What vitamin should not be taken with vitamin C?

Almost every vitamin on the standard "do not take with vitamin C" list got there by accident.

The NIH's fact sheet for health professionals gives two interaction examples, and neither of them is a vitamin. Supplement blogs routinely name five or six. The gap is not caution. It is a handful of findings from the 1970s and 1980s that were tested again and did not survive.

Here is what the evidence actually supports, vitamin by vitamin.

Table of Contents

• 1. The short answer: no vitamin has strong evidence against it
• 2. Vitamin E: the one pairing with real data behind it
• 3. Vitamin B12: how one 1974 paper became a permanent rule
• 4. Copper: a lab reading that moved, and a status that did not
• 5. Iron: the pairing that helps, and the one group it does not
• 6. Vitamin D, zinc and the rest: what the silence means
• 7. Choosing a vitamin C when you already take other supplements
• Frequently Asked Questions
• Conclusion

1. The short answer: no vitamin has strong evidence against it

Under interactions, the NIH names two examples: cancer treatment, and statins taken with niacin. Both are medications. No vitamin appears on that list, and no mineral does either. A reader arriving from a blog post naming six nutrients to avoid is reading something the evidence base does not contain.

There is a structural reason the real list is so short. Your body absorbs 70% to 90% of vitamin C at intakes of 30 to 180 mg a day, but above 1 gram a day absorption drops below 50% and the surplus leaves in your urine. An interaction needs a meaningful change in concentration to produce an effect, and vitamin C is unusually bad at producing one. Our guide to why most of your dose is wasted covers where that ceiling comes from, and the complete guide to liposomal vitamin C explains why delivery format is the lever that moves it.

One boundary before we start. This article is about vitamins and minerals you swallow alongside vitamin C. If your question is about medications, food, drink or blood tests, those have their own answers in our guide to what you should not mix with vitamin C. If it is about a serum on your skin, that is a different category of product entirely, and the 2 or 3 actives involved behave nothing like a swallowed dose.

2. Vitamin E: the one pairing with real data behind it

If any vitamin belongs in this conversation, it is vitamin E, and the reason is narrower than most people assume. In a double-blind randomised trial published in The Journal of Physiology, 54 healthy young men and women trained for 11 weeks while taking either 1,000 mg of vitamin C with 235 mg of vitamin E daily, or a placebo. The supplemented group showed a blunted rise in COX4, a mitochondrial protein that normally increases with endurance training.

The mechanism makes sense. Exercise raises oxidant production in muscle, and those oxidants are part of the signal that tells the cell to adapt. Two antioxidants at once, at doses several times the 90 mg and 75 mg daily recommendations for adults, appear to quieten that signal.

What happened next is the part that rarely gets quoted. A 2020 review reports a comprehensive meta-analysis in which vitamin E, taken alone or combined with vitamin C, neither enhanced nor blunted training adaptations across aerobic capacity, muscle strength, lean mass or endurance performance, with no evidence of a negative effect on maximal oxygen uptake. A protein marker moved in one trial. The outcomes people actually train for did not reliably follow.

So the honest guidance sits between the two:

• If you are not training seriously, there is no reason to separate them at all.
• If you are in a hard training block, taking the 2 supplements at different times of day costs nothing and removes the question.
• If you want a single rule, keep antioxidant doses modest around training rather than eliminating either vitamin.

3. Vitamin B12: how one 1974 paper became a permanent rule

This is the pairing you will see named most often, and it traces to a single source. In 1974, a 2-page report in JAMA claimed that high doses of vitamin C destroy substantial vitamin B12 when taken with food, and concluded that daily intakes of 0.5 g or more without monitoring B12 status were probably unwise.

Two years later, 2 independent laboratories rebuilt the same meals and tested them with standardised official methods. Their results, published in The American Journal of Clinical Nutrition, went 3 ways against the original: the meals contained manyfold more B12 than first reported, the values matched what the published literature predicted for those foods, and added ascorbic acid had no deleterious effect on the B12 present.

A further paper in 1980 explained why the first result appeared at all. When cyanide was used during extraction, the apparently lost B12 was fully recovered, identifying the 1974 finding as an artefact of the measurement rather than real destruction. That is roughly 50 years of correction, and the warning still circulates.

4. Copper: a lab reading that moved, and a status that did not

Copper is the one entry on the popular lists with genuine human data behind it, and the data is more interesting than the warning. In a 14-week metabolic study published in The Journal of Nutrition, men took 605 mg of vitamin C a day for 3 weeks. The oxidase activity of their serum ceruloplasmin fell by an average of 21%, while copper absorption, copper retention, total serum copper and ceruloplasmin protein were all unchanged.

An earlier study pushed the dose higher. Men took 500 mg with each meal, 1,500 mg a day, for 64 days. Serum ceruloplasmin activity fell significantly at every one of the 4 measurement points, serum copper showed a similar but non-significant trend, and copper rose significantly again 20 days after the supplement stopped.

The Linus Pauling Institute reviews both and reaches the conclusion that matters: neither study found vitamin C to adversely affect copper nutritional status. One enzyme reading responded. The body's copper supply did not. If you take a copper supplement, often bundled with zinc, and more than 1 gram of vitamin C daily, putting a few hours between them is a reasonable precaution that costs nothing.

5. Iron: the pairing that helps, and the one group it does not

Vitamin C and iron is the reverse case: not a pairing to avoid but the single best-documented reason to combine 2 nutrients. Vitamin C converts plant-based non-heme iron into a form the body absorbs more readily, which is why it appears in so many iron formulas. Our article on how the vitamin C and iron pairing works covers the mechanism.

Two honest limits apply. First, the effect shrinks outside the laboratory: a study in The American Journal of Clinical Nutrition found the enhancement from a complete diet is far less pronounced than from single test meals, which the authors offer as the explanation for why prolonged supplementation trials have not improved iron status. Second, in a randomised trial of 440 adults with iron deficiency anaemia, haemoglobin rose 2.00 g/dL with iron plus vitamin C and 1.84 g/dL with iron alone, a difference that met the trial's own definition of equivalence.

The common worry is the opposite one: that taking both will overload you with iron. In healthy people it does not. Serum ferritin averaged 46 µg/L before high-dose vitamin C supplementation and 43 µg/L after, with no significant effect after a further 20 months. A review in the International Journal for Vitamin and Nutrition Research reaches the same place: even high vitamin C intakes do not cause iron imbalance in healthy people, or probably in people who carry 1 copy of the haemochromatosis gene.

The exception is real and it is narrow. In diagnosed hereditary haemochromatosis, where the body already stores too much iron, chronic high-dose vitamin C works against the goal of lowering the iron burden. If that applies to you, this is a conversation with your doctor rather than a timing adjustment.

6. Vitamin D, zinc and the rest: what the silence means

Vitamin D, zinc, vitamin K, folate and vitamin A all appear on "do not mix" lists, and none of them has controlled human evidence of a problem with vitamin C. These 5 nutrients have been co-formulated in multivitamins for decades without a signal emerging. Our page on whether you can take vitamin D and C together goes through that pairing specifically.

Absence of evidence is not proof of safety, and it is worth saying so plainly. But it does change where your attention should go. The number that governs risk for almost everyone is not a combination at all: it is the 2,000 mg daily tolerable upper intake level for adults, which applies to your total vitamin C from every source at once. Our guide to how much vitamin C to take per day covers the ranges, and our guide to vitamin C interactions with medications and supplements covers the prescription side.

Three practical rules cover almost every situation:

• Count your total. A multivitamin plus a dedicated vitamin C plus a fortified drink can reach 4 figures faster than people expect.
• Space, do not stop. Where a gut-level interaction is plausible, as with copper, 2 or 3 hours between doses resolves it.
• Tell your prescriber, not the internet. The interactions that genuinely matter involve medications, and they are worth 1 sentence at your next appointment.

7. Choosing a vitamin C when you already take other supplements

If you take several supplements, the practical questions are usually about fit rather than chemistry: what else is in the formula, whether the allergen profile works for you, and whether the format lets you separate doses across the day when you want to.

Bio Absorb Nutraceuticals makes its Liposomal Vitamin C Liquid 1000mg (Corn-Free) and Liposomal Vitamin C Capsules 1000mg (Corn-Free) in a GMP-certified facility in Canada, third-party tested every batch. Both are verified corn-free, non-GMO, gluten-free, nut-free, dairy-free and vegan, which matters if you are already reading labels for one allergen and do not want to start managing a second.

The 2 formats differ in how they fit a routine rather than in what they contain. The liquid mixes into water or cold juice, which makes it easy to move to a different part of the day from your other supplements. The capsules need no refrigeration and travel well, which suits a fixed morning routine. Both carry a money-back guarantee.

Liposomal delivery uses phospholipid encapsulation to improve how much vitamin C reaches the bloodstream. The absorption advantage is established in the research; whether it changes clinical outcomes has not been settled, and we would rather say so. For anything quantitative, see current pricing and serving details on the product pages, where the figures stay current.

Frequently Asked Questions

Should I take vitamin C and vitamin E at different times?

Only if you are training seriously. The one trial showing a problem used 1,000 mg of vitamin C with 235 mg of vitamin E across 11 weeks of endurance training, and the effect showed up in a muscle protein rather than in performance. For general health, there is no evidence that separating them helps.

Does vitamin C destroy vitamin B12 in a multivitamin?

No. The claim comes from a 1974 report that 2 independent laboratories could not reproduce in 1976, finding no harmful effect on the B12 in meals. A 1980 paper showed the original loss was an extraction artefact that disappeared when the method was corrected.

Can I take vitamin C with zinc?

Yes. Zinc has no documented interaction with vitamin C, and the 2 are combined in immune formulas routinely. If your zinc supplement also contains copper, as many do, spacing it a few hours from doses above 1 gram of vitamin C is a sensible precaution based on the ceruloplasmin findings, though copper status itself was unaffected in both studies.

Is it safe to take vitamin C with an iron supplement?

For most people, yes, and it is the intended combination. High-dose vitamin C left serum ferritin essentially unchanged at 46 µg/L before and 43 µg/L after supplementation. If you have diagnosed haemochromatosis or another iron-overload condition, speak to your doctor before taking either.

How much vitamin C is too much when I take other supplements?

The tolerable upper intake level is 2,000 mg a day for adults, and it covers your total from every source combined, including multivitamins and fortified foods. Most people who run into trouble have stacked 3 products without adding up what is in them.

Does liposomal vitamin C change any of these answers?

Not materially. Liposomal delivery is designed to improve absorption, and the complete guide to liposomal vitamin C covers what that changes. Since none of the vitamin pairings above rests on a solid interaction to begin with, better absorption does not create one, though the 2,000 mg upper limit still applies to your daily total.

Conclusion

The honest answer to which vitamin should not be taken with vitamin C is that no vitamin has strong evidence against it, and the NIH's own list of 2 interaction examples names none. Vitamin E is worth spacing during hard training, copper is worth spacing at high doses, and iron is worth combining unless you have an iron-overload condition. If you are choosing a vitamin C to fit alongside other supplements, review the full product specification and bring it to your pharmacist.

Research References

1. Vitamin C: Fact Sheet for Health Professionals. National Institutes of Health, Office of Dietary Supplements. The reference document for vitamin C intake, absorption and interactions, giving two medication interaction examples and no vitamin interactions.
2. Vitamin C and E supplementation hampers cellular adaptation to endurance training in humans: a double-blind, randomised, controlled trial. The Journal of Physiology, Vol. 592, Issue 8 (2014), pp. 1887–1901. In 54 participants over 11 weeks, 1,000 mg vitamin C with 235 mg vitamin E blunted the training-induced rise in the mitochondrial protein COX4.
3. Antioxidants and Exercise Performance: With a Focus on Vitamin E and C Supplementation. International Journal of Environmental Research and Public Health, Vol. 17, Issue 22 (2020), article 8452. Reports a meta-analysis finding that vitamin E alone or with vitamin C neither enhances nor blunts exercise-induced training adaptations.
4. Destruction of vitamin B12 by ascorbic acid. JAMA, Vol. 230, Issue 2 (1974), pp. 241–242. The original report claiming that vitamin C taken with food destroys substantial vitamin B12.
5. Stability of vitamin B12 in the presence of ascorbic acid. The American Journal of Clinical Nutrition, Vol. 29, Issue 6 (1976), pp. 645–649. Two independent laboratories repeated the 1974 meal experiments with standardised methods and found no harmful effect of added ascorbic acid on B12.
6. Stability of vitamin B12 in the presence of ascorbic acid in food and serum: restoration by cyanide of apparent loss. The American Journal of Clinical Nutrition, Vol. 33, Issue 1 (1980), pp. 137–143. Apparent B12 losses were fully recovered when cyanide was used during extraction, identifying the earlier finding as a method artefact.
7. Effect of Varying Ascorbic Acid Intakes on Copper Absorption and Ceruloplasmin Levels of Young Men. The Journal of Nutrition, Vol. 117, Issue 12 (1987), pp. 2109–2115. At 605 mg a day, ceruloplasmin oxidase activity fell about 21% while copper absorption, retention and serum copper were unchanged.
8. Influence of ascorbic acid supplementation on copper status in young adult men. The American Journal of Clinical Nutrition, Vol. 37 (1983), pp. 553–556. At 1,500 mg a day for 64 days, serum ceruloplasmin activity fell significantly at every measurement point.
9. Copper. Micronutrient Information Center, Linus Pauling Institute, Oregon State University. Expert-reviewed synthesis concluding that neither vitamin C study found an adverse effect on copper nutritional status.
10. Effect of ascorbic acid intake on nonheme-iron absorption from a complete diet. The American Journal of Clinical Nutrition, Vol. 73, Issue 1 (2001), pp. 93–98. The enhancing effect of vitamin C on iron absorption from a complete diet is far less pronounced than from single meals.
11. The efficacy and safety of vitamin C for iron supplementation in adult patients with iron deficiency anemia: a randomized clinical trial. JAMA Network Open, Vol. 3, Issue 11 (2020). In 440 adults, iron alone was equivalent to iron plus vitamin C for haemoglobin recovery.
12. The effect of high ascorbic acid supplementation on body iron stores. Blood, Vol. 64, Issue 3 (1984), p. 721. Serum ferritin averaged 46 µg/L before and 43 µg/L after supplementation, with no significant effect after a further 20 months.
13. High-dose vitamin C: a risk for persons with high iron stores? International Journal for Vitamin and Nutrition Research, Vol. 69, Issue 2 (1999), pp. 67–82. Review concluding that even high vitamin C intakes do not cause iron imbalance in healthy people.

About the Author

David Kimbell is a health writer, digital entrepreneur and former aerospace engineer, based in Ottawa, Canada. He loves translating complex science into clear, actionable guidance for consumers seeking evidence-based solutions.

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Important Disclaimers

Medical Disclaimer: This article provides educational information only and is not intended as medical advice. Always consult with a qualified healthcare provider before starting any new supplement, especially if you have existing health conditions, take medications, or are pregnant or nursing.

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