Iron for women who train: inside your oxygen transport system
Every interval begins long before your muscles contract. Oxygen has to move from your lungs into your blood, travel to the working muscle and reach the machinery inside each cell. Iron is built into that transport system. Here is the biology behind it—and why The Daily Performance combines 14 mg of iron with vitamin C in one daily serving.
The route oxygen takes
Think of oxygen delivery as a relay. You breathe oxygen into the lungs. It crosses into the bloodstream and binds to haemoglobin inside red blood cells. The heart sends those cells towards the muscles doing the work. There, oxygen is released and can move into the muscle cells.
Iron sits at the centre of haemoglobin's oxygen-binding structure. It is also present in myoglobin, a related protein that handles oxygen inside muscle, and in iron-containing proteins within mitochondria—the cellular structures involved in converting nutrients into usable energy.
That is the link to training: not a dramatic shortcut, but a fundamental part of the normal system that supplies working tissue with oxygen.
One atom, one reversible grip on oxygen
A haemoglobin molecule contains four haem groups. At the centre of each group is an iron ion that can bind one oxygen molecule in the lungs and release it again where oxygen pressure is lower, including in active muscle.
Red blood cells circulate for about 120 days. When an old cell is dismantled, most of its iron is recovered and used again. The body therefore runs an efficient recycling system: transferrin transports iron through the blood, while ferritin stores it until it is needed.
Inside mitochondria, iron is also part of proteins in the electron transport chain. This is one reason the biology of oxygen transport and energy-yielding metabolism is so closely connected.
Why this matters to women who train
Training asks the oxygen transport system to work harder. During a run, a hard interval or a heavy set, blood flow rises and oxygen has to reach the muscle at speed. Iron contributes to normal oxygen transport, normal formation of red blood cells and haemoglobin, and normal energy-yielding metabolism.
Women who menstruate also have a regular route of iron loss that men do not. That does not make iron mysterious or alarming; it simply makes it a nutrient worth understanding when food, training and recovery are considered together.
Food iron comes in two forms
Haem iron is found in foods such as meat and fish. Non-haem iron is found in plant foods including legumes, whole grains, seeds and leafy vegetables. The body handles the two forms differently, and the composition of a meal affects how much non-haem iron is absorbed.
Vitamin C has a recognised role here. The authorised EU wording is precise: vitamin C increases iron absorption. It helps keep non-haem iron in a form that is easier to take up in the intestine.
How to read an iron label
The important number is the amount of elemental iron, not the total weight of the iron compound. The Daily Performance provides 14 mg of elemental iron as ferrous bisglycinate. This is a chelated form in which iron is bound to the amino acid glycine.
We chose a clearly defined form and a transparent daily amount: 14 mg is 100% of the EU nutrient reference value. The same serving contains 300 mg of vitamin C, equal to 375% of the nutrient reference value.
The authorised health claims
The following claims are authorised under Regulation (EU) No 432/2012:
- Iron contributes to normal oxygen transport in the body.
- Iron contributes to normal formation of red blood cells and haemoglobin.
- Iron contributes to normal energy-yielding metabolism.
- Iron contributes to the reduction of tiredness and fatigue.
- Vitamin C increases iron absorption.
The Daily Performance provides 14 mg of iron and 300 mg of vitamin C per daily serving.
Why they are together in The Daily Performance
A serious daily formula should make sense as a whole. That is why The Daily Performance does not present iron as an isolated headline ingredient. It pairs a full daily reference value of iron with vitamin C, which increases iron absorption, in one consistent serving.
The result is straightforward: a carefully selected form, clearly stated elemental iron and a complementary nutrient in the same scoop. One less combination to work out yourself—and a formula designed around the biology it is meant to support.
- Commission Regulation (EU) No 432/2012, authorised health claims for iron and vitamin C. EUR-Lex
- EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific Opinion on Dietary Reference Values for iron. EFSA Journal 2015;13(10):4254
Built to last, inside and out.