January 31, 2012

Iron deficiency in runners

Source


This is one of those subjects that I feel completely under qualified to tackle, but luckily many PhD students around the world have devoted sometimes-thankless hours to researching and writing about subjects that interest a handful of people. But based on the growing numbers of endurance sports participants, it's a hefty handful. 


My interest in iron deficiency started when I was pregnant with twins. I would walk by the detergent aisle at Target and think that the smell was delicious. Not just that it smelled nice, but that something about the chemical odor was satisfying. I also chewed ice like a maniac. Both of these are symptoms of pica, a disorder that is characterized by craving substances that don't have nutrition (chalk, dirt, detergent). Sometimes the cravings lead to actually eating those substances. In my case, I never tried eating detergent, but just imagining crunching the yummy-smelling granules in my teeth was worrisome enough. With my other two pregnancies, I didn't experience any of these awkward tangos with the detergent bottles, so I surmised that the demands of carrying twins was just a touch more than my body could handle. After I had the twins, the pica symptoms disappeared. Until recently. 


I started running at the beginning of last year, training for a half marathon. My training grew as I began to train for a full marathon in November and carried that training into more marathon training. That equals lots of foot pounding and sweating. Sometime at the end of last year, I noticed that some of my pica symptoms had returned. One of the first tip-offs was that walking by the tire rack at Sam's Club was a heavenly experience. The smell of all those rubber tires, which I normally hate, was somehow satisfying. If I had more minutes in my day, I would have just stood there and inhaled. Instead I thought, "Weird, I normally hate the smell of Sam's Club." Similar things were happening at the gas pump. Yum, gas smell. And again in the detergent aisle at the store. I'm not chomping ice like I was during my pregnancy, but all of this odd euphoria over chemical smells tipped me off that something might be wrong. And P.S., I'm definitely not pregnant. 


In doing interweb research, my problem is not unique, though I've never heard any of the runners in my circle talk about it. I've heard them talk about needing iron, but not the pica side of the deficiency. I found the same thing during pregnancy. I never actually knew anyone with the same symptoms as me, but according to the interweb, it is a frequent problem. 


Dr. McDougall's Health and Medical Center suggests several reasons runners may be anemic: 


Runner's anemia: More than 30 million long distance runners live in the United States today and many of them are developing iron deficiency anemia from no obvious cause. Several possible reasons for the loss of iron have been suggested: the destruction of blood cells when the feet hit the hard ground so frequently for so long a time, loss of blood through the kidneys, iron lost in the sweat, reduced absorption of iron from the gut, and decreased production of blood cells in the bone marrow.


Another article about iron deficiency in endurance athletes suggests that we are especially susceptible to iron loss if we are endurance athletes, and it explains that our blood levels may test normal for iron while our tissue levels are inadequate. Also, our aerobic efficiency can be decreased if our iron levels aren't up to snuff. 


And if you want more reading, here's a super nerd-alert article from the European Journal of Applied Physiology that packed a powerful information punch: Athletic induced iron deficiency: new insights into the role of inflammation, cytokines and hormones. This article explores even more ways that iron absorption may be blocked during/because of endurance exercise (think hormones produced during running that negatively impact iron absorption), but it is also a great overview of some of the more basic ideas behind iron deficiency.


Basically all of this info screamed to me, get to work on your iron consumption. I'm bad at food combining (meaning I don't always pay attention to which foods block iron absorption), but I eat tons of spinach and don't shy away from red meat. Also, I'm going to order some mineral drops like these to start adding to my water. 


Have you ever dealt with anemia or pica? 


Did you know that runners are at risk for poor iron levels? 


What would your first step be to increase iron intake?