GLP-1 drug users need nutritional monitoring: vitamin D, B vitamins, iron, and protein deficiencies found within 12 months | Research

The takeaway

GLP-1 receptor agonists are associated with inadequate protein intake, sarcopenia, and deficiencies in vitamin D, thiamine, iron, calcium, and magnesium within 12 months, yet no formal nutritional monitoring protocols exist.

No monitoring protocols exist
Despite causing nutritional deficiencies within 12 months, GLP-1 drugs lack the mandatory nutritional monitoring established for bariatric surgery

What the researchers found

GLP-1RAs reduce caloric intake with frequent protein inadequacy and sarcopenia. Deficiencies within 12 months: vitamin D (most common), thiamine/B vitamins, iron, calcium, magnesium, potassium. No formal monitoring protocols exist despite parallel mechanisms to bariatric surgery.

Why it matters

With millions on GLP-1 drugs for years, nutritional deficiencies could become a major public health issue. Establishing monitoring protocols now—before widespread deficiency-related complications emerge—is a preventive imperative.

How the study worked

Narrative review of PubMed and Embase OVID (August 2025) with three-stage screening. Comparison to bariatric surgery nutritional monitoring guidelines.

What this study cannot tell us

Narrative review with limited observational data. Causation vs association unclear for some deficiencies. Most data from short-term studies. Optimal monitoring protocols not yet validated for GLP-1 users.

How to read the evidence

Narrative review of observational evidence. Highlights an important clinical gap but evidence for specific monitoring protocols is not yet established.

When this study was published

Published in 2025; literature through August 2025.

The bigger picture

The rapid expansion of GLP-1 prescribing has outpaced safety framework development. This review draws an important parallel to bariatric surgery, where decades of experience led to mandatory nutritional monitoring—lessons that should be applied to GLP-1 therapy now.

Questions still open

Should baseline nutritional screening be mandatory before starting GLP-1 drugs?
Which specific supplements should be recommended for long-term GLP-1 users?
Does sarcopenia from GLP-1 drugs worsen long-term health outcomes?

Common questions

Can GLP-1 drugs cause vitamin deficiencies?

Yes. This review found that GLP-1 drugs reduce caloric intake enough to cause deficiencies in vitamin D, B vitamins, iron, calcium, magnesium, and potassium within 12 months. Protein intake is often inadequate, and some patients develop muscle loss (sarcopenia). Regular blood tests and dietary counseling are recommended.

Should I take supplements while on a GLP-1 drug?

Based on this review, it may be wise to discuss with your doctor about monitoring your vitamin D, B vitamins, iron, and other nutrients. A high-protein diet is especially important to prevent muscle loss. The authors recommend adapting the nutritional monitoring used after bariatric surgery for GLP-1 patients.

Read the original research

Macronutrient, Micronutrient Supplementation and Monitoring for Patients on GLP-1 Agonists: Can We Learn from Metabolic and Bariatric Surgery?

Nutrients, 17(23)

View on PubMed ↗Publisher’s paper ↗

Citation

Sibal, Rhea; Balamurugan, G; Langley, Jasmine; Graham, Yitka; Mahawar, Kamal. (2025). Macronutrient, Micronutrient Supplementation and Monitoring for Patients on GLP-1 Agonists: Can We Learn from Metabolic and Bariatric Surgery?. Nutrients, 17(23). https://doi.org/10.3390/nu17233659