Iron (Fe): what it does, how it is absorbed and why you shouldn't self-treat
Let's start with the theory: iron's functions, its types, what helps and hinders absorption, which tests to take — and why an iron excess is dangerous.
⚡ In short
- Iron carries oxygen and is part of many enzymes; in its free form it is toxic.
- Heme iron (meat, liver, fish) absorbs far better than non-heme (plants).
- Caffeine, calcium and inflammation hinder absorption; organic acids and beta-carotene help.
- Diagnosis needs at least 4 blood markers. Excess iron is dangerous — no supplements without a deficiency and a doctor.
Iron performs many important functions in the body. First of all it carries oxygen from the lungs to the tissues, and it is also a component of certain proteins and enzymes. About 70% of the body's iron is in haemoglobin and myoglobin. Yet free iron is toxic to the body — which is why balance is critical.
Why the body needs iron
- Involved in nerve myelination, forming connections between nerve cells (dendritogenesis) and producing neurotransmitters
- Has a direct effect on brain function and mental well-being; important for thinking and mental clarity
- In teenagers and children a deficiency raises the risk of mental disorders: mood swings, autism-spectrum disorders, ADHD
- A deficiency during pregnancy can cause neurological symptoms in the child; adequate levels in the foetus affect brain development for life
- Both a deficiency and an excess of iron can significantly lower the immune response
How iron is absorbed
Absorption is regulated by iron stores: with an excess it decreases, with a deficiency it increases. Over time, disturbances in iron metabolism gradually deplete the storage proteins and lead to various forms of anaemia.
Types of iron: heme and non-heme
- Heme — only in animal products (liver, red meat, poultry, fish). Absorbs far better and is present in high concentration
- Non-heme — in vegetables, fruit, dried beans, grains and nuts
- Red meat is the key source of iron: it is rich in heme iron with high bioavailability
What improves iron absorption
- Organic acids: malic, citric and lactic (for example, in sauerkraut)
- Beta-carotene: carrots (≈7 mg/100 g), as well as kale, spinach and chard
- Eating onion or garlic
What hinders iron absorption
- Duodenal dysfunction (this is exactly where iron is absorbed)
- Obesity (subclinical inflammation)
- High ferritin or hepcidin levels (rise with inflammation)
- Caffeine: tea, coffee, energy drinks
- Calcium-rich foods: cheese, milk, cottage cheese, etc.
- Medications: broad-spectrum antibiotics, antacids, bisphosphonates, neomycins
- Exercise helps spend and excrete iron faster
Practical tip
- ✓For an hour before and after iron-rich food, avoid the items listed above
- ✓Don't mix iron with them in one dish (for example «meat French-style»: cheese + meat)
- ✓Remove or treat the possible cause of iron-deficiency anaemia
Diagnosis: which tests to take
Serum total iron depends heavily on the time of day and other factors, so it is not suitable for diagnosis: it is usually low at night and high in the daytime, and it rises after an iron-rich meal. At least four markers should be assessed:
- 1Haemoglobin (Hb)
- 2Transferrin saturation (the iron transporter)
- 3Ferritin (iron stores)
- 4C-reactive protein (CRP, an inflammation marker)
Important: no self-treatment
- ✓Iron is toxic in itself — do not take supplements without a confirmed deficiency and a doctor's advice
- ✓An iron excess leads to hypothyroidism, infertility, arthritis and accelerates Alzheimer's disease
This material is for educational purposes and does not replace a medical consultation. Discuss iron supplements and any dietary changes with a specialist based on your test results.
