Iron is essential for life – every cell in your body needs iron to function. Understandably, athletes are often concerned about iron, because iron is part of hemoglobin in blood and myoglobin in muscles, helping deliver oxygen to cells. Low hemoglobin can result in fatigue and decreased aerobic capacity, leading some athletes to assume that extra iron will enhance performance. Indeed, some endurance athletes take iron supplements regardless of their iron status, even though excess iron might compromise their health. On the other hand, truly iron deficient athletes might not be aware of their status, and changes in their diet or iron supplements might reduce fatigue or improve performance. But dietary changes aren’t straightforward because iron absorption is a complicated phenomenon. Read on to find out
- if you might be at risk for iron deficiency
- how much iron you need and the best dietary strategies to increase your iron intake
- potential pitfalls to avoid when increasing dietary iron intake
Which Athletes Are at Greatest Risk for Iron Deficiency?
Endurance athletes, particularly females and adolescents, are at risk for reduced iron stores and anemia (reduced blood cell mass or hemoglobin concentration). Intense training increases iron demands, and exercise can deplete iron stores through increased red blood cell production, tissue inflammation, sweating, and destruction of red blood cells with impact (foot strike). Adolescents are growing rapidly and iron demands are high, and women lose iron through menstruation. Studies show that adolescents and women don’t consume enough iron in their diet, and experts believe that this inadequate intake is a major contributor to iron deficiency.
How Do I Know if I’m Deficient in Iron?
Athletes should consult a physician to get a blood test to screen for iron deficiency. Typically your doctor will look at complete blood count (CBC) measures, serum ferritin (estimate of stored iron) and possibly other specific tests to help diagnose low iron. A diagnosis of anemia often involves (1) low hemoglobin; (2) smaller than normal red blood cells; and (3) low serum ferritin.
A low ferritin level alone could be an early warning sign of anemia, so athletes with low ferritin should try to increase their iron status first by increasing the iron in their diet.
How Much Iron Do I Need?
The for daily iron intake are as follows:
- Females 14-18 yrs: 15 mg
- Females 19-50 yrs: 18 mg
- Females 51+ yrs: 8 mg
- Males 14-18 yrs: 11 mg
- In Canada, this is based on 14 mg iron (so 50% daily value means 1 serving contains 7 mg iron);
- In the US this is based on 18 mg iron (so 50% daily value means 1 serving contains 9 mg iron).
Iron Absorption
How well you absorb iron might be as important as the amount that you consume. But iron absorption is a complex phenomenon: your body only absorbs about 10-15% of the iron you eat, and the amount of iron you absorb from a food is influenced by (1) your body iron status; (2) the type of iron (heme iron is better absorbed than non-heme iron); (3) iron inhibitors; and (4) iron enhancers.
Iron Inhibitors are substances in foods that interfere with iron absorption (especially non-heme sources of iron). These include
- Calcium, dairy products, and eggs.
- Oxalates found in spinach, kale, beets, nuts, chocolate, tea, wheat bran, rhubarb, strawberries, and some herbs.
- Polyphenols – antioxidants found in some cereals and legumes, most fruits and vegetables, cocoa, coffee, tea (black, green, and herbal), some spices, and wine.
- Phytates – antioxidant compounds found in nuts, seeds, grains, soy proteins, and legumes.
You’ll notice that this list includes many healthful foods, and the health consequences of limiting or avoiding these foods (not to mention meal-planning headaches) likely outweigh the possible iron boosting benefits of avoiding them. My advice? Focus on Iron Enhancers.
Iron Enhancers
- Vitamin C helps your body absorb iron, and overcomes the negative influence of iron inhibitors. Some studies estimate that Vitamin C can increase iron absorption as much as four times. Try to include a vitamin-C rich food with meals and snacks. A bonus is that most vitamin-C rich foods are full of other protective nutrients important for health. This tables lists foods rich in vitamin C.
- Eating heme iron-rich foods with non-heme-iron rich foods helps increase iron absorption (for example, adding a small amount of meat to chili will help you absorb more iron from the beans).
- Carotenoids (beta-carotene, lutein and zeaxanthin – found in brightly-colored fruits and vegetables like carrots, greens, sweet potatoes, red peppers, cherries, cantaloupe, oranges) improve iron uptake and help overcome the effects of iron inhibitors.
- Cooking in cast iron can increase the iron content of food, especially acidic foods (i.e., tomato sauce). Studies have found that the iron content of cast-iron cooked foods was 2 to 12 times higher than foods cooked in other types of pots: more acidic, high moisture foods and longer cooking times results in more iron leaching into foods. One study estimated an increased daily iron intake of 14.5 mg for adults and 7.5 mg for children eating foods cooked in cast iron pots. (Cast iron is great ).
Designing Meals and Snacks to Maximize Iron Absorption
A main focus should be to include vitamin-C rich foods with your meals and snacks. Here are some other tips and meal ideas:
- A burrito or Mexican-inspired meal containing beans and rice with salsa and sweet peppers is a delicious iron-rich vitamin C combination. Add a little lean beef or chicken to increase the iron content even further.
- Bake with Blackstrap Molasses – it’s full of all the good stuff that’s left behind after processing sugar cane into sugar, including lots of iron and other minerals like calcium, magnesium, and potassium. Some people add 1 tbsp. to water or milk. A little can add a rich flavor to baked goods like yeast breads, quickbreads and muffins (I use 3-4 tbsp. for baking a large loaf of whole wheat bread). The flavor is intense – so experiment with just a little at first.
- For a pre- or after-workout snack, try trail mix with iron fortified cereal (shreddies/oat squares), dark chocolate, and dried fruit with vitamin C (mango, papaya, apricot) to increase iron absorption.
- Enjoy an iron-fortified breakfast cereal with fresh berries and milk or yogurt. This is a great post-workout snack too because it includes carbs and a bit of protein. Low-sugar/whole grain varieties are your best bet.
- Top a spinach salad with vitamin-C sources, like strawberries, or mandarin oranges, and peppers (all rich in Vitamin C).
- Finish off a meal with a vitamin-C rich fruit tart (try ) to improve the iron absorption of your meal.
- Add red peppers to any meal – they are the leading source of vitamin C to help iron absorption and full of other nutrients. Eat raw as a snack, add slices to sandwiches and wraps, dip into hummus, or cook into omelets, soups, and stews.
- Here are from my favourite cooking magazine Eating Well.
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