Do bananas have iron? The per-serving numbers

A medium banana carries about 0.3 mg of iron — near 2% of the 18 mg the NIH sets as the daily target for women aged 19 to 50. Bananas have iron the way white bread has iron: technically, and not in an amount worth planning around.

Do bananas have iron, and where the idea came from

The banana's headline mineral is potassium, roughly 420 mg in a medium fruit. Iron rides along on a vaguer association: bananas are marketed as an energy food, and in casual retelling "energy food" drifts into "blood-building food." Nothing in the fruit supports the move.

The 0.3 mg is also non-heme iron, the plant form the gut absorbs least efficiently and the form most affected by whatever else is on the plate — see heme vs non-heme iron for why the same milligram counts differently depending on its source. A banana isn't a bad food. It's just not an iron food.

Judge iron by the serving, not by 100 grams

Most food myths hide in the units. Nutrient databases report per 100 grams, which flatters anything light and bulky and punishes anything dense. A cup of chopped raw kale weighs about 21 grams. A cup of cooked beet slices weighs 170. Same "one cup," eight times the mass.

Here are the suspects checked at a serving you'd actually eat. Percentages run against 18 mg; double every figure for men and for women past menopause, whose target is 8 mg.

Food	Typical serving	Iron	Share of an 18 mg target
Banana	1 medium (118 g)	~0.3 mg	~2%
Beetroot, cooked	1 cup sliced (170 g)	~1.3 mg	~7%
Kale, raw	1 cup chopped (21 g)	~0.3 mg	~2%
Kale, cooked	1 cup (130 g)	~1.2 mg	~7%
Tuna, canned light in water	3 oz (85 g)	~1.4 mg	~8%
Shrimp, cooked	3 oz (85 g)	0.4–2.6 mg (disputed)	2–14%

How much iron in beetroot, per actual serving

Beets run about 0.8 mg per 100 grams cooked, so a cup of slices lands near 1.3 mg — small, but real, and it accumulates if beets are a regular side, not a garnish. Beetroot's actual claim to fame is dietary nitrate, which is why it shows up in endurance supplements. Iron was never the point.

The greens are the better half. Cooked beet greens carry roughly 1.9 mg per 100 grams, more than double the root, and a cooked cup gets close to 2.7 mg. Most people throw them away. Verdict on beetroot: modest, honestly labeled, and undersold on the leaf.

Iron in kale is real per gram and small per bowl

Raw kale sits near 1.5 mg per 100 grams, which reads well on a chart. Then you weigh a salad's worth and find 20-odd grams — about 0.3 mg, the same as the banana. Cooking doesn't add iron, but it collapses the volume, so a cooked cup delivers roughly 1.2 mg.

Kale does have one genuine edge over the green it always gets compared to. It's low in oxalate, the compound that binds non-heme iron and inflates spinach's paper numbers. The spinach iron myth has a second, funnier origin story on top of that. Kale's iron is less encumbered; there's just not much of it per bowl.

Iron in tuna and iron in shrimp are both smaller than they sound

Tuna is heme iron, which absorbs better than anything on the plant side, but the quantity is unremarkable. Canned light tuna comes in near 1.4 mg per 3-ounce serving, canned white albacore lower at roughly 0.7 mg, and a cooked yellowfin steak under 1 mg. Useful contributors, not sources.

Iron in shrimp is the messiest entry here, because the reference data disagrees with itself. Older USDA figures for cooked shrimp put iron near 3 mg per 100 grams; current FoodData Central entries are closer to 0.5 mg. That's an order of magnitude, and both numbers still circulate in published food lists — exactly how a modest food acquires an outsized reputation.

The shellfish that genuinely carry iron are the bivalves — cooked oysters run about 8 mg per 3 ounces on the NIH's own listing, a different league from shrimp. More of those comparisons live in iron-rich meat and seafood.

What the mislabeled foods have in common

Each of these is famous for something that isn't iron: potassium in the banana, nitrate in beetroot, vitamin K in kale, protein in tuna and shrimp. A food earns a reputation for being nutritious, then the general glow gets filed under whichever nutrient the reader happened to be searching for. Color helps it along — red foods read as blood foods, dark greens read as mineral-dense.

Sorted honestly, the five split three ways. Genuinely modest and correctly understood: beetroot, cooked kale, tuna. Genuinely mislabeled: the banana, and raw kale any time it's quoted per 100 grams. Genuinely unresolved: shrimp, until the databases agree.

The fix is unglamorous. Per-item milligrams stop being folklore the moment each food is logged and totaled against a target, which is the job Iron Tracker, an iron intake tracking app for iPhone, does.

FAQ

Is a banana a meaningful source of iron?

No. A medium banana holds about 0.3 mg, roughly 2% of the NIH's 18 mg daily target for women 19 to 50 and about 4% of the 8 mg target for men. Reaching a day's iron requirement would take dozens of them — the wrong tool for the job.

Do plantains have more iron than bananas?

Somewhat, largely because they're bigger. Raw plantain runs about 0.6 mg per 100 grams against the banana's 0.26, and a whole plantain weighs considerably more, so it can land near 1 mg. Still a footnote rather than a source.

Does cooking kale increase its iron content?

Cooking doesn't create iron. It drives off water and shrinks the volume, so a cup of cooked kale packs several times the leaf mass of a cup raw. Cooking in bare cast iron is a separate effect — acidic foods simmered in it do pick up measurable iron from the pan itself.

Are beet greens higher in iron than the beetroot?

Yes, by roughly double per 100 grams: about 1.9 mg cooked for the greens against 0.8 mg for the root. They cook down much like chard, and they're usually discarded with the tops.