What Vitamins Should Not Be Taken Together? The Dos and Don'ts

If you're one of those people who pop a handful of vitamins every day in hopes of improving your health, it's important to know that there are risks involved if you don't follow the proper guidelines. While vitamins can help fill nutrient gaps in your diet, certain vitamins should not be taken together in high doses due to negative interactions and harmful effects.

In this article, we will explore which vitamin and mineral supplements should not be taken together and provide practical advice on the dos and don'ts of supplement use to help you make informed decisions about your health.

Which vitamins should be taken together?

Some vitamins should be taken together to work properly or to improve effectiveness. While certain nutrient combinations may enhance absorption or provide synergistic health benefits, it's important to note that a balanced and varied diet is still the best way to obtain all the necessary vitamins and minerals. Below, we list 6 vitamin combinations that are often recommended for optimal health.

Vitamin D and calcium

Vitamin D and calcium are two nutrients that work hand in hand. Vitamin D helps the body absorb calcium, and calcium is essential for strong bone health and teeth.

Vitamin E and selenium

Both vitamin E and selenium are powerful antioxidants that help protect cells from damage. Studies have shown that consuming these nutrients together may have a synergistic effect on reducing inflammation and decreasing the risk of chronic diseases, including cancer.

Vitamin D and K

In 2020, a meta-analysis of eight randomized controlled trials with 971 subjects concluded that vitamin D and K in combination could induce better effects on improving total bone mineral density.

Vitamin C and magnesium

Findings show that taking vitamin C together with magnesium has synergistic benefits, including enhancing the anti-cancer effects of vitamin C and helping in alleviating joint pain and osteoarthritis.

Vitamin D and magnesium

Because magnesium assists in the activation of vitamin D, scientists recommend taking them together. They work together to support bone health, immune function, and overall health. Additionally, magnesium helps improve vitamin D absorption and also reduces the risk of vitamin D toxicity.

Multivitamin and vitamin D

If your multivitamin does not contain vitamin D, doctors highly recommend adding it due to its many health benefits in optimizing body function and reducing the risks of chronic diseases.

What vitamins should not be taken together?

In general, you can take vitamins together safely as long as they are within recommended dosages and instructions. However, there are some vitamins and minerals that should not be taken in combination, with noted undesirable effects, especially in high doses.

Calcium and iron

Calcium can inhibit iron absorption, so it's recommended to avoid taking these supplements together to prevent the development of iron-deficiency anemia. If you need to take both, it's best to take them at different times of the day.

Calcium and magnesium

While somebody may take calcium and magnesium together, high doses of calcium decrease magnesium absorption, so it's best to avoid taking them together at the same time.

Vitamin C and copper

High doses of vitamin C can interfere with copper absorption, which may lead to copper deficiency, so it's best to avoid taking them together. Most recent findings even show that this combination may induce systemic oxidative stress and kidney injury. If you decide to take them together, consume both at different times of the day.

Vitamin C and iron

Vitamin C can enhance the absorption of iron, so people with hemochromatosis or other conditions where they have excess iron in their bodies should not take them together as it may lead to harmful reactions.

Vitamin A and vitamin E

While both are fine in adequate levels, taking high doses of vitamin A and E together is harmful. For example, excess vitamin A may accumulate in the liver, leading to liver toxicity and injury. While excessive vitamin E intake increases the risk of bleeding and interferes with blood clotting.

How to choose the right vitamins

Choosing the right vitamins can be overwhelming, with so many options available. The best way to start is to identify which nutrients you may be deficient in through a blood test. This will help you prioritize which vitamins to focus on.

Here are some practical tips for choosing the right vitamins:

  1. Talk to your healthcare provider or a registered dietitian to determine which vitamins you may need based on your health status, lifestyle, and dietary intake.
  2. Choose reputable brands with a track record of producing high-quality supplements.
  3. Look for vitamins that are third-party tested (e.g., NSF, USP, BSCG) for purity and potency to ensure they contain what they claim and are free of contaminants.
  4. Choose vitamins in forms that are most easily absorbed and utilized by your body, such as methylated B vitamins, chelated minerals, and vitamin D3.
  5. Consider the dosage and form of the vitamin. Some vitamins may be better absorbed in lower doses throughout the day, while others may be best taken in a single dose.

Can you take too many vitamins?

It's important to be mindful of potential vitamin interactions. Some interactions may lead to decreased absorption or other negative effects.

The higher the number of vitamins taken at once, the higher the risk of interactions between the supplements, which can affect their absorption and effectiveness. For example, the effect of taking five different vitamins at once will depend on the specific vitamins and doses being taken. Hence, to ensure the safe and effective use of multiple vitamins, consult with a healthcare provider to develop an individualized supplement plan based on personal needs and goals.

If you take too many vitamins at once, it may lead to adverse effects, such as the following:

  • Dizziness
  • Nausea
  • Vomiting
  • Diarrhea
  • Blurred vision
  • Stomachache
  • Abdominal cramps
  • Increased bleeding
  • Organ damage, like in kidney/liver (in severe cases)
If taken at recommended doses, the risk of adverse effects from multiple vitamin intake is low.

Water-soluble vs. fat-soluble vitamins

Vitamins are categorized as water-soluble or fat-soluble, which impacts their absorption, storage, and excretion in the body. Water-soluble vitamins and fat-soluble vitamins are absorbed and metabolized differently in the body.

  • Water-soluble vitamins. Should be taken together and with a meal to enhance absorption.
  • Fat-soluble vitamins. Should be taken with a source of dietary fat, such as a meal containing healthy fats like avocado or nuts, to improve absorption.

In general, it's best to take water-soluble vitamins and fat-soluble vitamins separately to maximize absorption and reduce the risk of toxicity.

Here's a table outlining the differences between water-soluble and fat-soluble vitamins:

SolubilityDissolves in waterDissolves in fat
Storage in the bodyNot stored, excreted in urineStored in fatty tissues and liver
Risk of toxicityGenerally low riskRisk of toxicity with excessive intake
Absorption in the bodyAbsorbed directly into bloodstreamAbsorbed along with dietary fat through the lymphatic system
Daily intakeNeed to be consumed regularlyCan be stored for longer periods of time in the body
  • Vitamin B1 (thiamin)
  • Vitamin B2 (riboflavin)
  • Vitamin B3 (niacin)
  • Vitamin B5 (pantothenic acid)
  • Vitamin B6 (pyridoxine)
  • Vitamin B7 (biotin)
  • Vitamin B9 (folate)
  • Vitamin B12 (cobalamin)
  • Vitamin C (ascorbic acid)
  • Vitamin A (retinol)
  • Vitamin D (calciferol)
  • Vitamin E (tocopherol)
  • Vitamin K (phylloquinone, menadione)

  • What to consider when taking vitamins

    Since it's essential to be mindful of counterproductive interactions among supplements, healthcare professionals recommend a consultation to avoid unwanted side effects. Meanwhile, below are some general dos and don'ts for taking vitamins.

    Key takeaways:


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    prefix 1 month ago
    This isn't an extensive list. Such as Vitamin C can block B12 absorption so best to take separate.
    High amounts of Zinc can cause copper to be removed from the body so they recommend taking a little copper when you take zinc. Which is a common combination in the ration of 15:1. It is also believed that amino acids chelated ( bound to a mineral) often have better absorption. Such as Zinc Glycinate or . But, company's often just put the 2 compounds together unbonded (not chelated) and still call it by the bonded names. Or they call it "buffered" and have a mineral oxide that makes up a lot of the supplement instead of the chelated mineral. i.e. do some digging if taking a chelated supplement to be sure you are getting what you want.