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Iron, ferritin and your cycle, explained.
Short, plain answers to the questions people ask most about iron. Each one is drawn from The Iron Guide, with its sources listed.
24 answers and tools
Tools
- ToolsPeriod iron calculator: how much iron did you lose?Enter your flow day by day and see an estimate of the blood and iron your period cost, and how long food takes to put it back.
- ToolsFerritin and iron lab unit converterConvert ferritin, haemoglobin, serum iron, vitamin D, B12 and folate between the units labs use: µg/L, ng/mL, g/dL, µmol/L, nmol/L and more.
Your numbers
What your blood test says, and how far to trust it.
- Ferritin levels in women: normal vs optimalA ferritin inside your lab's range can still mean low iron stores. What ferritin measures, the usual lab range, the 50–80 µg/L goal and when to see a doctor.
- Low ferritin with normal haemoglobin: what it meansYour haemoglobin is fine but your ferritin is low. Why that is iron deficiency without anaemia, why it can still make you tired, and what to do next.
- Transferrin saturation: what your result meansTransferrin saturation is the share of iron carriers in your blood that are full. What a low or high result means, the 30–45% goal, and how to test it.
- Ferritin vs serum iron: what is the difference?Serum iron is the iron in your blood today. Ferritin is your stored iron. Why the two can disagree, which one to track, and what the guide aims for.
- Iron blood test: how to prepare and what to ask forPrepare for an iron blood test so the result is real: morning, fasting, supplement-free, not ill. Plus the full panel to ask for and the order to read it in.
- Why inflammation raises ferritin, and hides low ironFerritin rises with infection and inflammation, so a normal or high result can sit on top of empty stores. How hepcidin works and how to read ferritin with CRP.
Signs
What low iron can feel like, from tiredness to hair.
- Low iron symptoms in women: 10 signs to write downTiredness, brain fog, cold hands, hair shedding and more. Ten common signs of low iron in women, why they happen, and why a blood test comes next.
- Low ferritin and hair loss: what helpsLow ferritin is often found in women with hair shedding. The ferritin many specialists aim for, how long regrowth takes, and when to see a dermatologist.
Periods
What every period costs, and when it is too much.
- How much iron do you lose on your period?A typical period costs about 15 to 20 mg of iron, a heavy one 40 mg or more. Work out your own, see what counts as heavy, and how food compares.
- Heavy periods and low iron: breaking the loopLow iron can make periods heavier, and heavier periods drain more iron. How the loop works, when to see a doctor, and how to rebuild iron alongside treatment.
Food
What to eat, what to pair it with and what to keep apart.
- Iron-rich foods: what a real portion gives youIron per real portion, from mussels and liver to lentils and spinach. Which iron gets in easily, which needs help, and the myths worth dropping.
- Heme vs non-heme iron: why one gets in easilyHeme iron from meat and fish is absorbed easily. Non-heme iron from plants needs help. How the two differ, and how to get more from plant iron.
- Vitamin C and iron: how to pair themVitamin C turns plant iron into a form your gut can absorb. Which foods to use, why it must be in the same meal, and why cooking matters.
- Does coffee block iron absorption?Coffee can sharply cut the iron you absorb from a meal. How long to wait, why it barely affects meat iron, and how to keep your morning cup.
- Tea, matcha and iron: how long to waitBlack and green tea and matcha block plant iron. How long to wait around meals and supplements, which herbal teas are fine, and the afternoon tea habit.
- Calcium and iron: why they need separate mealsCalcium blocks both plant and meat iron. Which foods count as calcium, how many hours to keep them apart, and why butter is fine.
- Iron for vegetarians and vegans: how to get enoughVegetarians need about 1.8 times more iron. The richest plant foods, how to pair them so more gets in, and when food alone is not enough.
Supplements
How iron is taken well. Your dose comes from your doctor.
- Iron every other day: why alternate days can work betterEach iron dose raises hepcidin for about a day, which blocks the next one. What studies found about alternate-day iron, and how period week fits in.
- The best time to take iron supplementsWhen to take iron so more of it gets in: on an empty stomach, away from coffee, tea and dairy. Why bedtime works for many, and when food is better.
- Iron supplement side effects: what is normal and what helpsNausea, constipation, stomach pain and dark stools on iron: which side effects are common, what to try, and when to see a doctor the same day.
Progress
How long a rebuild takes, and what to check when it stalls.
- How long does it take to raise ferritin?First changes in 6 to 8 weeks, steady stores in 4 to 6 months. A realistic timeline for raising ferritin, when to recheck, and what slows it down.
- Why is my ferritin not going up?Taking iron and ferritin still won't rise? The usual reasons, in the order to check them: timing, inflammation, stomach acid, blood loss, thyroid and protein.
The Iron Guide
Not ready for an app?
Start with the guide.
Everything Ferritin is built on, in one illustrated PDF: how iron moves, which numbers matter, what to eat and when, how supplements are used well, and what to check when your iron stores will not move.
- 73 illustrated pages in 9 parts
- A 7-day ferritin menu with 21 recipes
- Printable lab tracker, period log and appointment sheet
PDF · 73 pages · in English · yours to keep