Iron is one of those important minerals your body simply can't function without. It's central to how oxygen moves around your body, how you produce energy, and how well your immune system works. Here's what iron does, where to find it, how to choose the best iron supplement for you, and when it's worth speaking to your GP.
Why do you need iron?
Iron's most important job is helping your body produce haemoglobin, the protein in red blood cells that carries oxygen from your lungs to the rest of your body. This is central to why iron is so strongly associated with energy: it contributes to normal oxygen transport, and to the normal formation of red blood cells and haemoglobin.
Iron has a genuinely broad range of authorised roles in the body:
- It contributes to normal oxygen transport in the body
- It contributes to the normal formation of red blood cells and haemoglobin
- It contributes to normal energy-yielding metabolism
- It contributes to the reduction of tiredness and fatigue
- It contributes to normal cognitive function
- It contributes to the normal function of the immune system
- It has a role in the process of cell division
Iron also contributes to normal cognitive development in children, which is one reason it's given particular attention in childhood and during pregnancy.
What are the signs you might need more iron?
The sign most people associate with low iron is persistent tiredness – a lack of energy that doesn't lift with rest. Others can include shortness of breath, noticeable heartbeats, and a pale complexion.
The important thing to understand is that these are all non-specific symptoms with any number of possible causes – so the only reliable way to know whether iron is behind them is a blood test arranged by your doctor. Low iron can happen for lots of reasons: not getting enough through diet, heavy periods, pregnancy, ongoing blood loss, or vigorous exercise. If any of that sounds familiar, speak to your doctor before starting a supplement, rather than assuming iron is the answer.
What are the best sources of iron?
Dietary iron comes in two forms. Haem iron is found in animal products and is absorbed more readily by the body. Non-haem iron comes from plants and is absorbed less efficiently, which is why anyone following a vegetarian or vegan diet needs to pay closer attention to their iron intake.
You'll find good amounts of iron in red meat and liver (though liver should be avoided during pregnancy). Shellfish is an excellent source, particularly clams, mussels and oysters. If you're vegetarian, look to beans and pulses like red kidney beans, chickpeas and edamame, and dark green leafy vegetables like curly kale and watercress, as well as nuts and fortified cereals.
Dried fruit can also be surprisingly rich in iron – dried apricots contain almost seven times more iron than fresh, and prunes are another particularly good source.
How much iron do I need?
The NHS recommends 8.7mg of iron a day for men aged 19 and over and women aged 50 and over, and 14.8mg a day for women aged 19 to 49. Women who continue to have periods after 50 may need the higher amount.
Who might need an iron supplement?
The Department of Health and Social Care advises that most people should be able to get all the iron they need from a varied and balanced diet. But certain groups find that harder:
- Women with heavy periods are at higher risk of low iron, which is why iron supplements for women are so widely used.
- During pregnancy, iron requirements rise considerably. Prenatal vitamins with iron are formulated with this in mind, but always speak to your midwife or GP before taking iron in pregnancy.
- Vegetarians and vegans absorb less iron from plant sources, so may need to be more deliberate about their intake.
- People with coeliac disease, Crohn's disease, or who've had gastric surgery may find it harder to absorb iron, and should ask their GP or pharmacist for advice.
If you do take iron, it's important not to take more than you need. The NHS advises that 17mg or less a day is unlikely to cause harm, though your GP may recommend a higher dose for you specifically. And this one really matters: always keep iron supplements well away from children, as high doses can be genuinely dangerous to them.
Which iron supplement is best for me?
The best iron supplement is usually simply the one you can take comfortably and consistently. Our range includes:
- Iron tablets – premium quality tablets, including gentle formulations designed to be easier on the stomach
- Capsules – including comprehensive formulas that combine iron with vitamin C and folate to support absorption
- Liquid iron – an easy-to-take option, including liquid iron gluconate, suitable from age two and often chosen during pregnancy and after birth
- Sachets – liquid iron sachets, convenient for taking on the go
- Oral sprays – a simple alternative if you'd rather not swallow a tablet
- Chewable tablets – a gentler format, particularly for children
If you've found traditional iron tablets difficult to tolerate, gentle iron formulations use forms of iron that are highly absorbable and less likely to cause digestive upset.
Whichever you choose, iron is best absorbed on an empty stomach, and taking it with a glass of orange juice will help your body absorb more of it – vitamin C is iron's great ally here. It's best to avoid tea, coffee and dairy around the same time, as these all make iron harder to absorb.
What are the common side effects of taking iron supplements?
It's worth knowing that iron supplements commonly cause constipation, stomach pain, nausea or diarrhoea, and can turn your stools dark green or black. That last one can be alarming the first time, but it's completely normal and harmless.
Explore further
This piece from our Discover blog picks up where this article leaves off:
- Supplements for energy support, explained – how iron and other nutrients fit into supporting normal energy levels.
Explore our range of iron supplements to support normal energy release and the reduction of tiredness and fatigue.