Spinach is the Worst Source of Iron

author avatar Dr. Eric Berg 10/07/2023

Ever chewed on a leaf of spinach, thinking you're doing your body a favor by packing in the iron? You're not alone. Spinach is often touted as an iron powerhouse - but how much truth is there to this claim?

Popeye's portrayal of spinach may not be as accurate as it seems. Yes, spinach does contain iron – but it's not that simple because our bodies don’t absorb all types of iron equally.

In this exploration, we'll investigate the difference between heme and non-heme iron and their bioavailability. We'll dive into why cooking methods matter when trying to squeeze every bit of nutrition out of those green leaves.

And finally, let's unmask other dietary culprits that may block your path to better absorption.

Ready for some food truths? Let’s get started!

Understanding Iron Bioavailability

The world of iron can be a bit tricky. Not all iron is created equal – there's heme and non-heme. The difference lies in their bioavailability or how well our bodies absorb them.

Key Stats: Heme vs Non-Heme Iron

Spinach isn't the superhero we thought it was regarding iron content. Why? Because the type of iron found in plants like spinach is called non-heme iron - its bioavailability is low, so our body struggles to use it effectively.

To put numbers on this, your body will only be able to absorb around 1.4% of the total non-heme iron present in that lovely green leaf.

But don't start throwing out your greens just yet. Spinach has many other health benefits and is an excellent addition to any diet.

In contrast with plant-based sources, animal products contain what's known as heme-iron, which boasts an impressive 20% bioavailability rate. This source explains more about hemes versus non-hemes.

So yes, while Popeye might have been onto something with his love for canned spinach (cooked spinach does increase available nutrients), you'd probably get more bang for your buck chowing down on some clams if it’s strictly an iron boost you’re after.

The Iron Content in Spinach

Spinach is often hailed as a powerhouse of iron. Although spinach has iron, its bioavailability is limited because of the oxalates and polyphenols present.

Impact of Cooking Methods on Spinach's Nutrient Content

Different cooking methods have varying effects on the nutrient content of spinach. For instance, steaming can reduce the amount of oxalates present and diminish vitamin C content—an essential component for adequate iron absorption.

Oxalate compounds found abundantly in leafy greens like spinach and Swiss chard bind with iron, making it almost entirely unavailable for absorption by our bodies. Research shows that nearly all the iron from these veggies may pass through us without absorption.

Polyphenols are another group of compounds present in plants, including spinach, that also block our ability to absorb dietary non-heme iron. The resulting bioavailability rate stands around 1.4%.

This doesn't mean you should avoid eating your greens. Instead, consider pairing them with foods rich in Vitamin C or heme-iron sources (from animal products), which can help enhance their overall nutritional impact.

Other Dietary Factors Affecting Iron Absorption

When it comes to iron absorption, your diet plays a pivotal role. Certain foods and substances can interfere with how well your body absorbs iron.

Role of Animal Products in Iron Absorption

Eating animal products and plant-based foods can help enhance iron absorption. The body more easily takes up heme iron from animal products than non-heme iron from plant sources.

Foods rich in phytates, like beans, legumes, seeds, nuts, and grains, often hinder the uptake of iron, zinc, and calcium. These naturally occurring compounds bind minerals together, making them less bioavailable.

To counter this effect, try including heme-rich options such as clams or liver in your meals regularly. Other excellent choices are kidney meat, oysters for seafood lovers, or eggs if you prefer something more straightforward.

Don't worry if none of these appeal to you. Red meats, fatty fish, mussels, and even octopus provide decent amounts of absorbable heme iron, too. Don't forget to prioritize nutrition when selecting what works best for you.

Alternatives to Spinach for Iron Intake

Despite its reputation as a great source of iron, the bioavailability of spinach's iron content may be hindered by oxalates and polyphenols. So, considering alternatives might be beneficial to increase your iron intake.

Comparing Heme Iron Sources

Dietary sources can provide two types of iron: heme and non-heme. Heme iron in animal products boasts a higher bioavailability than non-heme type.

You'd get more bang for your buck with foods like clams, liver, kidney, or oysters, which are excellent sources of heme-iron. Let's also throw octopus into this mix because who wouldn't love an excuse for some sushi?

These options offer significantly better absorption rates compared with plant-based sources.

If seafood isn't quite your style, many other options are still available. For instance, red meat - specifically lean cuts from beef or lamb - fatty fish like salmon and sardines all pack an impressive amount, too.

And let's not forget eggs; while they don’t top the chart on our list here, they certainly shouldn’t be overlooked.

Magnesium and Iron

Magnesium and iron are essential minerals in the body's functioning. While magnesium primarily supports muscle and nerve function, iron is crucial for carrying oxygen in the blood. It's necessary to strike a balance between these minerals in your diet.

When considering the best types of magnesium supplements, it's wise to choose varieties like magnesium citrate or magnesium glycinate that offer excellent absorption without interfering with iron absorption.

Balancing magnesium and iron intake is essential because excessive magnesium intake, especially from supplements, can interfere with iron absorption.

This balance ensures you receive both minerals' benefits without compromising your overall health. Consulting with a healthcare professional can help tailor your mineral intake to your specific needs.


So, is spinach a good source of iron? Not quite as you might think.

Remember the bioavailability battle. Non-heme iron in spinach isn't absorbed well by our bodies, unlike in animal products.

Consider cooking methods and their impact on nutrient content. Steaming reduces oxalates but also decreases vitamin C, which aids absorption.

Bear in mind other dietary factors that interfere with your body's ability to absorb this essential mineral - like phytates present in beans and legumes.

Last but not least, don't forget those heme-rich alternatives: clams, liver, kidney... they all beat out leafy greens for better-absorbed iron sources!

If you aim for an effective way to boost your iron intake, you know where the true power lies! Spinach may be tasty, but more potent options are available for optimal health benefits.

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