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  • Jackie K

Struggling while running? Low iron could be to blame

Did you know that low iron can impact your running performance?

About 2 years ago, I started having issues with my foot and not feeling quite right. I thought it was just stress, but my coach encouraged me to get my iron levels checked. Lo and behold, my ferritin (storage marker for iron) was 12 – and you’re officially deficient when your ferritin is less than 20!! It was no wonder I wasn’t having the greatest runs.


Low iron can really affect us as athletes. We need enough iron to make hemoglobin, which carries oxygen in the blood, and myoglobin, which helps accept oxygen in the muscles. Oxygen… it’s pretty important for life and for exercise, right? So without adequate levels, you’re more likely to be fatigued.

(how you feel when you're low on iron)

So low iron can make it harder for you to run fast and run hard – impairing your performance. It can also impact your immune function (so you’re more likely to get sick) and even cognition (so it might be harder to concentrate, for example).

Endurance athletes – like runners! – are at a higher risk of iron deficiency than the average person. Women especially are at a higher risk of having low iron levels. You might also be at risk if you’re plant-based, if you’re restricting your diet to try to lose weight, or if you’re a heavy sweater.

You might think you can prevent low iron by taking over-the-counter iron supplements. But I actually don’t recommend if you don’t know what your iron levels are (and if you’ve never been low before). Those pills can have unpleasant GI side effects, but can also decrease your ability to absorb other nutrients (like zinc) and be dangerous if you overdo it (it can even lead to organ failure!).


That said, many people DO need to supplement – talk to your doctor and/or dietitian and get lab work done!

Eating enough iron-rich foods will help prevent iron deficiency.

- Heme iron is found in animal foods like meat, poultry, and seafood. We can absorb around 15% of this type of iron.

- Non-heme iron is found in plant foods like beans and lentils, nuts and seeds, and fortified cereals and bread products. We absorb less of this type of iron – only around 3-8%. If you only eat non-heme iron, you need to eat more than the recommended amounts to make up for the decreased absorption!


(animal foods tend to be high in heme iron)


Some foods can increase your ability to absorb iron

- Eating a vitamin C rich food with a high-iron food will enhance your ability to absorb iron. Some examples are bell peppers, tomatoes, oranges, and strawberries.

- Eating heme iron with non-heme iron will also enhance the absorption – meaning if you have meat with beans, you’ll absorb more of the iron than if you had beans alone. (And meat + beans + tomatoes – like a chili dish – would be even better!)

Some foods will decrease your ability to absorb iron

- Drinking coffee or a black tea with an iron-rich food will decrease your body’s ability to absorb iron

- Dairy and calcium supplements can do this as well. So don’t drown your iron-fortified cereal with gobs of milk and wash it down with a glass of coffee. You won’t get nearly the benefit this way!


(delicious but doesn't help you absorb iron!)

So what can you eat to make sure you’re getting enough iron??

- Try a chili with lean ground beef, kidney beans, and tomatoes

- Turkey sandwich on whole wheat bread with fresh spinach and tomato slices (and other toppings of your choosing)

- Walnuts and blueberries as a snack

- Homemade trail mix with cheerios, peanuts, dried cranberries, and pumpkin seeds

- Chicken thighs, sautéed greens, and roasted potatoes

- Red lentil soup with tomatoes, kale, and other veggies

- Use a cast-iron skillet for cooking and sautéing

And if you need to take an iron supplement, pay attention to the foods that will increase the absorption, and try to avoid those foods that will decrease its absorption when you take it. Some iron supplements even have vitamin C in them to help you out!

Have you ever struggled with low iron levels? What did you do to improve your numbers?

Whether you're a meat eater or a plant-based warrior... adequate iron levels is a game changer. If you're low, or if you're not sure if you're low on iron, or if you want to make sure you never become low in iron... I can help. Schedule a free runner's nutrition strategy session to see how I can help you become the best runner you can be.

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