Vitamins to Take with Mounjaro: A UK Guide for GLP-1 Users
If you're on Mounjaro, Wegovy or Ozempic and you've noticed you're more tired, your hair's a bit thinner, or your nails are doing weird things — you might be running on empty in a way the prescription didn't warn you about.
GLP-1 drugs are remarkable. They also quietly create one of the largest preventable nutrient deficiencies in modern UK healthcare. Here's what the research shows you actually need to supplement — and why most of it isn't optional.
What the research actually says
A 2024 analysis highlighted by Harvard Health found GLP-1 users had a 49% higher risk of vitamin D deficiency at 12 months compared to non-users. By month 12, 13.6% of users were clinically deficient.
The study also found significantly elevated risks of deficiency in:
- Vitamin B12
- Iron
- Calcium
Observational data points to similar risks for B6, magnesium, zinc and selenium — nutrients that depend on calorie volume and a varied diet to absorb at adequate levels.
Why this happens
GLP-1 drugs work by suppressing appetite and slowing gastric emptying. That's the point. The side effect: you eat less of everything, including the foods that deliver the nutrients your body still needs.
If you're eating 30% fewer calories, and a chunk of what you do eat is whatever sits well with the new GI reality (often plainer, less varied), the maths is brutal. You aren't getting the same volume of nutrients you used to.
It's not your fault. It's the drug working.
The nutrients you actually need to replace
Vitamin D3 (with K2)
The most documented deficiency. Aim for 1,000 IU daily. K2 should be co-stacked so the calcium D3 helps you absorb goes to bones, not arteries.
Vitamin B12
Energy, cognition, nerve function. Often the first to show as fatigue. Animal-product based — and animal products are often the first thing GLP-1 users find hard to eat.
Vitamin B6
Mood and energy metabolism. Quietly depleted in calorie-restricted diets.
Magnesium
Sleep, muscle cramps. Already deficient in many UK adults pre-Mounjaro.
Zinc and selenium
Immunity. Both depleted when food volume drops.
Iron
Especially for women. We don't recommend supplementing iron without a blood test — the dose depends on your actual levels, and over-supplementing iron is uncomfortable and counterproductive.
Why one capsule beats six bottles
The honest reason most people on GLP-1s don't supplement properly isn't ignorance — it's friction. Nobody wants to take six pills with their morning coffee when coffee itself is making them queasy.
If you can't take it, it doesn't work.
We built Solmate as a single daily stack covering vitamin D3, K2, B2, B6, B12, magnesium, zinc, selenium, plus saffron extract for mood. Two capsules a day. It was designed for indoor Brits who don't get enough sun — but it happens to cover most of the deficiencies documented in published GLP-1 nutritional research.
The one thing we don't include is iron. If you're a woman on Mounjaro, get a full bloods panel before starting any iron supplement.
What to do next
- Ask your GP for a 25(OH)D test and a full iron panel.
- If you're below 50 nmol/L on vitamin D, you need at least 1,000 IU daily.
- Stack the documented deficiencies, not whatever's marketed loudest.
- Don't stop the drug — fix the gap it leaves.
This isn't medical advice. Solmate is a food supplement, not a treatment for nutrient deficiency. Talk to your GP or your GLP-1 prescriber before starting any supplement, especially if you're on other medications.