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Runner's Anemia: Know the Signs & Symptoms of Low Iron

PLUS learn ways that you might be sabotaging your efforts to increase your iron with supplements and food!

Are you EXHAUSTED? Like, all the time? Even MORE than normal? Are you having trouble on your runs - easy runs feel hard, and hard runs are impossible? You might have LOW IRON. Know the signs & symptoms of this VERY common condition, and learn how to incorporate more iron into your diet (but also, see a doctor and get your iron levels checked!!)

Runners Use a Lot of Iron

One of the reasons low iron is so common among runners is because running uses up a hell of a lot of iron! And more than that, certain parts of our training can interfere with absorbing the iron we DO take in.

Endurance training increases red blood cell production

One of the vital components of endurance training and fitness is an increase in your blood volume, including plasma volume and red blood cell count. Of course, creating new red blood cells requires... iron!

Running impact kills red blood cells ('footstrike hemolysis')

All impacts break apart red blood cells, but when you're out *literally pounding the pavement* for 1-2 hours a day, you will destroy (or squish, more accurately) a lot of red blood cells due to something called "footstrike hemolysis," or "red blood cell death because your foot hit the pavement." This is considered iron LOST, not necessarily iron USED (but of course, your body will use up iron when it creates new red blood cells to replace the dead ones).

Iron is lost through sweat & menstruation

Fun fact: your sweat contains iron! Yes, in trace amounts, but just like footstrike hemolysis, it can add up over the miles and the hours. Of course, menstruation also uses up iron, so women are hit with a double-whammy of iron usage here.

Hard workouts increase a protein (hepcidin) that interferes with iron absorption

Wait, what? At its core, increasing your running fitness requires you to stress your body and then recover from that stress to become stronger; it's the basis of all fitness gains, from pure endurance to pure strength and everything in between. When you do a taxing workout, like speedwork, or a tempo or long run, your body reacts with a host of physiological and cellular changes and activities.

Hepcidin's job is to regulate iron absorption. If there's too much hepcidin present, iron is NOT absorbed; on the flip side, if hepcidin is low, iron will accumulate in excess quantities, and in all sorts of places it's not supposed to be, leading to other issues entirely.

Inflammation causes the production of extra hepcidin, and what can cause inflammation? Intense exercise, of course, when your muscles and body are stressed to their limits! In this way, intense exercise INCREASES hepcidin, and higher hepcidin levels BLOCKS iron absorption. If you were to pop an iron supplement as soon as you got home from a hard workout, it would do almost nothing for your iron levels because very little of it would actually be absorbed.

If you are taking an iron supplement, don't take it within the 6 hours following an intense workout, either running or weightlifting.


The most common symptom is exhaustion: unexplained, persistent, bone-deep exhaustion that doesn't go away with extra sleep, extra caffeine, extra sugar, or ANYTHING ELSE you try. Furthermore, your running will feel like absolute GARBAGE; easy runs will be hard, fast paces will be impossible to hit, and your heart rate will be exceptionally high for the effort. This is because, in a way, your muscles are suffocating for want of oxygen, which they aren't getting. After all, without sufficient iron, your body can't deliver all the oxygen that your cells need to perform.

Other symptoms include low motivation (which can be exacerbated by poor performance, because who wants to run when it feels so terrible?); difficulty recovering from workouts; cold hands and feet; lightheadedness/dizziness; chest pain; and shortness of breath at rest or during very light exercise like walking.

Anemia is a serious condition that can be life-threatening. If you have any of these symptoms, see your doctor & get your iron checked!

Anemia/low iron can often be corrected with supplements and/or dietary changes, but it might take 4-8 weeks to feel "back to normal"


Many runners may find it challenging to get enough iron in their diets just through food alone. Consider taking an iron supplement to help support your iron levels; look for high-quality supplements from a reputable company, or ask your doctor if you need a prescription-strength supplement.

The most bioavailable forms (the ones most easily absorbed and used by your body) are ferrous sulfate and ferrous gluconate. Liquid iron is the most easily absorbed by your body but always get a flavored one, as unflavored liquid iron tastes horrific.

Taking Vitamin C at the same time can also help increase iron absorption.


Guess what the best dietary source of iron is? If you said spinach, that is incorrect!

Animal products contain heme iron, while non-animal products contain nonheme iron. Heme iron is the most usable, bioavailable form of iron, but nonheme iron is better than NOheme iron (ha!)

  • 3 ounces of clams or mussels

  • 3 ounces of oysters

  • 3 ounces of beef or chicken liver

3 oz contains 2.1+ milligrams heme iron per serving...

  • 3 ounces of cooked beef

  • 3 ounces of sardines or other small oily fish

3 oz contains 0.6+ milligrams heme iron per serving...

  • 3 ounces of chicken or turkey

  • 3 ounces of ham

3 oz contains 0.3+ milligrams of heme iron per serving...

  • 3 ounces of halibut, haddock, perch, salmon, or tuna

Believe it or not, one of the best nonheme sources of iron is fortified cereal, so check out your labels next time you're in the cereal aisle!

Good sources of nonheme iron include...

  • 1/2 cup lima beans, red kidney beans, or chickpeas

  • 1 medium baked potato

  • 1/4 cup of wheat germ

  • 1 oz of pumpkin, sesame, or squash seeds


Other things can interfere with your body's ability to absorb iron. These include calcium (whether dietary or supplemental calcium), caffeine (so nix taking your iron with your morning coffee!), and non-steroidal anti-inflammatory drugs (NSAIDs) like Tylenol, Aspirin, etc.


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