You Don't Need to Take Vitamin C With Your Iron Supplements, Study Suggests

Unseen woman pouring orange tablets from a bottle into her open hand.

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Key Takeaways

  • It's common practice to take vitamin C with iron supplements to help with absorption.
  • New research says there's not enough evidence to definitively support a need to take vitamin C with iron in people with iron deficiency anemia.
  • You should still avoid taking iron with any food, antacids, or calcium to achieve the best absorption.

According to a new study, people with iron deficiency anemia (IDA) might not need to take supplemental vitamin C along with oral iron supplements to help with absorption, despite longstanding advice to do so.

The standard practice for managing IDA has been for a person to increase dietary sources of iron and take an iron supplement, as well as supplemental vitamin C or foods rich in vitamin C, Nicole DeMasi Malcher, MS, RDN, CDCES, registered dietitian and founder of DeMasi Nutrition, tells Verywell. But now, Malcher confirms that recent data “suggests vitamin C might not be necessary to absorb non-heme [not animal based] iron supplements in the body.” 

What Is Iron Deficiency Anemia (IDA)?

Iron deficiency anemia (IDA) occurs when the body does not have enough iron. It can be diagnosed with a simple blood test. If untreated, IDA can cause a variety of symptoms, including chronic fatigue, headaches, and an irregular heartbeat.

Anyone can become iron deficient, but some people are more likely to develop the condition. For example, pregnant people are more at risk for developing IDA because iron needs increase throughout pregnancy.

Iron and Vitamin C

Traditionally, healthcare providers have suggested that people take iron along with vitamin C to help create an acidic gastrointestinal environment, which is thought to help dissolve the iron adequately for absorption.

The new study, which was published in the November issue of the Journal of the American Medical Association, notes that there has not been a randomized clinical trial (RCT) to assess whether vitamin C supplements are necessary for patients with IDA taking iron tablets. 

The Study

In the randomized clinical trial, 440 adult participants with newly-diagnosed IDA were randomly assigned to two groups. Participants in one group took oral iron supplements (in the form of ferrous succinate) plus vitamin C, and participants in the other took only oral iron supplements.

The participants who were in the iron-only group took 100-milligram (mg) iron tablets every 8 hours for three months. The participants in the iron-vitamin C group took the same dose of iron supplement plus an additional 200 mg of vitamin C.

During the several months of treatment, the researchers periodically evaluated blood samples taken from the subjects to check their iron levels.

Based on their findings, the researchers concluded that taking oral iron supplements alone provided hemoglobin level and iron storage recovery efficacy equivalent to that of oral iron supplemented with vitamin C.

It does not appear that the vitamin C boost offered benefits in terms of iron absorption.

The only possible benefit the researchers observed was that vitamin C might have a positive effect on changes in mean corpuscular volume (MCV)—the measure of the mean size of red blood cells. The researchers thought that the finding could be important because patients with IDA typically have lower than normal MCV values.

Iron Supplements

Iron supplements have been used as a standard practice for treating iron deficiency anemia. The logic behind supplementing with higher doses of iron is that the nutrition gap is filled and the deficiency can be resolved.

There are different forms of iron supplements—including ferrous succinate, the kind used in the recent study—that have been shown to be effective.

While the study suggests that combining iron supplements with vitamin C offers no clinical benefit in terms of iron absorption, other research has found otherwise.

In a 2019 article published in Geriatric Nursing, the author noted that in one study, taking 100 mg of vitamin C with a meal was found to increase iron absorption by 67%.

However, the dose matters when it comes to the data surrounding supplementation. In the recent study, “the participants took 100 mg of iron every 8 hours, which would be 300 mg per day total,” Grace Goodwin Dwyer, MS, MA, RD, LDN, a registered dietitian based in Nashville, Tennessee, tells Verywell. “In contrast, people taking over-the-counter iron supplements are probably taking 30 to 60 mg per day if they’re following the instructions on the packages on most major brands.”

Dwyer says "it would be interesting to see in a follow-up study about how vitamin C applies to lower dosages, like many of our patients are taking.”

Dietary Sources of Iron

While taking iron supplements is one way to treat IDA, including food sources of iron in your diet can also help you meet your needs.

There are two main types of iron that come from your diet:

  • Heme iron is found in foods like beef and seafood options
  • Non-heme iron is found in foods like vegetables, beans, and whole grains. Certain foods are also fortified with non-heme iron.

Heme iron appears to be better absorbed in the body than non-heme iron. Taking vitamin C with non-heme sources of iron may help maximize iron absorption with little risk.

Tips to Support Iron Absorption

If you're supplementing with iron, there are also some things you can do to help ensure that it's properly absorbed and used by your body—or at least, you can avoid doing things that would make it harder for your body to absorb and use the important mineral.

Take Iron Every Other Day

Data published in The Lancet in 2019 suggested that giving iron-depleted women daily iron supplements as divided doses reduced iron absorption. On the other hand, providing iron supplements in single doses on alternate days appeared to optimize iron absorption and might be a preferable dosing regimen.

Choose Your Dietary Sources Wisely

“If you’re looking to boost iron absorption in your body through food, it’s helpful to focus on animal sources,” Dwyer says. This is because of the heme form of the iron that these foods contain. Red meat, chicken, and shellfish can be helpful additions to your diet.

If you follow a vegetarian or vegan lifestyle, know that while there are dietary iron sources that are animal-free, you may need to consider taking a supplement to prevent anemia.

Take Iron On An Empty Stomach

Iron is best absorbed when taken on an empty stomach with a full 8-ounce glass of water or orange juice. If you get an upset stomach, you can take your iron with food or immediately after meals; however, know that taking an iron supplement with food will decrease absorption to 40%.

Avoid Taking Iron With Phytate-rich and/or Polyphenol-rich Foods

You also need to be mindful of the foods and drinks you consume when you take your iron. Absorption of oral iron is inhibited by phytates (which are found in cereals and certain vegetables) and polyphenols (which are found in some vegetables, fruits, cereals, legumes, tea, coffee, and wine).

Tea has been shown to reduce iron absorption by 90%.

Do Not Take Antacids Or Calcium Supplements With Iron

Antacids or calcium supplements can decrease iron absorption and should not be taken at the same time as iron supplements. It is best to space doses of these products out. Take antacids or calcium 12 hours apart from your iron.

Ensure You Are Not Deficient in Copper

Copper is a mineral that plays a key role in helping the body absorb iron. If your copper levels are low, your body might have a hard time absorbing iron.

Consider The Pros and Cons of Taking Vitamin C With Iron

Data appears to be mixed when it comes to the benefits of taking vitamin C with iron to support absorption. If you do choose to take a vitamin C supplement, make sure that you know how much vitamin C is in the product you've chosen.

It appears that vitamin C needs to be taken in a dose of 200 mg to reap the potential benefit.

While taking supplemental vitamin C is low-risk, it's not risk-free. For example, if you don't tolerate the dose, you might experience gastrointestinal symptoms like nausea and diarrhea. You should also know that some prescription and over-the-counter (OTC) medications don't mix with vitamin supplements, including vitamin C. If you're considering trying a supplement, talk to your healthcare provider.

What This Means For You

If you have iron deficiency anemia, your provider might recommend that you increase sources of heme and non-heme iron in your diet, as well as take an iron supplement. But despite the standard practice, you may not need to pair iron with vitamin C to help with absorption. Talk to your doctor before starting any kind of vitamin supplement.



10 Sources
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  1. Li N, Zhao G, Wanling W, Zhang M, Liu W, Chen Q. The efficacy and safety of vitamin C for iron supplementation in adult patients with iron deficiency anemia: A randomized clinical trial. JAMA Netw Open. 2020 Nov 2;3(11):e2023644. doi:10.1001/jamanetworkopen.2020.23644

  2. Cao G, Li K, Jin P, Yue X, Yang C, Hu X. Comparative bioavailability of ferrous succinate tablet formulations without correction for baseline circadian changes in iron concentration in healthy Chinese male subjects: a single-dose, randomized, 2-period crossover study. Clin Ther. 2011 Dec;33(12):2054-9. doi:10.1016/j.clinthera.2011.10.028

  3. Simonson W. Should vitamin C routinely be given with oral iron supplements?. Geriatr Nurs. May-Jun 2019;40(3):327-328. doi:10.1016/j.gerinurse.2019.05.007

  4. Stoffel N, Cercamondi C, Brittenham G, Zeder C, AJ Geurts-Moespotet, Swinkels DW, et al. Iron absorption from oral iron supplements given on consecutive versus alternate days and as single morning doses versus twice-daily split dosing in iron-depleted women: two open-label, randomised controlled trials. Lancet Haematol. 2017 Nov;4(11):e524-e533. doi:10.1016/S2352-3026(17)30182-5

  5. Pawlak R, Berger J, Hines I. Iron status of vegetarian adults: A review of literatureAm J Lifestyle Med. 2016;12(6):486-498. doi:10.1177/1559827616682933

  6. Milman NT. A review of nutrients and compounds, which promote or inhibit intestinal iron absorption: Making a platform for dietary measures that can reduce iron uptake in patients with genetic haemochromatosisJ Nutr Metabol. 2020;2020:1-15. doi:10.1155/2020/7373498

  7. Lopez A, Cacoub P, Macdougall I, Peyrin L. Iron deficiency anaemia. Lancet. 2016 Feb 27;387(10021):907-16. doi:10.1016/S0140-6736(15)60865-0

  8. Mayo Clinic. Iron Supplement.

  9. Collins J, Prohaska J, Knutson M. Metabolic crossroads of iron and copper. Nutr Rev. 2010 Mar;68(3):133-47. doi:10.1111/j.1753-4887.2010.00271.x

  10. Wishart DS, Feunang YD, Guo AC, Lo EJ, Marcu A, Grant JR, et al. Vitamin C - Ascorbic Acid. DrugBank Online. doi:10.1093/nar/gkx1037