Which Vegetable is Highest in Calcium?

November 21, 2025 •

3 min read

According to USDA FoodData Central, cooked lambsquarters contain a staggering 464 mg of calcium per cup, making it the vegetable with the single highest concentration of calcium, though accessibility can vary. While this wild green is a notable contender, more commonly available options like collard greens are often cited as the practical answer to which vegetable is highest in calcium, delivering an impressive 268 mg per cooked cup.

Quick Summary

This article examines the vegetables richest in calcium, with a focus on dark, leafy greens like collard greens, kale, and turnip greens. It highlights the importance of bioavailability, explaining why some calcium-rich vegetables are better absorbed than others. The content provides a comparison of calcium levels in various vegetables and offers practical tips for increasing dietary calcium intake for stronger bones.

Key Points

Collard Greens are a Top Source: Cooked collard greens are an excellent, widely available source of calcium, offering 268 mg per cup.
Bioavailability is Key: The body absorbs calcium more effectively from low-oxalate greens like collard greens, kale, and bok choy than from high-oxalate spinach.
Lambsquarters Hold the Highest Count: The wild green lambsquarters technically contains the most calcium at 464 mg per cooked cup, but it is less common.
Tofu and Soybeans are Excellent Options: Calcium-set tofu provides a concentrated calcium boost, while cooked edamame is another reliable source.
Variety is Important: To maximize calcium intake and nutrient absorption, incorporate a diverse range of leafy greens and plant-based foods into your diet.
Cooking Increases Absorption: For many vegetables, cooking helps to break down cell walls and increase the availability of calcium for the body to absorb.
Combine with Vitamin D: Ensure you have adequate vitamin D, from sunlight or fortified foods, to help your body absorb the calcium you consume.
Consider Frozen Vegetables: Frozen collard greens can have a higher calcium content than fresh versions, offering a convenient alternative.

The Surprising Champion: Lambsquarters

When seeking the absolute highest calcium content in a single vegetable, the lesser-known lambsquarters (or wild spinach) tops the charts with an exceptional 464 mg of calcium per cooked cup. This wild green, though not as readily available in most grocery stores, is a potent source for foragers and those with access to it. Its high concentration showcases the incredible nutrient density some wild plants possess. However, for most consumers, a more practical list of readily available vegetables is needed for daily dietary planning.

Collard Greens: The Practical Winner

For many, the most accessible and concentrated source of calcium among common vegetables is cooked collard greens. A single cooked cup provides approximately 268 mg of calcium, making it a powerful contender for bone health. Unlike spinach, collard greens have a relatively low oxalate content, meaning the body can absorb a higher percentage of its calcium. This combination of high content and high absorption makes collard greens an ideal addition to a diet focused on maximizing calcium intake through vegetables.

Why Bioavailability Matters: Comparing Spinach and Kale

It's not just about the raw number of milligrams; it's about how much calcium the body can actually absorb. This concept, known as bioavailability, is why spinach, despite appearing high in calcium on paper, is not as effective as other greens. While a cup of cooked spinach contains about 245 mg of calcium, it is also high in oxalic acid. This compound binds to calcium, inhibiting its absorption. In contrast, kale and bok choy contain far fewer oxalates, making their calcium much more readily available to the body. This distinction is crucial for anyone trying to rely on plant-based sources for their calcium needs.

Other Excellent Plant-Based Sources

Beyond the leafy greens, several other vegetables and plant-based foods offer significant amounts of calcium:

Turnip Greens: A cooked cup provides nearly 200 mg of calcium.
Bok Choy: A versatile and mild-flavored cabbage, one cooked cup offers around 158 mg of highly-absorbable calcium.
Broccoli Rabe: A cup of this cooked green provides about 100 mg of calcium.
Soybeans (Edamame): A cup of cooked edamame contains 175 mg of calcium.
Tofu (Calcium-Set): Tofu that has been fortified with calcium sulfate is a powerhouse, with some types containing over 86% of the daily value in a half-cup serving.

Maximizing Your Calcium Intake from Vegetables

To get the most calcium from your vegetable-based diet, consider these strategies:

Cook Your Greens: Cooking can often increase the bioavailability of calcium by breaking down cell walls and releasing the mineral.
Pair with Vitamin D: Vitamin D is essential for the absorption of calcium. While sunlight is the primary source, fortified foods or supplements can help.
Include Variety: Combine different calcium-rich vegetables to ensure you are getting a broad spectrum of nutrients and to offset the effects of oxalates from certain foods.

Comparison Table: Calcium Content and Bioavailability


Vegetable	Calcium (mg) per 1 cooked cup	Bioavailability	Notes
Lambsquarters	464 mg	High	A wild green, not widely available.
Collard Greens	268 mg	High	Low in oxalates, excellent absorption.
Amaranth Leaves	276 mg	Good	A concentrated source, though less common.
Spinach	245 mg	Low	High in oxalates, inhibiting absorption.
Turnip Greens	197 mg	Good	Lower oxalate content than spinach.
Kale	179 mg	High	Excellent absorption due to low oxalates.
Bok Choy	158 mg	High	Low oxalate levels.
Broccoli Rabe	100 mg	Good	A reliable, common source.

The Takeaway

While collard greens are a stellar choice for a readily available, high-calcium vegetable, the broader category of leafy greens and soybeans offers a wealth of options. To ensure optimal calcium absorption, focus on variety and be mindful of compounds like oxalates found in some greens. A well-rounded diet incorporating these vegetables, along with other calcium sources, is the best approach to maintaining strong bones and overall health. For further reading on bone health, visit the Bone Health & Osteoporosis Foundation website.

Conclusion

Ultimately, no single vegetable is the universal "highest in calcium" for all people, as factors like availability and bioavailability play a significant role. For those seeking the absolute highest numerical value, cooked lambsquarters stand out. However, for practical, everyday dietary needs, cooked collard greens are the most reliable and highly-absorbable option. A varied intake of greens like kale, bok choy, and turnip greens will ensure you receive a robust supply of this essential mineral for bone density and health. By understanding the nuance of calcium bioavailability, you can make informed choices to support your body's needs effectively.

Frequently Asked Questions

While the wild green lambsquarters has the highest calcium content per serving, cooked collard greens are the most practical and readily available vegetable with the highest amount of highly absorbable calcium.

Despite having a high calcium content on paper (245 mg per cooked cup), spinach is high in oxalates, which bind to calcium and significantly reduce its absorption by the body.

To increase calcium absorption, focus on eating low-oxalate vegetables like collard greens, kale, and bok choy. Pairing these vegetables with vitamin D, found in sunlight or fortified foods, also aids absorption.

Cooking vegetables can increase the amount of calcium available for absorption by breaking down the plant's cell walls, making it easier for the body to access the mineral.

Bioavailability refers to the proportion of a nutrient that is absorbed and used by the body. For calcium, it matters because some vegetables contain compounds like oxalates that prevent efficient absorption, making the raw calcium count less meaningful.

Yes, for those seeking to boost calcium intake, fortified foods like calcium-set tofu, certain cereals, and plant-based milks can be excellent, concentrated sources of the mineral.

It is possible for most people to meet their daily calcium needs through a varied diet rich in low-oxalate vegetables, fortified foods, and other non-dairy sources like nuts and seeds.