Iron content in spinach

Spinach is traditionally believed to be a food rich in iron. The bigger, older leaves even have a slight metal taste. While it is true that spinach has high levels of iron it seems to be another story if your body actually can use that iron and how much of it really ends up in your blood stream for hemoglobin production. Find out how to increase the iron absorption from spinach to prevent iron deficiency anemia.

How much iron do you need

Adequate daily iron intake is crucial in preventing iron deficiency anemia. It is essential for the production of hemoglobin and red blood cells. It’s so essential that it’s the only metal that isn’t excreted from the body. Knowing that, you might think that most people have high iron levels. Although even excess iron is not eliminated, it is very hard to overdose on iron. In fact quite the opposite is true. People are more often deficient in iron. Iron deficiency is the most common nutritional disorder in the world. Often young women, pregnant women and young children have low iron levels since they find it difficult to support their higher needs of iron through diet alone. The amount of iron you need depends on gender and age:

AgeMaleFemalePregnancyLactation
Birth to 6 months0.27 mg*0.27 mg*
7–12 months11 mg11 mg
1–3 years7 mg7 mg
4–8 years10 mg10 mg
9–13 years8 mg8 mg
14–18 years11 mg15 mg27 mg10 mg
19–50 years8 mg18 mg27 mg9 mg
51+ years8 mg8 mg

*adequate intake

How much iron do you really get from spinach

blood cells

The tricky thing when it comes to iron is that it’s not enough to eat iron rich foods. Most often a big portion of the iron from food is not absorbed. The bio availability of iron from food is quite low:

  • Iron from animal sources, so called heme iron is absorbed better with about 15-35% absorbed
  • Iron from plant sources, so called nonheme iron, is absorbed less with about 10-20% absorbed

So you see the amount of iron your body actually gets out of iron rich food is quite low. That’s why you have to eat quite a lot of foods that contain iron to get your daily recommended intake.

Your body absorbs only about 10% of the complete iron content from spinach.

Spinach has about 6.43 mg of iron in a serving of one cup boiled spinach. That’s very iron dense for a plant food. If you only look at these numbers, you would meet all your daily iron needs with 2-3 cups of spinach. That’s not too bad. But take in account that spinach has nonheme iron and that it’s absorbed on the lower end with about 10% (read why that is in the next section). That means that you actually only get 0.64 mg from 1 cup of cooked spinach. So if you’re a young woman who needs 18 mg of iron a day that means you would have to eat 28 cups of fresh spinach.

Spinach has a lot of iron, but it also contains inhibitors that don’t allow a lot of it to be absorbed into the blood stream. Nevertheless there are things we can do to maximize iron intake from spinach. Besides iron concentration, spinach has other very important health benefits and should be often on your menu. So if it’s going to be one of your staple foods, let’s see how you can get most out of it and maximize iron intake.

What inhibits iron absorption from spinach
Sauteed spinach

The main reason iron absorption from spinach is so low is because it contains oxalates in high amounts. Oxalates are naturally occurring organic acids that interfere with iron absorption. One cup of of raw spinach contains about 200 mg of oxalates, which is a lot. Oxalates are naturally found in your body and don’t cause any problems if you’re healthy. Oxalates have been linked to formation of kidney stones, since they are found in the urine of people with kidney stones. The jury is still out on that one because up to today’s research it is not quite clear if high oxalate intake from food like spinach can contribute to significant forming of kidney stones.

Spinach has a high content of oxalic acid. Oxalates inhibit iron absorption.

The fact is that most dark green leafy vegetables, which are sources of iron, have oxalic acid. It’s not something unique for spinach. That’s why the following tips can be helpful whenever eating plant based sources of iron like swiss chard, beet greens, collard greens, bok choy, asparagus ans spinach.

How to enhance iron absorption from spinach

There are some simple rules you can follow to increase iron absorption from spinach closer to the upper level. Most of these rules can be applied to all sources of plant based iron.

  • Eat spinach with lot’s of vitamin C Lemons for better iron absorption

    Vitamin C is a powerful enhancer of nonheme iron absorption. Heme iron absorption doesn’t depend on the composition of your meal. Almost the same amount of iron will be absorbed from animal sources regardless of what you eat with meat. Non heme iron absorption on the other hand is very sensitive to meal composition. You can greatly influence iron absorption from spinach by carefully combining it with vitamin C rich foods. This is very important for vegetarians who exclusively depend on plant based sources of iron.Foods high in vitamin C include bell peppers, berries, broccoli, lemon, oranges, pineapple,… For example you can eat a portion of spinach salad with red bell peppers and lemon juice to enhance iron absorption. You don’t have to necessarily combine vitamin C rich fruits in the same meal. Simply eat your spinach, fresh or cooked, and have a vitamin C rich fruit for dessert afterwards. Take care not to destroy the vitamin C by cooking when combining different foods with spinach. This will greatly improve the amount of iron you’ll get from spinach.

  • Sauté spinach in cast iron pans cast iron skillet

    This is maybe the most efficient way to improve iron content when eating nonheme iron. The iron which cast iron pans are made of is actually the same form of iron found in food. Several studies have consistently confirmed that cooking food in cast iron pans increases the amount of iron in food. The increase is quite significant. One study found that by cooking applesauce in cast iron pots it got additional 6 mg of iron and spaghetti sauce got 2 mg for every 100 g of food. These are significant increases. Some researches even suggest to introduce cast iron pots to prevent iron deficiency anemia. The longer food is cooked and the more often the pans are used the higher the iron migration from pan to food. That’s one more reason to ditch the non stick cook ware for good old cast iron pans.

  • Skip the cream when eating spinach

    Cream with spinach
    Calcium has an inhibiting effect on iron absorption. That’s why you shouldn’t take any calcium supplements or milk products right after eating spinach. Coffee with milk right after lunch is a bad idea if you want to maximize iron absorption.
    Spinach is traditionally often prepared with cream, sour cream or cheese. Just skip these ingredients since they are high in calcium and they will lower the iron content you get from a meal with lot’s of spinach.
    The good news is that people who eat a high calcium diet, which is recommended for small children and women, are not more likely to have iron deficiency anemia. According to studies long term intake of calcium rich foods does not seem to interfere with iron absorption. But if you’re anemic or want to boost your iron intake from food you should avoid high calcium foods right after eating a meal rich in iron.

  • Avoid coffee or tea after eating spinach Cooffee mug

    Black tea, herbal teas and coffee contain high amounts of polyphenols, which inhibit iron absorption as well. Black tea inhibits iron absorption the most compared to herb tea and coffee. If you’re at risk for iron deficiency anemia choose what you drink with your meals carefully. Orange juice has  shown to increase nonheme iron absorption for 85% due to it’s high vitamin C content.

  • Limit antacid intake Antacids in supermarket

    Certain antacids when taken directly after a meal lower the absorption of iron. Since the effectiveness of antacids against heartburn isn’t really proven, in fact it seems that long term use of antacids will likely worsen your heartburn, try to avoid these drugs as much as possible.
    Try some of these methods to fight heartburn, and if you’re taking antacids talk to your doctor about how it can effect iron absorption.

  • Cook spinach Cooking spinach in water

    One of the methods to get more iron out of spinach is to cook it. Oxalates that inhibit iron absorption are heat resistant but part of them are water soluble. So by cooking spinach you’re reducing the amount of oxalates in green leafy vegetables. This reduction is minor though. Moreover cooking spinach will make it lose other important nutrients. That’s why this method is the last on this list, because the above mentioned steps will contribute more to higher iron absorption than cooking.

Why to make spinach a regular at your table

Why bother then at all with spinach as an iron source ? You could just eat some meat and forget all about nonheme iron absorption. Spinach isn’t only a good source of iron it’s a power food with lot’s of other benefits. It contains high amounts  of vitamin K, vitamin A, manganese, folate and magnesium. It has powerful phytonutrients that act as antioxidants that prevent cell damage. It’s also rich in flavonoids and carotenoids that fight inflammation and cancer. The list of health benefits of spinach is long and includes:

  • Cancer prevention, especially prostate cancer
  • Bone health, because of vitamin K
  • Lowers blood pressure, because of it’s potassium content
  • Regulates gut health as a good source of fiber
  • Eye health, due to cartenoids lutein and zeaxanthin

Spinach should be in your diet not only because of it’s high iron content but because of all the other benefits this super food has to offer. Pick any kind of spinach and enjoy all the benefits you get from it.

Photo credit: Lemons, do you think there’s something wrong with the american diet?!, Watercress and Spinach Soup, spinaci, Designed by Freepik, 100-year-old Griswold Skillet