What has more iron, watercress or spinach?

December 15, 2025 •

3 min read

According to the CDC, watercress holds the top spot for nutrient density among all fruits and vegetables, beating out spinach. But when we zero in on the specific question of what has more iron, watercress or spinach, the answer is more complex than simple quantity, involving factors like bioavailability.

Quick Summary

Watercress contains a higher content of bioavailable iron per calorie due to its rich vitamin C, which enhances absorption. Spinach's iron content, while historically exaggerated, is hindered by compounds like oxalates and polyphenols that limit its absorption by the body.

Key Points

Iron Bioavailability is Key: Watercress's iron is more easily absorbed than spinach's, primarily due to its high vitamin C content and low oxalate levels.
Watercress has More Usable Iron: Despite spinach's higher raw iron content by weight, watercress provides more 'usable' iron because of better bioavailability.
The 'Popeye' Myth: The famous belief in spinach's exceptional iron content was based on a decimal point error and ignores crucial absorption factors.
Pair with Vitamin C: To maximize iron absorption from either green, always consume them with a vitamin C-rich food like citrus fruits or bell peppers.
Consider Cooking Method: Cooking can reduce the vitamin C in both greens, so consuming them raw, like in salads or smoothies, is often best for maximizing iron uptake.
Both are Nutrient Powerhouses: Both watercress and spinach are highly nutritious, with watercress ranking at the top of the CDC's nutrient-dense vegetable list.

The Surprising Truth About Iron Content

For decades, spinach has been a celebrated symbol of strength and iron, largely thanks to a misplaced decimal point in a 1930s study that greatly exaggerated its iron content. While spinach does contain iron, the actual amount, and more importantly, how much of it the body can use, is far different from common belief.

Watercress vs. Spinach: A Gram-for-Gram Breakdown

When comparing raw, gram-for-gram nutrition, watercress and spinach have different profiles. Watercress is a less dense green, meaning you need to consume more of it by weight to get the same total iron as a more compact portion of spinach. However, this simple quantity comparison doesn't tell the whole story. The type of iron and the presence of other nutrients, like vitamin C, play a much larger role in determining which green is the superior source for your body.

Iron Bioavailability: The Crucial Factor

Not all iron is created equal. Plant-based iron, known as non-heme iron, is less readily absorbed by the body than heme iron, which is found in animal products. Both watercress and spinach contain non-heme iron, but how well your body can absorb it depends on other compounds in the plant.

Spinach is high in compounds called oxalates and polyphenols, which bind to iron and inhibit its absorption. This means that a significant portion of the iron present in spinach is unavailable for your body to use. Watercress, on the other hand, is a much lower oxalate vegetable and is packed with vitamin C. Vitamin C is a potent enhancer of non-heme iron absorption, meaning the iron you get from watercress is far more bioavailable.

Watercress and Spinach Comparison Table


Feature	Watercress (Raw, per 100g)	Spinach (Raw, per 100g)	Analysis
Iron Content	~0.2 mg	~2.7 mg	Spinach contains more raw iron by weight, but this is misleading.
Bioavailability Factors	High Vitamin C (43 mg/100g) enhances absorption. Low in oxalates.	High in oxalates and polyphenols, which inhibit absorption.	Watercress's iron is more readily available for the body.
Vitamin C	Very High (43 mg)	Low (8.4 mg)	A major reason watercress's iron is more bioavailable.
Overall Nutrient Density	Perfect 100 score from the CDC.	High, but ranked slightly lower than watercress.	Watercress is a nutrient powerhouse per calorie.
Taste	Peppery, slightly bitter.	Mild, earthy.	Watercress offers a stronger, more distinct flavor.

Maximizing Iron Absorption from Leafy Greens

To get the most iron out of your leafy greens, remember these tips:

Combine with Vitamin C: Always pair your greens with a vitamin C-rich food. Adding lemon juice to a spinach salad or a handful of watercress to a smoothie with strawberries can significantly boost absorption.
Cook in Cast Iron: Using cast iron cookware can increase the iron content of your food naturally.
Avoid Absorption Blockers: Don't consume high-calcium foods (like dairy), coffee, or tea at the same time as your iron-rich greens. These compounds interfere with absorption.

Watercress and Spinach in Your Diet

Both watercress and spinach offer significant nutritional benefits and can be incorporated into a variety of dishes. Watercress's peppery flavor is excellent in salads, sandwiches, and pureed soups. Its delicate leaves cook much faster than spinach, making it a quick addition to a stir-fry. Spinach's milder flavor is more versatile and can be used in smoothies, pasta dishes, or as a sauteed side dish.

Conclusion: Which Green Should You Choose?

While spinach contains more total iron per gram, watercress offers a more bioavailable form of iron thanks to its higher vitamin C content and lower oxalate levels. This makes watercress a potentially more effective plant-based source for iron absorption. However, both are excellent sources of nutrients and can contribute to a healthy diet. The best approach is to enjoy a variety of leafy greens and to pair them with a source of vitamin C to maximize your body's ability to absorb their iron content. Ultimately, the choice between watercress and spinach may come down to personal preference for flavor, as both are among the healthiest vegetables available.

For more information on the nutrient density of various vegetables, consult the CDC's list of Powerhouse Fruits and Vegetables.

Frequently Asked Questions

Yes, cooking spinach can concentrate its iron content per portion due to water loss. However, it can also destroy some of the helpful vitamin C, and the non-heme iron remains difficult to absorb unless paired with another vitamin C source.

Spinach contains high levels of oxalates and polyphenols. These compounds bind to non-heme iron in the digestive system, forming insoluble complexes that the body cannot easily absorb.

The most effective way is to pair non-heme iron sources with a rich source of vitamin C. Squeezing lemon juice on a salad or adding greens to a fruit smoothie can dramatically boost absorption.

While leafy greens are a good source of iron, it's non-heme iron with lower bioavailability. It's best to include a variety of iron sources in your diet, including both plant-based foods and, if your diet allows, heme iron from animal products.

Yes, watercress is incredibly nutrient-dense, providing significant amounts of vitamins A, C, and K, as well as minerals like calcium and potassium.

Both are excellent choices. Watercress is often praised for its high nutrient density and bioavailable iron, while spinach is a versatile source of vitamins and minerals. The best choice depends on your dietary goals and how you prepare the vegetable.

For most people with healthy kidneys, the oxalate content in spinach is not a concern. However, individuals prone to kidney stones should monitor their intake of oxalate-rich foods and consult a healthcare provider.

While some sources claim watercress has more calcium than milk, it's important to remember that calcium absorption from watercress is also limited, although more bioavailable than spinach's calcium.