Dietary iron is something we all need but women, children and teenagers commonly eat less iron than they need.

In New Zealand it is estimated that about 42% of women aged 15 to 44 are eating less iron than is recommended. But before you rush out and self-prescribe an iron supplement it is better to stop and look at how you can improve your intake through food.

Iron supplements can interfere with the absorption of other important nutrients such as calcium and zinc so they should be used only when a deficiency is diagnosed in a blood test.

Iron is a mineral found in every cell of the body. It helps carry oxygen through the bloodstream, to create energy and sustain a healthy immune system.

The symptoms of iron deficiency are low energy levels; lowered immunity resulting in increased risk of infections; impaired learning and reduced resistance to cold.

Recommended Iron Intake

How much iron you need daily depends on your age and sex. The daily recommended intake takes into account that not all the iron in food will be absorbed by your body.

  • Children (1-13 years) — 8-10mg iron per day
  • Boys (14 – 18 years) — 11mg iron per day
  • Girls (14-18 years) — 15 mg iron per day
  • Women (19-50 years) — 18 mg iron per day
  • Pregnant women — 27mg iron per day
  • Women over 50 years — 8 mg iron per day
  • Men over 19 years — 8 mg iron per day

Types of Iron

There are two types of iron in the food we eat.

Haem-iron is found in blood-rich foods such as red meat, poultry and fish. This type of iron is up to 10 times more readily absorbed in the body than non-haem iron.

Non-haem iron is found in plant-based foods. Sources of non-haem iron include some vegetables, cereals, fruits and legumes (beans and peas).

The absorption of iron can vary depending on a person’s iron status at the time. A person with good iron stores may not absorb as much iron as a person with low stores.

While the iron from plant sources may not be as easily absorbed by the body there are some dietary factors that can assist iron absorption from plant foods. Red meat with a meal will aid the absorption of iron from plant based foods eaten at that meal. Vitamin C will also aid the absorption of iron from plant based foods. For instance, including some tomato with your wholegrain sandwich will aid the iron absorption from wholegrain breads.

Iron Content in some Foods

The iron content of some foods is given below:

Foods containing Haem iron:

  • Steamed mussels — 100g — 5.8 mg
  • Lean beef cooked — 120g — 4.6 mg (average of all cuts)
  • Lamb liver — 40g — 4 mg
  • Lean lamb cooked — 120g — 3 mg (average of all cuts)
  • 2 chicken thighs — 172g — 1.8 mg
  • Tarakihi baked — 120g — 0.6 mg

Non-haem foods

  • Tofu — 100g — 5.4 mg
  • Pumpkin seeds raw — 2 Tbsp — 2.5mg
  • Red lentils — 100g cooked — 1.7 mg
  • Cooked egg (whole) — 1.1 mg
  • Baked beans — ¾ cup — 1 mg
  • Spinach — ½ cup cooked — 0.6 mg

It can be seen that if you are not an eater of red meat it can be a challenge to meet your recommended iron intake. It is not impossible though – it just means that you need to pay special attention to your food choices.

There are some dietary factors that can inhibit iron absorption. Tea has a high tannin level and this can interfere with iron absorption. Ideally tea should be consumed between meals rather than with meals.

Diets with a high fibre intake can also inhibit iron intake. Phytates in wholegrain breads, cereals, nuts, seeds, fruit and vegetables bind with minerals such as iron, zinc and calcium, thereby reducing their availability. This may seem at odds with the recommendation to eat a diet containing wholegrain breads, cereals, fruit and vegetables. Aiming to eat from a wide variety of foods is again one of the key things you can do.

Remember it is recommended you get you iron from food rather than tablets, unless a supplement has been prescribed for you.

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Fiona Boyle is a registered dietitian and nutritionist. She runs a private practice and gives nutrition advice to individuals and families to help meet their health needs and personal goals.

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