Things You Should Avoid When Consuming Iron

You probably want to ensure that you get the most out of the iron you consume, whether from iron-rich foods or an iron supplement. Knowing what foods and substances can interfere with your body’s absorption of iron is one way to help you do that, which is exactly what I will outline here.

Avoiding Iron Absorption Inhibitors


Phytates (or phytic acid) bind with minerals such as iron, calcium and zinc which prevent the mineral from being properly absorbed. The inhibition of non-heme iron absorption is related to the amount of phytate compounds in a given food.

High amounts of phytates are found in legumes, rice and grains (wheat bran, whole wheat, oats, brown rice). The absorption of iron in legumes such as soybeans, black beans, split peas and lentils, has been shown to be very low (about 1% – 2%).

Vegetable proteins (such as soy protein found in tofu) have also been found to inhibit non-heme iron absorption; this effect is independent of the phytate content in food.


Coffee, tea and cocoa lovers may not want to hear this, but these favourites contain polyphenols which have been found to inhibit non-heme iron absorption. During the digestion process, iron binds to tannic acid, forming a complex that is insoluble and prevents proper absorption. Again, the effect of tannic acid is related to the amount that is present in a given food.

High amounts of polyphenols are found in coffee, herbal tea and black tea, red wine, some fruits (raspberries, blackberries, blueberries), and some herbs/spices (oregano, peppermint, chamomile). Depending on the total amount of polyphenols in a beverage, iron absorption can be reduced by 50% – 90%.


Though essential for your health, the calcium in foods and supplements may inhibit both heme and non-heme iron absorption. Although this interaction is not well understood, calcium partly inhibits iron absorption by interfering with the breakdown of phytic acid (phytates), as well as during transfer through the mucosal cell. This inhibitory effect on iron absorption is dose related.

High amounts of calcium are found in foods like milk, cheese, yogurt, figs, almonds, sardines, tofu, rhubarb, and broccoli – just to name a few. Your doctor may recommend taking your iron supplement separate from your calcium supplement to avoid the possible inhibitory iron absorption effects.

Heartburn/Acid Reflux Medications

The most common treatments for heartburn and acid reflux, including aluminum-based antacids, proton pump inhibitors (PPIs), and H2 inhibitors, interfere with iron absorption. Stomach acid helps the body convert the iron you consume into a form that is easier for the small intestine to absorb. Limiting the amount of stomach acid interferes with this process. Some aluminum-based antacids also contain higher doses of calcium which, as I already pointed out, can inhibit iron absorption.

I will note that this effect is not present with Polysaccharide-iron complex or Heme-Iron Polypeptide iron supplements – these forms of iron supplements do not require acid in the stomach to convert the iron for better absoprtion; these compounds are already the type of iron that the body likes to absorb.


Finally, please keep in mind that this is not to say that foods and substances which fall into the categories mentioned above should be removed from your diet. Instead, consider this tip: avoid these items for at least two hours prior to and following the consumption of iron supplements or your main iron-rich meal.


Content and advice provided on The Iron Maiden is for information purposes only and should not serve as a substitute for a licensed health care provider, who is knowledgeable about an individual’s unique health care needs

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15 thoughts on “Things You Should Avoid When Consuming Iron

  1. Corrine Caplin says:

    I am taking Palafer 300mgs. Recently, I have come to learn that your not suppose to take antibiotics when your on Palafer. I am taking an injection on a monthly basis, its a penicillin known as bicilin and its to help prevent cellulitis infections as I have gotten 7 after my cancer. Marketplace was doing on study on the above and it said that it was dangerous to mix the two medications when taken together. Could you ps. inform me if there any truth to their findings and should I stop taking one of them. I have already stopped the palafer until I speak with my doctor. Does anyone out there know anything about the comments I made above, please let me know. thanks. Corrine

    • Leona, RN & Blood Specialist says:

      Hi Corrine,

      Thanks for being a health care consumer; it makes me proud to see patients empowered enough to advocate for themselves!

      One of the biggest issues with media reports such as this is it sensationalizes general information without enough specific details. This may be encouraging patients to abandon treatment regimes without consulting their personal health care provider. I am happy to see that you are seeking the advice of your health care provider regarding this issue.

      Briefly, there is no confirmed interaction between penicillin and iron supplements. There are categories of antibiotics which do have interactions with iron. Your best course of action is to ensure your personal health care provider and your personal pharmacist is aware of all the medications you take, including supplements and herbals, so that they can guide you appropriately. Your personal health care team are the best equipped to guide your care.

      Thank you!

  2. carolyn says:

    Hello! My name is Carolyn. I am presently taking FerMax. I am noticing it is not changing my stools dark. The other irons did. Do you know why. Thank you for the information. Carolyn

    • Leona, RN & Blood Specialist says:

      Hi Carolyn,

      What a great question, offering an important teaching opportunity. As far as I know, the quick answer is that the reason you are not seeing the black tarry stool from FeraMAX is that you are absorbing more of it and what you’re not absorbing is diluted by water that the iron molecule draws into the colon to assist with its excretion.

      As I’ve discussed in many articles, iron salts must be converted into the type of iron our body likes to absorb. This conversion requires the presence of acid in the stomach and is obstructed by certain foods and medications. Polysaccharide Iron Complex (like FeraMAX as you mentioned) and Heme Iron, on the other hand, are already the type of iron our body can better absorb; I say that these irons are already the type of iron our body likes to absorb, and because of this, more can be absorbed and therefore is not visible in our stool. From my understanding, the black tarry stool we associate with the commonly used iron salts is in fact the iron that is not converted and/or absorbed.

      Thanks again and I truly hope you see improvement in your iron stores using FeraMAX.


  3. Marty says:

    I have a problem in that I’m always low in Iron. In the past two + years I’ve had three blood transfusions and about twenty Iron infusions. Taking orally iron pills because they bind me up. The reason why I can’t keep my iron levels is because of bleeding hemorrhoids. For me this is a very embarrassing topic and I don’t like to talk much about it other than with doctors and such.

    So my question to you is; what would be good natural Iron supplement that is high in iron that can be taken everyday?


    • The Iron Maiden says:

      Hi Marty,
      First, while I understand how self conscious you may feel about your hemorrhoids, I assure you that the office of your health care provider is a safe zone. I encourage you to speak to your health care provider and get definitive care for your condition as it is far better to live a life without dependence on supplements if possible.
      The good news is that not all iron supplements are alike. You should consider a polysaccharide iron or heme iron supplement. Both of these supplement types are known for not causing constipation. What is not absorbed of the Polysaccharide Complex Supplement sucks water with it into the colon resulting in a looser than normal stool.
      Good luck on your journey back to optimum health!

      • Marty says:

        Thank you for your advice as I did take you up on this advice and have been taking it everyday. I had my oncologist write a prescription for these so that my insurance company will cover 80% of the cost.

        Again thank you again.


  4. Martha says:

    I was confused about black beans when I read the nutrional facts because I know that calcium does not allow your body to absorb iron well. Black beans are high in iron and calcium. So after reading this article it helped explain black beans are not a good source of iron. What food do you consider a good source of iron? I have struggled with anemia most of my life and am taking iron supplements. I would eventually like to l get enough from foods. I would appreciate some suggested foods that are a good source of iron.

    • The Iron Maiden says:

      HI Martha,

      You are right in saying that calcium and iron compete with each other for binding sites in the hemoglobin molecule. It is hardly a fair competition though because whenever calcium and iron compete for calcium wins as such some legumes, including black beans, might be considered a less than stellar source of iron.

      The best and most absorbable irons are heme irons or “animal source” irons. These include beef, ground meats (chicken, pork, and turkey), chicken (specifically the dark meat of the legs thighs and wings) and clams. Although organ meats like beef and pork liver are excellent sources of heme iron, they are not recommended in those with high cholesterol.

      Vegetable source or “non-heme” irons include pumpkin seeds, soy based products, nuts and nut butters, hummus, black strap molasses, cream of wheat, steel cut oats, green leafy vegetables like spinach and kale, dried apricots and prunes.

      Non-heme irons must be converted from the type of iron they are to the type of iron our body likes to absorb. Some things inhibit this conversion like coffee, tea, cola, chocolate, dairy and dairy substitutes, foods rich in calcium, calcium substitutes and medications that decrease the acid in your stomach (proton pump inhibitors like losec and H2 Inhibitors like ranitidine). Some things assist with this conversion such as vitamin C (supplements or foods rich in vitamin C), heme irons and acidic condiments like vinegar.

      If you are having a salad of leafy greens skip the creamy dressing, which may inhibit the conversion of the non-heme iron, in favour of a vinegarette style dressing.

      While eggs are an animal source iron, the iron they contain is actually a non-heme iron. So rules that promote its conversion to the type of iron our body absorbs apply.

      Finally, cast iron cooking pans also liberate trace amounts of non-heme iron.

      Hope this helps your plans to increase dietary iron! Stay well!


  5. Sim says:

    Hello , my daughter who is 3 years old was started on feramax 75 mg daily for her ferritin level of 4 and hemoglobin being 67. We repeated bloodwork in 5 weeks and although her hemoglobin did come upto 85 but her ferritin dropped to only 3. And her stool has been ver dark and black , so does that mean she is not absorbing the iron from feramax? Should I try to change to different supplement and see if it will help? Any suggestion will be really helpful as I am very desperate to help my little one.

    • The Iron Maiden says:

      Hi Sim,

      I am sorry to hear of your daughter’s anemia. The use of FeraMAX powder is a very good choice, as children tend to like the taste – and therefore WANT to take it! Other irons are very difficult to get children to take as the taste alone is off putting.

      Your daughter’s reaction to the FeraMAX is exactly as I would have predicted. Anecdotally we know ferritin less than 20 is difficult, if not impossible to replete with oral iron. Oral iron will support and likely return her hemoglobin, over time, to normal range.

      I am not sure if you have done this, but I strongly recommend asking your physician for a referral to a pediatric hematologist, who can evaluate the best way to optimize both your daughter’s hemoglobin and iron stores.

      The darker stool you have noticed is the iron your daughter’s body didn’t absorb. No iron supplement is completely absorbed. The beauty of FeraMAX is that the unabsorbed portion sucks water into the colon reducing constipation commonly associated with iron supplements. Please make sure she does consume enough liquid in a day to facilitate this.

      There are a number of articles about introducing more iron into your child’s diet such as baking spinach into muffins etc.

      I am sorry you are having to deal with anemia with your child at such a young age. Consider reviewing the pediatric symptoms checklist in an attempt to discover if she is in an “at risk” group as this may give you some ideas regarding how to decrease her future risk of iron deficiency and related anemia.

      Good Job!


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