mineral · for chronic fatigue
Iron
Iron carries oxygen round your body. Low iron is the most common fixable cause of tiredness.
Say that in clinical terms
Iron is essential for hemoglobin (oxygen transport) and myoglobin (muscle oxygen storage). It is also a cofactor in mitochondrial cytochrome enzymes for ATP production. Iron deficiency is the most common cause of correctable fatigue worldwide.
How strong is the research?
2 papers read, 2 supporting.
Tested as: Iron (Ferrous Sulfate)
Who was studied: Women who were tired but not anaemic, with iron stores at the low end, from GP practices.
How much to take
daily on empty stomach or with vitamin C
18–36 mg
MUST test ferritin levels before supplementing. Take on empty stomach or with vitamin C. Avoid with calcium, tea, or coffee. Target ferritin >50 ng/mL.
Before you take it
- NIH ODS Tolerable Upper Intake Level (UL) for iron is 45 mg/day for adults (all sources combined: food and supplements).
- Levothyroxine interaction: concurrent ingestion significantly reduces levothyroxine efficacy; separate iron and levothyroxine by at least 4 hours.
- Tetracycline and fluoroquinolone antibiotic interaction is asymmetric: take the antibiotic at least 2 hours BEFORE iron, or at least 4–6 hours AFTER iron — not a simple equal-interval separation.
- Levodopa interaction: iron may reduce levodopa absorption via chelation; separate administration times (specific interval not fixed in NIH ODS guidance).
- Proton pump inhibitors (e.g., omeprazole, lansoprazole) reduce gastric acid and may impair non-heme iron absorption, potentially reducing efficacy of oral iron supplementation.
- Hereditary hemochromatosis (HFE gene mutation): iron supplementation is contraindicated; risk of iron overload, organ damage.
- GI side effects (constipation, nausea, abdominal discomfort) are common with oral iron; iron bisglycinate is better tolerated than ferrous sulfate in comparative trials but is not side-effect-free.
- Accidental ingestion by children can be fatal; child-resistant storage is essential.
- Iron supplementation without confirmed deficiency (serum ferritin or CBC) has no established benefit for symptom relief and risks cumulative toxicity approaching or exceeding the 45 mg/day UL when combined with dietary iron.
When to take it
Best taken: empty stomach
What we make of it
A real trial in 198 women, though it used ferrous sulfate rather than bisglycinate.
The detail
The study is a single randomised trial of 198 women, not the pooled analysis we labelled it. It used ferrous sulfate at 50 mg elemental iron, which is a different form from the one this claim names.