If you’re an athlete or an active person, you probably already know that exercise can put stresses on your body that ultimately increase your daily nutrient needs. What you may not know is that your daily intake of key vitamins and minerals is also crucial in supporting the body’s ability to exercise intensely. One essential nutrient that often goes unnoticed until it becomes a problem is the mineral iron.

To learn if you have iron deficiency and what you can do to increase your iron intake, read these guidelines from Joanne Adamidou, MS, a dietetic intern at Ohio State University who is pursuing her registered-dietitian credential, and Jenna Bell-Wilson, PhD, RD, LD, assistant professor of clinical allied medicine in medical dietetics at Ohio State University.

Iron’s Role in the Active Body

Iron plays a key role in oxygen transport and fuel utilization. But how exactly does this mineral affect peak physical performance? When an athlete operates without adequate iron, less oxygen is delivered to the muscles, maximal oxygen consumption (VO2max) drops, and physical performance suffers. Additionally, iron deficiency may impair immune and other physiological functions.

Iron Deficiency in the Athlete

Elite and recreational athletes who train hard will deplete their iron stores much faster than less physically active people. An athlete can lose iron through sweat, urine and the gastrointestinal tract, which makes iron deficiency among athletes very common. Female athletes are at greater risk of iron deficiency because of the added losses through menstruation. Adolescent athletes are also at high risk of iron deficiency and often have difficulty meeting iron requirements through diet.

While the stress of exercise is a significant factor, dietary choices cause most cases of iron deficiency . Vegetarian athletes are especially vulnerable in this regard, because they avoid animal sources of dietary iron, known as heme iron, which is more effectively absorbed than the nonheme iron from plant sources. In fact, heme iron provides up to one-third of all absorbed dietary iron.

Achieving Adequate Iron

Unfortunately, the body cannot manufacture its own iron and is thus dependent on food intake for an adequate supply. Most nutrition experts question the need and long-term safety of taking daily iron supplements to prevent iron depletion. That’s because there is a plethora of foods that are very good sources of bioavailable, or readily absorbed, iron. For a look at some common examples, see “Good Sources of Iron in Food.”

Here are some practical food-pairing ways that will optimize the iron in your diet:

  • Combine plant nonheme iron sources, such as lentils and green, leafy veggies, with foods that are high in vitamin C, such as orange juice.
  • Use cast-iron cookware, which may increase the iron content of cooked foods.
  • Don’t drink tea and coffee while eating iron-rich foods, since both beverages can impair iron absorption.
  • Avoid pairing iron-rich foods with
    certain grains, such as wheat bran, or with veggies such as spinach, rhubarb, chard and beet greens. These foods contain chemical compounds called phytates and oxalates, which impair iron absorption.
  • Don’t mix calcium-rich beverages, like milk and fortified orange juice, with foods that are high in iron, since calcium can also inhibit iron absorption.