Heme vs Non-Heme Iron: What Differs for Women

Heme iron comes from animal foods and is absorbed better than non-heme iron, which comes from plants and fortified foods and is more affected by what you eat with it. Neither form wins for everyone: your diet, life stage and blood tests decide what matters.

This page sits beside our look at beef organ supplements and iron and the wider guide to iron, energy and women's nutrition. Those pages ask what a capsule delivers; this one explains the two forms of iron themselves. Where the evidence is thin, we say so.

The short version

Dietary iron has two forms. Heme iron, found in meat, seafood and poultry, has better bioavailability than non-heme iron, the only form in plants and fortified foods. Vitamin C and meat help non-heme absorption, and phytate hinders it. Your own need depends on life stage, so a blood test beats guessing.

What is the difference between heme and non-heme iron?

Heme iron is iron bound inside a protoporphyrin ring, the form found in animal tissue. Non-heme iron is not part of that structure and is the only form in plants and iron-fortified foods. Meat, seafood and poultry contain both forms, so an animal food is never purely heme.

The NIH Office of Dietary Supplements adds a proportion that surprises many readers: heme iron contributes about 10 to 15 percent of total iron intake in Western populations. Even in diets that include meat, most of the iron eaten is non-heme.

What the 10 to 15 percent figure does and does not say

It describes intake, not absorption. It tells you how much of the iron on the plate is heme, not how much of it reaches the blood. The NIH states that heme iron has better bioavailability; we found no single absorption percentage on the current fact sheets, so we do not quote one.

Which foods contain each form of iron?

Lean meat and seafood are the richest dietary sources of heme iron, according to the NIH. Nuts, beans and vegetables contain non-heme iron, and wheat flours are often fortified with it, so bread and cereals count too. USDA values show how widely single foods differ.

Raw beef liver carries 4.9 mg of iron per 100 g, and cooked lentils carry 3.33 mg. The milligrams are close; the absorption is not, because the lentil iron is all non-heme. Spleen, at 44.6 mg per 100 g raw, is the outlier we describe in our iron guide.

What changes how much non-heme iron you absorb?

Vitamin C, as ascorbic acid, and eating non-heme iron alongside meat, poultry or seafood both help. Phytate hinders it. The NIH says these dietary components can significantly affect the bioavailability of non-heme iron, which is why the same plate can deliver different amounts for different meals.

The NIH consumer fact sheet names foods that contain vitamin C: citrus fruits, strawberries, sweet peppers, tomatoes and broccoli. Pairing a bean dish with one of them is a plate-level choice, not a supplement.

Calcium and iron supplements

The NIH notes that experts recommend taking calcium and iron supplements at different times, to avoid interference with iron absorption. If you take either, ask your pharmacist or physician how to space them.

How much iron does a woman need, and does the form change it?

The recommended intake is 18 mg a day for women 19 to 50, 27 mg in pregnancy, 9 mg while breastfeeding and 8 mg from age 51. The NIH says vegetarians who eat no meat, poultry or seafood need almost twice the listed amount, because non-heme iron is absorbed less well.

The form of iron therefore changes the target for people who avoid animal foods, not for everyone. The gap between 18 mg and 8 mg is linked to menstrual blood loss, which is why the requirement falls after menopause; our perimenopause article looks at what that means for a formula. The NIH states the 45 mg upper limit for adults includes all sources, and a doctor may prescribe more for a limited time.

Where do beef organs fit between the two forms?

Animal foods contain heme iron, and organs are animal tissue, but the amount varies sharply by organ. USDA lists raw beef liver at 4.9 mg per 100 g and raw spleen at 44.6 mg. A capsule serving weighs a small fraction of 100 g, so the milligrams stay small.

Eating liver as food and taking a capsule are different things, and the iron arithmetic belongs to the first. We did that arithmetic in full, with a conclusion we stand behind, in do beef organ supplements help with iron. Better absorption of a small amount is still a small amount.

Does Women Bloom contain iron?

Our Supplement Facts panel declares no iron. Two capsules carry 600 mg of freeze-dried beef organs (liver, ovary, kidney, heart and uterus), plus collagen peptides, biotin and zinc. We do not position Women Bloom as an iron source*, and we publish no iron figure for it.

The serving is two capsules of Women Bloom, and every ingredient and dose is printed as text on the Supplement Facts page. Laboratory results are on our lab tests page. If iron is your goal, a clinician and a blood test are the right first step.

What should you ask a clinician about iron?

Ask whether a blood test, including ferritin, is appropriate before you add iron from any source. Iron status is assessed with lab results, not by how tired you feel. The NIH says people with hemochromatosis should avoid iron supplements, and excess iron carries its own risks.

Also bring up your diet, because a plant-based eating pattern changes the target. And tell your clinician about calcium supplements and any medicine you take, since the NIH lists interactions between iron and several drugs, including levothyroxine and proton pump inhibitors.

Last reviewed: 7 October 2026. This article is general information, not medical advice. Talk to your physician before starting any supplement.

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.