The greatest loss of iron for distance runners is through footstrike hemolysis (loss of oxygenated red blood cells, see Journal of Applied Physiology article here ). If you’re putting in a lot of miles, that means more potential footstrike hemolysis and a greater need for iron to make new red blood cells (RBCs). Could shoe cushioning (or no shoes) have an impact on iron status? That would make for an interesting research study! My experience is the lighter the shoe (or no shoe!), the lighter your step (and potentially less iron loss? Who knows!). Does surface matter? Probably not, considering there’s no difference in impact force going from one surface to another– you simply change your “muscle tuning” so there’s no variation in impact force. Other losses come through the GI tract, sweat, and menstruation with women. Compound this with living and training at high altitude, where you have a greater need for making RBCs (and thus oxygen), and iron becomes incredibly important.
Being a bigtime red meat eater, I always assumed I was getting enough iron through my diet. I would also take an iron pill with OJ once a week, usually after my long runs. I always assumed my “tiredness” and “leg soreness” was simply a product of the high mileage and marathon training. I had also been through a few stressful years of grad school, so I assumed my underperforming was due to that.
It wasn’t until I went to train in Alamosa, CO in the summer of 2008 that I realized something wasn’t right. Knowing there was a greater need for iron at high altitude, I had upped my iron-supplementation regimen beforehand to ~3 iron pills a week, plus eating lots of red meat. When I got there, I continued this regimen. After a month in Alamosa, and a few headscratching performances, I realized I needed to get my ferritin checked to know what’s going on. While not extremely low compared to what you normally hear about with other runners, it was at the low end of “normal” (41). I purchased some liquid iron from Walmart (ferrous sulfate elixir, Qualitest brand, brown bottle with yellow label) and started taking it daily. Within a week, I felt ridiculously amazing, dropping 10 seconds per mile off of mile repeats. I also ran a 10K PR in Colorado Springs…. at 6,000ft. elevation!!! I continued to run one PR after another going into the fall. I knew I was onto something big…. something I had overlooked for YEARS of high mileage training!
I can’t stress enough to other runners the importance of iron! Ferritin is the storage protein for iron that is used, as needed, to make new RBCs, which contain hemoglobin that carries oxygen. It acts as an indirect serum marker of “stored iron”. Given the great demand by distance runners, ferritin can become depleted quite rapidly. If there isn’t enough of it, the body shuts off making red blood cells/hemoglobin, and anemia will follow. Thus, ferritin is the “gold standard” for early detection of iron depletion. If you only look at RBCs/hemoglobin/hematocrit, those things are affected later, and you may not detect the early signs of iron depletion (~low ferritin). Beside being used to make RBCs, iron is also directly used to make enzymes needed for aerobic metabolism.
Ok, so here’s the scoop: we/doctors/coaches are so used to hearing of runners with a ferritin of “0-30″ that we almost think it’s “normal”! People, this is NOT normal, if you want to perform at your best! Even being at the low end of the “normal” range for ferritin, 30-50, is likely not enough! That might be ok if you’re a sedentary person, but not for those pounding out 50-140+ miles per week! Given the high turnover rate, your ferritin needs to be MUCH HIGHER, or your RBCs/hemoglobin (carries the oxygen) will become depleted, leading to anemia. According to this Review article on iron supplementation in distance runners, you need to get your ferritin above 60. As mentioned in the article (and also this article ), you essentially have to supplement, somewhat, to maintain your ferritin this high. Most elite distance runners and their coaches know about this– that’s probably one reason why they are elite (and others are not). Unfortunately, not as many college/high school/sub-elites/doctors know about this.
If you don’t want to go through the time-wait/hassle of seeing a doctor to get your ferritin checked, you can do it through Health Check USA ($40, they’ll email you a form you take to your nearest clinic, a phlebotomist will do a small blood draw, and they’ll post the results online within 1-2 days). The research article I posted says to get your ferritin checked 2-3 times per year, ~in between seasons. If you begin closely monitoring your ferritin, you can get a general idea of what it is when you either feel good or feel bad– of course, it’s most important to know what it is when you feel good! Your ferritin may also be highly dependent on the individual– for example, I’ve been steady between 70-92 each time I’ve had my ferritin tested the past 2+ years. Some people may have no problem getting >100, while others have a hard time getting above the 30-50 range (but still feel fine, or at least think they do!). The higher you can get it, up to a certain point…. the better you’ll feel and perform. There may be great individual variance on what is ideal to feel at your best.
How much/what type of iron you need to take may depend on the individual (stomach sensitivity), where you’re located (sea level or high altitude), and what your ferritin value is. There are all sorts of recommendations (see previous research article, Iron supplementation process, plus David Martin’s talk ), whether taking 1-2 pills/day or 1-3 tsp/day for a few months (mixed in non-Calcium OJ/fruit juice)– if your ferritin value is lower, you’d want to take more to get it up more quickly. You also want to time it so that you’re not taking it with anything that will hinder absorption (see Pete Pfitzinger’s article), like Calcium and tea (~tannins hinder absorption). Meat (the “meat factor”– contains more readily absorbed heme iron), Vit. C., and a cast-iron skillet will enhance absorption– this is important, since iron is poorly absorbed. If you’re a vegetarian (and runner), getting enough iron and absorbing it is a real issue.
My personal experience (through trial and error) is that when I go to high altitude to train, I need to take liquid iron (1 1/2 tsp) in OJ every day. When I’m at sea level, I only have to take it 3-4 times per week (plus a meat-rich diet). I usually try to take it after my second run for the day and before dinner (a meat-rich meal). At one time I was taking the liquid iron in OJ every day at sea level, and I begin to experience GI problems and symptoms of tiredness/leg soreness (which actually closely mirrored anemia symptoms). I backed off, and have found that I feel fine taking it only 3-4 times a week. When you supplement with iron, you should definitely keep tabs on your ferritin value. Over time, you’ll figure out how much you personally need to take to “feel good”. Not only has iron supplementation helped me to feel better and perform better, but also to stay healthier, in terms of musculoskeletal health and also immune health. I haven’t had a cold in 3 years (although I still get hay fever when the seasons change).
Most people/dieticians/physicians are highly concerned about developing an iron toxicity with iron supplementation. Given the high prevalence of anemia amongst runners (and the physiological impact of what we do!), I don’t see iron toxicity ever being an issue. We have such a high need and high turnover of ferritin/RBCs that it doesn’t seem possible, unless you’re doing something crazy with the iron supplementation or have the genetic condition called hemochromatosis. Even moreso, women putting in high mileage esp. have a higher need for iron due to our monthly blood loss. Compound this with a vegetarian diet…. and well, the odds are very good you will start to have issues with anemia!
So take it for what it’s worth…. if you’re serious about your running, you should take your iron status seriously!
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