Raw spinach contains 2.7 mg of iron per 100 grams (about 3.5 cups), which is 15% of the daily value. That puts it among the more iron-rich vegetables, but the full story involves how much of that iron your body can actually use, which depends on how you prepare it and what you eat it with.
Iron Content by Serving Size
A 100-gram serving of raw spinach, roughly 3.5 cups, delivers 2.7 mg of iron. That’s the same amount found in 100 grams of ground beef, which surprises many people. Cooked spinach is where the numbers get more interesting: because spinach shrinks dramatically when heated, a single cup of cooked spinach packs far more leaves and therefore more iron than a cup of raw leaves. A cup of boiled spinach contains about 6.4 mg of iron, roughly 36% of the daily value.
For context, the recommended daily iron intake for adult men is 8 mg. Women between 19 and 50 need 18 mg due to menstrual losses, and that number jumps to 27 mg during pregnancy. After age 51, women’s needs drop back to 8 mg. A single cup of cooked spinach covers most of a man’s daily requirement on paper, though absorption complicates this picture significantly.
Why Your Body Absorbs Less Than You’d Expect
Spinach contains non-heme iron, the plant form. Animal foods like meat and seafood contain heme iron, which your body absorbs much more efficiently. On average, only about 10% of dietary iron gets absorbed from a balanced diet, and non-heme sources like spinach fall below that average. The iron in a steak and the iron in spinach are not equal once they reach your gut.
Spinach has an additional obstacle: oxalic acid. This naturally occurring compound binds to minerals in the digestive tract, and spinach is one of the highest-oxalate foods in a typical diet. The oxalic acid can form complexes with iron and calcium, making them harder for your intestines to absorb. So while 2.7 mg of iron sits in that pile of raw spinach, the fraction that actually enters your bloodstream is considerably smaller than what you’d absorb from an equivalent amount of iron in chicken or beef.
How Cooking Changes the Iron You Get
Your cooking method matters more than most people realize. Boiling spinach causes the greatest loss of both iron and vitamin C, because water-soluble nutrients leach into the cooking liquid. Steaming preserves more, and microwaving results in the smallest loss of iron and vitamin C across cooking methods tested in comparative studies.
If you do boil spinach, using the cooking liquid in a soup or sauce recaptures some of the iron that leached out. But if you’re draining the water, you’re pouring nutrients down the sink. For maximum iron retention, a quick steam or microwave is your best bet. Sautéing in a pan also works well since there’s no water to carry nutrients away.
How to Absorb More Iron From Spinach
Vitamin C is the single most effective way to boost non-heme iron absorption. Research on iron absorption found that increasing vitamin C from 25 mg to 1,000 mg alongside an iron-containing meal raised absorption from 0.8% to 7.1%, nearly a ninefold increase. You don’t need supplement-level doses to see a benefit. A squeeze of lemon juice, a side of bell peppers, or some sliced strawberries alongside your spinach all provide meaningful amounts of vitamin C.
Timing matters, though. Vitamin C needs to be in your stomach at the same time as the iron-rich food. Taking it hours before or after has much less effect. So building the pairing into the same meal or snack is key. A spinach salad with citrus vinaigrette, or sautéed spinach with diced tomatoes, are simple combinations that put both nutrients in the same place at the same time.
On the other side, certain foods reduce absorption further. Calcium, tannins in tea and coffee, and phytates in whole grains can all compete with iron for absorption. If you’re eating spinach specifically to boost your iron intake, avoid pairing it with a large glass of milk or a cup of black tea at the same meal.
Spinach vs. Other Iron-Rich Foods
Spinach often gets top billing as a plant iron source, but it’s not necessarily the most practical one. Here’s how common iron-rich foods compare:
- Cooked lentils (1 cup): 6.6 mg of iron, 37% of the daily value
- Tofu (half cup): 3.4 mg, 19% of the daily value
- Raw spinach (100 g): 2.7 mg, 15% of the daily value
- Ground beef (100 g): 2.7 mg, 15% of the daily value
Lentils provide more than double the iron of spinach per serving, and they don’t contain the same oxalic acid burden. For people relying on plant-based diets for iron, lentils, chickpeas, and fortified cereals often deliver more usable iron than spinach alone. That said, spinach brings plenty of other nutrients to the table, including folate, vitamin K, and vitamin A, so it’s still worth eating regularly.
Oxalate and Kidney Stone Risk
Because spinach is high in oxalic acid, people prone to calcium oxalate kidney stones (the most common type) are often advised to limit their intake. Mayo Clinic recommends restricting high-oxalate foods like spinach and rhubarb for people with a history of stones. One practical workaround: eating calcium-rich foods alongside spinach. The calcium binds to oxalate in the gut before it reaches the kidneys, reducing the amount that ends up in urine where it could form stones. Adding cheese to a spinach dish, for example, can help offset the oxalate load.
For people without a stone history, normal spinach consumption isn’t a concern. Eating a few servings per week is well within safe territory for most adults.