Iron Deficiency: Why It's So Common and How Organs Can Help
You're tired. Constantly. Your period is heavy. You're cold when nobody else is. Your nails are brittle. Your hair falls out. You've tried iron supplements but they made you constipated and didn't actually help. The problem isn't iron itself. It's the type of iron you're eating, and where it's coming from.
Reviewed by Pedro Rodrigues, Agronomist · 
The problem isn't iron itself. It's the type of iron you're eating, and where it's coming from.
Iron is not created equal
There are two types of iron: heme and non-heme.
Heme iron comes from animal sources. It comes from the haem molecules in red blood cells and muscle tissue. Your body absorbs 15-35 percent of the heme iron you eat.1 It's absorbed directly through dedicated heme iron transporters in your intestines. Nothing interferes with this absorption. It doesn't matter if you have low stomach acid, inflammation, or if you drank coffee with your meal. Your intestines recognise it and transport it efficiently.
Non-heme iron comes from plant sources and fortified foods. Your body absorbs only 2-8 percent of non-heme iron.1 This depends entirely on your stomach acid, your calcium levels, your antacid use, whether you've eaten tea or coffee with it, and dozens of other factors. If you have low stomach acid from chronic stress or medication, you might absorb almost none of it. Non-heme iron is also called ionic iron, and it's poorly bioavailable by design.
Vegans and vegetarians are eating non-heme iron almost exclusively, which is why iron deficiency is endemic in those populations despite eating what appears to be adequate iron quantities. They're absorbing 2-8 percent of what they eat. A vegan eating 30 mg of iron daily might absorb only 0.6 to 2.4 mg. A meat-eater absorbing even 20 percent gets more absolute iron from half the quantity.
Meat-eaters can access heme iron, but only if they're eating the right cuts. Beef provides heme iron, but organ meats provide vastly more.
Beef liver contains 5-7 mg of heme iron per 100g serving. A similar serving of spinach contains 2.7 mg of non-heme iron that your body will barely absorb. The maths isn't even close.
Why women are disproportionately affected
Women lose blood monthly. Over 30-40 years of menstruation, that adds up. A woman losing 30 mL of blood monthly loses approximately 15 mg of iron annually. Heavy periods (over 80 mL monthly) result in 40 mg of iron loss yearly. That's equivalent to eating beef liver forty times annually just to break even.
Heavy periods make iron deficiency nearly inevitable without intervention. The conventional approach is to prescribe iron supplements. But most oral iron supplements are non-heme iron or poorly absorbed forms that cause side effects. Ferrous sulphate supplements constipate because they're poorly absorbed and your intestines rebel. Ferrous fumarate causes nausea. Ferric compounds are even worse. Women are told the side effects are worth it, then they stop taking them because they're miserable.
Women are told to eat more spinach. But spinach is high in oxalates, which bind iron and make it even less absorbable. This is advice given with good intentions but it doesn't work. You can eat spinach salad every day and still be iron deficient.
Men rarely become iron deficient unless they have hidden bleeding from ulcers, polyps, or bowel disease, or are vegan. Post-menopausal women lose the menstrual blood loss risk, but by then many are already profoundly depleted from decades of insufficient iron intake.
The ferritin and haemoglobin distinction
When your doctor tests iron status, they usually measure haemoglobin and maybe serum ferritin. This is insufficient.
Haemoglobin tells you whether you currently have enough iron to make red blood cells. If it's low, you have anaemia. This is a late sign. Your ferritin has to be completely depleted before haemoglobin drops significantly. Haemoglobin is the last thing to fall.
Ferritin is your body's iron storage molecule. It tells you whether you have iron reserves. If ferritin is low (below 30 ng/mL for women), you're iron deficient even if haemoglobin is normal. This is functional iron deficiency. You're not anaemic yet, but you will be if it continues. Many women experience symptoms at ferritin levels between 15 and 30.
Many women have low ferritin with normal haemoglobin and are told nothing is wrong. They're told to eat better or exercise more. In reality, they're iron deficient and need treatment. If you're tired and your haemoglobin is normal, ask specifically for ferritin testing. Don't accept "your haemoglobin is normal, so you're fine." That's an insufficient interpretation. Your ferritin matters more for how you feel.
Why supplements fail where food succeeds
Oral iron supplements have several problems. First, the absorption is poor. Most people taking ferrous sulphate absorb maybe 5-10 percent because ferrous iron requires adequate stomach acid and specific pH conditions. Women with low stomach acid (common with stress and age) absorb even less.
Second, they cause side effects. Constipation is the most common, along with nausea, black stools that alarm people, abdominal discomfort, and metallic taste. Many women stop taking supplements because the side effects are worse than the symptoms they're treating. Constipation from iron supplements can last months after stopping them.
Third, they don't address the underlying cause. If you have heavy periods, iron supplements are a band-aid. You need to address the bleeding through medical treatment, or you'll need supplements forever. Supplementation without addressing the source is unsustainable.
Heme iron from food doesn't have these problems. You absorb it easily without needing perfect stomach acid. It doesn't cause constipation or nausea. And if you're eating organ meats regularly, you're getting doses of iron that oral supplements can't match in terms of both quantity and bioavailability.
The organ solution
Beef liver is the single richest source of heme iron on the planet. 100g of beef liver contains 5-7 mg of heme iron, and you'll absorb 15-35 percent of that, meaning you'll absorb 0.75 to 2.45 mg from a single serving. That's more iron absorption than most women get weekly from their entire diet.
Other organ meats are nearly as rich. Beef kidney contains 3-5 mg heme iron per 100g. Beef heart contains 3-4 mg per 100g. These are the apex sources.
Regular red meat provides heme iron too, though less concentrated. 100g of lean beef contains about 2-3 mg heme iron. It's still superior to plant sources by orders of magnitude.
The practical protocol is straightforward. Eat organ meats 2-3 times per week. Beef liver is the easiest to start with. If the taste is unfamiliar, prepare it as liver pate, mix it into minced beef at a 20-30 percent ratio, or use desiccated liver capsules as a supplement. Eat red meat 4-5 times per week. This combination will raise your iron stores faster than any oral supplement can.
If you have heavy periods, also address the bleeding. This might mean hormonal contraception, endometrial ablation, or treating underlying conditions like fibroids or polyps. Iron supplementation without addressing the source of blood loss is like bailing water from a boat with a hole in it. You'll never get ahead.
A woman eating beef liver twice weekly will raise her ferritin faster than she will on oral supplements. The food works where the pills fail.
Timeline for recovery
If you're starting from depleted ferritin, recovery takes consistent effort over weeks.
Weeks 1-2. You might not feel different yet. Your body is rebuilding iron stores, but you don't have enough circulating iron to feel the difference. Don't get discouraged.
Weeks 3-4. Fatigue begins to lift noticeably. You have slightly more energy for daily tasks. Cold intolerance improves. You might need fewer blankets at night.
Weeks 5-8. Your energy is noticeably better. Brain fog clears. Hair loss slows markedly. Nails stop breaking. The changes are real enough that others comment on how you seem more energetic.
Weeks 9-12. Your ferritin has recovered if you've been consistent with organ meats. Your energy is back to normal baseline. The symptoms have resolved completely.
Get retested at 8-12 weeks to confirm ferritin has recovered to above 50 ng/mL3. If it hasn't, you might need injections (intramuscular iron, which bypasses absorption issues entirely) or there might be ongoing bleeding you don't know about requiring investigation.
The bottom line
Iron deficiency is endemic in women and easily fixed with the right approach.2 Not spinach. Not supplements that make you constipated. Not pills. Organ meats. Specifically beef liver, beef kidney, and beef heart, eaten regularly. Recovery is gradual but real. Get your ferritin tested. Start eating organs. Give it twelve weeks. Your energy will return, and it will stay.
References
- 1. NIH Office of Dietary Supplements. Iron fact sheet for health professionals. ods.od.nih.gov/factsheets/Iron-HealthProfessional.
- 2. NHS. Iron deficiency anaemia: overview. nhs.uk/conditions/iron-deficiency-anaemia.
- 3. British Society for Haematology. UK guidelines on the management of iron deficiency in pregnancy and postpartum. b-s-h.org.uk/guidelines.
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