Sports nutrition often focuses on hydration, electrolytes, protein and carbohydrate intake. While these play an important role, there is one important mineral that often gets overlooked for athletes – iron.
Iron is used by red blood cells to move oxygen to the mitochondria (the power houses of our cells) in our heart and muscles. This is especially important for endurance athletes. Iron is a critical mineral for sports performance, and is also the most common nutrient deficiency worldwide.
Food Sources of Iron
There are two types of iron we can get from food;
- heme iron which comes only from animal sources, and
- non-heme iron which is in both plants and animal sources
The iron in meat is a combination of around 40% heme and 60% non-heme iron. Eggs and dairy only have non-heme iron. The absorption of non-heme iron can be affected (positively or negatively) by combinations in your diet.
How Low Iron Levels Evolve
Changes in iron levels happen gradually, with effects showing up over months and years. This is why it’s often overlooked as compared to electrolytes or carbohydrates, where deficiencies would show up the same day in your training.
The body is good at recycling iron and keeps iron stores. Low iron levels start with a drop in the body’s iron reserves. This won’t affect performance yet, if the reserves become depleted it will impact the body’s ability to produce red blood cells. This affects oxygen transport, reducing our VO2 max and our ability to perform. Less oxygen available to the muscles means lower capacity aerobic performance.
Low Iron Symptoms
A slight shortness of breath and fatigue are the two most common symptoms of low iron levels. This can be confusing for athletes, as these are common with endurance sports. If iron levels are significantly low, you might feel dizzy during longer workouts. Keep an eye on these symptoms, especially if they appear for no apparent reason, it might be time to see your doctor about a blood test. Low iron levels cannot be self-diagnosed. You’ll need to get a blood test from your doctor to see your levels.
Causes of Iron Loss
There are many reasons why people lose iron, some are specific to athletes:
- Sweating – it’s normal to lose a little iron each time we sweat. People who train for long hours or multiple times per day will lose more than the average person.
- Menstruation losses for women and female athletes are a factor for low iron.
- Low dietary intake – diets that are low in iron rich foods mean that iron isn’t being replenished.
- Running – the impact of running damages red blood cells, which can contribute to low iron levels.
- Genetics – can play a big part in an individual’s iron absorption.
- Digestive system illness or inflammation – like Celiac disease for example, means iron may not be properly absorbed.
How to Prevent Iron Deficiency
For most people, including iron rich foods is enough to prevent iron deficiency. Foods that are high in iron include: dark leafy greens, beans and iron fortified cereals, breads and pastas. For athletes, a daily supplement is a good idea as well.
Vitamin C helps with non-heme iron absorption so it’s a good idea to combine iron rich foods with food with vitamin C (a food source or supplement).
One way to ensure optimal iron absorption is to avoid drinking coffee and tea with meals, as caffeine can inhibit iron absorption. If you want to have caffeine, space it out 45-60 minutes before or after you eat.