Iron (period support)

Iron is an essential mineral required for hemoglobin (oxygen transport), myoglobin (muscle oxygen storage), and many enzymes including those involved in dopamine and serotonin synthesis. Menstruating women lose iron with each period; women with heavy menstrual bleeding (menorrhagia) lose substantially more, and are the highest-risk group for iron deficiency in the general population.

Unlike most supplements covered here, this one is more about identifying deficiency than improving normal physiology. Iron supplementation matters when you are low, and creates problems if you are not.

Consult a provider before starting supplements, especially if pregnant, breastfeeding, or on medications. Iron should be tested before supplementing.

Why menstruating women are high risk

A typical period sheds 30 to 80mL of blood, equivalent to roughly 15 to 40mg of iron lost per cycle. Over a year, that is enough that intake must consistently exceed loss to maintain stores. Iron-rich diets (red meat, dark leafy greens, legumes) cover this for many users but not all.

Risk factors for deficiency:

  • Heavy bleeders. Cycles with more than 80mL loss can erode stores faster than intake replaces them.
  • Vegetarians and vegans. Plant iron (non-heme) is less bioavailable than heme iron from animal sources.
  • Frequent blood donors.
  • Endurance athletes. Foot-strike hemolysis and exercise-induced hepcidin elevation reduce iron status.
  • Pregnancy and postpartum.
  • GI issues affecting absorption (celiac, IBD, PPI use).

What deficiency feels like

Iron deficiency presents on a spectrum:

  • Low ferritin without anemia: fatigue, period brain, reduced exercise tolerance, hair shedding, cold intolerance, restless legs, brittle nails, pica (craving ice or non-food items).
  • Iron-deficiency anemia: the above plus pallor, breathlessness, palpitations, more severe fatigue.

A common pitfall: hemoglobin can be normal while ferritin (iron stores) is very low. Many users feel terrible at ferritin levels considered "normal" by labs but functionally suboptimal.

What to test

Ferritin is the most useful single test for iron status. It reflects stored iron and drops well before hemoglobin does.

Functional reference ranges for menstruating women:

  • Below 15 to 30 ng/mL: clearly low; symptoms likely.
  • 30 to 50 ng/mL: suboptimal for many users; symptoms common.
  • 50 to 100 ng/mL: generally adequate.
  • Above 100 ng/mL: ample stores; supplementation usually unnecessary.

Standard lab "normal" ranges often start as low as 10 to 15 ng/mL, which is well below the level where many people feel well. A complete panel (CBC, ferritin, transferrin saturation, sometimes serum iron and TIBC) gives the best picture.

Ferritin is also an inflammatory marker. Acute inflammation can artificially raise it. If ferritin looks higher than expected with deficiency symptoms, check CRP.

How to replace

Replacement is straightforward and slow.

Forms:

  • Ferrous sulfate, ferrous gluconate, ferrous fumarate: classic options. Effective but often poorly tolerated (constipation, nausea, dark stools).
  • Iron bisglycinate (ferrous bisglycinate): better tolerated, comparable absorption at typical doses.
  • Heme iron polypeptide: well tolerated; lower elemental iron per dose.

Dose: typically 30 to 100mg of elemental iron daily, depending on severity and tolerance. Higher doses do not always absorb better and increase side effects.

Timing: every-other-day dosing absorbs better than daily dosing (hepcidin response). Taking iron with vitamin C (200mg+) improves absorption. Avoid coffee, tea, calcium, and dairy within 2 hours of dosing.

How long: rechecking ferritin every 3 months is reasonable. Replacing depleted stores typically takes 3 to 6 months, sometimes longer if loss continues.

Where to get it. For non-severe deficiency, look for iron bisglycinate (Amazon) as the better-tolerated default. Severe deficiency or anemia warrants a provider's input on dose and form rather than self-prescription.

Cautions

  • Do not supplement without testing. Iron overload (hemochromatosis) affects about 1 in 200 people of European descent and is worsened by unnecessary supplementation.
  • Constipation is the most common side effect.
  • Stool darkening is expected, not concerning.
  • Take separately from thyroid medication, calcium supplements, and certain antibiotics.

Where it fits

Iron is not a "cycle syncing" supplement in the prescription sense. It is a deficiency-driven intervention that resolves symptoms when they are due to low stores. Heavy bleeders should get baseline labs before chasing energy or mood issues through other supplements.

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