Which Type Of Iron Needs Vitamin C For Absorption


Effects Of Vitamin c On Iron Absorption

Iron is an essential component of many proteins involved in oxygen transport in the human body and also plays an integral part in the regulation of cell growth and differentiation. The bioavailability of iron depends on several factors, including the form that it takes. Heme iron is the most readily absorbed form of iron and is found in foods such as red meat, shellfish, poultry, and fish.
Nonheme iron is less readily absorbed by the body and is found in foods such as fortified cereal, rice, black beans, soybeans, eggs, wheat, and spinach. Although nonheme iron is harder for the body to absorb, it is still an important source of dietary iron. When patients become deficient in iron and diet alone cannot restore iron levels back to normal within a sufficient time frame, iron supplementation with reduced compounds such as ferrous sulfate is indicated.
Vitamin C, also known as ascorbic acid, is a water-soluble vitamin thought to increase the absorption of nonheme iron.
Vitamin C acts as a reducing agent to facilitate iron absorption from the GI tract and to enable its mobilization from storage. The vitamin C and iron combine to form an iron chelate complex, which increases the solubility of iron in the small intestine, resulting in increased uptake across the mucus membranes of the duodenum. For this reason, the vitamin C must be consumed at the same time as the iron in order to be effective. Foods such as broccoli, bell peppers, red cabbage, sweet potatoes, tomatoes, cantaloupe, oranges, mangos, and strawberries are considered excellent sources of vitamin C. Vitamin C can also be taken in oral supplement form. Simultaneous consumption of 25-100 mg of vitamin C has been shown to increase the absorption of nonheme iron by four-fold. However, an excess of 200 mg of vitamin C per 30 mg of elemental iron is required to enhance the absorption of highly available iron salts, such as ferrous sulfate. The amount of iron absorption is considered directly proportionate to the amount of vitamin C taken in.
In addition, vitamin C is also thought to counteract the effects of dietary phytates and tannins, which are known inhibitors of iron absorption. Phytates, found in grains, legumes, nuts, and rice, can decrease the absorption of iron by up to 50 percent. Tannins are found in wine, chocolate, teas, and coffee. Eating foods containing vitamin C or taking vitamin C supplements along with these foods can make up for their inhibiting effects by chemically reducing iron and preventing the formation of less soluble compounds.
Several clinical studies have shown the ability of vitamin C to increase serum iron, ferritin, and hemoglobin concentrations. Overall, increased vitamin C intake through supplementation or dietary consumption represents an important strategy for improving an individual’s iron status. However, it is important to assess each individual patient’s needs, as supplementation is not always necessary, especially for patients whose diet contains plenty of vitamin C.

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

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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.2

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%.3

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.

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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.4


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.5

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%.3


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).6


Tea has been shown to reduce iron absorption by 90%.7

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. 8 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.9


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.3 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.10 If you’re considering trying a supplement, talk to your healthcare provider.


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