What you need to know about iron

What you need to know about iron

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Naturopath Jennifer McLennan looks at why iron is so important for women and explains how you can get enough of it.

Premenstrual women require an average of 18 mg of iron each day – more than double the amount needed by men. This is largely due to the loss of iron experienced in menstruation; however, women who exercise frequently or who eat a vegetarian diet are at further risk of iron deficiency(ID), or iron deficiency anaemia (IDA).

Iron is needed in the transport of oxygen to cells. When an oxygen molecule reaches a cell, it is transformed to help make energy. Lack of iron means less energy is available to cells, and this can result in fatigue, lack of concentration, muscle weakness and sometimes light-headedness.

Can I get enough iron from my diet?

On average, it is thought that 4200 kilojoules (1000 cal) of food provides approximately 6 mg of iron. Therefore based on an average kilojoule intake of 8400 kilojoules (2000 cal) per day, a shortfall is likely to occur unless careful attention is paid to diet.

Iron from food can be divided into haem iron (from meat) and non-haem iron (from non-meat sources). Haem iron is absorbed more readily than non-haem iron forms, found in vegetables, nuts, seeds and grains. Ways to increase the absorption of non-haem iron are:

  • Eating foods high in vitamin C when consuming iron-rich foods. Vitamin C increases the absorption of non-haem iron. 
  • Choose acidic salad dressing such as lemon juice and vinegar as acid increases the absorption of non-haem iron.
  • Incorporate bitter herbs (dandelion and gentian) and bitter greens in your diet. Also, eating fruit such as grapefruit before a meal will increase acidity and therefore improve absorption of iron.
  • Avoid drinking black tea with your meals, as the tannins in tea can bind with iron, preventing absorption.

Below is a table listing foods that contain iron. Click in the hyperlink and be directed to the Australian Food Standards website for a comprehensive list of foods and their iron content.

Average amounts of Iron per 100 g food portion

Food Type  Amount of Iron   Kilojoules (calories)
Turkey, deli-style 1.2 mg/100 g  608 (143)
Chicken breast, lean, baked 0.5 mg/100 g  637 (151)
Almonds, with skin 3.9 mg/100 g  2503 (596)
Chickpea, canned drained 1.8 mg/100 g  446 (106)
Eggs, hard-boiled  1.6 mg/100 g  545 (130)
Spinach, English boiled 3.9 mg/100 g 80 (19)

I have been told to take iron – what is the best form to take?

Iron supplements are many and varied, and it is always best to discuss your individual needs with your healthcare professional. The most common forms are:

  • Ferrous (iron) sulphate and fumerate – these are inorganic (non-haem) forms of iron found commonly in iron supplements. They are prescribed for the treatment of iron deficiency anaemia. Ferrous sulphate may cause irritation in the gastro-intestinal tract and constipation, so try taking your supplement with food to minimise these effects. Studies show comparable results when taking iron supplements weekly compared to daily.
  • Iron amino-acid chelate 20-30 mg per day is a general recommendation.
  • Iron phosphate is an easily absorbed iron supplement.

When should I take my iron supplements?

This will depend on the type and strength of your iron supplement. High strength iron supplements, containing greater than 40-50 mg of elemental iron, should be taken with a meal to avoid irritation on the stomach. Low dose iron supplements of 5-10 mg can be taken in between meals to increase the absorption and decrease the competition with other elements.

How long will it take to notice a difference?

This can depend on many factors, such as how mild or severe the deficiency or anaemia is, ongoing iron losses, increased demands (such as pregnancy) and the amount or strength of the supplement taken. It may take several months for iron stores to be restored.

Will I have any side effects?

Gastro-intestinal effects may include irritation, cramping, constipation and dark stools when supplementing with iron.

Is too much iron dangerous?

It is always best to check with your healthcare professional and get a blood test before actively increasing your iron intake.

References available on request