What iron and magnesium do in the body

Energy metabolism: from food to usable energy

Every cell obtains energy by converting nutrients from food into ATP — the molecule that serves as the universal currency for energy in the body. This process takes place largely in the mitochondria and depends on a series of coordinated enzyme reactions.

Iron in mitochondrial electron transport

Within the respiratory chain there are several protein complexes that pass electrons on step by step, until enough energy is available at the end for ATP synthesis. Iron is a component of heme groups and iron-sulfur clusters, which act as electron carriers within these complexes. Without functioning iron-containing cytochromes, electron transport stalls and the cell's energy production is restricted.

Iron is also involved in the activity of various enzymes of the citric acid cycle, such as aconitase, which catalyses an important intermediate step in the utilisation of carbohydrates and fats.

The reference value for daily iron intake under EU Regulation 1169/2011 is 14 mg.

Magnesium as a cofactor in energy metabolism

Magnesium, ATP and the enzymes of glycolysis

Magnesium forms a complex with ATP (Mg-ATP) which is the actual biologically active form of the molecule. Numerous key enzymes of glycolysis — including hexokinase and phosphofructokinase — require this Mg-ATP as a substrate in order to break down glucose step by step. Magnesium is also involved in several enzymatic steps in the citric acid cycle and in oxidative phosphorylation.

A further aspect concerns the stability of mitochondrial cell membranes: magnesium contributes to the structural order of the membrane phospholipids, which matters for an orderly respiratory chain.

The reference value for magnesium in the EU is 375 mg per day.

Cell division: how the body renews itself continuously

Besides energy production, cell division is one of the most fundamental processes in the body. Skin, intestinal mucosa and blood cells, for example, are renewed continuously, which requires cells to divide regularly and to duplicate their complete DNA without error in the process.

DNA replication before division

Before a cell divides, all of its genetic information must be copied. Ribonucleotide reductase plays a key role in this: the enzyme converts ribonucleotides into deoxyribonucleotides — the building blocks of DNA. Iron is required as a cofactor of this enzyme so that enough building blocks are available for the new DNA copy.

In parallel, magnesium is involved in the activity of the DNA polymerases, which produce the actual copy strand by strand. Magnesium ions also stabilise the spatial structure of the DNA double helix during this delicate process.

Iron and magnesium in everyday life

A varied diet generally supplies both minerals, although their bioavailability differs depending on the food. Iron from animal sources (heme iron) is absorbed more efficiently by the body than iron from plant sources (non-heme iron). Vitamin C taken alongside can increase the absorption of non-heme iron, while tannins from coffee or tea can reduce it.

Magnesium is absorbed mainly in the small intestine, with the absorption rate tending to fall as intake increases — a homeostatic mechanism of the body. When using dietary supplements, the stated recommended daily dose should not be exceeded.

Answers to recurring questions

Does an iron deficiency affect cell division?

Because iron is required as a cofactor of ribonucleotide reductase, an inadequate iron supply can impair the provision of DNA building blocks. Whether and to what extent this has an effect in an individual case is a medical question to be clarified by a physician.

Why does magnesium play a role both in energy metabolism and in cell division?

Magnesium is involved in a great many enzymatic reactions in the body, because it stabilises phosphate groups and thereby makes numerous enzymes functional in the first place. This broad involvement explains why magnesium appears in different metabolic pathways — from ATP formation to DNA replication.

How do energy metabolism and cell division differ from each other?

Energy metabolism describes the continuous conversion of nutrients into usable energy (ATP), while cell division refers to the periodic process of cell multiplication and renewal. The two processes run independently of one another, but they share common cofactors such as iron and magnesium.

Is diet alone enough to cover iron and magnesium requirements?

A balanced and varied diet can supply both minerals in sufficient amounts for most people. Individual factors such as diet, life stage or existing conditions can affect requirements, however — a physician is best placed to advise on this.