What Is Iron?
Iron is a mineral essential for making haemoglobin, the protein in red blood cells that carries oxygen around the body. It’s one of the most common nutrient deficiencies worldwide, and iron-deficiency anaemia is the most common form of anaemia in the UK — particularly among women of reproductive age.
There are two dietary forms: haem iron (from animal sources, well absorbed) and non-haem iron (from plant sources, less well absorbed but still useful, especially combined with vitamin C).
Why Your Body Needs It
EFSA-authorised health claims for iron include:
- Contributes to the reduction of tiredness and fatigue
- Contributes to normal cognitive function
- Contributes to normal formation of red blood cells and haemoglobin
- Contributes to normal oxygen transport in the body
- Contributes to normal energy-yielding metabolism
- Contributes to normal function of the immune system
- Has a role in the process of cell division
Signs of Iron Deficiency
Iron deficiency develops in stages — reduced stores first, then reduced red blood cell production, and eventually iron-deficiency anaemia if unaddressed. Common signs include:
- Persistent tiredness and low energy
- Pale skin, especially inside the lower eyelid
- Shortness of breath during normal activity
- Heart palpitations
- Headaches and dizziness
- Brittle nails, hair thinning
- Restless legs
- Unusual cravings for non-food items (a specific sign called pica, though uncommon)
Because these overlap heavily with B12 and general fatigue, a GP blood test (ferritin, full blood count) is the only reliable way to confirm iron deficiency rather than assuming from symptoms alone.
Who’s Most at Risk
- Women with heavy periods — the single most common cause of iron deficiency in the UK
- Pregnant women — iron requirements roughly double during pregnancy
- Vegetarians and vegans — non-haem iron from plants is less bioavailable than haem iron from meat
- Endurance athletes — increased red blood cell turnover and iron loss through sweat and foot-strike haemolysis
- People with gastrointestinal conditions — coeliac disease, IBD, or previous bariatric surgery affecting absorption
- Frequent blood donors
Food Sources
- Red meat, particularly liver — the richest source of well-absorbed haem iron
- Poultry and fish
- Beans, lentils, and chickpeas
- Fortified breakfast cereals
- Dark leafy greens (spinach, kale) — non-haem iron, absorption improved when eaten with vitamin C-rich foods
Tip: Tea and coffee consumed close to meals can significantly reduce non-haem iron absorption — worth spacing out if you’re relying on plant sources.
Choosing an Iron Supplement
- Bisglycinate (gentle iron) forms are generally better tolerated with less constipation than standard ferrous sulfate
- Pair with vitamin C to improve absorption
- Don’t supplement iron without a confirmed deficiency — iron overload is a real risk, particularly for people with the genetic condition haemochromatosis, and unnecessary supplementation isn’t harmless
Our pick: Solgar Gentle Iron Bisglycinate — a well-tolerated form suited to people who find standard iron supplements upset their stomach.
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This page is for general educational purposes only and is not medical advice. Persistent fatigue, breathlessness, or palpitations should be checked by a GP with a blood test before starting iron supplementation — taking iron without a confirmed deficiency can cause harm.
Sources & Further Reading
- NHS — Iron deficiency anaemia
- NIH Office of Dietary Supplements — Iron Fact Sheet
- EFSA — Health claims on iron
- Linus Pauling Institute — Iron Micronutrient Information
- Examine.com — Iron
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