Disclosure
This article contains an affiliate link. Healthycell, discussed near the end, runs an affiliate programme we participate in, and we may earn a commission if you buy through our link. We say plainly below that a multivitamin is a partial answer rather than a solution. Read our full affiliate disclosure.
This page is informational only and is not medical advice. Testing beats guessing — ask your prescriber rather than self-treating suspected deficiencies.
The short version
A 2026 narrative review in Clinical Obesity found vitamin D deficiency in 7.5% of GLP-1 users at six months and 13.6% at twelve, iron depletion frequent, and more than 60% consuming below requirements for calcium and iron.
It also noted that unlike bariatric surgery, there are no consensus guidelines for micronutrient monitoring in GLP-1 users. If nobody is checking, that job falls to you and your prescriber.
Why This Happens
There is nothing exotic about the mechanism, which is part of why it gets overlooked. GLP-1 medications suppress appetite, delay gastric emptying, substantially reduce caloric intake and frequently cause gastrointestinal side effects. Eat markedly less for a sustained period and micronutrient intake falls alongside calories — and for some nutrients, absorption is affected too.
None of that makes the medication unsafe. It means a predictable consequence of eating much less deserves the same attention the calories get.
What the 2026 Review Found
| Nutrient | Reported finding |
|---|---|
| Vitamin D | The most common abnormality — deficiency in 7.5% at six months, rising to 13.6% at twelve. Average intake ran at about 20% of recommendations. |
| Iron | Depletion frequent. GLP-1 users showed ferritin 26–30% lower than a comparator group on SGLT2 inhibitors. |
| Calcium | More than 60% of users consumed below estimated requirements, alongside iron. |
| Thiamine and B12 | Deficits increased over time. Case reports linked GLP-1 use to severe thiamine deficiency including Wernicke encephalopathy and beriberi. |
| Protein | Insufficiency contributed to lean mass loss, together with calcium. |
The gap that matters most
The review is explicit that unlike bariatric surgery, there are no consensus guidelines for micronutrient monitoring in GLP-1 users. Bariatric patients eating comparable volumes receive structured supplementation protocols and scheduled bloodwork as standard care.
A large share of GLP-1 patients receive neither — particularly through telehealth providers that require no lab work at any point, which describes most of the providers in our provider reviews. That absence is a reason to ask rather than a reason to assume you are fine.
What to Actually Do
- Eat enough protein. It is the shortfall with the clearest downstream consequence — lean mass — and the one no pill fixes. Our muscle loss guide covers the 1.2–1.6g per kg target.
- Ask for baseline bloods, then repeat them. Vitamin D, ferritin and full blood count, B12 and folate is a reasonable starting panel. Baseline first, so you know what changed.
- Prefer providers that require lab work. Sunlight, Hone Health and Everlywell all build testing into the programme. Most do not.
- Treat prolonged vomiting as a flag, not a nuisance. Sustained poor intake with vomiting is the setting in which the serious thiamine cases arose. That warrants medical attention rather than endurance.
- Supplement what is low, not what you assume is low. Iron in particular should not be taken speculatively — excess is harmful, and it needs a ferritin result behind it.
Where a Multivitamin Fits
A daily multivitamin is a sensible, cheap hedge against broad low-level shortfall while you are eating substantially less. It is not a substitute for eating enough, and it is not a treatment for a diagnosed deficiency — but as insurance against the gradual erosion the review describes, it is reasonable.
Healthycell makes its multivitamin in a gel format rather than a tablet, marketed as MicroGel, with a claim of 165% greater absorption than tablets and one gel pack replacing fourteen pills. Its Bioactive Multi is $59.95 for 30 gel packs with 15% off on subscription; it also sells Heart & Vascular Health and Joint Health & Mobility at $64.95, a Bone Strength formula at $59.95, and a Glucose Support product. Products are independently label tested, tested for heavy metals, GMP certified, non-GMO, gluten- and soy-free, and carry a 30-day money-back guarantee and the standard FDA structure/function disclaimer. The company also publishes educational content specifically about GLP-1 medications and nutrient gaps, which is more engagement with the issue than most supplement brands manage.
What it will not do
It will not correct a diagnosed deficiency. Vitamin D repletion typically needs a higher dose than any multivitamin contains, iron deficiency needs targeted treatment guided by a ferritin result, and B12 sometimes needs injection rather than oral dosing.
It also will not supply protein, which is the shortfall with the most direct consequence. And at roughly $60 a month, a multivitamin is a premium-priced hedge — a basic one from a pharmacy covers most of the same ground for a fraction of the cost. What you are paying extra for here is the format and the absorption claim.
Independently tested, GMP certified, guaranteed for 30 days, in a format that is genuinely easier to take when your appetite is suppressed — and from a company that actually writes about the GLP-1 nutrient question. Scored down for price: about $60 a month for a multivitamin is a premium over a pharmacy equivalent, and no multivitamin addresses the protein gap or a diagnosed deficiency.
A multivitamin · Not a treatment for a diagnosed deficiency · Get the bloods first
Frequently Asked Questions
Do GLP-1 medications cause nutrient deficiencies?
Not directly, but they create the conditions for them. A 2026 narrative review in Clinical Obesity set out the mechanisms: appetite suppression, delayed gastric emptying, substantially reduced caloric intake and gastrointestinal side effects together reduce both how much you eat and, in some cases, how well you absorb it. The reported figures are meaningful — vitamin D deficiency in 7.5% of users at six months rising to 13.6% at twelve, and GLP-1 users showing ferritin levels 26–30% lower than a comparator group on SGLT2 inhibitors.
Which nutrients are most at risk?
Vitamin D leads the reported deficiencies. Iron depletion is frequent. More than 60% of users were found to consume below estimated requirements for calcium and iron, and average vitamin D intake ran at about 20% of recommendations. Thiamine and cobalamin (B12) deficits increased over time. Protein shortfall matters too, and specifically contributes to the lean mass loss covered in our muscle loss guide.
How serious can this get?
Usually mild, occasionally severe. The review noted case reports linking GLP-1 use to severe thiamine deficiency, including Wernicke encephalopathy and beriberi. Those are rare but genuinely serious — Wernicke encephalopathy is a medical emergency presenting with confusion, unsteady gait and eye-movement abnormalities, typically after prolonged poor intake or persistent vomiting. If you have been eating very little and vomiting for a sustained period, that combination is a reason to seek medical attention rather than wait.
Is anyone monitoring this?
Largely no, and that is the point of this page. The 2026 review states plainly that unlike bariatric surgery — which has established micronutrient monitoring protocols — there are no consensus guidelines for micronutrient monitoring in GLP-1 users. Bariatric patients eating similar volumes get structured supplementation and scheduled bloodwork. GLP-1 patients frequently get neither, particularly at telehealth providers that require no lab work at all.
Will a multivitamin fix it?
It is a reasonable and cheap hedge against broad shortfall, and it is better than nothing. But it is not a complete answer. Iron and B12 deficiencies often need targeted repletion at doses a multivitamin does not contain, vitamin D repletion frequently requires a higher dose than a multi provides, and no supplement substitutes for eating enough protein. The better sequence is: eat enough, ask for the relevant bloods, and supplement what is actually low.
What should I ask my prescriber for?
A reasonable starting request is a baseline and periodic check of vitamin D, ferritin and full blood count, B12 and folate — and, if you have had prolonged vomiting or very low intake, a conversation about thiamine. Providers that require lab work as part of their programme make this easier; several we review do not require any bloodwork at all, which puts the responsibility on you to ask.
Where to Go Next
- Muscle loss on a GLP-1 — the protein half of this problem, with the numbers
- When to talk to a doctor about supplements — which combinations warrant a conversation
- GLP-1 provider reviews — including which providers actually require lab work
Medical Disclaimer
We're not doctors, and this article is for education only — it isn't medical advice. GLP-1 medications are prescription-only and require evaluation by a licensed healthcare provider. Individual results vary widely, and only a clinician who knows your history can determine what is safe and appropriate for you. See our full medical disclaimer.
Keep Comparing
Every provider we've researched, with published pricing, medication type, and what's actually included.
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