Which vitamins should you take when on Wegovy?

Why eating less can quietly affect your nutrient levels

Wegovy works partly by reducing how hungry you feel, and for many people that means significantly smaller meals. That's the point. But it creates a practical problem: if you're eating a third less food than before, you're also absorbing a third fewer vitamins and minerals from your diet unless you're being deliberate about what's on your plate.

The nutrients most vulnerable to this squeeze are the ones already borderline in many UK adults. NHS guidance on semaglutide notes that treatment should sit alongside dietary changes, and those dietary changes need to stay nutritionally adequate, not just lower in calories. Protein tends to get the most attention (rightly so, to protect muscle during weight loss), but it's the micronutrients that often go unnoticed until a blood test flags something.

There's no single list of vitamins that every person on Wegovy needs. The useful question is: given how I'm eating right now, what am I probably short of? The sections below frame the main decisions.

The vitamins most worth considering, and why

Vitamin D is the most widely discussed, and for good reason. It was already deficient in an estimated one in five UK adults before GLP-1 medicines existed, according to data from the Health Survey for England. Reduced sun exposure, limited oily fish and fortified dairy in the diet, and the body-fat relationship with vitamin D storage all play a role. On Wegovy, if your overall food volume drops, you have fewer opportunities to top it up through diet. A daily supplement of 10 micrograms (400 IU) is the baseline recommendation for most UK adults regardless of treatment; your GP can test your serum 25-hydroxyvitamin D level if you want a more precise picture. The vitamin D and Wegovy page goes into this in much more detail.

Vitamin B12 matters because semaglutide slows gastric emptying, which changes the environment in which B12 is absorbed. If you eat less animal protein generally, or if you're over 50, deficiency risk is higher. Symptoms develop slowly (fatigue, tingling, cognitive fog) and are easy to attribute to weight loss itself, which makes a blood test more useful than watching for symptoms.

Iron and folate are worth checking if you menstruate, are vegetarian or vegan, or have historically had low levels. Calcium deserves attention if your dairy or fortified-food intake is falling alongside overall food volume. A review of the best vitamins to take with Wegovy sets out the evidence base for each of these in practical terms.

What 'just take a multivitamin' gets right, and where it falls short

A broad-spectrum multivitamin covering the main bases is a reasonable default, and it's what many prescribers suggest as a starting point. It costs little, it's safe for most people, and it provides a nutritional floor when your appetite is unreliable. That's the case for it.

The case against relying on it entirely: multivitamins are formulated for average intake levels and contain nutrients in amounts that may be too low for an established deficiency, or occasionally too high for a specific micronutrient you're already getting plenty of from food or another supplement. Vitamin D at 400 IU in a multivitamin is fine for maintenance; it won't correct a deficiency that a blood test has already confirmed.

The honest answer is that a blood panel through your GP (checking vitamin D, B12, ferritin and folate as a minimum) takes the guesswork out. It tells you whether you're supplementing from a low baseline or just maintaining an already adequate level. If you're considering starting Wegovy privately and want to understand costs alongside this kind of nutritional planning, the Wegovy cost and pricing guide sets out what's included and what to factor in. Talk to your prescriber or GP about which tests are worth doing before or during treatment. You can also explore what vitamins to take on Wegovy with a focus on individual circumstances.

Practical points: timing, interactions, and telling your prescriber

Most standard vitamin and mineral supplements don't interact with semaglutide in a clinically significant way. The main practical consideration is timing for the Wegovy tablet form, where oral semaglutide must be taken on an empty stomach with only water, and you should wait at least 30 minutes before anything else, including other oral medicines or supplements. For the weekly injection, timing of supplements relative to your dose isn't a clinical concern.

One thing that does matter: tell your prescriber what you're taking. That includes supplements, not just prescribed medicines. Some nutrients at high doses (vitamin A, for instance) carry risks during weight loss, and a few can affect lab results that your clinical team uses to monitor your progress. Your prescriber at nume reviews your treatment before every repeat, that's the right moment to mention any changes to what you're taking.

The guide to vitamins while on Wegovy covers how to structure supplementation across different stages of treatment. If you'd like to discuss your individual situation with a clinician, speak to our prescribers through a free consultation.