Iron

Iron is an essential mineral required by the body for a number of different functions. It’s most well known role is it’s attachment to the red blood cell protein, haemoglobin. The iron in haemoglobin binds to oxygen and delivers it to all the cells of the body. Metabolic respiration, the process where cells create energy from breaking down nutrients (carbohydrates, fats and proteins), cannot occur effectively without sufficient supply of oxygen so iron has a very important job. Iron is also found in myoglobin, the protein that carries oxygen specifically in muscles.

Iron deficiency is one of the most common mineral deficiencies in the world, particularly in developing nations. Even in more developed, industrial countries such as Australia and the United States, iron deficiency is a significant public health concern in children and young women. Symptoms of iron deficiency begin to appear once iron stores become depleted. This is why symptoms can be non-existent or minimal even when the diet is insufficient. The body is able to mobilize iron from it’s stores to make up for what it’s not getting from the diet. Once stores become depleted iron deficiency anaemia results. It impairs the transport of oxygen in the blood causing fatigue and a decrease in the ability to perform normal, everyday activities. It also impairs immunity, energy metabolism and can delay cognitive development. If deficiency occurs in children, the cognitive impairment may not be reversible.

Individuals most at risk of iron deficiency are teenage and adult women of childbearing age due to the monthly loss of blood through the menstrual cycle and a low iron diet.

Food Sources of Iron

Iron from our diets comes in several forms. Heme iron and non-heme iron.

Heme iron comes from animal food sources such as beef, pork, lamb, seafood, kangaroo, other game and poultry. The iron in these foods is present as hemoglobin and myoglobin, hence the name ‘heme iron’.

Non-heme iron is the form of iron that comes from all other food sources. Foods such as spinach, dark green leafy vegetables, kidney beans, other legumes and sesame seeds are non-heme sources of iron. Other non-heme sources are foods that have been enriched or fortified with iron such as breakfast cereals and drink bases (Milo, Ovaltine etc). The iron from non-heme sources is what we call less bio-available. This means that due to a variety of different factors, the iron in these foods is not easily absorbed by the body.

For more information about iron and the factors affecting its absorption by the body check out this post: 3 Steps to Decrease Your Risk of Iron Deficiency

How Much Iron Do We Need?

The Recommended Daily Intake (RDI) for Iron is 8mg/day for men and 18mg/day for women of childbearing age. During pregnancy this increases to 27mg/day and falls to 9mg/day during lactation, assuming the woman has not recommenced menstruating. Once menstruation has ceased after menopause iron needs fall to 8mg/day (NHMRC). Due to poor absorption from non-heme iron sources vegetarians would need iron intakes about 80% higher.

Meal and Snack Ideas

  • BBQ Steak served with tomato salsa
  • Seafood served with a drizzle of lemon juice
  • Green leafy salad with lemon juice dressing served with a portion of red meat (beef, lamb, pork, veal or kangaroo)
  • Sprinkle a green leafy salad & tomatoes with sesame seeds, serve with kangaroo sausages (highest source of iron) and a glass of orange juice.
  • Enjoy a iron fortified breakfast cereal (Weetbix) with chopped fruit (strawberries, banana etc).

Too Much of a Good Thing?

Iron is stored by the body and as such it can build up to levels that start to become toxic. An Upper Level has been set of 45mg/day.  Intakes above this level, particularly from supplements and highly fortified foods can cause nausea and vomiting, stomach irritation, diarrhea and impaired absorption of other trace minerals. It is always important to seek health advice before taking any vitamin or mineral supplement.

References:
  • Nutrient Reference Values for Australia and New Zealand, National Health and Medical Research Council
  • Wardlaw’s Perspectives in Nutrition 8th Edition, Byrd-Bredbenner, 2009.
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About Kate Freeman
Kate Freeman is a Registered Nutritionist who is passionate about providing honest, simple nutrition advice and doing it in such a way that inspires and motivates you to make positive lifestyle changes to achieve your health and nutritional goals. She's married with 2 children and live in New South Wales, Australia.

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