What Vitamins Should I Take With Mounjaro? - Guide | Cured Pharmacy

What Vitamins Should I Take With Mounjaro?

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Tarun Kumar, Prescribing Pharmacist at Cured Pharmacy

Medically reviewed by

Tarun Kumar, Prescribing Pharmacist (GPhC 2233073)

Reviewed on: 12 June 2026

Last Updated: 12 August 2026

If you have recently started Mounjaro or are considering it as part of your weight loss journey, one of the most important questions you can ask is what vitamins should I take with Mounjaro to stay healthy and get the most out of your treatment. Mounjaro, known generically as tirzepatide, significantly reduces appetite and food intake, which means many people unintentionally consume far fewer nutrients than their body needs. Over time, this can lead to nutritional deficiencies that affect your energy levels, bone health, muscle mass, immune function, and overall wellbeing. Understanding which supplements to prioritise alongside your Mounjaro treatment is not just sensible — it is essential.

Quick Summary

Mounjaro reduces appetite substantially, which can leave your body short on essential vitamins and minerals. Supplementing smartly from the start can protect your health, preserve muscle mass, and keep your energy levels strong throughout your treatment.

  • Vitamin D, B12, iron, calcium, and zinc are the most commonly depleted nutrients during Mounjaro treatment.
  • A daily high-quality multivitamin is a practical foundation for most people on Mounjaro.
  • Protein intake must also be prioritised alongside vitamins to prevent muscle loss.
  • Regular blood tests every three to six months help monitor your nutrient levels accurately.
  • Always speak to a pharmacist or GP before adding new supplements to your routine.

Mounjaro Vitamin Deficiency Risk Checker

Select any symptoms you have been experiencing since starting Mounjaro to identify which vitamins you may need to discuss with your pharmacist or GP.

Table of Contents

Why Vitamins Matter When Taking Mounjaro

Mounjaro works by mimicking both GIP and GLP-1 hormones, powerfully suppressing appetite and slowing gastric emptying. For many people using weight loss treatments like tirzepatide, this means eating significantly smaller portions — often far below the recommended daily caloric intake, especially in the early months. While this drives impressive weight loss results, it also creates a real risk of nutritional shortfall if you are not intentional about what you eat and supplement.

The human body requires a broad spectrum of vitamins and minerals to function properly. When calorie intake drops dramatically, so does your intake of these vital micronutrients. Unlike macronutrients such as fat and carbohydrates, vitamins cannot be produced by the body in adequate amounts — they must come from food or supplements. On Mounjaro, many people simply are not eating enough variety or volume of food to meet these needs naturally.

In 2026, UK healthcare professionals increasingly recognise that nutritional support is a critical but often overlooked aspect of GLP-1 and GIP-based medication management. Deficiencies can develop silently over weeks and months, eventually showing up as fatigue, hair thinning, low mood, brittle bones, or weakened immunity. Addressing this proactively — rather than reactively — makes a meaningful difference to how you feel and how sustainable your results are long-term. Understanding what vitamins should I take with Mounjaro is therefore not an optional extra; it is a fundamental part of your treatment plan.

  • Reduced appetite leads to lower overall micronutrient intake.
  • Nutritional deficiencies can silently develop within three to six months.
  • Supplementing proactively protects energy, bones, mood, and immunity.
  • UK prescribers now routinely advise vitamin support alongside GLP-1 treatments.

What Vitamins Should I Take with Mounjaro: The Essential List

Not all vitamins carry the same level of urgency when you are on Mounjaro, but several stand out as particularly important based on the eating patterns most people develop during treatment. Here is a detailed look at the vitamins most likely to become depleted and what you should consider supplementing.

Vitamin D

Vitamin D is already one of the most widespread deficiencies in the UK population, with Public Health England recommending supplementation for everyone during autumn and winter. When you are eating less food overall, your dietary vitamin D intake drops further. Vitamin D supports bone mineralisation, immune function, muscle strength, and mood regulation — all areas that matter enormously when you are actively losing weight. A daily dose of 1,000 to 2,000 IU is considered safe and appropriate for most adults, though your GP may prescribe higher doses if a blood test confirms significant deficiency.

Vitamin B12

Vitamin B12 is critical for nerve health, red blood cell formation, and energy metabolism. It is found almost exclusively in animal products — meat, fish, eggs, and dairy — which are foods people on Mounjaro often eat less of as portion sizes shrink. Deficiency can develop gradually and is notoriously easy to miss until symptoms like fatigue, tingling extremities, and cognitive difficulty become noticeable. A daily sublingual (under-the-tongue) B12 supplement offers excellent absorption and is well-tolerated alongside tirzepatide treatment.

Vitamin C

Vitamin C plays a role in immune defence, collagen synthesis, and iron absorption — making it especially important if you are also taking iron supplements. As fruit and vegetable intake may dip due to reduced appetite, a modest vitamin C supplement of 500mg daily can help bridge any dietary gaps without causing gastrointestinal side effects, which matters given that Mounjaro can already cause nausea in some users.

Folate (Vitamin B9)

Folate supports cell production, DNA repair, and healthy red blood cells. Reduced intake of leafy greens, legumes, and fortified cereals — all commonly eaten in smaller amounts on Mounjaro — can lower folate levels over time. A B-complex supplement that includes folate alongside B12 and B6 offers a convenient solution that addresses multiple B vitamin needs simultaneously.

  • Vitamin D: 1,000–2,000 IU daily, especially through autumn and winter in the UK.
  • Vitamin B12: Sublingual form for superior absorption; 500–1,000mcg daily.
  • Vitamin C: 500mg daily to support immunity and iron absorption.
  • B-complex including folate: Addresses multiple B vitamin gaps at once.

Key Minerals and Nutrients to Prioritise Alongside Vitamins

Beyond vitamins, several essential minerals are equally at risk of depletion during Mounjaro treatment. When thinking about what vitamins should I take with Mounjaro, it is important not to overlook these mineral cofactors, as they work synergistically with vitamins to maintain your health.

Iron

Iron-deficiency anaemia is one of the more common nutritional complications associated with significant calorie restriction. It is particularly relevant for women of childbearing age who are menstruating. Symptoms include fatigue, pale skin, dizziness, and shortness of breath. However, iron supplementation should only be started after a GP-confirmed blood test, as excess iron can cause its own problems including constipation and gastrointestinal distress — side effects that may compound the nausea some people already experience on Mounjaro.

Calcium

Calcium is essential for bone density, muscle contraction, and nerve signalling. During weight loss, particularly rapid weight loss, bone resorption can increase. If dairy and calcium-rich foods are being eaten less frequently due to suppressed appetite, calcium levels may fall. Adults need approximately 700mg of calcium per day, ideally from food sources, but a supplement of 500mg can be useful if dietary intake is consistently low. Always pair calcium with vitamin D for optimal absorption.

Zinc

Hair thinning is one of the most distressing side effects reported by people on GLP-1 and GIP weight loss medications. While some degree of telogen effluvium (stress-related hair shedding) is a normal response to rapid weight loss, low zinc levels can make it significantly worse. Zinc also supports immune function, wound healing, and taste perception. A low-dose zinc supplement of 8–15mg daily is generally sufficient and well-tolerated.

Magnesium

Magnesium is involved in over 300 enzymatic reactions in the body. It supports energy production, sleep quality, muscle function, and blood sugar regulation. Given that Mounjaro already improves blood sugar control, adequate magnesium levels help optimise this effect further. Many people are mildly deficient in magnesium even before starting any weight loss treatment, so a daily supplement of 200–300mg elemental magnesium is a sensible addition.

  • Iron: Confirm deficiency with a blood test before supplementing.
  • Calcium: 500mg supplemental calcium if dietary intake is consistently low.
  • Zinc: 8–15mg daily to combat hair thinning and support immunity.
  • Magnesium: 200–300mg daily to support energy, sleep, and muscle function.

Mounjaro Vitamin and Supplement Reference Table

Vitamin / Mineral Why It Matters on Mounjaro Recommended Daily Amount Best Food Sources Supplement Form
Vitamin D Bone health, immunity, mood support 1,000–2,000 IU Oily fish, eggs, fortified foods Softgel or spray
Vitamin B12 Energy, nerve health, red blood cells 500–1,000 mcg Meat, fish, eggs, dairy Sublingual tablet or spray
Vitamin C Immunity, collagen, iron absorption 500 mg Citrus fruit, peppers, broccoli Chewable tablet or capsule
Folate (B9) Cell production, DNA repair, red blood cells 400 mcg Leafy greens, legumes, fortified cereals B-complex tablet
Iron Prevents anaemia, supports energy As prescribed by GP Red meat, lentils, spinach Ferrous sulfate (GP prescribed)
Calcium Bone density, muscle contraction 700 mg (total daily) Dairy, fortified plant milk, sardines Calcium carbonate or citrate
Zinc Hair health, immunity, wound healing 8–15 mg Meat, shellfish, pumpkin seeds Zinc gluconate or citrate
Magnesium Energy, sleep, blood sugar regulation 200–300 mg Nuts, seeds, dark chocolate, greens Magnesium glycinate or citrate

Protein and Diet: Why Nutrition Goes Beyond Just Supplements

Supplements are an important safety net, but they cannot replace a thoughtfully structured diet. Protein is arguably the most critical macronutrient for people on Mounjaro. When you lose weight rapidly, your body does not just shed fat — it also risks losing lean muscle mass if protein intake is inadequate. Preserving muscle is vital not only for physical strength and metabolic rate but also for long-term weight maintenance once treatment ends.

Aiming for at least 1.2 to 1.6 grams of protein per kilogram of body weight per day is a reasonable target for most adults on Mounjaro. This might look like prioritising high-protein foods at every small meal — Greek yoghurt, eggs, lean chicken, fish, tofu, or cottage cheese. Even with suppressed appetite, small, nutrient-dense meals that lead with protein make a measurable difference to how much muscle you retain.

Omega-3 fatty acids, found in oily fish such as salmon, mackerel, and sardines, also deserve a mention. They support cardiovascular health, reduce inflammation, and may help with mood — all relevant when your body is undergoing significant metabolic change. If oily fish is not a regular part of your diet, a daily omega-3 supplement providing at least 500mg of combined EPA and DHA is a worthwhile addition.

Hydration is another overlooked factor. Mounjaro slows gastric emptying, which can sometimes reduce the sensation of thirst. Aiming for at least 1.5 to 2 litres of water daily helps support kidney function, nutrient transport, and the management of constipation — a side effect that some people experience during treatment. Thinking holistically about diet, hydration, and supplementation ensures that your weight loss journey is as healthy and sustainable as possible.

  • Target 1.2–1.6g of protein per kg of body weight daily to preserve muscle.
  • Prioritise protein at every small meal — eggs, fish, Greek yoghurt, legumes.
  • Omega-3 supplements (500mg EPA/DHA) support heart and mood health.
  • Stay hydrated with 1.5–2 litres of water daily to aid nutrient absorption.
  • Focus on nutrient-dense foods rather than high-calorie, low-nutrient options.

What to Avoid Taking with Mounjaro

Just as important as knowing what to take is knowing what to avoid. Certain supplements can interact with how Mounjaro works or cause side effects that are counterproductive to your treatment goals. Understanding these considerations is part of answering the broader question of what vitamins should I take with Mounjaro — because supplementation is not simply about adding more, it is about adding wisely.

High-dose fat-soluble vitamin supplements — particularly vitamin A (retinol) and vitamin E — should be approached with caution. Fat-soluble vitamins accumulate in body tissue over time and can reach toxic levels if over-supplemented. Since Mounjaro may reduce fat absorption slightly due to its effect on gastric motility, the interaction with high-dose fat-soluble vitamins is worth discussing with your pharmacist before starting.

Herbal supplements such as St John's Wort should generally be avoided during Mounjaro treatment. St John's Wort is known to interact with a wide range of medications by inducing liver enzymes, which can affect drug metabolism. While direct evidence for tirzepatide interaction is still emerging, the precautionary approach is to avoid it unless your GP advises otherwise.

Stimulant-based weight loss supplements — including those containing high-dose caffeine, synephrine, or ephedra — are not only unnecessary alongside Mounjaro but may also increase cardiovascular strain. Similarly, very high-dose iodine supplements can interfere with thyroid function, which is already a consideration given that Mounjaro use requires caution in people with a personal or family history of thyroid conditions.

  • Avoid high-dose vitamin A (retinol) — toxicity risk with fat-soluble accumulation.
  • Avoid St John's Wort — may interfere with medication metabolism.
  • Skip stimulant-based weight loss supplements — unnecessary and potentially unsafe.
  • Be cautious with very high-dose iodine — may disrupt thyroid function.
  • Always inform your prescriber of every supplement you are taking.

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Key Takeaways

  • Mounjaro significantly reduces appetite, making vitamin and mineral deficiencies a genuine risk that requires proactive management from the start of treatment.
  • Vitamin D, B12, vitamin C, folate, iron, calcium, zinc, and magnesium are the most important nutrients to monitor and supplement during tirzepatide treatment.
  • A high-quality daily multivitamin provides a solid baseline, but targeted single supplements may be needed based on blood test results.
  • Protein intake of 1.2–1.6g per kg of body weight daily is essential to preserve lean muscle mass during rapid weight loss.
  • Always confirm deficiencies with a blood test and consult your GP or pharmacist before adding new supplements to your routine.

When to Seek Professional Advice

While general vitamin supplementation is safe for most adults, there are specific situations where you should speak to a GP or pharmacist rather than self-prescribing supplements. If you experience any of the following, book an appointment promptly:

  • Persistent fatigue or weakness that does not improve despite supplementing and eating adequately.
  • Significant hair loss beyond the normal adjustment period of the first few months.
  • Tingling, numbness, or weakness in your hands or feet, which may indicate B12 or nerve-related deficiency.
  • Symptoms of anaemia including dizziness, pallor, and breathlessness.
  • Muscle cramps, spasms, or irregular heartbeat, which may indicate electrolyte imbalance.
  • Any new symptoms you are unsure about — never assume a symptom is simply a side effect of Mounjaro without checking.

Regular monitoring is strongly advised for anyone on long-term Mounjaro treatment. A baseline blood test before starting, followed by checks every three to six months, allows your clinical team to identify deficiencies early and adjust your supplement plan accordingly. Your GP may also refer you to a dietitian for personalised nutritional support, which can make a significant difference to your outcomes.

Scientific References

  1. Public Health England — Vitamin D Supplementation Guidance for Health Professionals (GOV.UK) [Accessed 12 August 2026]
  2. NHS — Vitamins and Minerals: What They Do and Where to Find Them (NHS.uk) [Accessed 12 August 2026]
  3. NICE Guideline NG238 — Obesity: Identification, Assessment and Management (NICE.org.uk) [Accessed 12 August 2026]
  4. Type 2 diabetes in adults: management, NICE guideline NG28, National Institute for Health and Care Excellence, 2022 [Accessed 12 August 2026]
  5. Mounjaro 2.5 mg solution for injection – Summary of Product Characteristics, Electronic Medicines Compendium, Eli Lilly, 2023 [Accessed 12 August 2026]
  6. Vitamin D: advice for all age groups, UK Health Security Agency, 2022 [Accessed 12 August 2026]
  7. Tirzepatide monograph, British National Formulary, NICE/BMJ Group, 2024 [Accessed 12 August 2026]
  8. Tirzepatide (Mounjaro), Diabetes UK, 2023 [Accessed 12 August 2026]
  9. Hjerpsted JB et al., Semaglutide improves postprandial glucose and lipid metabolism, and delays first-hour gastric emptying in subjects with obesity, Diabetes, Obesity and Metabolism, 2018 [Accessed 12 August 2026]

Frequently Asked Questions

Can you take a multivitamin with Mounjaro?

Yes, you can take a multivitamin with Mounjaro. Taking a high-quality multivitamin with Mounjaro is generally safe and often recommended, as reduced food intake can lower your nutrient levels. Choose a formulation that includes vitamin D, B12, iron, calcium, and zinc, and take it at a different time to your Mounjaro injection.

Is it safe to take vitamin B12 while on Mounjaro?

Yes, it is safe to take vitamin B12 while on Mounjaro. Vitamin B12 supplementation is actively encouraged for people using Mounjaro, as reduced appetite and lower food intake can deplete B12 levels over time. Low B12 can cause fatigue, nerve issues, and low mood, so supplementing daily is a sensible precaution.

How long does it take for vitamin deficiencies to develop on Mounjaro?

Vitamin deficiencies on Mounjaro can develop within a few months of starting treatment, especially if food intake is significantly reduced. Nutrients like vitamin D, B12, and iron can drop noticeably within three to six months. Regular blood tests every three to six months are recommended to monitor your levels and adjust supplementation accordingly.

What is the best time of day to take vitamins with Mounjaro?

The best time to take vitamins with Mounjaro is at a separate time from your weekly injection, ideally with a meal to improve absorption. Fat-soluble vitamins like D and K are best taken with food containing healthy fats. Water-soluble vitamins such as B12 and C can be taken at any time of day.

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