By Alex Hutchinson
My column in the Globe and Mail this week looks at iron levels for athletes, and in particular at new evidence that you can have normal hemoglobin levels but still be suffering negative effects from iron depletion. Endurance athletes have been warned for decades that they need more iron than the general population because their training causes an expansion in the amount of red blood cells in their veins; this means that their hemoglobin levels may seem normal but their ferritin levels (a marker of the iron reserves stored in the body) may be low. That's a problem, because we're now realizing that, in addition to assisting with oxygen transport, iron has a lot of other important roles in the body, including energy metabolism, immune function, and brain processes.
So how much ferritin do you need? That's more controversial. But recent studies have suggested that even non-athletes may need more than previously thought:
[...] In 2011, Swiss researchers published a study in which 90 women suffering from unexplained fatigue received injections of either iron or placebo. All of the women had normal hemoglobin levels but low levels of ferritin, which is a marker of how much iron your body has in its reserves, primarily stored in bone marrow. For women with the lowest ferritin levels, 82 per cent had reduced fatigue after receiving iron compared to just 47 per cent who reported improvement in the placebo group.The threshold for "normal" ferritin in athletes is often pegged at 30 micrograms/L, but there's really not a lot of research identifying exactly where problems start. When I chatted with Laura Garvican, a researcher at the University of Canberra and Australian Institute of Sport who's studying iron in endurance athletes (and who is also an accomplished runner), she said that in a perfect world she'd aim to keep her levels closer to 60 micrograms/L -- which is easier said than done for many athletes, since iron absorption can be a challenge. That's just speculative at this point (and as I blogged about a few months ago, some athletes seem to be able to perform exceptionally well even with ferritin levels below 30). But it's something to keep an eye on if blood tests show you're in the questionable range.
A subsequent study published last year in the Canadian Medical Association Journal, from another Swiss group, found similar results for 198 women with unexplained fatigue and low ferritin levels using oral iron supplementation. [...]