Low iron is very common in athletes. Heavy training can increase the iron needs of athletes. This is especially the case for athletes in running based activities because the impact of ground contact increases red blood cell destruction. Additionally, hard exercise increases the level of a hormone called hepcidin. Hepcidin is the master iron regulator and decreases iron absorption. The combination of increased needs, and decreased absorption can greatly increase an athlete’s risk of becoming iron deficient and this can negatively impact performance. In this blog I cover all things iron supplement.

Iron supplements should only be taken if you are iron deficient. In order to determine if you are iron deficient, you must get blood work done. Just because you feel tired doesn’t necessarily mean that you are iron deficient, so it’s important to get this checked before you start taking an iron supplement. Further, many athletes may have low iron without even realizing it. There are various stages of iron deficiency. Ferritin represents your body stores of iron. Generally, a ferritin level of <30 ug/L is considered iron depletion. While iron depletion may not yet impact athletic performance, it is important to address in order to prevent movement through to the stage of iron deficiency anemia. At this stage, hemoglobin levels become low. Typically, a hemoglobin <115 g/L, paired with a ferritin <12 ug/L is considered iron deficiency anemia.

If found to be iron deficient then 100 mg of ferrous sulfate per day is typically recommended. However, alternative day dosing (AKA taking a supplement every other day) may be just as effective while reducing GI side effects, such as stomach pain or constipation. The only caveat with taking an iron supplement every other day is it can become easy to forget as it doesn’t become a normal part of daily routine. Recovering iron stores doesn’t happen over night. It will take time for your iron stores to increase. Generally, ferritin levels can increase by 40-80% over 8-12 weeks.

When you choose to take your iron supplement can have a big impact on how much is absorbed. This is because exercise causes a rise in hepcidin about 3 hours after exercise. As I mentioned, hepcidin decreases iron absorption. As a result, if you took your iron supplement about 3 hours after finishing your exercise, the high hepcidin levels may interfere with iron absorption. In order to avoid this, you should aim to take an iron supplement within 60 minutes of completing exercise, which gives it enough time to reach the gut before the post-exercise hepcidin peak. Alternatively, you can wait more than 6 hours after exercise before taking your iron supplement. This gives enough time for hepcidin levels to return to normal. However, there is also a natural rise in hepcidin throughout the day. This means in the morning, hepcidin levels are lower, making it a better time to take an iron supplement.

An additional factor to consider is what you consume with your iron supplement. Iron is absorbed best on an empty stomach. By not consuming food or beverages (with the exception of water) within the 1-hour period of taking your supplement, it can be better absorbed. You could also consume a vitamin C supplement with the iron supplement to enhance its absorption. Some people do find GI distress if they take an iron supplement on an empty stomach. If this is the case then it is a good idea to avoid food and beverages that inhibit iron absorption with your iron supplement. This includes phytic acid found in whole grains and legumes; polyphenols found in coffee, herbal teas, red wine, and chocolate; and calcium rich foods. Rather, you should consume a food or beverage rich in vitamin C with the supplement to enhance absorption.

For all the hard work that you put into training, don’t let low iron sabotage your ability to perform at your best. It’s a good idea to periodically get iron levels checked to ensure that they are in the normal range. If you do need to take an iron supplement, carefully plan how you take it so that you can get the most bang for your buck.

Categories: Megan Kuikman

Megan Kuikman

Hello! I’m Megan Kuikman. I’m a Registered Dietitian with specialized training in sports nutrition. My goal is to help athletes and active individuals achieve a healthy attitude towards health, training, and food. I empower athletes to fuel properly for training in order to restore their health and enhance performance. You can get in touch with me at: hello@megankuikmanRD.ca


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