Iron Deficiency in Women: Signs You're Low and How to Fix It

Iron deficiency is the most common nutritional deficiency in the world, and women are disproportionately affected. If you menstruate, are pregnant, or have been pregnant, your iron needs are significantly higher than the average person's. And yet it's one of those things that gets dismissed constantly - told you're "just tired" or "a little anemic" without anyone really digging into what that means for your daily life.

Here's what's actually going on and what you can do about it.

Why women are at higher risk

Every menstrual cycle, you lose iron. The heavier your periods, the more you lose. Women with fibroids, heavy bleeding disorders, or IUDs that cause heavier periods are at even greater risk. Pregnancy ramps up iron demands dramatically because your blood volume expands and you're supplying a growing fetus. Breastfeeding adds another layer of depletion.

Then there's diet. Women statistically eat less red meat than men (either by choice or portion size), which matters because meat contains heme iron - the form your body absorbs most efficiently.

The symptoms that aren't fatigue

Yes, fatigue is the big one. But it's also the most generic symptom on earth, which is why iron deficiency gets missed so often. The more telling signs include:

• Restless legs syndrome - that crawling, uncomfortable urge to move your legs at night
• Cold hands and feet even when the room is warm
• Hair shedding beyond your normal baseline
• Brittle nails, or nails with ridges and a spoon-like shape (called koilonychia)
• Brain fog and trouble concentrating
• Shortness of breath during exercise that feels disproportionate to your effort
• Pale inner eyelids or gums
• Unusual food cravings, particularly for ice (a condition called pagophagia)
• Headaches, especially on exertion

You don't need all of these. Two or three alongside fatigue is worth investigating.

Ferritin vs hemoglobin: the number that actually matters

Most standard blood panels check hemoglobin - the protein in red blood cells that carries oxygen. Your hemoglobin can be completely normal while your ferritin is rock bottom. Ferritin is your iron storage protein. When stores are depleted, your body starts pulling iron from tissues before hemoglobin drops. That's the window where symptoms show up but tests look "fine."

If a doctor tells you your iron is normal, ask specifically whether they checked ferritin. Request that number. Conventional lab ranges often flag ferritin under 12 ng/mL as low, but many functional practitioners aim for 50-100 ng/mL for women to feel optimal. If you're symptomatic with ferritin in the 15-30 range, that's low enough to explain how you feel. For a deeper look at which labs actually give you useful information, see the guide to functional lab tests for women.

Food sources: heme vs non-heme iron

Heme iron comes from animal sources and is absorbed at roughly 15-35%. Non-heme iron comes from plants and is absorbed at 2-20%, depending on what else you eat with it.

Good heme iron sources: beef, chicken liver, oysters, clams, sardines, dark meat chicken and turkey.

Good non-heme iron sources: lentils, white beans, tofu, fortified cereals, pumpkin seeds, dark leafy greens.

Two things that change how much non-heme iron you absorb:

Vitamin C dramatically improves absorption. A squeeze of lemon on your lentils, a glass of orange juice with your morning oatmeal, or bell peppers in your bean salad all make a real difference.

Calcium competes with iron for absorption. Drinking a glass of milk with your iron-rich meal, or taking a calcium supplement at the same time as an iron supplement, can cut absorption significantly. Space them apart by at least two hours.

Coffee and tea also inhibit non-heme iron absorption if consumed with meals.

Supplement types

Ferrous sulfate is the most common, cheapest, and most studied form. It works. The downside is gastrointestinal side effects - constipation and nausea are common enough that people stop taking it.

Ferrous bisglycinate (also called iron bisglycinate or iron glycinate) is gentler on the gut, absorbed well, and worth paying slightly more for if you've had trouble tolerating iron before. It's the form most functional medicine practitioners now recommend.

Slow-release formulations exist but often absorb less well. Liquid iron is an option for people with significant GI sensitivity.

Typical supplemental doses range from 18 mg (maintenance) to 150-200 mg of elemental iron per day for active deficiency - but this should be confirmed with your doctor based on your actual ferritin levels. Don't supplement iron without testing first. Too much iron is toxic and you can overshoot.

What else affects iron absorption

Low stomach acid makes it harder to absorb iron (and many other minerals). If you're on long-term proton pump inhibitors or antacids, mention this to your doctor. Magnesium doesn't directly compete with iron the way calcium does, but it's relevant because deficiencies often cluster together when diet is poor or absorption is compromised across the board.

Underlying gut issues like celiac disease, inflammatory bowel disease, or SIBO can impair iron absorption even when intake is adequate. If you're eating well, supplementing, and still not raising your ferritin, that's worth investigating.

Hair loss and iron

Hair shedding is one of the more distressing symptoms of iron deficiency. The research suggests ferritin levels below 30 ng/mL are associated with increased telogen effluvium (the kind of diffuse shedding where you lose more than usual all over). Raising ferritin typically slows the shedding over several months, though regrowth takes time. If you're losing hair and taking biotin, know that biotin alone won't fix shedding caused by iron deficiency.

When to see a doctor

• Ferritin under 20 ng/mL, especially with symptoms
• Heavy periods that are interfering with your quality of life
• Iron not rising despite supplementing for 3+ months
• Any signs of active bleeding you can't account for
• Hemoglobin low enough to diagnose anemia

Iron deficiency anemia sometimes requires IV iron infusions, which work quickly and well. They're not just for severe cases. If oral iron isn't moving your numbers after a genuine trial, it's a reasonable conversation to have.

Low ferritin is fixable. The frustrating part is that it often takes months to fully replenish stores, even with consistent treatment. Track your levels, give it time, and don't let anyone dismiss how bad low iron actually feels.