Spinach is high in iron, but it also contains oxalic acid, which inhibits iron absorption.1 The amount of iron in plants surpasses the content in animal sources, but much less of it is absorbed (about 1% to 15% of intake).2

The body needs iron to help make hemoglobin (a protein in red blood cells that transports oxygen from the lungs to the rest of the body), myoglobin (a protein that provides oxygen to muscles), and some hormones.3

Spinach: High in Iron?

The two types of iron in food are:

• Heme iron is found in meat, fish, and poultry. Its absorption rate is 15% to 35% of intake.4
• Nonheme iron is found in plant and animal sources. It has a lower absorption rate than heme iron.

Spinach contains nonheme iron, so even though spinach is high in iron, the body absorbs only a small amount of it. The oxalic acid in spinach makes it harder for the body to absorb iron from it, preventing more than 90% of its iron from being absorbed.5

In contrast, iron from red meat is absorbed about 10 times more than iron from vegetables. Regarding quantities, less red meat than vegetables can be consumed to get the iron the body needs.6

Phytate (found mainly in grains, legumes, nuts, and seeds), and polyphenols (found in vegetables, cereals, spices, tea, coffee, red wine, and cocoa) can also inhibit nonheme iron absorption. Calcium can inhibit both nonheme and heme iron absorption.4

Be mindful of the other foods and drinks you consume when you are eating foods to increase your iron intake. For example, eating dairy products and drinking coffee with your meal may inhibit the absorption of the iron your meal contains.

Ascorbic acid

(vitamin C) can increase the absorption of iron when they are consumed together. Adding foods to your meal that are high in ascorbic acid, such as citrus and tomatoes, can enhance the absorption of the iron in the foods you are eating at the same time.

Despite not living up to its iron source reputation, spinach is still worth including in your diet. It contains beneficial nutrients like:7

• Carbohydrates
• Minerals
• Proteins
• Vitamins

Raw vs. Cooked Spinach

One cup of raw spinach contains 0.813 milligrams (mg) of iron.8

One cup of cooked spinach contains about 6.4 mg of iron.9

The same volume of cooked spinach has more than 6 times the amount of iron than raw spinach because raw spinach has a high water content, which takes up more room than when the water has been cooked out.1

Other Iron-Rich Greens to Try 

Leafy green vegetables are full of nutritious components, including iron. The iron absorption rate for green, leafy vegetables is about 7% to 9%, which is lower than meats, but higher than other plant sources of iron such as grains (4%) and dried legumes (2%).4

In addition to spinach, vegetables that are high in iron include:10

• Beet greens
• Broccoli
• Chard
• Collard greens
• Dandelion greens
• Kale
• Peas
• String beans
• Sweet potatoes

Who Needs More Iron?

Individuals have different iron needs. Iron deficiency anemia (IDA) occurs when iron levels are too low to produce enough healthy red blood cells to transport oxygen effectively. IDA affects about 4 million to 5 million Americans each year.11

Groups at risk for IDA include:11

• People who are pregnant: More red blood cells need to be produced during pregnancy.
• People who menstruate: Heavy bleeding during menstruation can contribute to IDA.
• Infants and children: Rapid growth increases iron needs.
• Older adults: With increasing age comes an increased risk of poor nutrition and chronic inflammatory diseases that can lead to anemia.
• Vegetarians and vegans: Eating a diet that doesn't include meat means more nonheme iron needs to be consumed to compensate for the lack of heme iron.
• Endurance athletes: Running can cause what’s known as "foot-strike hemolysis

• ," in which small blood vessels of the feet are broken down due to the feet striking the ground repeatedly. Running can also cause trace amounts of gastrointestinal bleeding.
• People with chronic kidney failure on dialysis: Kidney failure reduces the production of erythropoietin

• (EPO), a hormone that stimulates red blood cell production. There is also some blood loss involved with hemodialysis.

Iron Deficiency

Iron deficiency occurs in stages, as follows:11

1. Decrease in stored iron from a low-iron diet or excessive bleed
2. Greater depletion of iron stores and a drop in red blood cells
3. Iron deficiency anemia (iron stores are used up, and there is a significant loss of total red blood cells)

Signs of IDA include:11

• Confusion
• Fatigue
• Hair loss and/or brittle nails
• Light-headedness
• Loss of concentration
• Pale skin
• Pica (cravings for ice or nonfood items such as dirt or clay)
• Rapid heart rate
• Sensitivity to cold
• Shortness of breath
• Weakness

IDA is usually treated with oral iron supplements. Do not take iron supplements just because you think you have low iron, get your levels checked with a blood test through a healthcare provider to see if you need it.

Too much supplemental iron can be dangerous and, in some cases, fatal (particularly for children—keep iron supplements where children can't access them).12

High-Iron Meal and Snack Ideas 

Food sources of heme iron include:11

• Beef11
• Canned light tuna
• Canned sardines
• Organ meats
• Oysters, clams, and mussels
• Poultry

Food sources of nonheme iron include:

• Avocado
• Beans, legumes, soybeans, tofu
• Cooked spinach, asparagus, and green beans
• Dark chocolate (at least 45% cacao)
• Enriched rice or bread
• Fortified breakfast cereals
• Lentils11
• Most dark-green leafy vegetables (such as watercress and curly kale)13
• Nuts
• Potato with skin
• Seeds
• Some dried fruits (like apricots, raisins, and dates)
• Soybean flour
• Whole grains (like brown rice)
• Whole wheat breads, cereals, pasta, quinoa, and oatmeal14

Try to pair high-iron foods with high-vitamin C foods to help with iron absorption.

The Nutrition Source at Harvard University gives this example of a dish that combines foods that are high in nonheme fiber and vitamin C:11

1. Using a large bowl, combine cooked beans or lentils, diced fresh tomatoes, raw baby spinach, pumpkin seeds or cashews, and raisins or dried chopped apricots.
2. Make a lemon vinaigrette by combining 2 tablespoons of lemon juice, half a teaspoon of Dijon mustard, 3 tablespoons of olive oil, and 1 teaspoon of honey (optional).
3. Add the lemon dressing to the mixture in the bowl and stir well.
4. Allow to sit for at least 15 minutes so the flavors can incorporate.

Summary

Spinach is high in iron, but it also contains components that make it hard for the body to absorb that iron. Heme iron, which comes from meat, is more easily absorbed than nonheme iron, which comes from plant and animal sources. Vitamin C can help increase iron absorption when consumed at the same time.

Some people are at higher risk of low iron, such as pregnant people, menstruating people, people who don't eat meat, and children.

People with iron-deficiency anemia may need to take iron supplements. Don't take iron supplements unless your healthcare provider tells you you need them to avoid getting potentially dangerous high amounts of iron. Keep iron supplements away from children, as they contain enough iron to be fatal for a child.