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Vitamins on GLP-1: What Nutrients Should You Pay Attention To?

Aimee Senior
Aug 24
8 min read

If you're eating significantly less since starting a GLP-1 medication, you may be wondering whether you need to take vitamins.


It's a good question.


Medications like Zepbound, Wegovy, Mounjaro, and Ozempic can dramatically decrease appetite and portion sizes. While that's part of what makes these medications effective for weight management, eating less food also means you have fewer opportunities to get the vitamins and minerals your body needs.


So, do you automatically need supplements?


Not necessarily.


But vitamins on GLP-1 medications are something worth paying attention to, particularly if your overall food intake has become very low.


Five wooden spoons hold assorted supplements on a white background

Do GLP-1 Medications Cause Vitamin Deficiencies?


GLP-1 medications themselves aren't the same as bariatric procedures that alter the gastrointestinal tract and may directly affect nutrient absorption.


The bigger nutritional concern for many people taking a GLP-1 is much simpler:


You're eating less food.


If you're eating half of what you previously ate—or regularly skipping meals because you aren't hungry—you're potentially consuming less protein, iron, calcium, vitamin D, B vitamins, zinc, magnesium, and other important nutrients too.


That doesn't mean everyone taking a GLP-1 will develop a deficiency.

It means that the quality of your diet becomes increasingly important as the quantity of food decreases.


Should You Take a Multivitamin on a GLP-1?


A basic daily multivitamin may be appropriate for some people taking GLP-1 medications, particularly if their overall food intake is significantly reduced.


But supplements shouldn't become a substitute for food.


Whenever possible, I want people to get nutrients from a varied diet containing protein foods, fruits, vegetables, whole grains, legumes, dairy or appropriate alternatives, and healthy fats.


Food provides much more than isolated vitamins and minerals.


That said, when portions become very small, a multivitamin can sometimes provide an additional layer of nutritional support.


Your individual needs should be based on your diet, medical history, medications, lab work, and recommendations from your healthcare team.


Iron


Iron is essential for making hemoglobin, which helps transport oxygen throughout your body.


Iron deserves particular attention if you menstruate, have a history of iron deficiency, eat little or no meat, or have significantly reduced your overall food intake.


Common symptoms of iron deficiency may include:


  • Fatigue

  • Weakness

  • Shortness of breath with activity

  • Dizziness or lightheadedness

  • Headaches

  • Feeling cold

  • Pale skin

  • Increased heart rate or heart palpitations

  • Reduced exercise tolerance

  • Hair shedding

  • Brittle nails

  • Craving non-food substances such as ice


Don't automatically start a high-dose iron supplement just because you're experiencing one of these symptoms.


Iron supplements can worsen constipation, and taking more iron than you need can cause problems. If iron deficiency is a concern, talk with your healthcare provider about appropriate lab testing.


Vitamin B12


Vitamin B12 plays an important role in red blood cell production, DNA synthesis, and normal nervous system function.


B12 is naturally found primarily in animal foods such as meat, fish, eggs, and dairy, as well as fortified foods.


People following vegan or highly restrictive diets may be at greater risk of inadequate intake.


Certain medications and gastrointestinal conditions can also affect B12 status.


Symptoms of vitamin B12 deficiency may include:


  • Fatigue

  • Weakness

  • Pale skin

  • Shortness of breath

  • Numbness or tingling in the hands or feet

  • Balance problems

  • Changes in memory or concentration

  • A sore or smooth tongue


Neurological symptoms from significant B12 deficiency are particularly important to address, so persistent numbness, tingling, or balance changes shouldn't simply be attributed to your GLP-1.


Folate


Folate is another B vitamin involved in DNA production and red blood cell formation.


Good sources include leafy green vegetables, beans, lentils, citrus fruits, avocado, and fortified grains.


If your food intake has become very limited or you've eliminated several food groups, your intake may decrease.


Symptoms of folate deficiency may include:


  • Fatigue

  • Weakness

  • Pale skin

  • Shortness of breath

  • Irritability

  • Difficulty concentrating

  • Headaches

  • A sore or swollen tongue

  • Mouth sores


Folate is particularly important for anyone who is pregnant or could become pregnant because adequate intake helps prevent neural tube defects.


Vitamin D


Vitamin D is important for bone health, muscle function, and many other processes in the body.


Vitamin D insufficiency is common in the general population, regardless of GLP-1 use.


Because relatively few foods naturally contain large amounts of vitamin D, this nutrient may already have been difficult to obtain through food alone before starting medication.


Vitamin D deficiency may cause:


  • Muscle weakness

  • Muscle aches

  • Bone pain

  • Fatigue

  • Mood Dysfunction such as depression


Mild deficiency may cause few or no obvious symptoms, which is one reason blood testing can be more useful than trying to diagnose vitamin D deficiency based on symptoms alone.


Your healthcare provider can check your vitamin D level and recommend an appropriate supplement if needed.


Calcium


Calcium is essential for bone health as well as normal muscle and nerve function.


When people begin eating less, foods that don't seem as "important" as protein are sometimes the first things to disappear. That can include dairy products and other calcium-rich foods.


Good sources include milk, Greek yogurt, cottage cheese, cheese, fortified dairy alternatives, calcium-set tofu, certain leafy greens, and some canned fish with edible bones.


Low calcium intake usually doesn't cause obvious symptoms right away. Over time, inadequate calcium intake can contribute to loss of bone mineral density.


When blood calcium becomes abnormally low, symptoms can include:


  • Muscle cramps or spasms

  • Tingling around the mouth

  • Numbness or tingling in the fingers

  • Muscle weakness

  • In severe cases, abnormal heart rhythms or seizures


Importantly, a normal blood calcium level doesn't necessarily tell you whether your dietary calcium intake is adequate because the body tightly regulates calcium in the bloodstream.


Zinc


Zinc supports immune function, wound healing, taste and smell, skin health, and many other processes in the body.


It also tends to come up when people experience hair loss during significant weight loss.


Symptoms of zinc deficiency may include:


  • Hair loss

  • Poor wound healing

  • Changes in taste or smell

  • Reduced appetite

  • Skin changes

  • Increased susceptibility to infections


However, hair loss alone doesn't mean you have a zinc deficiency.


Rapid weight loss, inadequate calories, inadequate protein, iron deficiency, illness, stress, hormonal changes, and other nutritional deficiencies can also contribute to hair shedding.


Taking excessive zinc can interfere with copper absorption, so high-dose zinc shouldn't be taken indefinitely without a specific reason.


Magnesium


Magnesium is involved in hundreds of processes throughout the body, including muscle and nerve function.


Food sources include nuts, seeds, beans, whole grains, and leafy green vegetables.


If overall intake decreases and food variety becomes limited, magnesium intake may decrease as well.


Symptoms of significant magnesium deficiency may include:


  • Fatigue

  • Weakness

  • Muscle cramps

  • Muscle twitching

  • Numbness or tingling

  • Nausea

  • Loss of appetite

  • Cold fingers and toes 

  • Constipation

  • Anxiety

  • Difficulty Sleeping

  • Restless Legs at night


More significant deficiencies can affect heart rhythm and other important body functions.


Magnesium supplements are commonly marketed for constipation and sleep, but the type and dose matter—and supplementation isn't appropriate for everyone.


Thiamine (Vitamin B1)


Thiamine deserves special attention when someone is barely eating or experiencing frequent vomiting.


Your body has relatively limited thiamine stores, so prolonged inadequate intake or repeated vomiting can become a concern.


Early symptoms of thiamine deficiency may include:


  • Fatigue

  • Weakness

  • Poor appetite

  • Irritability

  • Numbness or tingling

  • Difficulty concentrating

  • Memory and concentration issues


Severe deficiency can affect the heart and nervous system and can become medically serious.


If you're taking a GLP-1 and experiencing persistent vomiting or are unable to maintain adequate food intake, don't simply rely on a multivitamin and wait it out. Contact your healthcare provider.


What About Hair, Skin, and Nail Vitamins?


When hair shedding starts, it's understandable to want to fix it quickly.


But adding a high-dose "hair, skin, and nails" supplement isn't necessarily addressing the actual cause.


Before piling on supplements, look at the bigger nutritional picture:


Are you eating enough?

Are you meeting your protein needs?

Has your weight loss been extremely rapid?

Are you getting iron-rich foods?

Is your diet varied?

Could lab work help identify a deficiency?


A supplement can't compensate for chronically inadequate nutrition.


Many Deficiency Symptoms Overlap


Here's where things get tricky.


Fatigue could be related to iron, B12, folate, vitamin D, inadequate calories, dehydration, poor sleep—or something completely unrelated to nutrition.


Hair loss could be related to iron or zinc, but it can also happen after rapid weight loss or inadequate calorie and protein intake.


Dizziness might have nothing to do with a vitamin deficiency and instead be related to dehydration, inadequate food or salt intake, medications, blood pressure, or another medical issue.


Symptoms can give us clues, but they don't diagnose a nutrient deficiency.


That's why your overall diet, medical history, symptoms, and appropriate lab testing should be considered together.


Consider Lab Work When Appropriate


If you've been taking a GLP-1 for an extended period, have significantly reduced your food intake, have a history of nutrient deficiencies, follow a restrictive diet, or develop symptoms such as significant fatigue, weakness, numbness and tingling, or hair loss, talk with your healthcare team about whether lab testing is appropriate.


Rather than taking multiple supplements and hoping one works, testing can sometimes help identify whether an actual deficiency is present.


The specific labs that make sense will depend on your symptoms, medical history, medications, and dietary intake.


More Vitamins Aren't Always Better


One of the biggest mistakes I see with supplements is the assumption that they're harmless because they're available over the counter.


They're not automatically harmless.


Some vitamins and minerals can accumulate in the body, interact with medications, cause side effects, or interfere with the absorption of other nutrients.


You also may be getting the same nutrient from several products—a multivitamin, electrolyte drink, protein shake, greens powder, hair supplement, and individual vitamin, for example.


Suddenly, you're taking much more than you realized.


Supplement strategically rather than taking everything "just in case."


Focus on Nutrient-Dense Foods First


One of the best things you can do nutritionally while taking a GLP-1 is make your smaller portions count.


Try to regularly include:


  • High-quality protein sources

  • Fruits and vegetables

  • Whole grains and other fiber-rich carbohydrates

  • Beans and legumes

  • Dairy or appropriate alternatives

  • Nuts, seeds, and healthy fats


You don't need a perfect diet.


But if your portions are considerably smaller than they used to be, the foods you are able to eat become even more important.


Your Vitamin Needs Should Be Individualized


Taking a GLP-1 doesn't automatically mean you need a long list of supplements.


It does mean that if you're eating considerably less, your nutrient intake deserves attention.


Start with food. Look at your overall eating pattern. Use supplements when they fill an actual need, and involve your healthcare team when symptoms or lab results suggest something needs additional attention.


Your medication may help you eat less—but we still want the food you eat to support your long-term health.



Related GLP-1 Resources

If you're working on getting adequate nutrition while taking a GLP-1, you may also find these helpful:

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