The importance of iron

What is iron?

The chemical element iron is the most common element on our planet by mass. It has the atomic number 26 and its symbol is Fe (from ferrum, it’s name in Latin).

Iron, which his a metal, forms much of Earth’s outer and inner core, and it is the fourth most common element in the Earth’s crust.

A human male of average size should have approximately 4 grams of iron in his body. For females, the number is about 0.5 grams lower. In the human body, the iron is distributed throughout the body and is for instance found in blood, muscles, bone marrow and internal organs. Approximately 75% of the iron forms a part of the hemoglobin in the red blood cells. The human body is good at recycling the iron in the hemoglobin so that it can be used over and over again. Despite this, we also need to get a certain amount of iron from our diet.

iron rich food

Why is iron important for my health?

Iron is important for many things in the human body, including oxygen transport and the creation of certain enzymes.

Oxygen transport

Iron is necessary for the production of hemoglobin and myoglobin.

  • Hemoglobin is an oxygen-carrying metalloprotein present in your red blood cells. Hemoglobin carries oxygen from the lungs to the rest of the body.
  • Myoglobin is the primary oxygen-carrying pigment in muscle tissue in your body.


Many of the chemical reactions that take place in the human body rely on enzymes to speed up the process. Without these enzymes, each reaction would take way too long. In many of the necessary redox enzymes in the human body, iron is of imperative importance. Iron is, among other things, involved in very important reactions concerning cellular respiration.

Iron deficiency

Globally, iron deficiency is one of the most common nutritional deficiencies in humans. Examples of population groups especially likely to be deficient are children, women of child-bearing age and people with a poor diet.

When the body’s loss of iron isn’t adequately compensated by new iron being absorbed from the diet (or from other sources, such as iron injections), the body will start suffering from a mild case of iron deficiency. If the situation isn’t remedied, iron deficiency anaemia can develop.


Here are a few examples of things that can cause iron deficiency in humans:

  • Inadequate iron intake
  • Inadequate absorption of iron from the diet, e.g. due to underlying health problems in the gastrointestinal tract. There are also substances that can interfere with the body’s iron absorption, including some naturally occurring elements in certain foods.
  • Blood loss; either chronic (such as heavy menstrual bleedings) or acute (such as major wound). Many health issues can cause chronic blood loss, e.g. ulcerative colotis, ulcers and colon cancer.
  • Fluoroquinolone antibiotics
  • Certain inflammatory diseases, including rheumatoid arthritis and inflammatory bowel disease
  • Certain parasitic infestations


Many symptoms of iron deficiency are the type of symptoms that are produced by a wide range of health issues, such as fatigue, dizziness and irritability. Without a blood test specifically looking for iron deficiency, it is difficult to know if the symptoms are caused by iron deficiency or by something else – or if iron deficiency is only a part of the problem. As shown above, iron deficiency can in itself be a symptom of an underlying health issue.

Please note that symptoms of iron deficiency can manifest even before the condition has progressed to iron deficiency anaemia.

Examples of symptoms of iron deficiency

  • Dizziness / being lightheaded
  • Fatigue
  • Irritability
  • Weakness
  • Impaired immune function
  • Twitching
  • Restless legs syndrome
  • Pallor (an unhealthy pale appearance)
  • Hair thinning
  • Loss of hair
  • Brittle nails
  • Grooved nails
  • Pica, which is a craving to eat substances other than normal food. In particular, craving and chewing ice (pagophagia) is often associated with iron deficiency anemia.
  • Plummer-Vinson syndrom, which is a painful atrophy of the mucous membrane covering the tongue, pharynx and esophagus
  • Iron deficiency anaemia
  • Elevated platelets (thrombocytes) count
  • Irregular heartbeat
  • Certain pregnancy complications
  • Delayed growth in children

Iron is required for many enzymes to function properly in the human body, which is why an iron deficiency can manifest in so many different ways and produce symptoms from many different parts of the body.

What foods are rich in iron?

The type of iron most easily absorbed by the human body is heme iron. Compared to non-heme iron, the heme iron is more readily absorbed by the body and it is also less likely to be inhibited by medications or by compounds in the food.

When foods, e.g. cereals, are fortified with iron, they are fortified with non-heme iron.

Examples of good sources of heme iron

  • Liver
  • Blood food, such as blood pudding and blood sausage
  • Clams, oysters, molluscs, mussels
  • Sardines canned in oil
  • Read meat
  • Insects

Examples of good sources of non-heme iron

  • Lentils
  • Beans
  • Chickpeas
  • Black-eyed peas
  • Green leaf vegetables
  • Blackstrap molasses
  • Tofu
  • Pistachios

Cooking in iron pots and pans

Cooking in a cast iron skillet can make your food significantly richer in iron.

For an extra boost, cook acidic foods with a high moist content, such as a tomato based pasta sauce, because such dishes are especially good at absorbing iron from the pan. It is also a good idea to opt for food that will spend a long time in the pot, e.g. a slow-cooked sauce rather than some quickly fried up tomatoes. Scrubbing the bottom of the skillet a bit as you stir the dish, and stirring it frequently, will also increase the iron content in the food.

In a study published in the Journal of the American Dietetic Association, 100 grams of spaghetti sauce cooked in a cast iron pot increased its iron content from 0.6 mg to a whopping 5.7 mg.

Dietary supplements

  • One way of making iron more available to the human body is to chelate it to amino acids. This type of iron dietary supplements are often a bit more expensive.
  • Standard iron supplements will typically contain iron (II) fumarate. Iron (II) sulfate is found in some products, and is absorbed equally well as iron (II) fumarate.
  • Elemental iron (reduced iron) is not particularly well absorbed by the human body, but is often the iron of choice for fortified food products, such as enriched breakfast cereals and enriched wheat flour. Compared to iron sulfate, elemental iron is absorbed at only 1/3 to 2/3 the efficiency.

How can I increase my iron absorption?

  • Eat food that is rich in heme iron. (Non heme iron is more difficult for the body to absorb.)
  • If you need a dietary supplement, chose one where the iron is chelated to amino acids.
  • Oxalates form insoluble complexes that bind iron in the gut, preventing your body from absorbing the iron. Avoiding oxalate-rich ingredients can therefore be a good idea when you are making an iron-rich meal. Examples of oxalate-rich foods are sorrel, rhubarb, buckwheat, carambola, parsley, spinach, swiss chards, and many members of the genus Oxalis.

    Leaves of the tea plant (Camellia sinensis) are rich in oxalic acid relative to other plants, but the beverage created by putting tea leaves in hot water will typically contain only low to moderate amounts of oxalic acid.

  • Phytic acid form insoluble complexes that bind iron in the gut, preventing your body from absorbing the iron. Avoiding ingredients rich in phytic acid can therefore be a good idea when you are making an iron-rich meal.

    Phytic acid is found within the hulls of seeds, including grains, nuts and pulses. Many common food preparation techniques will break it down, including the acid fermentation that takes place in a sourdough and when food is pickled.

    As a food additive, phytic acid is used as a preservative and called E391.

  • Non-heme iron is more readily absorbed if consumed together with vitamin C.