Iron may be considered a micronutrient in our daily diets, but there’s nothing small-scale about the role that this mineral has in keeping endurance athletes — or anyone, for that matter — feeling good and performing optimally. 

Iron is a major player in hemoglobin, the protein found in red blood cells that delivers oxygen from the lungs to every muscle and organ of the human machine. If there's not enough iron, there's not enough oxygen to power your body, from your brain down to your toes. To put it bluntly, your cells begin to suffocate.

Women of child-bearing age, runners and other endurance athletes, and individuals following plant-based diets are at increased risk of iron deficiency. This means that you have depleted iron stores — our bodies should be storing 3-4 grams — from risk factors and/or are insufficiently replacing iron through food (or perhaps supplements). No athlete, regardless of fitness level, performs optimally when starved of oxygen or hungry in any way.

It's critical for athletes to understand how much iron is needed, and make smart food choices that will add more of this micromineral to mealtime.

Related: 10 Signs You’re Not Getting Enough Protein

The standard estimate of some form of iron deficiency is 3 to 11 percent in male athletes, and 15 to 35 percent in female athletes. However, an article in Outside Magazine points out that these numbers are culled across many sports, and suggests that in endurance sports, the numbers could be as high as 50 percent.

The 2 Main Symptoms of Iron Deficiency

Athletes with iron deficiencies commonly tell me that they are constantly fatigued and are prone to subpar performances. Both of those symptoms require more than just an extra day's rest.

Obstacle racers that train hard are no strangers to feeling tired, worn down, and in need of rest and recovery. (That’s how they get stronger, after all!) But fatigue caused by low iron stores doesn’t go away after rest. On the contrary, it is lingering and can be overwhelming, depending on the overall severity of the iron deficit

Other low-iron symptoms that an athlete might notice include muscle weakness, shortness of breath, increased heart rate, feeling cold, trouble sleeping, a foggy brain, and headaches. Confusingly, they overlap with the telltale symptoms of overtraining, so make sure to consult your doctor if you're having these symptoms.

Related: 4 Tips to Avoid Mental Fatigue and (Still) Get Your Workout in

Eating an Iron-Rich Diet

Eating an iron-rich diet on a regular basis is a smart way to keep the proverbial tank topped off before an iron deficiency can sneak in. Iron is found in many foods, including beef, poultry, seafood, beans, and green, leafy vegetables. It's also often added to packaged products like cereals, breads, and pastas.

Supplements can also be used to boost iron, but should be taken for serious deficiencies and at the advice of a medical professional, as they often have unpleasant side effects such as nausea, diarrhea, and constipation.

Not All Iron Is Created Equal

Not all dietary iron is created equal. Although heme iron (meat and seafood) and non-heme iron (fruits, vegetables, grains, nuts, some animal products) are both beneficial to the body, heme iron has more bioavailability once entering the body. According to The American Journal of Clinical Nutrition, those who follow plant-based diets or vegan diets and consume iron from strictly non-heme sources are more susceptible to deficiencies.

Pro Tip: Eating foods that are high in vitamin C (like citrus, bell peppers, broccoli, or strawberries) can help increase iron absorption.

Related: The Health Benefits of Strawberries + 7 Tasty Recipes

How Much Iron Do You Need?

According to the National Institutes of Health, healthy adult men and women need 8 milligrams of iron per day (with the exception of non-pregnant women of child-bearing years, ages 19-50, who need 18mg). Also, keep in mind that iron doesn’t fall into the “more is better” category. Too much iron can cause hemochromatosis and lead to life-threatening health issues such as liver disease, heart issues, and diabetes. That’s why taking any type of iron supplement to treat symptoms, or as a preventative, should be discussed with a medical professional first.

The first line of defense in ensuring that iron levels are optimal is eating a balanced diet comprised of quality whole foods. Check out the infographic below, courtesy of The Fit Fork, for ideas on how to add more iron into your daily diet.

Boost Your Iron Levels With This Steak Spinach Salad

One of my favorite iron-rich training meals is a steak spinach salad, loaded with both heme and non-heme iron sources. This salad alone provides almost half of the recommended daily iron intake. 

Whether hot off the grates or using leftover grilled steak, piling bite-sized pieces of beef on a mound of spinach is a winning iron twofer. Plus, I add other high-iron ingredients like dates and nuts, and I even mix molasses into the dressing. Note that by adding a vitamin-C veggie, like bell peppers, the absorption rate of iron will be improved.

I’m a huge fan of selecting beef as my protein choice in my training diet. Not only is it delicious, but it’s nutrient-dense and includes lots of iron. Also, a sirloin or strip is tender yet still very lean — under 10 grams of fat, 4.5 grams or less of saturated fat, and less than 95 milligrams. If you are following a vegan or vegetarian diet, feel free to swap in your favorite plant-based alternative.

Related: Bison: Food of the Week

The Recipe and Ingredients

• 3 oz grilled flat iron strip or sirloin steak. (Season and grill to your own taste.)
• 3 cups fresh baby spinach
• ½ cup brown rice (optional)
• 1/3 cup red or yellow bell pepper slices
• 2 Medjool dates, seeded and chopped
• ½ oz shelled pistachios (about 23)
• 2 tbsp prepared light balsamic dressing
• 1 tbsp blackstrap molasses
  
  

Chop leftover warm or cold steak into bite-sized pieces. Pile it on top of baby spinach and rice (if desired), and garnish it with bell pepper slices, chopped dates, and pistachio kernels. In a small bowl, use your fork to whisk together balsamic dressing with molasses. Drizzle it over salad, add any other toppings you just can’t live without, and enjoy! You can also layer it as a jar salad and take it for lunch, or enjoy it as a post-workout meal or snack.

The Nutrition Facts: 516 calories, 44% DV iron, 56g carbohydrates, 5g dietary fiber, 18g fat, 34g protein