What plant has the highest iron content?

January 6, 2026 •

4 min read

While the classic cartoon character Popeye famously touted spinach for its iron, several other plants actually contain significantly higher concentrations. Knowing which plant has the highest iron is crucial for maximizing this essential mineral on a vegetarian or vegan diet, where the non-heme iron is less easily absorbed than animal-based heme iron.

Quick Summary

This article identifies the plant with the highest iron content and reveals other key vegetarian and vegan iron sources. It also provides actionable strategies for enhancing non-heme iron absorption to effectively meet your nutritional needs.

Key Points

Natto is an Iron Leader: Fermented soybeans (natto) often top the charts for iron content in plant-based foods, providing a significant amount per cup.
Seeds are Powerhouses: Nutrient-dense seeds like sesame and pumpkin are exceptional plant-based iron sources that can be easily added to many meals.
Spinach Isn't the King: Though famous for iron, spinach contains oxalates that inhibit absorption; other leafy greens or optimized preparation can yield more usable iron.
Vitamin C Boosts Absorption: To maximize iron intake from plants, always pair iron-rich foods with a source of vitamin C, like bell peppers, tomatoes, or citrus fruits.
Soak and Cook Wisely: Soaking legumes and cooking with a cast-iron skillet are simple techniques to reduce absorption inhibitors and increase iron in your food.
Diverse Diet is Best: The most effective strategy for getting enough iron from plants is to eat a variety of sources, rather than relying on one single food.

Top Contenders for the Highest Plant-Based Iron

While many people assume spinach is the king of plant-based iron, research shows that other plants, particularly certain seeds and legumes, often contain higher iron levels by weight. Among the contenders for the highest iron content, fermented soybeans (natto), sesame seeds, and specific varieties of seaweed lead the pack. These nutrient-dense options pack a powerful punch of minerals, making them excellent additions to a balanced diet.

Fermented Soybeans (Natto)

Natto, a traditional Japanese food made from fermented soybeans, is an exceptionally potent source of iron. The fermentation process not only enhances flavor but also helps to increase the bioavailability of nutrients. A single cup of natto can contain over 15 mg of iron, making it one of the most iron-rich plant foods available. This makes natto a superior option for those seeking to boost their iron intake from plant sources. For comparison, a cup of cooked spinach typically provides only around 6.4 mg of iron, significantly less than natto.

Seeds: Sesame and Pumpkin

Seeds are another class of plants offering substantial amounts of iron. Sesame seeds, in particular, are incredibly rich, providing over 10 mg of iron per 100g, while tahini, a paste made from sesame, also retains a high iron content. Pumpkin seeds are another nutrient powerhouse, delivering more than 11 mg of iron per cup. These versatile seeds can be easily incorporated into salads, trail mixes, and baked goods to boost your daily iron intake without major dietary changes.

Dark Leafy Greens: Beyond Spinach

While spinach is a well-known source, other dark leafy greens offer notable iron content. Amaranth leaves have been cited for their high iron content in some studies, and cooked spinach, swiss chard, and beet greens all contribute a significant amount of iron per cooked cup. The important distinction for leafy greens like spinach is their high oxalate content, which can inhibit iron absorption. However, pairing them with vitamin C-rich foods can counteract this effect and significantly increase absorption.

Maximizing Iron Absorption from Plant-Based Foods

Since non-heme iron from plants is less bioavailable than heme iron from animal products, optimizing absorption is crucial for maintaining healthy iron levels. Several simple strategies can help your body make the most of the iron you consume.

Best practices for enhancing non-heme iron absorption:

Pair with Vitamin C: Consuming iron-rich plants with a source of vitamin C, such as citrus fruits, bell peppers, tomatoes, or strawberries, can increase absorption up to five-fold.
Use a Cast-Iron Skillet: Cooking acidic foods, like tomato sauce, in a cast-iron skillet can increase the iron content of your meal.
Soak and Sprout: Soaking and sprouting legumes, grains, and seeds can reduce phytate levels, which are compounds that can inhibit iron absorption.
Limit Inhibitors at Mealtime: Avoid drinking coffee, black tea, or excessive dairy near iron-rich meals, as the tannins and calcium can interfere with absorption.
Include Allium Vegetables: Onions and garlic may also increase iron absorption from grains and legumes.

The Iron Content of Top Plant Sources: A Comparison

To give you a clearer picture of which plant has the highest iron, here is a comparison of common plant-based sources based on available data.


Plant Food (Cooked)	Serving Size	Approximate Iron (mg)
Fermented Soybeans (Natto)	1 cup	15.1
White Beans	1 cup	6.6
Lentils	1 cup	6.6
Spinach	1 cup	6.4
Amaranth Grain	1 cup	5.2
Soybeans	1 cup	4.5
Tofu	1/2 cup	6.6
Quinoa	1 cup	2.8

This table illustrates that while fortified foods and certain niche products like natto may have the highest absolute iron content per serving, common and accessible foods like lentils and white beans are also excellent, reliable sources.

The Role of Fortified Foods

Fortified cereals and breads can be a significant source of iron in many diets. Certain brands of breakfast cereal can contain a very high amount of added iron, sometimes exceeding 15 mg per serving, and are often the highest single iron-providing food for some people. However, the iron is in non-heme form, so combining fortified cereals with a splash of orange juice is a smart way to increase absorption.

Conclusion: Looking Beyond a Single Plant

While fermented soybeans like natto may take the technical prize for the highest iron content per serving, focusing on one single plant is not the most effective strategy for managing iron levels. A more comprehensive and successful approach involves incorporating a variety of iron-rich plant foods—including legumes, seeds, whole grains, and dark leafy greens—into a well-rounded diet. By pairing these foods with vitamin C, using cast-iron cookware, and limiting inhibitors, individuals on plant-based diets can easily meet and maintain healthy iron levels. Always consider absorption factors and the diversity of your diet rather than relying on a single source. If you have concerns about iron deficiency, it's best to consult with a healthcare professional or registered dietitian for a proper assessment and personalized advice.

Frequently Asked Questions

Fermented soybeans, known as natto, are often cited as one of the highest plant-based sources of iron, with a single cup potentially providing over 15 mg.

While spinach does contain a good amount of non-heme iron, its high oxalate content can hinder absorption. Cooking can help, and pairing it with a source of vitamin C is crucial to maximize the iron your body can use.

You can improve non-heme iron absorption by pairing iron-rich foods with vitamin C sources, cooking in cast-iron cookware, and soaking or sprouting legumes and grains.

Excellent plant-based iron sources include legumes like lentils and beans, nuts and seeds such as sesame and pumpkin seeds, whole grains like amaranth and quinoa, and certain fortified cereals.

Yes, many fortified breakfast cereals provide a significant amount of iron per serving and can be a reliable part of your iron intake. Pairing them with orange juice can further boost absorption.

With a well-planned, diverse diet, vegans and vegetarians can meet their iron needs. However, because plant-based non-heme iron is less bioavailable, it is important to focus on maximizing absorption and consulting a doctor if concerns arise.

Yes, cooking acidic foods like tomato sauce in a cast-iron skillet can measurably increase the iron content of the meal, as some of the iron from the pan leaches into the food.