The Relationship Between Iron and Diet

What is iron deficiency anemia? How can you improve the absorption of iron from the foods that make up the diet? In the following article, we'll delve into the relationship between iron and diet.
The Relationship Between Iron and Diet

Last update: 15 January, 2020

Iron is present in all body cells. However, this compound is rarely alone. It’s almost always bound to proteins or, freely, such as hemoglobin, myoglobin, or bound to respiratory enzymes. It can also be linked to storage proteins such as ferritin or hemosiderin. Here’s everything you need to know about the relationship between iron and diet.

Iron absorption is inversely proportional to the amount contained in the food. Of the iron that’s ingested, it’s absorbed–between one and 50 percent.

Your body is smart: if you’ve suffered from blood loss or anemia, there’s an increased synthesis to replace iron, so more is needed and there’s a greater percentage of absorption.

The variability of iron absorption depends, above all, on the way in which it’s present in food as well as on the dietary factors that modulate its absorption, rather than on the amount ingested.

In this sense, heme iron comes from the food of animal origins. Your body easily absorbs this type of iron and you use a relatively large percentage – between 20 and 75 percent – because it enters easily and has almost no absorption inhibitors.

On the other hand, non-heme iron comes from plant-based foods, and their bioavailability is lower. This means that it’s more difficult to mobilize and use it, but that doesn’t imply that it’s of lower quality. To improve its bioavailability it can be consumed together with certain activators.

Activators and inhibitors

Calcium inhibits the absorption of heme iron, while the consumption of meat (along with foods rich in it) favors its absorption.

In the case of non-heme iron, you can absorb it better when you take it alongside foods rich in ascorbic acid, citric acid, malic acid, and animal proteins.

Iron-rich foods help women suffering from a deficit of this nutrient.

You need to look for healthy sources of iron to add to your diet. What’s a good option? You could try a plate of lentils! Lentils are a source of plant-based protein-rich in the nonheme type. In other words, they contain less absorbable iron than a beefsteak.

In order to enhance the absorption of iron from lentils, you can consume them alongside an activator, such as ascorbic acid. How does this work?

Ascorbic acid, also known as vitamin C, is present in citrus fruits such as lemons, oranges or strawberries, and in other foods such as tomatoes or vinegar, among others. Thus, one way to favor the absorption of iron from lentils is to take an orange for dessert or accompany the lentils with sweet pepper.

In the case of non-heme iron absorption, the most prominent inhibitors are calcium, phytates, oxalates and non-animal proteins.

Phytates are common in the bran and germ of cereals, legumes, and seeds. Spinach, chard or chocolate are good sources of oxalates that, as already mentioned, hinder the absorption of nonheme.

Iron supplements

And what happens with iron supplements? To prevent iron deficiency, you should take iron supplements on an empty stomach. Sometimes, other foods can interfere with iron supplements so avoid them if possible. You should also complement supplements with an orange juice, or better yet, a whole orange.

Iron deficiency

Fifteen percent of the world’s population suffers from iron deficiency. This can vary from a moderate decrease in reserves – ferritin – to iron deficiency anemia, which occurs when depletion levels are very high.

Analytically, to know if someone has iron deficiency you’ll have to take into account circulating iron, ferritin and the number of red blood cells. To diagnose iron deficiency, a doctor should take into account all of these parameters.

Having an iron-rich diet

To get adequate iron intake, you should consume foods rich in bioavailable iron and, when necessary, add iron supplements. Here’s how to have an iron-rich diet:

  • Boost your intake of iron-rich foods of both animal origin as well as vegetables.
  • Promote the consumption of these foods alongside absorption activators, especially foods rich in the non-heme type.
meat is very rich in iron
  • Reduce the consumption of iron inhibitors.
  • Avoid having coffee and tea with meals.
  • Don’t take dairy with your main meals: eat them two hours later.
  • Control your fiber intake and keep its consumption separate from the iron-reach meals.


Iron supplementation is the main way to treat iron deficiency anemia. To minimize side effects, it’s important to start with a low dose and gradually increase it. Some of the most frequent side effects of iron supplementation are nausea, gastric discomfort, diarrhea, and constipation.

Overall, the relationship between iron and diet is very important. As with most essential nutrients, it’s best to ingest this mineral in the right proportions. Speak with a professional when the need arises to remedy the situation.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

  • Salas-Salvadó J, Sanjaume AB et al. Nutrición y dietética clínica. 2019. Elsevier Health Sciences.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.