Endurance runners are known to have a higher prevalence of iron-deficiency anemia than the general population (other at-risk groups include women and those who restrict calories). Indeed, I encounter many a client who is struggling to improve their iron-levels. In fact, the Journal of Internal Medicine published a study showing systemic iron deficiency was found in 56% of the runners they tested.
Why are endurance runners ‘gifted’ with an increased susceptibility to iron-deficiency? Because we lose iron in sweat, through gastrointestinal bleeding due to hard/long runs, and through breakdown of red blood cells caused by the ‘trauma’ of repeated foot strikes on hard surfaces. And we don’t absorb iron well for up to 6 hours following a run longer than 60 minutes (due to an elevated hormone called hepcidin).
To offset these risk factors, we know we must eat many iron-rich foods and if diagnosed clinically deficient or anemic, take supplements. But what about those runners who diligently supplement as prescribed by their doctor (it should take between 1-3 months to replenish iron stores) and eat iron-rich foods regularly – yet upon abandoning the supplement their iron stores plummet once again? Or the runners who take supplements as prescribed but still struggle to see an improvement? It may be there is an underlying issue that is preventing the iron from being absorbed properly.
One such underlying issue is celiac. It’s an established fact that anemia is a common symptom of celiac disease because gluten damages the microvilli. This is really not good because it’s the microvilli that absorb the nutrients from the food we eat. You’re likely thinking at this point, “Well, I’m not celiac so I’ve got nothing to worry about here”. Which may not be entirely true. A recent Canadian Celiac Health survey reported it took approximately 12 years after the onset of symptoms for adults to actually be diagnosed with celiac. I note this connection simply for those frustrated by not being able to increase their iron-levels, removing gluten from the diet may be something to consider trying (the experiment would need to be lengthy to determine if this was the case, at least 6 months to allow for healing to occur, absorption to take place and finally iron levels to increase).
Another underlying cause could be regular use of NSAID’s (which can cause bleeding in the stomach). Or for females, heavy menstrual cycles can cause chronic low iron levels (the solution would be to balance hormonal levels to hopefully prevent these heavy cycles). There are of course other less common underlying causes – anyone with an iron-deficiency should talk to their doctor about what may be behind their case.
For others, it may simply be that they need to be more consistent in be eating iron-rich foods, such as those listed below (I’ve listed both vegetarian non-heme and animal heme sources for reference points and included amounts as they are found in common serving sizes). Sometimes we think we’re getting enough… But we’re not. Track your intake for a few days to find out if you are indeed getting enough. The established recommended daily intake for iron is 8 mg per day for men and 18 mg per day for women. However, some studies recommend iron intakes of 17.5 mg per day for male distance runners and 23 mg per day for normally menstruating female distance runners.
- Cow liver (3 oz) – 5.4 mg heme iron
- Venison (3 oz) – 3.8 mg heme iron
- Lentils, uncooked (1/4 cup) – 3.8mg non-heme iron
- Cow heart (3 oz) – 3.7 mg heme iron
- Blackstrap molasses (1 Tbsp) – 3.6 mg non-heme iron
- Spinach (½ cup boiled or 3½ cups fresh) – 3.2 mg non-heme iron
- Lean beef sirloin (3 oz) – 2.9 mg heme iron
- Red kidney beans, cooked (½ cup) – 2.6 mg non-heme iron
- Tahini (2 Tbsp) – 2.6 mg non-heme iron
- Pumpkin seeds (1 oz) – 2.5 mg non-heme iron
- Chickpeas, cooked (½ cup) – 2.3 mg non-heme iron
- Asparagus (6 spears) – 2.1 mg non-heme iron
- Tofu, firm (½ cup) – 2 mg non-heme iron
- Quinoa, uncooked (¼ cup) – 2 mg non-heme iron
- Potato with skin (1 large) – 1.9 mg non-heme iron
- Cashews, raw & unsalted (1 oz) – 1.9 mg non-heme iron
- Skinless chicken breast (3 oz) – 1.8 mg heme iron
- Spinach, raw (2oz /2 cups) – 1.6 mg non-heme iron
- Artichokes (1) – 1.6 mg non-heme iron
- Tomato sauce, plain (½ cup) – 1.3 mg non-heme iron
- Almond butter (2 Tbsp) – 1.2 mg non-heme iron
- Kale, raw, chopped (1 cup) – 1.1 mg non-heme iron
- Kale, raw (1 cup chopped) – 1.1 mg non-heme iron
- Rolled oats, dry (1/3 cup) – 1.1 mg non-heme iron
- Almonds, raw & unsalted (1 oz) – 1 mg non-heme iron
- Tomato paste (2 Tbsp) – 1 mg non-heme iron
- Egg (1 large) – 0.9 mg non-heme iron
- Raisons (1/4 cup) – 0.9 mg non-heme iron
- Potato without skin (1 large) – 0.9 mg non-heme iron
- Green beans (½ cup) – 0.8 mg non-heme iron
- Apricots, dried (5 halves) – 0.8 mg non-heme iron
- Chia seeds (1 Tbsp) – 0.7 mg non-heme iron
- Cocoa powder (1 Tbsp) – 0.7 mg non-heme iron
- Beets (1 med) – 0.7 mg non-heme iron
- Yam (1 cup cubed) 0.7 mg non-heme iron
- Salmon (3 oz) – 0.7 mg heme iron
- Nutritional Yeast (2 Tbsp) – 0.7 mg heme iron
- Dates (3) – 0.6 mg non-heme iron
- Avocado (½ a fruit) – 0.5 mg non-heme iron
Last but not least, here are a few iron-rich recipes for you:
Eat clean, run strong, be well… Cheers,
Sarah J Cuff, RHN
PS. Check out Chris Cochran’s story – she began eating 2 run just over a year ago… And the results are impressive. Click here to find out how she increased her energy levels, recovered more quickly from her long and hard run workouts, and finally successfully managed to kick a cold in a few short days – just in time to run her strongest half-marathon ever!