Iron (Serum Iron, TIBC & Transferrin Saturation)

Optimal ranges

What is the optimal range for Iron?

The clinical range defines what is considered medically “normal” — broad enough to cover 95% of the population. The performance range reflects where research and clinical experience suggest most people feel and function at their best. A result in either range suggests typical status and is not a diagnosis; any individual reading should be interpreted by a qualified clinician.

Why it matters

Why Iron matters for performance

Iron deficiency is the most common nutritional deficiency in the UK, affecting an estimated 3% of men and up to 25% of women of reproductive age according to the NHS. For active people, iron demands are significantly higher — endurance training, heavy sweating, and even foot-strike haemolysis from running can deplete iron stores faster than diet replaces them. Low iron doesn't just mean anaemia: even subclinical deficiency impairs oxygen delivery to muscles, slows recovery, and causes persistent fatigue and brain fog that many people attribute to stress or poor sleep. A full iron panel catches problems that a standalone ferritin test can miss, such as iron-loading disorders or poor absorption despite adequate intake.

Symptoms

What are the symptoms of low or high Iron?

Dietary sources

Which foods support Iron levels?

Supplementation

How do you improve Iron levels?

Iron bisglycinate is the gold standard supplemental form — absorbed 2-4x better than ferrous sulphate with far fewer gut side effects. Typical dose: 15-25 mg elemental iron daily when deficiency is confirmed by blood testing. Always take with 200 mg vitamin C (or alongside vitamin C-rich foods like citrus or peppers) to boost absorption by up to 67%. Avoid taking iron within 2 hours of calcium supplements, tea, coffee, or dairy, as these inhibit absorption. Never supplement iron without testing first — excess iron is toxic and cannot be easily excreted. The hereditary condition haemochromatosis (affecting ~1 in 200 people of Northern European descent) causes dangerous iron overload. Retest after 90 days to confirm response and adjust dosing.

Testing

How is Iron tested in the UK?

Iron is measured from a blood sample. With Helvy, that means a finger-prick kit taken at home and posted to a UKAS-accredited UK laboratory, with results in around 5 days, reviewed by a qualified clinician. Your result is reported against both the clinical range (10-30 µmol/L (serum iron)) and the performance-optimal range (15-25 µmol/L (serum iron), 20-45% transferrin sat.), so you can see not just whether you are “normal” but whether you are optimal. If you make a change, retest after 8-12 weeks to confirm it worked.

Research

Key study