10 Nutrient Deficiencies to Watch for While Taking a GLP-1

GLP-1 agonists such as semaglutide and tirzepatide are treatments that work well for type 2 diabetes and obesity. They reduce your appetite and slow digestion, so you eat less. But eating less may also mean taking in less protein, vitamins, and minerals, which can raise your chances of nutritional deficiencies. About 1 in 5 people develop nutritional deficiencies within a year of starting a GLP-1. Knowing which nutrients may be at risk can help you address these deficiencies early on. 

Vitamin D is the most common deficiency linked to GLP-1 drugs. About 13% of people are deficient in this vitamin within a year of starting the medication. This may happen because you tend to eat less overall while taking GLP-1s. Also, delayed stomach emptying may affect how your body absorbs fat-soluble vitamins such as vitamin D. Low levels of this vitamin can weaken bones and affect muscle and immune function. Look for vitamin D in fatty fish like salmon and fortified dairy foods and cereals. 

Calcium deficiency may be a concern for people taking GLP-1 drugs. Calcium and vitamin D work together to keep your bones strong, so getting too little of either may be a concern during weight loss. Getting enough calcium and vitamin D through your diet can help support bone health, especially during rapid weight loss. Choose low-fat dairy, leafy greens, fatty fish, and fortified orange juice and plant milks.

Low B12 can cause fatigue, tingling in your hands, memory problems, or mood changes. Your body needs stomach acid to release vitamin B12 from food. GLP-1 drugs may reduce stomach acid along with reducing your appetite. Together, this may make it harder for your body to get and absorb enough of this vitamin. Ask your doctor about checking your B12 levels if you have symptoms or eat mostly plant-based foods. Good sources include red meat, poultry, seafood, and dairy.

Thiamine or vitamin B1 helps your body turn food into energy and keeps your nerves running properly. Your body only stores small amounts of thiamine, so eating less food can quickly lower your levels. Severe thiamine deficiency can cause confusion, balance problems, weakness, or nerve damage. Talk to your doctor if you experience symptoms such as persistent vomiting. Many foods are fortified with it, and whole grains, lean meats, and fish have it as well. 

Side effects that include nausea, vomiting, and diarrhea are common with GLP-1s. This can lower your stores of important electrolytes, including magnesium. If you’re low in this nutrient, it can cause muscle cramps, fatigue, weakness, or irregular heartbeat. Talk to your doctor if these symptoms don’t go away. You can get magnesium from fish, beef, and poultry and plant foods like beans, dark green leafy vegetables, whole grains, and fortified cereals. 

Nausea and reduced appetite from GLP-1s may make it difficult to eat iron-rich foods. Studies suggest that your body’s ability to absorb iron goes down when you take GLP-1s. Your levels of a protein called ferritin that helps you store iron in your blood may go down as well. Low iron can lead to anemia, fatigue, pale skin, or shortness of breath. Ask your doctor about checking your iron or ferritin levels if you have these symptoms. Look for iron in organ meats, lentils, spinach, and fortified foods.

Weight loss with GLP-1 drugs can lead to loss of lean muscle along with body fat. Getting enough protein can help to you hold onto muscle as you lose weight. But a lessened appetite can make it harder to meet your protein needs. Ask your doctor how much protein you should take daily if you are losing weight rapidly. Protein is in many foods, including whole grains, beans, nuts and seeds, dairy, and lean meat. 

These are fat-soluble vitamins, which means your body also needs dietary fats to absorb them properly. Low levels of them over time can affect your vision, immune function, and blood clotting. Because GLP-1s slow stomach emptying, fats can trigger symptoms like diarrhea and gas. When taking them, avoid saturated fats and focus on heart-healthy fats like those in nuts, seeds, avocados, and fish like salmon. Leafy greens, nuts and seeds, and orange foods like carrots and sweet potatoes are good sources too. 

Zinc deficiency may happen during GLP-1 treatment because a lower appetite can reduce the intake of zinc-rich foods such as meat, seafood, nuts, and seeds. Zinc supports immune function, wound healing, and the sense of taste and smell. Low zinc levels can cause frequent infections, slow healing of wounds, and changes in taste. Talk to your doctor if you notice these symptoms.

Having less of an urge to eat means you may also cut your folate intake during GLP-1 treatment. Folate helps your body make red blood cells and DNA. Low levels can cause fatigue, weakness, mouth sores, and a type of anemia. Talk to your doctor if you notice these symptoms, especially if you also have low vitamin B12. You can find folate in dark green leafy vegetables, whole grains, eggs, and many fortified foods. 

A reduced appetite can make it harder to get enough vitamin C from fruits and vegetables. Your body needs vitamin C for wound healing, protection from free radicals, and immune function. Vitamin C deficiency can lead to fatigue, bleeding or swollen gums, slow wound healing, and easy bruising. Citrus, strawberries, tomatoes, and white potatoes are good sources of this vitamin.

Nutrient deficiencies develop gradually, especially if GLP-1s cause ongoing nausea, vomiting, and low appetite. Your doctor can figure out whether you need routine blood tests for nutrients such as vitamin D, B12, iron, or calcium based on your symptoms and health history. Talk to your doctor if your symptoms go on for a while, as they may mean nutrient deficiencies.

To make sure you’re eating enough to stay healthy when you’re taking a GLP-1, it may help to take a few steps. Stimulate your appetite with some light exercise before meals, like a short walk. Eat smaller meals more often instead of three big ones. If food isn’t appealing, whip up a smoothie or sip a broth. But don’t fill up on liquids right before or during meals. And make your meals a pleasant way to recharge: Sit down and be comfortable as you eat, and take time to enjoy the meal.