At one point or another during our training, we’ve all felt the onset of fatigue, constant tiredness, or just that sudden wave of mid-run weakness. While we may chalk it up to an increase in mileage or stress from our lives outside of running, there’s a chance your fatigue is due to low ferritin levels.
Ferritin, a blood cell protein that contains iron, is vital to athletic performance, particularly in female runners who tend to suffer from iron deficiency more often than males. (More on why that is below.) Normal ferritin levels range from 12 to 300 nanograms per milliliter of blood (ng/mL) for males and 12 to 150 ng/mL for females, according to MedicineNet.com. Once ferritin levels drop below 50 ng/mL, you’ll start to notice signs such as dizziness, headaches, irritability and trouble breathing.
So why does iron deficiency, also known as anemia, cause fatigue, burnout and an overall feeling of weakness? Elyse Kopecky, former cross country athlete and co-author of Run Fast. Cook Fast. Eat Slow. says, “An adequate supply of iron must be available to enable red blood cells to transport oxygen to your hardworking muscles. Mild anemia can impact athletic performance since it causes a general feeling of tiredness.”
So you’ve noticed some symptoms of anemia, what should you do next?
Examining your diet is the first step to combating anemia. Incorporating foods high in iron such as red meat, leafy greens, lentils, and even dark chocolate are beneficial to raising ferritin levels in the blood. Some iron rich go-to recipes for Kopecky include the Beef and Lentil Minestrone recipe in Run Fast. Cook Fast. Eat Slow. “It provides significant iron from the grass-fed ground beef and the kale, plus the tomatoes add vitamin C which helps with iron absorption,” says Kopecky. This iron-rich snack recipe from Kopecky is great for post-run fuel.
If you’re still feeling burnt out or weak during your training, having blood tests performed by a medical professional will determine if your ferritin count is still low. “Runners should work with a doctor to determine if the levels are so low that a supplement is needed,” says Kopecky. “Iron supplements can be difficult on digestion and lacking in other important nutrients that are also essential to raise iron levels, but in some cases a supplement can provide a much-needed initial boost. Taking too much iron is harmful, so it’s best to consult with a doctor.”
Why is iron deficiency anemia more common for female runners?
Anemia is a condition in which you lack enough healthy red blood cells to carry adequate oxygen throughout the body. Because women lose blood monthly when they menstruate, they also lose the iron within those red blood cells. This is why you may feel extra tired or weak when training during your monthly cycle. It’s important to eat plenty of iron-rich foods during and after your cycle to restore the red blood cells your body loses. Women runners who are suffering from iron deficiency might end up with athletic amenorrhea as well, which is the absence of menstruation and is typically due to low estrogen levels and not enough iron in the blood. It requires more than just an increase in iron-rich foods or an iron supplement. Working healthy fats into your diet such as whole-milk Greek yogurt, avocados, and salmon can help restore your monthly period. Another line of defense against athletic amenorrhea is to incorporate vitamins and minerals such as folic acid, vitamins A, B, C and E, and calcium.
My iron levels are up to par, what are some other key nutrients I should be concerned about?
Vitamin D is another nutritional component of success for runners. It aids in absorbing calcium which is vital for bone health. If you’re prone to stress fractures, you may want to examine how much vitamin D is in your diet. The recommended daily intake from the U.S. Institute of Medicine is 400-800 IU. Before reaching for the 1000 IU vitamin D supplements, incorporate fatty fish like canned tuna, salmon, oysters, and mackerel into your diet. Three ounces of cooked salmon has more than 450 IU of vitamin D. You can buy milk and certain cereals that are fortified with vitamin D as well.
Kopecky mentions vitamin C when discussing her iron rich go-to meals. Vitamin C is key to absorbing iron from non-heme foods. Heme iron comes only from meat, poultry and seafood. Non-heme iron comes from fruits, vegetables, grains, and beans, among other sources. Vitamin C is crucial to iron absorption if you rely on non-heme iron sources. Runners who practice a vegetarian or vegan diet should pay particular attention to their vitamin C intake since they don’t take in heme iron found in meat. Foods that are high in vitamin C include bell peppers, broccoli, tomatoes, kiwi fruit, oranges, strawberries and sweet potatoes. If you’re taking iron supplements, which don’t contain heme iron that is only found in meat, be sure to eat something high in vitamin C or a vitamin C supplement along with it.
While the information above can help you improve your training, (and maybe your PRs), be sure to consult with your physician before making any drastic changes to your diet.