8 Vitamin and Mineral Combinations That Should Not Be Taken Together

Many people rely on vitamins and mineral supplements to make sure they’re getting all the nutrients they need. But they don’t always work well together when taken at the same time. Certain combinations may block each other or make it harder for your body to absorb and use the nutrients. 

Learning which vitamins and minerals are okay to take together — and which ones shouldn’t — can help you get the most out of them. 

In general, you can take all of your vitamins and minerals together. After all, this is what you’re doing when you take a multivitamin. But you should be cautious if you take individual vitamins or minerals on their own, especially in large doses. Some combinations are known to cause problems. 

So which vitamin and minerals shouldn’t be taken together? Let’s dive in.

1. Vitamins K and E

Your body relies on vitamin K to help your blood clot. Vitamin E has the opposite effect — it helps keep blood vessels open and prevents blood from clotting. If you take vitamins K and E together, they may counteract each other’s effects.

High doses of vitamin E have been shown to lower vitamin K levels, increasing the risk of bleeding. Scientists aren’t sure why this happens exactly, but it may be related to your body using more vitamin K when you take vitamin E. In some cases, the increased bleeding could be minor, but it could also be very dangerous, like a brain bleed.

What to know: Both vitamin K and vitamin E deficiencies are rare in healthy adults. If you don’t need them, it’s best to avoid taking them as individual supplements. 

2. Vitamins B12 and C

Vitamins B12 and C are both important when it comes to keeping your body healthy. Vitamin B12 supports your blood and nerve cells. And your body uses vitamin C to fight off germs and heal wounds. But when taken together, high levels of vitamin C may break down vitamin B12.

Lab research has found that vitamin B12 may break down quicker in supplements that also contain vitamin C. It’s not clear if the same thing happens inside the human body. Still, some experts suggest avoiding more than 0.5 g of vitamin C per day unless your vitamin B12 levels are being checked. 

EXPERT PICKS: WHAT TO READ NEXT

• Do you really need a multivitamin? Multivitamins can be expensive. And you might be surprised to learn what the research says about the benefits of a multivitamin. 

• Natural vs. synthetic vitamins: Is one better than the other? Yes, but it also may depend on why you’re taking them.

• Vitamins for vegans: Many critical vitamins and minerals come from animal products. If you follow a plant-based diet, here are the nutrients you may need.

Low levels of vitamin B12 can make you feel tired and weak. It can also lead to long-term nerve damage, like numbness and tingling in your hands and feet. So it’s important to make sure you’re getting enough.

What to know: If you’re healthy and eat animal food sources, you’re likely getting enough vitamin B12 from the foods that you eat. Vitamin B12 isn’t found in plant food sources. If you follow a vegetarian or vegan diet, avoid high doses of vitamin C and/or take a vitamin B12 supplement.

3. Calcium and magnesium

Calcium helps build strong bones and teeth. Magnesium also keeps bones healthy and helps regulate other bodily functions like blood sugar and blood pressure. 

But when you take calcium and magnesium supplements together, they can block each other’s absorption in your gut. If you take these supplements, it’s best to take them 2 to 4 hours apart so your body can absorb and use both more effectively.

You’ll notice a similar theme for the next two examples.

4. Calcium and zinc

Zinc helps keep your immune system strong. Like magnesium, calcium and zinc also compete for absorption when taken together. This is another combination you should take at least 2 to 4 hours apart.

5. Calcium and iron

The same idea applies to calcium and iron. 

Iron deficiency is more common than previously thought, so many people rely on supplements to keep their iron stores up. And iron is a critical nutrient your body needs to make red blood cells. If you take your iron supplement together with calcium, the calcium may block how well your body absorbs the iron. 

What to know: Consider taking calcium supplements between meals (about 2 hours after eating). This can help your body absorb nutrients like calcium, zinc, and magnesium from your food.

6. Zinc and iron

Zinc interacts with more than just calcium. There are a few more minerals you shouldn’t combine with zinc.

Zinc and iron can also block each other’s absorption. In fact, taking 25 mg or more of iron can decrease your zinc levels. Research suggests that waiting about 30 minutes between taking the two supplements is a good target.

7. Zinc and copper

Zinc also blocks your body from absorbing copper. Copper helps your body make energy. It also plays an important role in the health of your brain and immune system. To make sure your body is absorbing enough copper, avoid taking more than 40 mg of zinc per day. Experts recommend you don’t take more zinc than this anyway, since higher doses can be harmful. Most adults only need 8 mg to 12 mg a day.

8. Zinc and magnesium

Zinc may also block your body from absorbing and using magnesium. But there isn’t a lot of research on this combination. The one study where this effect was seen was done in a small group of men who were also taking calcium supplements. And they were taking very high doses of zinc (142 mg a day or more). 

What to know: Stick to the recommended daily limits of zinc and iron if you’re taking supplements. For zinc, the upper limit is 40 mg daily for adults. For iron, it’s 45 mg daily for adults.

Why trust our experts?

Written by:

Cherilyn Davis, MD

Cherilyn Davis, MD, is a board-certified pediatrician in NYC. She's held local and national roles at the American Medical Women's Association, including board member of the physician division and physician chair of social media.

Edited by:

Katie E. Golden, MD

Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.

Our editorial standards

Meet our experts