Iron Requirements – What Female Athletes Need to Know

Why is iron important

Iron is an essential mineral used in haemoglobin. Haemoglobin carries the oxygen we breathe around the body delivering it to our muscles and organs including our brain.

Iron helps in producing energy from food and is needed to support the aerobic and anaerobic energy systems in our bodies.

Iron helps our immune system cells work efficiently to help fight off illness. A mild drop in iron levels reduces the body’s ability to uptake oxygen and reduces endurance exercise capacity.

How much iron do I need?

The Recommended Dietary Intake (RDI) for iron in Australia:

Source: NHMRC Nutrient Reference Values for Australia and New Zealand 2006

Specific iron requirements for athletes participating in different sports is not currently defined. 

However, it is thought that endurance athletes (runners, triathletes, rowers, etc) lose the highest amounts of iron and thus will have the highest iron absorption requirements.

Some studies recommend iron intakes of 17.5 mg/day for male endurance athletes and 23 mg/day for females (menstruating) but these intakes may be unachievable without abnormally high energy intakes.

Due to losing blood whilst menstruating and having lower energy intakes and higher iron requirements then men it is difficult for females, particularly female athletes to reach their iron requirements.

Are female athletes more at risk of iron deficiency?

Female athletes have a high risk of iron depletion for several reasons:

1. High initial iron requirements

• Increased red blood cell mass means athletes have higher iron needs. These needs are disproportionally high when the athlete is living through periods of physical growth.

2. Activity causing iron losses

• As iron is lost by the body through sweating, sports with high physical exertion activities have greater iron losses (ie a tennis player will likely lose more iron through sweating than a golfer)
• Iron can be lost through strenous exercise via gastrointestinal bleeding caused by minor damage to stomach and intestinal lining. 

3. Athlete Dietary issues

Many athletes have restricted/ limited food intakes:

• Iron ingestion is often sub-optimal to begin with due to dietary restrictions
• Low kilojoule intakes are often are an attempt to minimise body weight to improve athletic performance
• Ill-advised and poorly balanced vegetarian/vegan diets
• Avoidance of meat, chicken or fish in an effort to enhance carbohydrate intake or fear of saturated fats
• High reliance on snacks, processed and convenience foods and failure to consume regular meals
• Avoidance of commercially fortified foods such as breakfast cereals

What are good food sources of iron?

A large amount of iron in food is unavailable for absorption.

• The most readily absorbed form is call ‘haem iron’ and comes from animal protein
• 15 – 35% of iron is absorbed from beef, lamb, pork, fish, seafood and poultry
• Iron from plant foods, ‘non-haem’, is poorly absorbed because of other naturally-occurring substances in these foods
• 2 – 15% of iron is absorbed from cereal grains, legumes, dark green vegetables and nuts

What foods improve iron absorption?

Foods high in Vitamin C will help the absorption of non-haem iron. Therefore, try to include a vitamin C source with your meals. 

Good sources of Vitamin C include:

• Fruit: Oranges (or 100% juice) orange juice, berries, grapefruit, kiwi or pineapple.
• Vegetables: Green and Red peppers. Broccoli, Brussel Sprouts, Tomatoes.
• Starchy vegetables: Potatoes, squash or pumpkin

Adding fruits and vegetables to meals includes beans and pulses, whole meal breads and fortified cereals. Vegetarians should eat these foods daily.

What foods stop iron absorption

Certain foods can slow or stop the absorption of iron from the diet, particularly from the non-haem sources. Avoid eating your main iron sources with these foods:

• Tannins (found in tea and coffee)
• Red wine
• Unprocessed bran (e.g. bran flakes breakfast cereals)
• Calcium (dairy products)
• Soy products

Three simple steps to an iron-rich diet

1. Choose foods high in absorbable iron at each meal
2. Combine non-meat meals with good sources of vitamin C to increase absorption of non-haem iron
3. Drink tea and coffee between (not with) meals – components of these inhibit the absorption of non-haem iron

Breakfast:

• Choose cereals that have been fortified with iron
• Add a piece of vitamin C-rich fruit (strawberries, kiwi fruit, rockmelon, orange) to increase absorption of non-haem iron in cereals/bread
• Wait until morning tea to have a cup of tea or coffee

Lunch:

• Add haem iron foods to your sandwich or salad; red meat will help absorb the non-haem iron in the bread and/or vegetables (by up to 4 times!)
• Add vitamin C-rich vegetables (capsicum, broccoli or citrus fruits) to vegetables/vegetarian meals to increase absorption of non-haem iron

Dinner:

• Eat red meat 3 – 4 times per week
• Choose iron-rich foods such as legumes (baked beans, lentils, three-bean mix) and add vitamin C-rich vegetables (broccoli, cabbage, cauliflower, capsicum) to increase non-haem iron absorption
• Wait a while before having an after-dinner cuppa

And a few final notes…

• Eat lean red meat, poultry or fish, preferably daily
• Eat lean red meat at least three to four times a week
• Combine iron-rich plant foods (e.g. legumes, breakfast cereal and dark vegetables) with vitamin C-rich foods (citrus, strawberries, cabbage, capsicum, kiwi fruit, broccoli)
• Avoid consuming strong tea or coffee when you eat breakfast cereal or sandwiches
• Seek the advice of a sports dietitian if you are vegetarian or vegan or have low iron levels to ensure you are meeting your requirements
• Do not take iron supplements without the recommendation of a doctor and/or sports dietitian

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