12 best iron-rich foods, ranked by mg per 100g

Daily iron requirements: women vs men

Each food shows how much you'd need to eat to hit a full day's iron. The reference is the women's RDA of 18 mg/day (ages 19–50, as it is the most demanding group for iron requirements). Men and post-menopausal women need only 8 mg/day — so divide the amounts below by a little over 2 for that group. Vegetarians and vegans should aim 1.8× higher though! (more on that further down)

Iron content per serving: what real portions actually deliver

Per 100g is the standard scientific reference, but it doesn't reflect how we actually eat — no one consumes 100g of spirulina in a sitting, while 100g of clams is just one small can. The per-portion view below shows what each food delivers in a realistic serving instead, which gives a more accurate insight.

The 12 highest-iron foods (per 100g)

All values below are per 100g of food, sourced from USDA FoodData Central. Where it matters (like spirulina), we've added a note about realistic serving size — because who eats 100g of dried algae in a sitting?!

1. 1 Spirulina, dried 28.5 mg
   Caveat: a typical serving is 5–10g, so a single dose delivers ~1.4–2.9 mg. High mg/100g doesn't always mean high per portion intake. Daily intakeYou'd need ~63g (about 12 tablespoons) for 18 mg! That makes spirulina quite impractical as an everyday iron source. Realistic spoonfuls give only a small fraction of your daily intake.
2. 2 Clams 28.0 mg
   By far the highest practical source. Also high in vitamin B12 and selenium and available canned all year-round. Daily intakeJust ~65g — roughly one small drained can — exceeds 18 mg and your daily intake in a single serving.
3. 3 Blood sausage ~20 mg
   Traditional varieties (morcilla, blutwurst, kaszanka, black pudding) are exceptionally high in heme iron — content varies by recipe and blood ratio (USDA standard sausage entry is closer to 6 mg/100g; artisan varieties reach 20–30 mg). Daily intakeA single 50g slice can deliver ~10 mg — over 50% of a woman's daily 18 mg target, and well past a man's 8 mg. Among the most iron-dense foods available in supermarkets in Eastern Europe, Spain, Germany, and the UK.
4. 4 Dark chocolate 70%+ 11.9 mg
   Yes, really. A 30g portion (2–3 squares) delivers about 3.6 mg of iron — plus magnesium and antioxidants. Daily intakeYou would have to eat ~150g (1.5 standard bars) for 18 mg. A 30g portion (2–3 squares) still covers 20% of daily needs.
5. 5 Chicken liver 11.6 mg
   Higher iron content than beef liver (see comparison below). More importantly, it contains highly bioavailable heme iron. Daily intake~155g — about one large liver or two small ones — meets 18 mg in a single meal.
6. 6 Pumpkin seeds 8.8 mg
   The top plant-based source on this list. A 30g serving = 2.6 mg of iron, plus zinc and magnesium. Daily intakeYou would need ~205g (~1.5 cups!) for 18 mg — that's a huge amount. A normal 30g handful of pumpkin seeds sprinkled on a salad or as a snack gives 15% of your daily needs.
7. 7 Oysters 7.2 mg
   Heme iron + record amounts of zinc and vitamin B12. Daily intake~250g (8–10 medium oysters) covers 18 mg — generous AND expensive, but for some still achievable in one meal.
8. 8 Beef liver 6.5 mg
   A classic iron boosting solution for a reason: high in not only iron, but also vitamin A, B12, and copper. Daily intake~280g (a 10 oz slice) for 18 mg. A normal 100g portion = 36% of daily needs. Moreover, beef liver contains high levels of copper as well, which is absolutely crucial for iron metabolism.
9. 9 Tofu, firm 5.4 mg
   The most accessible plant iron source for vegetarians. Pair it with vitamin C to boost absorption. Daily intakeYou need ~335g (about one standard block) for 18 mg. A typical 150g portion delivers ~8 mg.
10. 10 Soybeans, cooked 5.1 mg
    Whole cooked soybeans (not the same as edamame or processed tofu). A standard 1-cup serving delivers about 8.7 mg of iron — nearly half a woman's daily target. Common in East Asian and South American cuisines. Daily intake~353g (about 2 cups cooked) for the full 18 mg. A normal 170g (1-cup) serving covers ~48% of women's daily needs and easily exceeds a man's 8 mg RDA.
11. 11 Lentils 3.3 mg
    A 1-cup serving (~200g) delivers ~6.6 mg — a third of a woman's daily needs. Daily intake~545g (~3 cups cooked) for 18 mg — that's a lot. One realistic 200g serving = 37% of daily needs. Black beluga lentils and red lentils have slightly higher iron content than green and brown lentils.
12. 12 Spinach 2.7 mg
    Famous, but the iron is non-heme (plant-based) and the absorption is low (1–10%). Still useful when combined with vitamin C though. Daily intake~670g raw (15+ packed cups) for 18 mg! Cooked spinach is denser — about 4 cups cooked. Remember - combine sources rather than relying just on one.

Iron content comparison — per 100g

Heme vs non-heme: why the source matters as much as the amount

Iron from animal sources (heme iron) is absorbed at 15–35% efficiency. Iron from plants (non-heme) is absorbed at only 2–20%, and can be inhibited by tea, coffee, calcium, and phytates in grains and legumes. This is why a 6 mg meal of lentils isn't nutritionally equivalent to a 6 mg meal of liver — you'll absorb significantly less from the lentils.

The fix for plant sources: pair them with vitamin C. Squeeze lemon on your spinach. Add bell peppers to your lentil curry. Vitamin C can triple non-heme iron absorption.

Chicken liver vs beef liver: which has more iron?

Chicken liver wins by a meaningful margin. Cooked chicken liver contains about 11.6 mg of iron per 100g, while beef liver contains roughly 6.5 mg. Both are excellent sources — both deliver heme iron at high bioavailability — but if maximising iron is the goal, chicken liver is nearly double.

That said, beef liver has roughly 4× the vitamin B12 and 3× the vitamin A. More importantly, it also contains high levels of copper, which is an important mineral for iron metabolism and transport in the body. If you can tolerate the strong flavour, beef liver is the nutrient density champion overall — chicken liver is the iron-specific winner.

Don't aim at eating liver every day though. Other than elevating cholesterol, exessive intake and high levels of vitamin A and copper can lead to toxicity and liver damage. It is generally safe to consume liver once or twice a week.

Are clams really one of the highest iron sources?

Yes — and they're under-rated. A standard 100g serving of cooked clams delivers around 28 mg of iron, putting them at the very top of practical iron sources. That's more than four times the iron in beef liver, and the iron is heme, so absorption is high.

Clams are also a quiet nutritional powerhouse: a single serving covers 1,400% of the daily value for vitamin B12, plus significant selenium, manganese, and protein, all with very little fat. Canned clams (drained) are nutritionally similar to fresh, making them one of the cheapest and most shelf-stable ways to add iron-rich seafood to your diet.

Worth noting: clams concentrate environmental contaminants more than fish, so reputable sourcing matters. A serving 2–3 times a week is generally considered safe for adults.

Spirulina iron content: superfood or overhyped?

Spirulina has 28.5 mg of iron per 100g — on paper, more than any other food on this list. But that 100g figure is misleading: a realistic spirulina serving is 5–10 grams, so a typical dose delivers 1.4 to 2.9 mg of iron, not 28.

The bioavailability of spirulina iron is also debated. Some studies show comparable absorption to other plant sources; others suggest binding compounds in the algae reduce uptake. Verdict: useful supplement, but oversold superfood.

Best plant-based iron sources (vegetarian & vegan)

Plant foods rarely match animal sources mg-for-mg, but several deliver enough iron — when eaten consistently and paired with vitamin C — to comfortably meet daily needs. The strongest plant sources, ranked by mg per 100g are:

1. Pumpkin seeds — 8.8 mg
2. Tofu, firm — 5.4 mg
3. Soybeans, cooked — 5.1 mg
4. Lentils — 3.3 mg
5. Chickpeas — 2.9 mg
6. Spinach — 2.7 mg
7. Navy beans — 2.4 mg
8. Black beans — 2.1 mg
9. Quinoa — 1.5 mg

How much do vegetarians actually need to eat?

Because plant iron absorbs at lower rates, vegetarians and vegans should aim for ~32 mg/day (women) or ~14 mg/day (men) — that's 1.8× the omnivore RDA. Hitting 32 mg from a single plant source means eating a lot:

1. Pumpkin seeds: ~365g (about 1.5 large bags)
2. Tofu: ~600g (about 2 standard blocks)
3. Soybeans (cooked): ~630g (about 3.5 cups)
4. Cooked lentils: ~970g (~5 cups)
5. Chickpeas: ~1100g (~1.1 kg, or about 6 cups)

No realistic diet relies on one food. A typical iron-conscious vegetarian day might look like:

Iron deficiency symptoms: 8 warning signs

Iron deficiency affects an estimated 1.2 billion people globally and is the most common nutritional deficiency in the world. Early symptoms are easy to dismiss because they're vague:

1. Unusual fatigue that doesn't improve with rest
2. Pale skin, especially inside the lower eyelid
3. Shortness of breath during normal activity
4. Heart palpitations or a racing pulse at rest
5. Brittle nails or spoon-shaped (concave) nails
6. Hair shedding beyond normal daily loss
7. Cold hands and feet even in warm environments
8. Restless legs or pica (cravings for ice, clay, starch)

If you have several of these together, get a blood test — specifically, ask for serum ferritin, not just hemoglobin, which can read normal even when iron stores are depleted.

Frequently asked questions

Which food has the highest iron content per 100g?
By weight, spirulina (dried) leads with about 28.5 mg of iron per 100g, but a realistic serving is only 5–10g, so cooked clams (around 28 mg per 100g) are the highest practical source.

Does cooking food affect its iron content?
Cooking does not destroy iron, and in fact iron content per 100g often appears to increase after cooking because water is lost. Cooking in cast iron cookware can even add small amounts of iron to food.

Can you get enough iron from a plant-based diet?
Yes, but you need to eat 1.8× the recommended intake to account for lower absorption of non-heme iron from plants. Pairing plant iron sources with vitamin C (citrus, peppers) significantly improves absorption.

What blocks iron absorption?
Coffee, tea, calcium-rich foods, and high-phytate foods (whole grains, legumes) all reduce iron absorption. Try not to drink coffee or tea within an hour of iron-rich meals.

Sources & references

• U.S. Department of Agriculture. FoodData Central (SR Legacy). All nutrient values per 100g.
• National Institutes of Health Office of Dietary Supplements. Iron: Health Professional Fact Sheet.
• European Food Safety Authority. EFSA Dietary Reference Values for Iron.
• World Health Organization. Anaemia and iron deficiency.

This article is for informational purposes only and is not a substitute for professional medical advice. If you suspect iron deficiency, consult a qualified healthcare provider.

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