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An Athlete's Guide to Iron
By:  Ingrid Hagberg   (2013/03/08)


Several weeks ago Ontario Ski Team coach, Pavlina Sudrich, wrote a blog post about the importance of getting your blood tested for iron, Vitamin B12 and CBC levels. The outcome? Within a couple weeks, a few of my teammates discovered that they had low iron, and not a good idea of how to change that! As someone who has spent the last 4 years closely studying nutrition, Iím always surprised at not only the prevalence of low iron, but that most athletes donít even consider iron when looking at their diet. Hopefully Iíll be able to provide some good insight on the importance of iron and how to avoid detrimental low iron levels.

What does Iron do in the body?

For athletes, iron is arguably one of the most important nutrients in our diet. Most of the iron found in our body is bound to hemoglobin, the protein responsible for transporting oxygen throughout our body. Iron is also found in myoglobin in our muscles, where it assists in transporting oxygen from the blood stream into our muscle cells. Sound important? Without adequate amounts of iron in our blood, we canít get oxygen into our cells and that leads to more anaerobic metabolism (think lactic acid). And yet, iron deficiency is the most common nutrient deficiency in the world.

What are the consequences of low iron?

As athletes, we have a greater risk for iron deficiency than the general population. Higher training hours leads to an increase in hemoglobin production, requiring more iron, while at the same time promoting iron loss through sweat, injuries, and red blood cell damage from high impact training (eg. foot-striking while running). As the extent of iron depletion increases through the body, symptoms become more severe. In addition, females are much more likely to be iron deficient from their menstrual cycle. Keep in mind that deficiency symptoms can be very similar to over-training, making iron deficiency hard to diagnose.


  • Pale Skin
  • Brittle Nails
  • Decreased mental capacity
  • Decreased motivation
  • Frequent illness
  • Chronic Fatigue
  • Decreased aerobic capacity

How much iron do we need?

Health Canada recommends that males aged 19 & over get 8mg/day, 14-18 year old males have 11mg/day, and 14-50 year old females get a whooping 18mg/day. But wait!†Why do we all have different requirements of iron, and yet the Nutrition Facts Table for foods only has one value for iron?†Iím so glad you asked! The % daily value on this table is calculated using a 14mg/day requirement. This is especially tricky for females, who will actually be getting much less of their recommended iron intake from a food than is stated on the label.

Iron absorption: Not all iron is created equal

Most of the iron we ingest is not absorbed into our body, and is excreted. While our recommended intake of iron includes both absorbed and non-absorbed iron, obviously we get more benefits if we absorb as much iron as possible. The iron in our diet can be divided into two categories: Heme iron, from animal sources, and non-heme iron, from plant sources. Heme iron is absorbed much more readily than non-heme iron. Generally, if you want to absorb more iron, you will do much better getting it from meat, rather than plant sources. Be warned of the iron paradox: the less iron you ingest in your diet, the more youíll absorb, compared to the more iron you have in your diet, the less youíll absorb. For example, someone getting 1000mg of iron may absorb 200mg, while another person ingesting 2000mg may only absorb 300mg.

What are good iron sources?

Good news: there are many different ways to get iron in your diet. Animal sources include red meat, liver (beef, pork, and turkey), clams and oysters. Plant sources include spinach, lentils and legumes/beans. Most cereals and breads are fortified with non-heme iron. Whatís the best food for iron? Clams, with over 20mg per 90g serving. Thatís well over the daily requirement! Worried about getting too much iron from clams? The tolerable upper intake level for iron is 45mg, still leaving lots of breathing room.††††††††


Enhancers of Iron absorption

Not all iron is absorbed by the body, but certain foods can certainly increase that amount. Vitamin C is excellent at enhancing the absorption of non-heme iron in the body. Look for vitamin C in peppers, oranges, grapefruit, strawberries, and broccoli. Fish, beef, and poultry all help increase the absorption of non-heme iron, regardless of how much iron is present in the meat itself. To best increase your absorption of non-heme iron, try to consume your iron and enhancer as close together as possible. Ingesting vitamin C four hours after a meal will not help your iron absorption.

Inhibitors of Iron absorption

Just as there are foods that increase iron absorption, there are others that block its absorption, and these should be avoided when eating iron-rich foods. Calcium is a well-known inhibitor of iron absorption and only very small amounts of the mineral are needed to have a significant reduction in iron absorption. Watch out for dairy products, or supplemented foods when consuming iron. Other inhibitors include phytates (found in legumes and grains), coffee, tea, and red wine. Give yourself at least an hour before and after eating an iron-rich food until you consume any inhibitors. If you have to eat both inhibitors and iron, try to include vitamin C or meat to counteract the inhibition as much as possible.

Iron for Vegans and vegetarians

No meat in your diet cuts out all sources of heme iron, and also prevents the benefits of increased absorption of non-heme iron from meat. This drastically decreases the amount of iron that your body absorbs, which is why Health Canada recommends vegans and vegetarians eat 1.8 times the amount of iron that regular people do. That amounts to 14mg/day for adult males, and 32mg/day for females. Since vegans and vegetarians only consume non-heme iron, it becomes even more crucial to include absorption enhancers and avoid inhibitors when consuming iron-rich food. A good meat-free diet should include lots of legumes, spinach, and other good sources of non-heme iron, so getting adequate amounts of iron is not difficult. Meat-free diets can be very rewarding but must be done properly to maintain adequate nutrition, so make sure you are getting extra iron in your diet.

Closing Remarks

Iron is crucial in allowing us to perform in endurance sports, and low iron levels can be disastrous. Since itís hard to differentiate between low iron and over-training, having a good understanding of your diet and blood iron levels are critical in preventing anemia. If†you've†been experiencing chronic fatigue and decreased performance, a good place to start would be by looking through your training diary (preferably with a coach) to look for signs of over-training. If you†aren't†100% sure the fatigue is caused by over-training, get your iron levels tested, donít wait for the symptoms to worsen and ruin your sports performance!

Interesting Reading. . .
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