What vitamins should not be taken together?

In this article:

• What vitamins should not be taken together? 
• Which vitamins should be taken together?
• FAQs
• Bottom line

In this article

• What vitamins should not be taken together? 
• Which vitamins should be taken together?
• FAQs
• Bottom line

From collagen powder and probiotics to prenatal vitamins and St. John’s wort, the sale of vitamin, mineral, and herbal supplements is skyrocketing. In fact, according to data from the most recent National Health and Nutrition Examination Survey, an estimated 57% of Americans older than 20 took at least one dietary supplement in the past 30 days. Multivitamins, vitamin D, and omega-3 fatty acids are the most popular.

Maybe you take a daily multivitamin to enhance your overall health and wellness. Or perhaps you rely on supplements to fill in essential nutrient gaps. Either way, it’s important to be aware of possible interactions. Vitamins are organic compounds that are essential in small amounts to support  metabolism and other bodily functions. Taking certain vitamins or minerals together can affect their absorption in the body, sometimes reducing and other times improving bioavailability.

Additionally, some vitamins can interfere with the efficacy of medications and even increase side effects. Although measuring blood levels of several vitamins is widely available, testing for deficiencies is usually unnecessary. Here’s what you need to know about using vitamin supplements wisely.

What vitamins should not be taken together?

It is very important to read the label and the suggested dosing instructions for each supplement you are taking, advises Jenna Litt, RD, CDN, a registered dietitian at Northwell Health’s Lenox Hill Hospital in New York. “For example, some supplements may need to be taken with food, some may be administered daily, multiple times a day, or even weekly,” she says. “If you are not sure about dosage, contact your healthcare provider to ensure you are taking proper dosages.”

It’s also important to know which vitamins should not be taken together. Here are supplements that don’t go together—or shouldn’t be taken with food.

Magnesium and calcium

Why not together: These two minerals work together for bone, muscle, and nerve health. Magnesium can help promote calcium absorption indirectly by activating vitamin D. However, large doses of calcium may interfere with the absorption of magnesium. Research also indicates that a calcium-to-magnesium ratio above 2:1 is linked to an increased risk of metabolic, inflammatory, and cardiovascular disorders, so getting the right dose is important.

Recommendations: To be sure you’re taking the right amount, consult with your provider for guidance, especially since large doses of calcium and magnesium may need to be avoided or separated.

Iron and calcium

Why not together: Research shows that iron deficiency is common among adults in the U.S., with around 14% having absolute iron deficiency. Your healthcare provider may recommend taking iron supplements if you’re not getting enough iron through your diet. But if you also supplement with calcium, your best bet is spacing out the doses. Calcium can temporarily reduce iron absorption, meaning iron supplements won’t be as effective.

Recommendations: For best results, take iron supplements at least two hours before or after calcium supplements, dairy products, and calcium-rich foods for maximum absorption.

Iron and green tea

Why not together: It’s not a good idea to take your iron supplement (or eat iron-rich foods) at the same time as green tea. That’s because one of the main components in green tea, epigallocatechin gallate (EGCG), binds with iron and reduces its absorption. A case study linked drinking large amounts of green tea with the development of iron deficiency anemia.

Recommendations: Green tea has health benefits, though, so feel free to drink it. However, drink it one to two hours before or after taking an iron supplement or eating iron-rich foods.

Vitamin C and B12

Why not together: It’s not advised to take vitamin C and vitamin B-12 at the same time, says Litt. That’s because high doses of vitamin C can reduce the amount of vitamin B12 that’s absorbed and metabolized by the body, she says. However, this interaction is based on older studies in test tubes, and studies in humans suggest there is no impact on vitamin B12 absorption. Still, some healthcare providers recommend separating the doses out of caution.

Recommendations: Most people can safely take vitamin C and vitamin B12 together, but if you’re taking high-dose vitamin C supplements (1,000 mg or more), you may want to separate them by at least two hours as a precaution.

RELATED: Can you take too much B12?

Vitamin C and copper

Why not together: Most people don’t need to take a copper supplement, but individuals with celiac disease, Menkes disease (a rare genetic disorder), and those taking high amounts of zinc may. Taking high doses of vitamin C can reduce the absorption of copper. In addition, some research in mice suggests that mixing the two supplements can cause oxidative stress and kidney damage.

Recommendations: Play it safe by spacing out your copper and vitamin C supplements by two to three hours, especially if you’re taking high-dose vitamin C supplements.

Vitamin E and K

Why not together: Vitamin E and vitamin K have opposite effects, with vitamin E acting as a blood thinner at high doses and vitamin K increasing blood clotting. Taking both vitamins could cancel out their effects. However, this interaction is more of a concern when taking high doses of vitamin E and a blood thinner like warfarin.

Recommendations: It’s uncommon to have a vitamin E or vitamin K deficiency, but it’s important to consult a healthcare provider before taking these supplements, especially in high doses or while taking a blood thinner like warfarin.

Calcium, iron, and zinc

Why not together: High doses of calcium or iron can reduce zinc absorption when taken at the same time, especially on an empty stomach. Zinc is essential for immune function and wound healing, so this is worth knowing if you’re supplementing with more than one of these minerals.

Recommendations: Take zinc at a different time of day than calcium or iron supplements, or pair it with a meal that doesn’t include a calcium or iron supplement dose.

 

Vitamin interactions chart
Vitamin	Interactions	How to improve absorption and reduce side effects
Magnesium	High-dose calcium supplements	Consider separating the timing of these supplements, especially in high doses
Iron	Green tea and calcium supplements	Take iron with vitamin C and avoid two hours before or after calcium supplements
Vitamin C	Vitamin B12	Separate these supplements by at least two hours, especially if you’re taking high-dose vitamin C
Vitamin E	Vitamin K	Consult a healthcare provider before using high-dose vitamin E and keep vitamin K intake consistent while on a blood thinner
Zinc	High-dose calcium or iron supplements	Space doses of zinc and calcium or iron supplements by at least two hours

Which vitamins should be taken together?

In general, water-soluble vitamins can be taken together with or without food, while fat-soluble vitamins are best absorbed with food containing fats. The following combinations of supplements may be more effective when combined.

Vitamin D, vitamin K2, and other fat-soluble vitamins

Vitamin D coupons  Vitamin K coupons

Vitamin D and vitamin K (especially K2) complement each other, Virgilio Sanchez, MD, a board-certified family physician at Conviva Care Center in Miami, Florida, says.  “Vitamin K2 helps calcium move from the blood to the bones,” he says, “whereas if you take large doses of vitamin D without sufficient K2, the calcium can go to the wrong places.”

Vitamin K1, or phylloquinone, is present in dark leafy greens, while vitamin K2 (menaquinones) is found in fermented and some animal-based foods. Research indicates the two fat-soluble vitamins (vitamin D and vitamin K2) may work synergistically to ensure that calcium is absorbed by the bones rather than building up in your arteries.

Fat-soluble vitamins, such as A, D, E, and K, can generally be taken at the same time. According to Sean Ormond, MD, an interventional pain physician at Atlas Pain Specialists in Phoenix, Arizona, fat-soluble vitamins are stored in the body’s liver, fat, and muscles and should be taken with fat from a meal in order for your body to best absorb and use them. “A lot of fat is not required. Healthy plant-based foods like avocado or nuts do just fine,” Dr. Ormond says.

Magnesium and vitamin D3

Magnesium coupons  Vitamin D3 coupons

Magnesium can help the body activate and use vitamin D. A study published in The American Journal of Clinical Nutrition shows that without enough magnesium, vitamin D synthesis and metabolism in the body is impaired. In other words, magnesium is required to convert vitamin D into a form that the body can use. That’s why your provider might advise combining these two supplements.

Copper and zinc

Copper coupons Zinc coupons

When it comes to combining copper with zinc supplements, it’s all about balance. Zinc interferes with copper’s absorption, with high-dose zinc supplementation increasing the risk of a copper deficiency over time. If you’re taking high-dose zinc supplements over extended periods, your healthcare provider may recommend a copper supplement to support healthy copper levels.

Omega-3s and vitamin E

Omega-3 coupons  Vitamin E coupons

Taking these two supplements together may help support heart health. Omega-3 fatty acids are essential fats that may help protect against medical conditions like high blood pressure, heart disease, and stroke, while vitamin E is an important nutrient with antioxidant properties. One small study of 60 male patients with coronary artery disease found that a combination of omega-3s and vitamin E had beneficial effects on serum insulin and insulin resistance. Research has linked increased insulin resistance with the development of heart disease. Ask your provider if you’d benefit from this combination.

Iron and vitamin C

Iron coupons  Vitamin C coupons

Iron deficiency is the most common mineral deficiency in the United States. Iron is a major component of hemoglobin, a protein in red blood cells that transports oxygenated blood from the lungs to other areas of the body. Iron deficiency could lead to anemia, resulting in fatigue and often making it necessary to supplement with iron.

Although vitamin C is known to increase the absorption of iron, the jury’s still out on whether taking both improves outcomes. A randomized clinical trial of 440 individuals with iron deficiency anemia found no significant difference in iron absorption among the group who took iron with vitamin C and the group who took iron alone. That said, taking both supplements is generally safe and may be recommended, especially for those who get little vitamin C from their diet.

RELATED: How to make sure you absorb your supplements

If there are no known interactions between vitamins, it is okay to take multiple vitamins at once, Litt says. If you are unsure if an interaction exists, contact your healthcare provider.

Frequently asked questions

What vitamins should you not mix with vitamin D?

In general, vitamin D can be taken with other vitamins, like vitamin B12 and C. However, vitamin D should be taken with a meal that contains some fat for optimal absorption.

What vitamins should you not take at night?

Fat-soluble vitamins like A, D, E, and K are absorbed best with a meal that contains fat, so they’re generally better suited to daytime; some people also find B vitamins overly energizing before bed.

What vitamins can I take together daily?

Many vitamins can be taken together; for example, magnesium and vitamin D can be taken together since magnesium can help support the metabolism of vitamin D, while vitamin D and vitamin K can also complement one another to support bone health.

Is it safe to take a multivitamin with individual supplements?

Usually yes, but check your multivitamin’s label first so you don’t unintentionally double up on a nutrient like iron, zinc, or calcium.

How far apart should I space vitamins that interact?

A spacing of around two hours is often recommended for supplements that can compete for absorption, but it’s best to check with your provider if you take multiple supplements.

Bottom line

The best way to stay in good health is to get your nutrients from a balanced diet, but sometimes that’s not possible. Always consult a healthcare provider for medical advice before combining supplements with OTC or prescription medications to avoid potential interactions.

RELATED: Vitamin interactions: 6 types of medication that don’t mix

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