Iron is an essential trace mineral in our diet. This means it’s necessary (essential) to get it from a food source because our bodies can’t produce it, but is only needed in small (trace) amounts.
Iron is found in a range of plant and animal food products, but despite this, one in four Australian women have inadequate iron intakes (compared to one in thirty men). Men require around 8 mg/day to achieve their Recommended Daily Intake (RDI). The RDI for women aged 31-50 years is ~18mg/day. Pregnant women require more (~27 mg/day) and vegetarian women require ~32mg/day.
This blog post will explore why iron is important for health, and what food sources can provide it.
Why do we need iron?
Iron plays an essential role in transporting oxygen around the body. Iron is at the centre of haemoproteins such as haemoglobin in red blood cells and myoglobin in muscles. Oxygen is transported by binding to this iron. Iron is also needed for our cells to generate energy. Not enough iron means not enough oxygen, and without enough oxygen, our body cannot function as it should.
Iron also functions as part of a wide range of enzymes, which are proteins that act as catalysts for our body’s metabolic activities. Inadequate iron can impact our body’s ability to metabolise vitamin A and amino acids (the building blocks of proteins), and synthesise other products the body needs for immunity, growth and other aspects of health.
What happens when we don’t consume enough iron?
The body is very good at preserving its iron stores. Iron is mostly lost through bleeding, which is why women of menstruating age require more iron than other groups. Some iron is also lost through shedding skin, body cells, and hair. When we’re consistently using or losing more iron than we’re consuming, we may be at risk of iron deficiency.
Symptoms of iron deficiency include:
- reduced physical work capacity
- lowered cognitive function
- impaired immunity
- shortness of breath
- impaired heat regulation
- heart palpitations
As previously mentioned, women (especially vegans/vegetarians and pregnant women) are likely to have an increased requirement for iron. Other groups who may be at increased risk of iron deficiency include infants, children and adolescents (because they’re growing!), elite athletes, the elderly, and people with gastrointestinal diseases or conditions such as coeliac disease and cystic fibrosis.
How is iron deficiency diagnosed?
The three stages of iron deficiency can only be diagnosed through a blood test. Even if you have the clinical symptoms of iron deficiency and your diet appears low in iron, this is not enough to form a diagnosis. If you think you may be at risk of iron deficiency, speak with your doctor or dietitian to organise a blood test. Do not self medicate with iron supplements, as this can be harmful to your health.
Why do vegetarians need to consume more iron?
Did you know there are two types of dietary iron? They are called haem and non-haem iron. Haem iron is found in meat products. Non-haem iron is found in eggs, dairy, and plants.
They’re slightly different from a biochemical standpoint, but this difference affects how they are absorbed in our digestive tract. Haem iron is readily absorbed (~25% of ingested haem iron is absorbed), whereas non-haem iron has to be converted before it can be taken up by the body. While our bodies are working to convert non-haem iron, other compounds can interfere. These compounds bind to the non-haem iron and render it insoluble, so our bodies cannot absorb it. This results in a lowered level of absorption – estimates suggest up to ~8% of ingested non-haem iron is absorbed.
Because of this, it is suggested that vegans and vegetarians require substantially more iron in their daily diet, to compensate for the absorption interference.
What foods are good sources of iron?
Red meat is the richest, most bioavailable source of iron. Liver (10mg/100g), mussels and oysters (6-8mg/100g) provide the biggest iron hit. Red meats provide around 3-5mg/100g, and white meats will give you 1-2mg/100g. Remember, these sources are more readily absorbed so if you’re eating 2-3 serves a week, you’re doing well as far as dietary iron goes.
But what about those who avoid meat and seafood? Here’s a few ideas to get more iron into your diet. Measurements are mg iron per 100g of the food product.
- Wheat bran: 13mg/100g
- Muesli: 11mg/100g
- Cocoa powder: 11mg/100g (that’s about a cup of cocoa powder!)
- Iron-fortified* breakfast cereals: 4-9mg/100g
- Dried fruit: 4-7mg/100g (especially apricots)
- Spinach: 4mg/100g
- Legumes, tofu and beans: 3mg/100g
- Nuts: 2-5mg/100g
- Wholemeal/white bread: 3mg/100g, 2mg/100g
- Egg: 2mg/100g
Fun fact: curry powder contains a whopping 58mg/100g iron! Not that anyone in their right mind would be regularly chowing down on that much curry powder.
How can you boost your iron absorption?
Iron absorption is enhanced by vitamin C, simple sugars, and food acids such as citric acid. If you want to boost your body’s ability to absorb iron, try consuming your iron-rich food alongside a source of one of these options.
Iron absorption can be reduced by a variety of compounds including some polyphenols found in tea and coffee. Having your tea or coffee separately to your iron-rich meal can be a simple and effective way of increasing your iron absorbing ability.
If you’re needing to increase your iron or calcium intake, consider consuming calcium-rich and iron-rich foods separately, as they can interfere with each other’s absorption. For example, have a tub of yoghurt for a morning snack and a handful of nuts for an afternoon snack.
Meal ideas for vegetarians
Not sure how to incorporate more iron into your diet? Here’s a few ideas to get you started.
This information is general in nature and does not replace the individualised advice of your doctor or dietitian.
- Australian Health Survey Media Release, 6 March 2015
- Gropper, S., & Smith, J. (2013). Advanced nutrition and human metabolism (6th Edition ed.).
- NHMRC – Nutrient Reference Values: Iron
- NHMRC – Australian Dietary Guidelines
- Nutrition Australia – Iron
- QLD Health – Nutrition Education Materials Online. (2015). Iron for pregnant women.
- Reid, M., Marsh, K., Zeuschner, C., Saunders, A., & Baines, S. (2012). Meeting the nutrient reference values on a vegetarian diet.
- Saunders, A., Craig, W., Baines, S., & Posen, J. (2012). Iron and vegetarian diets.
- Cereal: Ryan Pouncy on Unsplash
- Egg sandwich: Joseph Gonzalez on Unsplash
- Salad: Isidor Emanuel on Unsplash
- Woman running: Francesco Gallarotti on Unsplash
- All other photos are my own.