THE IRON STORY
MOST ENDURANCE ATHLETES are somewhat familiar with iron. Often low iron stores is loosely, even casually, used to explain ongoing fatigue or poor performance. But guessing at iron deficiency isn’t very helpful – properly screening for, diagnosing and treating this real and serious issue is important. You also want to rule out, or address, any other reasons for ongoing fatigue – whether those are medical, or simply because you are following the well-worn path of many triathletes and overdoing your training.
As a refresher, iron is an essential mineral. Its vital not only for sports performance, but also general health. Iron is required to form haemoglobin, the oxygen- and carbon-dioxide-carrying molecule in our blood that is necessary for energy production. For athletes, maximal oxygen delivered to working muscles equals increased work capacity and optimal recovery. Iron is also found in the myoglobin of muscle cells (which also store oxygen) and is stored as ferritin. Thus, in a regular blood test, both haemoglobin and ferritin levels are assessed to determine iron status. Reduced iron stores lead to fatigue, poor performance and can also impact immune function, mood, cognitive function and other aspects of health.
Iron deficiency in sport is pretty common – especially for women, and especially for endurance athletes. For this reason, it’s usually recommended that you get tested at least yearly, and as often as quarterly, if you have a history of iron deficiency, are racing at an elite level or have other health concerns. Aside from losses in sweat, urine, foot strike and during menstrual cycles, there is another piece that complicates the iron story in athletes that is important to understand when it comes to “fixing” the problem of “low iron.” Hepcidin is a hormone that influences iron absorption. It is released from the liver and increases during iron overload, or in response to inflammation, in order to prevent or slow iron absorption. This is a finely tuned system that generally works well – iron overload is inherently dangerous.
However, in hard-training athletes, like triathletes who usually train multiple times a day, hepcidin is emerging as the likely reason why so many endurance athletes (as much as 50 per cent of females, slightly less for males) will at some stage struggle with iron deficiency. This is because exercise, especially hard training, elicits an inflammatory response. That means there are large portions of the training week where iron absorption will be suppressed. For female athletes, this hampered rate of absorption is exacerbated even further – hepcidin levels may also increase at the peak of menstruation, again due to inflammatory mediators, putting them at heightened risk of deficiency. Once the bleed begins, hepcidin may decrease to promote iron absorption – but further research is needed in this area with female athletes to better understand this effect.
These effects are coupled in with the fact that many endurance athletes are often under-fuelled, whether by design or oversight. They are simply not consuming enough calories for their workload. Dietary and energy restrictions are perhaps the biggest risk factor in iron deficiency.
If dietary measures are not sufficient, you may also be recommended an iron supplement. Again, getting the timing of this supplement right is worthwhile both to enhance effectiveness, but also to reduce risk of GI distress, a common complaint for relatively high doses of ferrous sulphate. Hepcidin actually rises following a high dose, reducing your ability to absorb iron for around 24 hours, so skipping a day and taking iron supplements every second day may actually be a better solution. Your doctor will likely follow a 60- to 90-day period of iron supplementation with a review test to make sure it’s working to boost ferritin levels, but also to check you aren’t getting an overload of iron, which can have dangerous consequences for internal organs.
The last resort is an intravenous injection of iron, which can only be done under strict supervision of an experienced sports doctor, and with ongoing monitoring after one month and again at six months. These are highly effective, but not without risk, and usually only explored if dietary and supplementary avenues prove ineffective.
Pip Taylor is a pro triathlete and nutritionist from Australia.