Do Runners Need More Iron? What All Runners Should Know

  Apr 19, 2020  |  #Marathon Training

Do you have questions about iron needs for runners and how to find iron rich foods for runners? This post will discuss symptoms of low iron in runners and explain why iron is important for endurance athletes. 

Many athletes often overlook the power of micronutrients in their diets. There is a huge focus on macronutrients, especially carbohydrates and protein, but micronutrients are necessary, too.

I like to support my athletes in consuming a well-varied diet, so they are most likely meeting baseline recommendations for micronutrients, like iron and calcium. However, we are all different and some people may not metabolize certain nutrients as well. 

woman running on road with text overlay

Furthermore, some people follow more restrictive diets whether for ethical, health or personal reasons, like eating vegetarian, vegan or plant-based. Usually, these athletes need more specific guidance to meet their overall needs. 

I can’t give specific advice on this platform, but we do have a whole module in our Nail Your Nutrition Endurance Fueling Course that covers iron needs and how to meet them if you follow a vegetarian or vegan diet. 

Iron for Runners 101: Do Runners Need More Iron?

First off, let’s discuss why iron is important for the body. Iron is essential for many of our bodily functions, including transporting oxygen throughout our body. Iron is a component of the protein hemoglobin.

Hemoglobin is found in our red blood cells, which supply oxygen to our working muscles when we run.


Runners and other endurance athletes need to be aware of their iron status, since it is so important for these supply of oxygen to our muscles and tissues.

Low iron stores can result in impaired muscle function and limited aerobic capacity. 

Another important thing to consider is the effect of iron on the immune system. Heavy exercise can impact our immune system and iron is an important cofactor for a healthy, functioning immune system. 

As discussed in this research study, Exercise-Induced Illness and Inflammation, adequate iron is required for our bodies to mount an effective immune response. Therefore, iron deficiency is suggested to impact cell-mediated immunity (Castell, Nieman, Bermon & Peeling).

Therefore, it is important to try to quickly attend to any iron deficiency in endurance athletes. 

How Do Runners Lose Iron?

  1. Urine, feces, sweat and intravascular hemolysis – Like any person, runners lose iron through excretions. However, these losses are likely exaggerated in endurance athletes due to their high training and higher volumes of sweat. Even in the winter months, athletes still sweat during training and may not be as conscious about their winter hydration needs, sweat loss, and hence, micronutrient loss. 
  2. Menstruation – This can add up for blood loss. 
  3. Foot strike hemolysis – Since running involves a lot of pounding, the impact of the foot striking can lead to the hemolysis (damaging) of red blood cells, which releases iron. 

Woman running on trail

What Are The Symptoms of Low Iron in Runners?

The list below confers some symptoms of low iron. It’s important to understand that not every person will experience all of these symptoms. 

However, if you have several of these, I would definitely recommend seeing your doctor and digging deeper. 

  • Decline in exercise capacity and performance
  • Weakness and general fatigue (moreso than normal, assuming sleep is adequate)
  • Increased heart rate and shortness of breath 
  • Headaches, dizziness
  • Heavy periods
  • Feeling cold in extremities
  • Getting sick more often 
  • Spoon-shaped nails or brittle nails
  • Cracked lips and/ or pale appearance
  • Craving non-food items (like dirt, ice, or clay)

Iron Deficiency In Runners

Now that we’ve talked about symptoms of low iron in runners, how we lose iron, and why iron is important for runners and endurance exercise, let’s talk about the groups at the highest risk of iron deficiency.

Distance runners, vegan and vegetarians, pregnant women, regular blood donors, those undergoing strenuous training, and those restricting calories are at the highest risk for iron deficiency in runners. 

females running at risk of iron deficiency

Low iron in female runners and iron deficiency in female runners is quite problematic, as it can be a signal or symptom of relative energy deficiency in sport (RED-S).

As mentioned in the Academy of Nutrition and Dietetics Sports Nutrition Position Paper, “iron requirements for all female athletes may be increased by up to 70% of the estimated average requirement” (Thomas, Erdman & Burke). 

Another reason female athletes are at a larger disadvantage is because women likely aren’t eating as much, and many may be undereating.  We absorb about 6 mg of iron per 1,000 calories eaten. You can see why you may be low in iron if you are restricting calories and training intensely on top of that.

If so, you can schedule a free introduction call with me if you’re interested in working together. 

Best Food Sources of Iron

The best way to increase your iron intake is through your diet. The most bioavailable iron-rich foods are red meats. However, there are plenty of other ways to get iron. 

Those low in iron should also consider cooking in cast iron skillets! Iron intake from cast iron skillets can make a difference of a few mg in a meal. 

Iron rich foods for vegetarians on chalk backboard

Iron Rich Foods for Vegan and Vegetarian Athletes

As mentioned, there are ways to meet iron needs without solely relying on meat. It does take extra caution and awareness since vegetarians and vegans are at a higher risk of iron deficiency.

Here are some vegan foods high in iron:

  • 1/2 cup lentils, cooked – 3mg (make this lentil hummus dip!)
  • 2 Tbsp pumpkin, hemp seeds or flaxseeds – 1-4 mg
  • 1/2 cup chickpeas – 2-2.5 mg 
  • 1/2 cup white navy beans, kidney beans, lima beans – 2.5-3 mg
  • 1 cup spinach – 3-6 mg
  • white potatoes – 3 mg
  • 1 cup oatmeal – 2 mg
  • sweet potatoes – 2  mg

Also, keep in mind that another way to increase iron intake through the diet is by pairing Vitamin C with iron-rich foods. Vitamin C helps our body absorb more iron, particularly from plant sources.

So, if you’re eating spinach or legumes, you could add some broccoli, red bell peppers or tomatoes to boost absorption.

What Impedes Iron Absorption?

While boosting absorption is important, it’s also helpful to know what may interfere with optimal iron absorption. 

Coffee, tea and foods high in calcium can all interfere with and decrease iron absorption, so it’s best to space out your iron foods with calcium food sources or supplements.

Breakfast of cottage cheese with oatmeal, apple and milk

Years ago when I was trying to increase my iron, I thought it would work by taking a multivitamin supplement. Well, there are so many things that can work against the iron in that supplement.

Moral of the story is if you’re low in iron, it’s best to take a specific iron supplement separate from when you’re taking a multivitamin, calcium supplement or eating calcium-rich foods.

How Much Iron Do We Need Each Day?

Women typically need 18mg of iron per day, while the RDA (recommended daily intake) for men is 8 mg.

These needs increase during pregnancy, during heavy training sessions, and for those with heavy periods.  

We also have some research showing that vegetarians and vegan athletes should take in more iron since it is less bioavailable (not as optimally absorbed). 

Should You Take an Iron Supplement?

Short answer: Not necessarily. I would start with increasing iron in your diet, first. Iron supplements for runners can be dangerous and toxic if not done correctly or the right dose, and especially, if not medically necessary.

Research has shown that the intake of iron supplements in the period immediately after strenuous exercise is contraindicated because there is a potential for elevated hepcidin (a protein and regulator of iron levels in the body) levels to interfere with iron absorption (i).

It’s best to meet with your doctor to figure out the best course of action for increasing your iron. High levels of iron can be toxic in the body. 

Want More Runner Specific Sports Nutrition Posts?


Castell, L. M., Nieman, D. C., Bermon, S., & Peeling, P. (2019). Exercise-Induced Illness and Inflammation: Can Immunonutrition and Iron Help?, International Journal of Sport Nutrition and Exercise Metabolism29(2), 181-188. 

DellaValle, Diane M. PhD, RD (2013). Iron Supplementation for Female Athletes: Effects on Iron Status and Performance Outcomes. Current Sports Medicine Reports: 12(4), 234-239 doi: 10.1249/JSR.0b013e31829a6f6b

Thomas D.T, Erdman K.A., Burke L.M. (2016). Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American
College of Sports Medicine: Nutrition and Athletic Performance Journal of the Academy of Nutrition and Dietetics, 116 (3), 501-528


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14 responses to “Do Runners Need More Iron? What All Runners Should Know

  1. Iron is SO important! I never actually realised just how important it was until my body stopped absorbing it (as a result of damage from undiagnosed coeliac!) and I needed iron infusions and a body without iron is notttttttt a fun experience 😛

    As for favourite taco toppings. I’m happy with anything as long as there’s guac on top 😉

  2. Yay for freekeh! I really want salmon patties now too! I haven’t had salmo nin such a long time! Gotta restock on my nutritional yeast supply too–I ran out of that last weekend when I was making cheeseless pizza. :O

    That poodle is adorable. <3

  3. Those stuffed squashes are so cute, and I didn’t realize that iron was so important for runners. It’s amazing how God has made our bodies to need all those different balances of nutrients. I think I”m probably ok on iron because I don’t have any of those symptoms, but maybe I will try to eat more iron rich foods?

  4. Great reminder about the iron! 90% of the time after I finish a race or long run I find myself craving meat (and I usually eat meat only 1-2 times/month) and I always attribute to my inner cravings for iron! Love Freekah and experimenting with new grains!

  5. This is so interesting and definitely something runners need to be careful about. I think I am ok right now- I eat lots of foods with iron and am not running very much- but its something to keep in mind at whatever point I get back to marathon training!

  6. Thanks for those handy iron tips! It was a huge problem for me when I was vegetarian a few years ago (am no longer now) but definitely something I need to still be aware of.

    I really enjoyed the book Girl on the Train and was curious about the movie! My fav taco toppings… guacamole and salsa. I also love frying up onions and peppers to put inside, maybe some roasted sweet potatoes too. And now I am hungry!

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