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