Published on April 29, 2025
Key takeaways:
- We don’t know for sure how GLP-1-related medications such as Ozempic (semaglutide) affect nutrient levels in your body. But there’s some evidence that they may reduce the absorption of iron while you’re using them.
- GLP-1-related medications can reduce your appetite, and a low-fat diet is often recommended while you’re using them. This could lead to lower levels of vitamins A, D, E and B12.
- Talk to your prescriber before taking any supplements. Avoid weight-loss supplements as well as calcium unless your prescriber OKs them.
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GLP-1 medications, such as Ozempic (semaglutide) and Wegovy (semaglutide), have quickly become some of the most popular medications in the U.S.
It’s common to have less of an appetite while taking a GLP-1-related medication. That’s one way they help with obesity and Type 2 diabetes. But these health conditions are often associated with low levels of certain vitamins. And eating less can make deficiencies even more likely. So adding certain supplements to your routine while you use Ozempic or other GLP-1 medications might be beneficial.
Below we’ll look at supplements to consider if you’re taking a GLP-1-related medication. Keep in mind that not everyone will experience low levels of these vitamins and nutrients. So it’s best to talk to your prescriber before adding any of them to your regimen. They can run tests to determine which supplements are appropriate for you.
1. Vitamin B12
One small study found lower vitamin B12 levels in people using semaglutide for weight management and diabetes after weight-loss surgery. We don’t know for sure if semaglutide affects B12 levels in people who haven’t had weight-loss surgery. But low B12 levels have been linked with both obesity and Type 2 diabetes (conditions GLP-1 medications treat).
Vitamin B12 plays an important role in energy levels and metabolism. Food sources include beef, poultry, and animal-based dairy products. It’s also available as an over-the-counter (OTC) supplement as well as a prescription medication. Your prescriber will let you know what form and dose of vitamin B12 is best for you.
2. Iron
Low iron is the most common nutrient deficiency in the world. And a recent study shows that GLP-1 medications may reduce iron absorption. This may increase your risk for low iron levels as well as iron-deficiency anemia (low red blood cells).
Iron-rich foods include seafood, red meat, and dark poultry meat. Beans, seeds, and leafy greens also contain iron, but it’s harder for the body to absorb than animal sources.
Ask your prescriber to check your iron levels if you’re using GLP-1 medications. They can make sure you’re getting enough from your diet and recommend an OTC or prescription iron supplement if needed. But don’t take extra iron on your own — too much iron can cause dangerous side effects.
3. Fiber
It’s estimated that only 5% of U.S. adults meet the recommended amount of fiber in their diet. And this number is even lower for adults who are considered overweight or obese. The reduced appetite caused by GLP-1 medications may reduce fiber intake even further.
- What is a balanced diet? A dietician shares some examples of what a balanced diet looks like to help you get the nutrients you need.
- Weight-loss strategies: Managing your stress and getting more sleep can help you reach your weight goal. We review 12 science-backed strategies to lower your weight.
- How to save: Treatment with glucagon-like peptide-1 (GLP-1) medications doesn’t have to break the bank. Explore ways you can save on your GLP-1 prescription.
Fiber has a lot of health benefits, from better digestion to improved blood sugar and cholesterol levels. Good food sources of fiber include:
- Whole grains
- Beans, peas, and lentils
- Nuts and seeds
- Fruits and vegetables
Fiber is also available as an OTC supplement, such as psyllium (Metamucil). It’s a good idea to add fiber to your diet slowly over time and avoid taking too much — this can help reduce gas, bloating, or diarrhea.
4. Vitamin D
About 25% of people have low levels of Vitamin D. And people living with obesity or Type 2 diabetes are even more likely to have low Vitamin D levels.
Vitamin D is important for bone health. It also works in the body to fight inflammation, keep your immune system strong, and help your body break down sugars.
Food sources of Vitamin D include fatty fish and fortified foods, such as cereal and dairy products. It’s also available as an OTC supplement and a prescription medication. Your prescriber will recommend a product and dosage for you if your vitamin D levels are low. But it can be toxic if you take too much, so you should only take vitamin D if your prescriber recommends it.
5. Vitamins A & E
Low vitamin A and vitamin E levels are more likely in people living with obesity as well as Type 2 diabetes. Vitamin A and vitamin E are also fat soluble vitamins. This means they’re absorbed better in the presence of fat. If you’re following a low-fat diet, which is often recommended with Ozempic and other GLP-1 medications, you may be at an even greater risk of vitamin A and vitamin E deficiency.
Vitamin A is important for vision, skin, and a healthy immune system. Food sources of vitamin A include carrots, sweet potatoes, and spinach.
Vitamin E is an antioxidant that protects your cells from damage and helps prevent blood clots and some cancers. Nuts, seeds, and vegetable oils are good sources of vitamin E.
Vitamin A and vitamin E are available as OTC supplements. But both can be harmful if you take too much. So it’s best to talk to your prescriber first to see if your levels are low and determine the best dosage for your needs.
6. Magnesium
Magnesium plays a key role in regulating your blood pressure and blood sugar levels. It also helps your nerves and muscles work properly and supports your immune system.
Older adults and those living with Type 2 diabetes are more likely to have low magnesium levels. There have also been reports of low magnesium levels in people using semaglutide. This may be due to semaglutide side effects, such as severe vomiting and diarrhea, which may affect magnesium levels. It’s also more likely if you’re taking other medications that can lower magnesium levels, such as proton pump inhibitors.
Food sources of magnesium include nuts, whole grains, and leafy greens. It’s also available as an OTC supplement. Your prescriber can advise you on the right magnesium dosage if your levels are low, but you shouldn’t take it on your own. Too much magnesium can lead to diarrhea as well as more serious heart-related side effects.
7. Potassium
Potassium is another mineral that can be affected by vomiting that can happen with GLP-1 medications. Low potassium is more common for those living with diabetes, and it often appears along with low magnesium levels.
High potassium foods include avocados, beans, and raisins. It’s also available as an OTC or prescription supplement. Too much potassium can cause heart problems and even lead to death in severe cases. So you shouldn’t take potassium unless your prescriber recommends it.
Should you take a daily multivitamin if you’re using a weight-loss medication like Wegovy?
It’s usually better to get the vitamins and minerals you need through the food you eat, rather than from a supplement. So a daily multivitamin isn’t typically recommended if you’re using a GLP-1 related weight-loss medication.
That being said, if you eat a restrictive diet (such as a vegan or vegetarian) or aren’t getting enough nutrients from your food, a multivitamin can help. In most cases it isn’t harmful to take a daily multivitamin. But it’s still a good idea to check with your prescriber first. They can check your blood levels to help determine which supplements, if any, are best.
What supplements should you avoid taking with Ozempic and similar medications?
You should avoid taking other weight-loss supplements along with GLP-1 medications. This includes products such as ephedra, green tea extract, and garcinia cambogia. These medications can further reduce your appetite, as well as your risk of nutrient deficiencies. We also don’t know if it’s safe to combine them with prescription weight-loss medications.
It’s also a good idea to check with your prescriber before taking calcium supplements along with GLP-1 medications. In studies, participants reported high calcium levels with GLP-1 medications. Taking extra calcium could raise this risk. Your prescriber can check your calcium levels and make sure a calcium supplement is safe for you.
The bottom line
It’s too soon to know if GLP-1 medications such as Ozempic (semaglutide) increase the risk of vitamin and mineral deficiencies. But there’s some evidence that these medications may impact iron levels.
GLP-1 medications like Ozempic can lower appetite, which may lead to low levels of vitamins A, B12, D, and E — especially for people already at risk due to obesity or Type 2 diabetes. And digestive side effects, such as vomiting or diarrhea, can lead to low magnesium and potassium levels.
Not everyone needs to take a supplement while using GLP-1 medications. Focus on a balanced diet with plenty of fiber to get the nutrients you need. Your prescriber can also check your nutrient levels and let you know if a supplement may help. But avoid taking weight-loss supplements or calcium without medical advice, as they may do more harm than good.
Why trust our experts?
Alex Evans, PharmD, MBA
Stacia Woodcock, PharmD
Patricia Pinto-Garcia, MD, MPH
References
Agarwal, S., et al. (2015). Comparison of prevalence of inadequate nutrient intake based on body weight status of adults in the United States: An analysis of NHANES 2001–2008. Journal of the American College of Nutrition.
Albai, O., et al. (2024). Vitamin D—a new therapeutic target in the management of type 2 Diabetes patients. Journal of Clinical Medicine.
