Vitamins and minerals on a GLP-1: getting enough from less food

A GLP-1 medicine can shrink your meals a lot, and smaller meals carry fewer vitamins and minerals along with fewer calories. This guide covers which nutrients are worth watching, how to get them from food first, and when a supplement is something to raise with your care team. Questions about your medicine or your dose are for your prescriber.

Do you need vitamins on a GLP-1?

Many people can cover most of their needs with food, but eating much less raises the chance of gaps, so it’s worth planning for.

A 2025 joint advisory from four nutrition and obesity medicine groups (ACLM, ASN, OMA and TOS) says a large, fast drop in intake can leave people short on essential vitamins and minerals. It flags the risk as highest below about 1,200 kcal a day for women and 1,800 kcal a day for men. It adds that stomach side effects can make absorption worse.

The advisory’s answer is food quality first: a variety of nutrient-dense, minimally processed foods like fruits, vegetables, whole grains, legumes, lean proteins, nuts and seeds. It says supplements can be considered ahead of time for at-risk nutrients, and names vitamin D, calcium and B12, tailored to each person.

Which nutrients can run low when you eat less?

Calcium, vitamin D and vitamin B12 are the ones the advisory names, and iron and fiber are worth watching too.

Here are the daily amounts the NIH Office of Dietary Supplements (ODS) lists for adults:

Fiber isn’t a vitamin, but it drops fast when portions shrink. The advisory encourages fluids and fiber from foods, especially when constipation shows up. More in constipation and fiber.

How do I get enough calcium and vitamin D from food?

Dairy, fortified soy milk, calcium-set tofu and canned salmon do a lot of the work in small portions.

The ODS says milk, yogurt and cheese are the main calcium sources for most people in the US, and that canned salmon and sardines with bones also contain calcium. Very few foods have vitamin D naturally. Most US milk is fortified, many plant milks are too, and fatty fish like salmon and tuna are among the best natural sources.

Rounded USDA FoodData Central values. Check your label, since fortification varies by brand.

Your skin also makes vitamin D in sunlight, but the ODS notes that age, darker skin, clouds and sunscreen all lower how much. It lists people with obesity among those who may need more vitamin D than others. For a deeper look, see calcium and vitamin D.

What about iron and B12?

Meat, fish, eggs and dairy carry B12, and iron comes from both animal and plant foods, with plant iron absorbed better alongside vitamin C.

• B12. The ODS says B12 is found in animal foods, and plant foods have none unless fortified. A 3 oz (85 g) serving of canned pink salmon has about 4.2 mcg, above the 2.4 mcg daily amount (USDA). Fortified cereals and nutritional yeast are options too.
• B12 and metformin. Some people on a GLP-1 also take metformin. The ODS says metformin might reduce B12 absorption and lower blood levels. If that’s you, mention it to your doctor.
• Iron. Lean meat, seafood, poultry, lentils, beans, spinach and fortified cereals all count. Half a cup of cooked lentils (99 g) has about 3.3 mg of iron, 9 g of protein and 8 g of fiber (USDA). The ODS says eating plant iron with vitamin C foods like citrus, strawberries, peppers, tomatoes or broccoli helps you absorb it.

Should I take a multivitamin on a GLP-1?

It might help some people, and it’s a good question to bring to your care team rather than decide from a store shelf.

The ODS says people on low-calorie diets, with a poor appetite, or who avoid certain foods might consider a multivitamin/mineral supplement. It also says these products can’t replace a variety of foods, and that basic ones are usually low in calcium and magnesium. Taking several products, or eating lots of fortified foods, can push some nutrients like iron, vitamin A and zinc too high.

The advisory suggests extra checks before starting for some people, such as those with past bariatric surgery, celiac disease or a previous deficiency. It also suggests re-checking nutrient levels during therapy. So the most useful step is often a conversation, not a purchase.

When you talk to your care team, it helps to bring:

• Roughly what you eat on a typical day
• Any supplements you already take, with their labels
• Other medicines, such as metformin or acid reducers
• Any symptoms that worry you

How can I fit more nutrients into small meals?

Lead with protein, then add one colorful plant and one calcium-rich or fortified food where you can.

When you can only manage a few bites, every bite works harder. Some small plates that cover several nutrients at once:

On days when eating feels hard, see when you’re not hungry. The protein finder helps you spot foods that bring protein in small portions, and protein on a GLP-1 covers how much to aim for.

How does Imi help?

Imi helps you get more out of smaller meals.

• Meals planned around your targets. Imi plans from your saved recipes, with protein and water at the top of each day.
• Easy logging. Log meals by photo, barcode, text or voice.
• Gentler days. Log nausea or a dose, and Imi plans lighter meals for the days that follow.
• Quick swaps. Ask Imi to swap a meal, like “make dinner gentler.”

Imi helps with food. Your prescriber handles your medication. For the bigger picture, read eating well on a GLP-1.