Why Female Endurance Athletes Should Pay Closer Attention to Their Iron Intake

For many women who run regularly, that creeping sense of fatigue on longer efforts — heavy legs, breathlessness that seems out of proportion to the pace, a general feeling of running on empty — can feel frustratingly hard to explain. Training load, sleep, hydration and nutrition all get scrutinised, yet one common culprit often goes unchecked: iron.

According to Women’s Running, iron deficiency is a genuine concern for endurance athletes, and addressing it doesn’t have to mean reaching straight for a supplement bottle.

Why Runners Are Particularly Vulnerable

Iron plays a central role in producing haemoglobin, the protein in red blood cells responsible for carrying oxygen to working muscles. When levels drop, even modestly, the body’s ability to sustain effort suffers — and for anyone training across long distances, the effect can be pronounced.

Women face a higher baseline risk of low iron than men, owing to monthly blood losses through menstruation. Layer endurance training on top of that, and the picture becomes more complicated. Repeated foot-strike during running can cause a phenomenon known as foot-strike haemolysis, where red blood cells are broken down through impact with the ground. Intense training also elevates the hormone hepcidin, which temporarily suppresses iron absorption in the gut — meaning eating well isn’t always enough on its own.

What makes the situation particularly tricky is that iron deficiency can exist without full-blown anaemia. Ferritin, the protein that stores iron, can be depleted well before a standard blood test flags anything alarming. This is why many female runners spend weeks attributing their sluggishness to overtraining or poor sleep when the real issue lies elsewhere entirely.

Rethinking How You Top Up

Traditional iron supplements have a well-earned reputation for causing gastrointestinal discomfort — nausea, constipation and bloating are common complaints, and for runners, gut sensitivity is already a live concern. Women’s Running highlights that there are now gentler alternatives worth exploring, suggesting that supplementation doesn’t have to come at a cost to digestive comfort.

From a WSS perspective, this matters because gut distress is one of the most frequently cited reasons women abandon a supplement routine before it has any meaningful effect. If the vehicle for correcting a deficiency is itself causing problems, compliance drops — and the underlying issue persists.

Dietary sources remain the most sustainable long-term strategy. Haem iron, found in red meat and oily fish, is absorbed more efficiently than the non-haem iron in plant foods such as lentils, spinach and fortified cereals. Pairing plant-based sources with vitamin C-rich foods can meaningfully improve uptake, while avoiding tea or coffee around mealtimes helps prevent compounds that inhibit absorption from interfering.

What to Do If You Suspect a Problem

Any woman experiencing persistent fatigue that doesn’t resolve with rest should consider asking her GP for a full iron panel — including ferritin levels — rather than a standard haemoglobin check alone. Self-diagnosing and supplementing without testing isn’t advisable, as excessive iron carries its own health risks.

For active women, the broader takeaway is simple: unexplained tiredness during training deserves proper investigation. Iron is one of the more correctable variables in endurance performance, and getting it right can make a meaningful difference to how you feel on the road.