Iron
Only supplement if you've tested low. Iron is essential, but supplementing without need causes oxidative stress and GI misery.
Treating iron-deficiency anemia is one of the most consistently effective interventions in medicine. Fatigue, hair loss, restless legs, exercise tolerance all respond dramatically. Energy effects within 2–4 weeks; hemoglobin normalisation 6–12 weeks; ferritin restoration 3–6 months.
Iron is the oxygen-carrier — it's at the centre of hemoglobin in red blood cells and myoglobin in muscle. Deficiency causes fatigue, brain fog, hair shedding, exercise intolerance, restless legs, pica, and the classic 'low energy that nothing fixes' picture. Menstruating women, pregnant women, frequent blood donors, distance runners, and vegetarians/vegans are the highest-risk groups. The flip side: too much iron is genuinely dangerous (oxidative tissue damage, cardiovascular risk, accumulates in liver/heart) — so iron is the one supplement where 'test, don't guess' really matters.
- Form
- Iron bisglycinate (chelated, far gentler on the stomach than traditional forms — same absorption). Heme iron (from animal sources — best absorbed, no GI side effects). Lactoferrin-bound iron (well tolerated). Ferrous sulfate is the cheap standard but causes nausea, constipation, and dark stools in many people. Avoid 'iron polypeptide' marketing terms without specifics.
- Dose
- Only if low on labs. 18–25 mg elemental iron daily for mild deficiency. 65 mg every other day (newer evidence shows alternate-day dosing absorbs better than daily). For severe anemia, prescription-level dosing or IV iron under a doctor.
- Timing
- On an empty stomach with vitamin C (doubles absorption). Far from calcium, coffee, tea, dairy (all reduce absorption). PM is common to avoid daytime GI issues.
- Schedule
- Alternate-day dosing (Mon/Wed/Fri) is now recommended — better absorption than daily, fewer side effects. Re-test at 8–12 weeks. Stop or reduce when ferritin reaches target.
- Side effects
- Constipation, dark or black stools (normal — not GI bleeding), nausea, stomach pain, metallic taste. Bisglycinate causes the least of these. Alternate-day dosing reduces them further.
- Interactions
- Reduces absorption of levothyroxine, tetracyclines, fluoroquinolones, bisphosphonates, levodopa — separate by 4 hours. Calcium, coffee, tea, and dairy reduce iron absorption (separate by 2 hours).
- Contraindications
- Hemochromatosis (genetic iron overload — affects ~1 in 200 of Northern European descent) — supplementing iron is dangerous. Thalassemia, sideroblastic anemia, anemia of chronic disease — these are not iron-deficiency anemias and don't respond to iron. Active infection (iron feeds bacterial growth). Always test ferritin first.
- Lab markers
- Ferritin — the storage marker, the most useful single test. Target ranges debated: above 30 ng/mL is mainstream-normal but symptom-relief often requires 50–100. Above 50 is suboptimal-floor for active women. Hemoglobin (the late marker — drops only when storage is empty). Iron + TIBC + transferrin saturation for full panel. Note ferritin is also an inflammatory marker — high ferritin doesn't always mean iron overload.
- Food sources
- Heme iron (best absorbed): red meat, liver, oysters, mussels, sardines, dark poultry meat. Non-heme iron: lentils, beans, tofu, pumpkin seeds, spinach, fortified cereals. Always pair non-heme sources with vitamin C (pepper, citrus, tomato) and away from coffee/tea.
Pairs with
Vitamin C with each dose — doubles absorption of non-heme iron. Lactoferrin (synergistic iron carrier). Vitamin A and copper (cofactors for iron metabolism).
within Minerals