Anemia for Athletes: What is Iron Deficiency Anemia?

What, technically, is it?

There are several types of anemia, but all result in the body not having enough healthy red blood cells. This matters because red blood cells carry oxygen to cells. If you think back to cell biology in high school, oxygen is the final electron acceptor in the electron transport chain . Without oxygen, cellular respiration can’t happen, and your body can’t make ATP (aka energy) very well and have to rely on anaerobic respiration, which produces way less energy. In fact “way less energy” is generally a good descriptor for a person with anemia: physical activity becomes really difficult, you’re tired all the time, you get winded much more easily because your body isn’t able to move the oxygen around as it normally would – it’s no good.

Iron Deficiency Anemia (IDA) results from (you guessed it) – iron deficiency. Lack of iron results in lack of red blood cells, because iron is part of the hemoglobin molecule present in the cytoplasm of red blood cells. In fact, it’s the iron in hemoglobin to which oxygen binds. Less iron = less oxygen binding = less oxygen available to cells = less energy (literally and figuratively).

Why it happens

A person can become iron deficient for several reasons:

  • Increased losses – Bleeding heavily or bleeding small amounts for long durations results in a significant loss of iron, there can be losses of iron through sweat, and there is some research to indicate that repeated foot strike on hard surfaces can cause foot strike hemolysis, or a breakdown of blood cells in the area of impact that results in increased loss of red blood cells.
  • Poor absorption – Iron is absorbed in the duodenum of the small intestine. If something is going on with this area of the intestine, like the inflammation in IBD or a blunting of microvilli that can occur with autoimmune diseases or celiac disease, absorption of iron may be impaired. Additionally, some food sources are more easily absorbed than others, and the other nutrients that iron is eaten with can affect its absorption. Calcium and iron compete for the same transporter, so consuming these together will result in an overall decreased absorption of iron.
  • Inadequate intake – Iron is an essential nutrient, meaning we need to get it in our diets. Simply not eating enough of it can cause deficiency.

Who is at risk

  • Women – Women are at high risk for iron deficiency because of our monthly cycles. If you tend to have heavy bleeding, you’re at an even further increased risk due to the excess blood loss. If your periods are shorter than 28 days and therefore you bleed more frequently, you are at increased risk. Basically if you’re bleeding once a month, you’re losing iron.
  • Athletes – As mentioned previously, iron can be lost in sweat. Active people sweat a lot, which is partially why athletes are at increased risk for iron deficiency anemia. Additionally, foot strike hemolysis can affect runners.
  • People with ulcers and IBD – Inflammatory Bowel Disease (Crohn’s and Colitis) can cause bleeding in the GI tract that is often not significant enough to be life-threatening, but over time can deplete stores. Peptic ulcers do the same thing.


The tricky part about IDA is that a lot of the symptoms are non-specific. Raise your hand if you’ve ever experienced the following:

  • Feeling tired
  • Poor athletic performance
  • Shortness of breath
  • Dizziness
  • Malaise (a personal favorite non-specific symptom)
  • Brittle nails
  • Headache
  • Pica – the persistent eating of substances such as cornstarch or ice that have no nutritional value

Probably everyone said yes to just about everything but brittle nails and pica. It’s especially tough for athletes, because pretty much all of these overlap with overtraining or just having a heavy training load (find me someone who isn’t tired in the peak weeks of marathon training and I’ll buy you a sandwich). Dizziness could just be dehydration, you’re not running as fast in workouts because you’re running a bunch of miles, you’re feeling tired because you’ve got work and school and training and friends, etc. See how it can be tough to realize something is wrong?

How it’s diagnosed

Blood tests are used to diagnose IDA. The standard labs your doctor draws during your annual physical will include a Complete Blood Count (CBC) can detect several indicators of anemia, including the variance in the size of your red blood cells (RDW), the amount of hemoglobin in your blood, and the % of red blood cells in blood (hematocrit). If IDA is suspected, further exploration can be done via an iron panel, which includes ferritin, transferrin, and total iron binding capacity.

PRO TIP a quick and dirty method of checking your iron levels is to head to a blood drive. Before you give blood, they always test either hemoglobin or hematocrit (it varies, I’m not sure why some have machines for one versus the other). If it’s low, they won’t let you donate and you’ll know to either get it checked out further or start supplementation. If it’s within range, you’ll be lucky enough to save some lives!

How to cure it

If a slow bleed is the cause, it’s important to figure that out and stop the bleeding. For IBD patients this is something to work with your gastroenterologist with, and for women with heavy or frequent periods an oral contraceptive or other hormonal control (like an implant) can help to regulate periods. Most cases of IDA will respond to supplementation quickly and effectively, but there are some other ways to increase iron in the diet as well:

  • Cook with cast iron and use some acid like lemon juice, tomato products or vinegar in your dishes – this will leach some of the iron into your food (molecular amounts, you won’t taste it I promise)
  • Add more red meat. Use this guide to help find lean cuts
  • Make your own trail mix using fortified breakfast cereals. Most cereals will have iron in them, but like I mentioned previously the calcium in milk competes for absorption, so eating dry as a snack is a great way to maximize benefit
  • Eat the dark meat. Chicken thighs have much more iron than chicken breast and are seriously delicious. Try this recipe.
  • #Treatyoself to some oysters, they are actually pretty high in iron!
  • Go meatless and eat some beans, another great source of iron.

Favorite Supplements

  • SlowFe is great because it’s a time-released formulation of iron that reduces GI symptoms (aka you can get constipated with some supplements but not this one)
  • PalaFeR was recommended to me by a friend, and while the image on Amazon looks super sketchy, I trust him and the results he and others have had using this ferrous fumarate supplement.




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