The Importance of Iron and Which Foods to Eat

Most of the iron in your body is found in your red blood cells, which plays an important role in transferring oxygen from your lungs to your tissues. When you have insufficient iron stores you may not be able to meet the needs of red blood cell production. This means that red blood cell production will be reduced along with oxygen distribution around your body. We also need iron for healthy immune function and for the production of white blood cells and antibodies.

Iron is necessary for the production of energy from glucose, which is the main fuel for both the brain and the rest of the body. Iron deficiency can lead to anaemia. The groups within the population who are at most risk from iron-deficiency anaemia include those with the highest iron needs: infants, pre-schoolers, adolescents and pregnant women.

Symptoms if Iron Deficiency include (2): 

• Fatigue and a reduced training capacity
• Pale skin and inner eyelids, mouth
• Decreased cognitive (brain) function and motor performance
• Reduced temperature regulation/always feels cold
• Decreased immune function/unresolved infections
• Poor appetite
• Symptoms can be confused with overtraining

Individuals most at risk of iron deficiency include (1):

• Individuals with high iron requirements; such as high growth periods (ie adolescents)
• Individuals with increased losses of urine (sweating), menstrual
• Engaged in prolonged strenuous exercise
• Individuals with a Low energy intake or an imbalanced diet (<1200kcal/day)
• A low intake of iron rich foods (e.g. meat) especially for Vegans/vegetarians
• A Copper deficiency
• Individuals who take calcium supplements (as it inhibits iron absorption)

Daily Requirements

• For Men the RDI is 8mg/day
• For Women aged 19-50 the RDI is 18mg/day
• For women aged 51+ the RDI is 8mg/day

Dietary Sources of Iron

Iron is present in Ferric or Ferrous states, the latter being more soluble.  Dietary content, bioavailability, storage iron levels and the rate of red blood cell production influence the absorption of iron.

There are two different types of Iron found in foods

• Haem iron: is derived mainly from haemoglobin and myoglobin found in animal foods, such as meat, fish and poultry. Unlike non-haem iron, haem iron is well absorbed under all conditions, and meal composition does not affect the amount absorbed.
• Non-haem iron: is supplied by plant foods and milk, cheese and eggs. Non-haem iron consists mainly of iron salts, which are bound to foods, and therefore must be hydrolysed or solubilised prior to absorption. Gastric acid is essential for solubilizing the non-haem iron. This, along with enhancers or inhibitors of non-haem iron, such as vitamin C, calcium and phytates outlined below, all determine the extent of absorption of Non-haem iron.

Wholegrain cereals, meats, fish and poultry are the major contributors to iron intake in Australia and New Zealand, but the haem form is more bioavailable to humans than the non-haem form of iron.

Factors that can affect Iron Absorption

• The presence of other nutrients such as vitamin C and organic acids such as citric, lactic or malic acid can increase the absorption of non-haem iron.
• Consumption of meat, fish and poultry can also increase non-haem iron absorption from plant foods consumed at the same time.
• Calcium and can inhibit the absorption of both haem and non-haem iron
• High iron intakes can, in turn, affect the absorption of other nutrients such as zinc or calcium.
• Oxalates impair the absorption of nonheme iron. Oxalates are found in foods such as spinach, kale, beets, nuts, chocolate, tea, wheat bran, rhubarb, strawberries and herbs such as oregano, basil, and parsley. The presence of oxalates in spinach explains why the iron in spinach is not absorbed.
• Polyphenols are major inhibitors of non-haem iron absorption. These are found in apples, peppermint and some herbal teas, and tannins found in black teas, coffee, cocoa, spices, walnuts, fruits such as apples, blackberries, raspberries and blueberries all have the ability to inhibit iron absorption. Swedish cocoa and certain teas demonstrate the most powerful iron absorption inhibiting capabilities, in some cases up to 90%.
• Coffee is high in tannin and chlorogenic acid; one cup of certain types of coffee can inhibit iron absorption by as much as 60%.   These foods or substance should not be consumed within two hours prior to and following your main iron-rich meal
• Phytate is a compound contained in soy protein and fiber and can inhibit non-haem Iron. Even low levels of phytate (about 5 percent of the amounts in cereal whole flours) have a strong inhibitory effect on iron bioavailability. Phytate is found in walnuts, almonds, sesame, dried beans, lentils and peas, and cereals and whole grains. Phytate compounds can reduce iron absorption by 50 to 65 percent.

Tips for increasing Iron

• Iron is best absorbed from animal sources. Eat more lean red meat. Chicken, fish and eggs.
• Beef protein increases iron absorption up to 80% better than chicken protein
• If you are low in iron, when you eat meals containing non haem iron, avoid including ingredients high in phytates, oxalates and polyphenols as outlined above, which may reduce the iron absorption.
• If you are a vegetarian eat more wholegrains and cereals including wheat germ, legumes, nuts and seeds
• Add LSA mix to your breakfast cereal or yoghurt
• Iron fortified products are available such as breads and cereals
• Adding foods rich in Vitamin C to a meal can increase iron absorption. Try drinking orange juice with baked beans and eggs on toast, or adding fruit such as Kiwi fruit to breakfast cereal
• Avoid drinking coffee or tea within an hour before or after an iron rich meals as they contain polyphenols and oxalates which can inhibit iron absorption
• Calcium is the only known substance to inhibit absorption of both non-haem and haem iron. It is found in foods such as milk, yogurt, cheese, sardines, canned salmon, tofu, broccoli, almonds, figs, turnip greens and rhubarb. Try and reduce these ingredients in iron rich animal meat meals in particular.
• Zinc and magnesium supplements may inhibit the absorption of Iron, so try and get your nutrients from food, not supplements.

Treatment

Treatment includes dietary changes and/or iron therapy if anaemia exists and your health care practitioner recommends this approach (supplements or Iron injection) (2).

Foods high in Iron

 

References

1. Sinclair, Lisa M., and Pamela Sue Hinton. “Prevalence of iron deficiency with and without anemia in recreationally active men and women.” Journal of the American Dietetic Association6 (2005): 975-978.
2. World Health Organization. “Iron deficiency anaemia: assessment, prevention and control: a guide for programme managers.” (2001).