced stomach acid - Slower digestion means less acid production, which impairs the release of vitamin B12 from food.
• Lower food intake - You're eating less overall, so you're getting fewer vitamins and minerals from diet alone.
• Changes in gut motility - Food moves more slowly through your digestive tract, which can affect how nutrients are absorbed.

These aren't minor issues. Low B12 can cause fatigue and nerve problems. Insufficient vitamin D affects bone health and immune function. Iron deficiency leads to anaemia, which leaves you feeling drained even when you're losing weight.

What micronutrients are most affected

Based on current evidence, the nutrients most at risk during GLP-1 therapy include:

• Vitamin B12 - because reduced stomach acid impairs its release from food
• Folate - due to lower intake of leafy greens and fortified grains
• Iron - especially in women, as appetite suppression reduces red meat and bean consumption
• Vitamin D - from less time outdoors and lower dairy intake
• Calcium - which often drops alongside vitamin D levels

Researchers are still investigating whether other nutrients like zinc, magnesium, and selenium are also affected. The VITAGLP trial will measure blood levels of several markers before and after multivitamin use, giving us clearer answers.

Why a targeted supplement matters more than a generic multivitamin

Not all multivitamins are created equal. A generic one-a-day might contain 100% of the daily value for a dozen vitamins, but it may not address the specific absorption challenges GLP-1 patients face.

For example, standard vitamin B12 in multivitamins is cyanocobalamin, which requires intact stomach acid to be absorbed - exactly what GLP-1 drugs reduce. A targeted formula might instead use methylcobalamin or include sublingual options. Similarly, iron absorption is enhanced by vitamin C, and calcium needs vitamin D to be effective. A generic multivitamin rarely accounts for these interactions.

This is why the VITAGLP trial is so important. It will show whether a standard multivitamin is enough, or whether GLP-1 patients need something more specific.

What the research says so far

The Urbina review also highlighted that nutrient deficiencies on GLP-1 are often asymptomatic at first. You might not feel tired or notice hair thinning until levels drop significantly. By then, correcting the deficiency takes longer.

A 2024 study in Nutrients found that 40% of participants on semaglutide had low vitamin B12 levels after six months. Another study showed that bone density loss accelerates in the first year of GLP-1 use, partly due to calcium and vitamin D deficits. These early findings suggest that proactive supplementation could make a real difference.

How to support your nutrient intake while on GLP-1 medications

While we wait for the VITAGLP trial results, there are steps you can take now to protect your health.

Focus on protein first

Protein intake on Wegovy, Ozempic, or Mounjaro is critical. You need at least 1.2 to 1.5 grams of protein per kilogram of body weight to prevent muscle loss. That's roughly 80 to 120 grams per day for most people. Prioritise lean meats, eggs, Greek yogurt, and plant-based proteins like lentils and tofu.

Choose nutrient-dense foods

Every bite counts when you're eating less. Focus on foods that deliver multiple nutrients: leafy greens for folate and iron, fortified dairy or plant milks for calcium and vitamin D, and fatty fish for omega-3s. If you're struggling with nausea, try smoothies or soups that pack nutrients into a smaller volume.

Consider a targeted supplement

A generic multivitamin might not cut it. Look for a formula designed for GLP-1 patients that includes methylated B12, active folate, and chelated minerals for better absorption. Some patients also benefit from separate magnesium or omega-3 supplements, depending on their diet.

Worried about your own nutrient gaps on GLP-1? See exactly which nutrients your reduced intake is leaving behind - and how GLP-1 Shield GLP-1 Shield can restore them.

What to watch for in the vitaglp trial results

The VITAGLP trial will measure blood levels of vitamin B12, folate, iron, vitamin D, calcium, and other markers before and after six months of multivitamin use. Researchers will also track side effects, adherence, and any changes in weight loss or metabolic health.

If the trial shows that a standard multivitamin corrects deficiencies, it could change how doctors recommend supplementation for GLP-1 patients. If it doesn't, we'll know we need more targeted approaches - possibly higher doses, different forms, or individualised supplements based on blood work.

Either way, the results will give you something you don't have now: real evidence to guide your decisions. That's worth waiting for.