If you've had your iron levels checked and been told they're "low normal," or you're on a multivitamin and still exhausted, this one's for you. As a naturopath, iron deficiency is one of the most common things I see in clinic, especially in menstruating women, and especially in pregnancy and postpartum, when the body's iron demands go up dramatically. But the fix isn't always "take more iron." It's often "take the right kind."
Heme Iron vs Non-Heme Iron: What's the Difference?
Iron in food and supplements comes in two forms:
- Heme iron: found only in animal foods (red meat, organ meats, poultry, seafood). This is the form your body evolved to absorb efficiently.
- Non-heme iron: found in plant foods and most standard supplements (ferrous sulfate, ferrous fumarate, plant-based iron tablets).
The difference matters because of how each one gets into your bloodstream. Heme iron is absorbed directly through a dedicated pathway in the gut. Non-heme iron has to be converted first, and that conversion is easily blocked by things like phytates in grains, tannins in tea and coffee, and calcium in dairy, which is a big part of why a lot of women take iron religiously and still don't see their levels move.
What the Research Shows
A 2024 systematic review and meta-analysis of randomized controlled trials comparing heme and non-heme iron supplementation found that clinical evidence shows heme iron absorption of around 15–35%, compared with 2–20% for non-heme iron, particularly in people who are already iron deficient (Ekpor et al., 2024). In children with iron deficiency anaemia, heme iron produced meaningfully greater increases in haemoglobin than non-heme iron. Just as importantly for anyone who's stopped taking iron because it wrecked their stomach: heme iron was associated with a 38% relative reduction in gastrointestinal side effects like constipation and nausea compared to non-heme forms.
Older nutrition research backs this up from a different angle: heme iron is absorbed at roughly 25%, against 17% or less for non-heme iron, and while heme iron makes up only 10–15% of the iron in a typical omnivorous diet, it accounts for around 40% of total iron actually absorbed (StatPearls, Dietary Iron).
Worth being upfront about: the 2024 review also found no statistically significant difference between heme and non-heme iron on haemoglobin or ferritin specifically in pregnant women, and rated the overall evidence quality as low given how few trials exist. So we're not going to tell you heme iron is a miracle cure. But between better absorption, fewer side effects, and being the form your body is built to recognise, it's a genuinely reasonable place to start if regular iron tablets haven't worked for you or upset your stomach.
Who Should Pay Attention to This
- Anyone who's pregnant, postpartum, or trying to conceive: iron requirements roughly double in pregnancy, and low iron in the third trimester is extremely common.
- Menstruating women generally: monthly blood loss is the single biggest driver of iron deficiency in women of reproductive age.
- Anyone who's tried a standard multivitamin and felt no different: most multis use non-heme iron in small doses, alongside calcium and other minerals that compete with it for absorption, unlike whole-food formulations such as The Multi, which sources its iron from beef liver rather than ferrous sulfate.
- Anyone noticing hair thinning or shedding: low iron is one of the most common, and most overlooked, causes of hair loss in women. We cover this in more depth in How to Improve Hair Health.
- Vegetarians and vegans: not because you can't get enough iron, but because you're relying entirely on the less bioavailable non-heme form, so it's worth being more deliberate about pairing it with vitamin C and getting levels checked regularly.
Getting Therapeutic Iron From Food and Whole-Food Supplements
The richest natural source of heme iron, by a wide margin, is organ meat, beef liver in particular. It's also naturally rich in B12, folate, and copper, all of which your body needs alongside iron to actually build healthy red blood cells (iron on its own, without its cofactors, only gets you so far).
This is exactly why we built The Beef the way we did: 100% grass-finished Australian beef liver in capsule form, no synthetic ferrous sulfate, no fillers. It's not a substitute for medical care if you're significantly deficient (that's a conversation for your GP or naturopath, and you should always get your iron levels tested rather than guessing), but as a gentler, food-based way to support your iron intake day to day, it's worked well for a lot of our customers, including several who've told us their next blood test showed the first real improvement in years.
If you're not sure where your levels actually stand, that's step one, always. Get tested, work with a practitioner, and then decide what form of iron makes sense for your body, rather than cycling through multivitamins and hoping one sticks. You can see the full whole-food range, including The Beef and The Multi, in our Supplements collection.
The Research
Dietary Iron: StatPearls, NCBI Bookshelf
Iron Metabolism in Normal and Pathological Pregnancies and Fetal Consequences
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