The importance of iron
World Iron Awareness week is 27th of August - 2nd of September, so it's a good time to take a look at your eating habits with regard to this important mineral.
One of the main biological functions of iron is to enable the transport of oxygen, via our bloodstream, to all the tissues in our body. Each red blood cell contains around 280 million specialised molecules called haemoglobin, and each haemoglobin molecule contains four iron ions (ferrous iron, an iron atom that has lost two electrons). That's a lot of iron - around 50mg of iron per kilogram of body weight, or between 3-4 grams of iron per person!
That's not all iron does though. Due to it's ability to gain and lose electrons, iron is a co-factor in enzymes involved in many chemical reactions in the body, and is an integral part of an important chain reaction in energy metabolism. Iron is also is required for a healthy immune system.
Iron is so important our body has a way of storing it for times of need, so these biological processes can continue as required. The main stores of iron in the body are found in the liver, spleen and bone marrow. In times of dietary insufficiency and/or increased requirements, these stores are called upon. When iron requirements continue to outstrip iron in the diet, these stores can become depleted. If this situation continues, the rate of red blood cell production slows, along with a decrease in iron levels in the blood. The third stage, or iron-deficiency anaemia, is characterised by a fall in haemoglobin levels and a further decrease in iron levels in the blood.
"Iron deficiency is the most frequently encountered nutritional deficiency in man."
MacPhail, A.P. (2012). Essentials of Human Nutrition (4th ed.).
As you can imagine, you'll feel pretty terrible should it get that serious. Common symptoms include fatigue, pale skin, feeling cold all the time, reduced cognitive ability, hair loss, dizziness, spoon-shaped nails, and mouth ulcers. In adults, these symptoms can be relieved by a combination of dietary and supplemental measures, however, in the case of children it can be far more serious, and lead to irreversible consequences. After the first 6 months of life (babies are born with sufficient iron stores to last this long), adequate iron intake is crucial due to the rate of babies' growth. Iron is particularly important for brain development, and the introduction of iron-fortified cereals, along with a variety of iron-rich foods, is recommended to meet this need.
According to the latest statistics, the iron status of many New Zealanders is cause for concern. Over a third of females aged 15-18 years have an inadequate iron intake, as do 15% of women aged 31-50. The figures are worse still for Maori and Pasifika.
So how do you ensure you are getting enough iron?
Include a variety of iron-rich foods in your diet. Iron comes in two forms: heme (from animal sources) and non-heme (mostly from plant sources, and in fortified foods). Heme iron is readily absorbed, whereas non-heme iron is not, so a vegetarian diet requires a bit more planning and a couple of iron-boosting tips:
Sources of heme iron: meat (especially liver), fish and shellfish, poultry, cheese, eggs, cow's milk.
Sources of non-heme iron: wholegrain cereals and breads, fortified cereals, tofu, spinach, broccoli, carrots, potatoes, mango, apples, bananas, peaches, strawberries, sunflower seeds, legumes.
Iron-boosting tips: consuming foods high in vitamin C at the same time as non-heme iron foods will boost the absorption of this form of iron. Examples include red capsicum in a salad, or a piece of fruit with your wholegrain breakfast cereal or with a main meal. Avoid drinking tea with your meal, and wait at least an hour after eating, as compounds found in tea inhibit iron absorption.
For those of you just following a more plant-based diet, including a little meat in your meal will enhance iron absorption from non-heme sources too.
Beef + Lamb. (2018). World Iron Awareness Week. [Website]. Retrieved August 25, 2018, from https://www.ironweek.co.nz
MacPhail, A.P. (2012). Iron. In Mann & Truswell (Eds.). Essentials of human nutrition (4th ed., 267-286). Oxford, UK: Oxford University Press.
National Health and Medical Research Council & Ministry of Health. (2006). Nutrient reference values for Australia and New Zealand: Including recommended dietary intakes. Retrieved from https://www.nhmrc.gov.au/guidelines-publications/n35-n36-n37
New Zealand Nutrition Foundation. (2018). Infants and toddlers. [Website]. Retrieved August 25, 2018, from https://nutritionfoundation.org.nz/healthy-eating/Infants-and-Toddlers
New Zealand Nutrition Foundation. (2018). Iron. [Website]. Retrieved August 25, 2018, from https://nutritionfoundation.org.nz/nutrition-facts/minerals/iron
University of Otago and Ministry of Health. (2011). A Focus on Nutrition: Key findings of the 2008/09 New Zealand Adult Nutrition Survey. Wellington: Ministry of Health.