Best Vitamins to Take on Mounjaro (UK): What You Actually Need

The best vitamins to take on Mounjaro, Wegovy or Ozempic: what NHS weight-management services advise, which nutrients are most at risk when you eat less, protein, hair shedding, tiredness, and what to ask your prescriber.

By GUUDIES Editorial Team Published 11 April 2026 Updated 26 October 2026 7 min read

By the GUUDIES Editorial Team · Updated 25 October 2026 · Based on NHS and peer-reviewed guidance (sources below).

Disclosure: GUUDIES sells a daily gummy pouch. This guide is general information, not medical advice. If you are prescribed tirzepatide (Mounjaro) or semaglutide (Wegovy, Ozempic), your prescriber or GP is the right person to check your diet, blood results and any supplements with.

The short answer: the best vitamins to take on Mounjaro are the ones that cover what you are no longer eating. Some NHS weight-management services suggest a daily A to Z multivitamin while you are on treatment, everyone in the UK should consider vitamin D in autumn and winter, and B12, iron, calcium, magnesium and zinc are the nutrients most worth watching. A supplement does not replace food: protein at every meal and a varied diet still matter most.

Do you need vitamins on Mounjaro, Wegovy or Ozempic?

Not everyone does, but many people benefit from a simple safety net. GLP-1 medicines such as Mounjaro and Wegovy work partly by making you eat less, and eating less food means taking in fewer vitamins, minerals and less protein. Patient information from Cambridge University Hospitals NHS Trust on tirzepatide says supplements are not essential, but recommends a daily A to Z multivitamin because the medicine may reduce how much you eat. In 2025, four obesity and nutrition societies (the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association and The Obesity Society) published a joint advisory listing the prevention of micronutrient deficiencies, and enough protein to protect muscle, among the nutrition priorities for people on GLP-1 treatment.

You are more likely to fall short if you are eating very small portions for months, losing weight quickly, eating a narrow range of foods, or following a vegan diet.

The best vitamins and minerals to take on Mounjaro

Nutrient	Why it matters	Good food sources
Protein	Contributes to the maintenance of muscle mass, which can fall during weight loss	Fish, eggs, Greek yoghurt, tofu, beans, lentils, lean meat
Vitamin D	Contributes to the maintenance of normal bones and muscle function and to the normal function of the immune system; the NHS advises 10µg a day in autumn and winter for everyone in the UK	Oily fish, eggs, fortified foods (and a supplement in winter)
Calcium	Needed for the maintenance of normal bones	Dairy or fortified plant milks, tofu set with calcium
Iron	Contributes to the reduction of tiredness and fatigue; women of childbearing age need more	Red meat, pulses, fortified cereals, dark leafy greens
Vitamin B12	Contributes to the reduction of tiredness and fatigue; only reliably found in animal foods or fortified foods	Fish, meat, eggs, dairy, fortified plant milks and yeast extract
Magnesium and zinc	Magnesium contributes to normal muscle function; zinc contributes to the maintenance of normal hair, nails and skin	Nuts, seeds, wholegrains, pulses, shellfish

A blood test is the only way to know whether you are actually low in something like iron, B12 or vitamin D. Ask your GP if you have symptoms.

Protein comes first

When your appetite drops, it is easy to skip protein and fill up on whatever feels easy. Losing weight quickly without enough protein can mean losing muscle as well as fat. Practical steps: start each meal with the protein part of your plate, keep easy options in the fridge (eggs, yoghurt, tinned fish, tofu), and add strength exercise if your clinician agrees. Vitamin supplements do not provide meaningful protein, so food has to do this job.

Hair shedding on GLP-1 medicines

Hair loss is listed as a common side effect in NHS patient information for tirzepatide. Shedding during fast weight loss is often temporary and linked to the weight loss itself rather than the drug. Eating enough protein and avoiding very low intakes of iron and zinc are sensible; biotin and zinc contribute to the maintenance of normal hair, but taking more than you need will not speed regrowth. See your GP if shedding is heavy or lasts more than a few months.

Tiredness and brain fog

Feeling weak or tired is common on tirzepatide, probably because you are eating fewer calories. NHS guidance suggests regular small meals and a balanced diet. Drink enough fluids, and if tiredness is persistent ask your GP whether to check iron, B12, vitamin D and thyroid function rather than guessing.

Ozempic and Wegovy versus Mounjaro: is the advice different?

No. Ozempic and Wegovy contain semaglutide and Mounjaro contains tirzepatide. They work slightly differently, but all reduce appetite, so the nutrition advice is the same: protein at each meal, a varied diet, vitamin D in winter, and a multivitamin if your intake is low. Ozempic is licensed in the UK for type 2 diabetes; Wegovy and Mounjaro are licensed for weight management.

What to avoid

Any product that claims to boost, copy or replace a GLP-1 medicine. Food supplements cannot do what a prescription medicine does.
High-dose single nutrients without a reason. More is not better: for example, adults should not take more than 100µg (4,000 IU) of vitamin D a day unless a doctor advises it.
Stacking several products without adding up the totals. A multivitamin, a separate vitamin D and fortified foods all count.
Starting or stopping anything without telling your prescriber if you take other medicines.

Where GUUDIES fits

GUUDIES is a daily pouch of six gummies, including a multivitamin and greens gummy with 20µg (800 IU) of vitamin D3, B12 and zinc. It is a convenient way to cover everyday vitamin and mineral basics, not a weight-loss product and not a substitute for protein or meals. It does not contain iron or meaningful amounts of calcium or magnesium, so check those with your GP if you are low. Five of the six gummies are vegan; the Marine Collagen gummy contains fish collagen, so it is not suitable if you avoid fish or are allergic to it. Check the full ingredient list with your prescriber if you are unsure, and add up your totals if you take other supplements.

Common questions

What are the best vitamins to take on Mounjaro?
A daily A to Z multivitamin is what some NHS services suggest, plus vitamin D in autumn and winter. B12, iron, calcium, magnesium and zinc are worth watching if you are eating much less, and a blood test tells you what you actually need.

Should I take a multivitamin on Mounjaro?
Many people do. Some NHS services recommend a daily A to Z multivitamin while on tirzepatide because you eat less. It is not essential if your diet is still varied and your blood results are normal.

Do supplements interfere with Mounjaro or Wegovy?
Standard-dose vitamins and minerals are not known to interact with these medicines, but tell your prescriber about anything you take, especially if you are on other medicines too.

Will vitamins stop hair loss on Mounjaro?
Not on their own. Shedding is mostly linked to fast weight loss. Eating enough protein matters, zinc contributes to the maintenance of normal hair, and shedding usually settles.

How long should I take supplements for?
For as long as your food intake is reduced. Review it with your GP or prescriber as your appetite and diet change.

Sources

Cambridge University Hospitals NHS Foundation Trust, Your obesity treatment: tirzepatide (Mounjaro): cuh.nhs.uk
Mozaffarian D et al. Nutritional priorities to support GLP-1 therapy for obesity: a joint advisory (ACLM, ASN, OMA, TOS), May 2025: obesity.org
NHS, Vitamin D: nhs.uk
GB Nutrition and Health Claims Register: gov.uk