Sluggish, irritable, and unmotivated? Stop beating yourself up, it may not be entirely your fault! A simple blood test of your hemoglobin and ferritin levels will allow you to determine if your symptoms are the result of low iron.
The Importance of Iron
Iron is required to produce hemoglobin—the “transport system” in our red blood cells that is responsible for carrying oxygen from our lungs to our muscles. If hemoglobin levels are low, less oxygen reaches the muscles, therefore compromising an athlete’s VO2 max making it very difficult for even the most well trained athlete to perform to their potential.
Symptoms of being Iron Deficient
Elevated Heart Rate
Limited or no positive response from training stimuli
Decreased immune function
Lack of Motivation
What Makes Runners More at Risk
According to renown running coach Pete Pfitzinger (see Pfitzinger Lab Report), runners are more at risk for being iron-deficient due to: “increased blood volume, low iron intake, foot strike hemolysis, iron loss through sweat and urine, and iron loss through the gastrointestinal (GI) system.” Pfitzinger also indicates that women’s physiology and the blood loss from menstruating can contribute to low iron.
Points to consider…
A physiological training effect among runners is an increase in their blood volume. While this is a positive effect, it can also dilute the hemoglobin concentration in the blood.
Some runners ignore the nutritional requirements of being an endurance athlete often resulting in a low iron intake. Consider meeting with a dietician to discuss your current diet to ensure you are meeting your iron needs. The dietician may suggest meal options or a supplement.
One of the most fascinating causes of low iron in runners is what’s called ‘Foot Strike Hemolysis’. It has been proven that each time the foot strikes the ground red blood cells breakdown. While this may not be an issue for most runners, this could be a contributing factor for those who run high mileage on hard surfaces.
Several studies have shown that a significant number of runners experience a loss in blood through their gastrointestinal system. This tends to be more common in the elite running population.
Male: 12-300 ng/ml
Female: 12-150 ng/ml
Note: ng/ml = nanograms per milliliter
Keep in mind these numbers are for normal adults not endurance athletes. Endurance athletes require increased iron stores due the greater demands placed on their bodies. Some studies suggest that an athlete’s performance is affected when ferritin levels are below 20 ng/ml.
The United State Department of Agriculture has an excellent Interactive tool that allows you to plug in your sex, age, height, weight and level of activity and it will print out a guideline for your Dietary Reference Intake for various macronutrients, vitamins and minerals (including iron).
Consult a Physician & Dietician
At your next doctor’s visit be sure to inform your doctor of your endurance training and the demands you place on your body. If your doctor suggests that you have your iron tested make sure you ask to have both your hemoglobin and ferritin serum levels checked. The hemoglobin test will measure hemoglobin protein levels while the ferritin serum test will determine your built up iron stores in your body—both are important to your success as an endurance athlete.
Meeting with a Dietician will allow you to learn more about iron-rich foods and supplements that may help you to increase your low iron stores and prevent future iron-deficiency. Ask your dietician about ideal times to consume iron and what foods to avoid eating at the same time to increase absorption rate.
The Center for Disease Control and Prevention warns people that “Substances (such as polyphenols, phytates, or calcium) that are part of some foods or drinks such as tea, coffee, whole grains, legumes and milk or dairy products can decrease the amount of non-heme iron (plant based iron) absorbed at a meal.” Pfitzginger suggests consuming iron in conjunction with eating vitamin-C rich foods and advocates for using cast-iron cookware when preparing acidic foods.
Good Food Sources of Iron
The chart below ranks food sources of iron by milligrams per standard amount.
* indicates non-heme iron source or plant based iron source
Keep In Mind
Be sure to consult a doctor if you are experiencing symptoms of iron-deficiency. Taking a few moments out of your day to have your iron levels checked could save you minutes on race day while making the training process and your daily life more enjoyable!
About the Author: Chantelle Wilder is the Senior Editor and Co-Founder of Runners Feed. She also competes for the New Balance Silicon Valley club in the Bay Area of California. When she isn’t running, or editing she can be found enjoying the fruitful wines of nearby Napa Valley while challenging her husband to a game of Bananagrams®.