Iron deficiency is one of the most common mineral deficiency in the world. It is believed that about half a billion people in the world suffer from iron deficiency. Iron deficiency develops step by step: first body´s iron stores are depleted (ferritin) and after that anemia, i.e. low hemoglobin level, will develop. Iron deficiency anemia is most common in children before age 2, teenagers and women in fertile age. Men have 4–5 g and women 2–3 g of iron in their body. Most of the iron is in hemoglobin of the red blood cells and enzymes consisting of iron. The rest of the iron is body´s iron stores, which are possible to measure by checking your ferritin level [1].


  • little amount of absorbable iron from food
  • increased need for iron, e.g. during pregnancy, growth phase or menstruation
  • increased loss of iron due to certain illnesses and e.g. intestine bleeding caused by internal parasites
  • excessive use of dairy products [1]

We get two different forms of iron daily from food: heme-iron from animal products and non-heme-iron from plant-based products. How do these two forms differ from each other? The difference lies in the absorption.

The absorption of iron just like other minerals, vitamins and nutrients, takes place in the small intestine. Iron from non-heme iron is absorbed around 1–20% and 15–35% from heme-iron. Omnivores get on average 10–15% heme-iron from food, but due to its better absorption, it makes up to almost 40% of the total daily iron need [1].

Weak absorption of iron is taken into account when calculating the recommended daily intake of iron. E.g. women in fertile age need about 1,3 mg of iron a day and men 1 mg. In order to achieve this, we should get about 13 mg of iron a day.

How much iron should a vegetarian get from food?

What contributes to the absorption of heme- and non-heme iron?

Iron form Increases absorption Decreases absorption
HEME-IRON Low iron stores (ferritin) Higher iron stores (ferritin)
  Small amount of heme-iron from food Greater amount of heme-iron from food
  Meat Calcium (mainly dairy products)
NON-HEME-IRON Low iron stores (ferritin) Higher iron stores (ferritin)
  Pregnancy Stomach´s low acidity
  Certain illnesses, e.g. aplastic anemia, hemolytic anemia, hemacromatosis Phytates (whole grain, legumes, bran)
  Certain organic acids, e.g. vitamin C (ascorbic acid) and citric acid Iron binding phenolic compounds, e.g. tea, cocoa, wine
  Meat, fish, seafood Calcium (mainly dairy products)

How to increase the absorption of non-heme-iron from food?

It is a well-known fact that the consumption of vitamin C together with food increases the absorption of non-heme-iron. It is also important to avoid the consumption of calcium-rich food at the same time with iron. E.g. dairy products contain a lot of calcium, which binds iron and, thus, decreases the overall absorption of iron in the body. Calcium has often been added to plant-based drinks as well.



[1] A.Aro, M.Mutanen, M.Uusitupa. Nutrition Science. 4th-7th volume, 2017

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