Which vegetable is considered calcium-rich? A Guide to Plant-Based Sources

November 25, 2025 •

4 min read

According to dietary guidelines, many adults need 700 to 1,200 mg of calcium daily to maintain bone health. For those looking beyond dairy, knowing which vegetable is considered calcium-rich is essential for meeting these daily requirements through plant-based foods.

Quick Summary

This article breaks down the best plant-based calcium sources, focusing on vegetables like collard greens, kale, and bok choy. It explains why bioavailability matters and how to boost your dietary intake.

Key Points

Collard greens and kale are top sources: These leafy greens provide large amounts of highly absorbable calcium due to their low oxalate content.
Bioavailability is key: The body absorbs calcium better from some vegetables than others; total calcium content can be misleading.
Avoid relying on spinach: Despite a high calcium listing, spinach contains high oxalates that block most calcium absorption.
Bok choy is an excellent option: This vegetable offers high bioavailability and a generous amount of calcium, similar to collard greens.
Cooking can improve absorption: Boiling some vegetables helps reduce oxalate levels, potentially increasing the amount of absorbable calcium.
Incorporate a variety: For maximum benefit, include a mix of low-oxalate, calcium-rich vegetables and fortified foods in your diet.
Pair with Vitamin D: Ensure you have enough Vitamin D, as it is critical for your body to absorb and utilize calcium effectively.

The Importance of Calcium from Plant-Based Sources

Calcium is a vital mineral, primarily known for its role in building and maintaining strong bones and teeth. It is also essential for nerve signaling, muscle function, and blood clotting. While dairy products are often the go-to source for calcium, many vegetables offer significant amounts, making them crucial for vegans, those with lactose intolerance, or anyone seeking to diversify their nutrient sources. However, the picture is more complex than simply checking the total calcium content on a nutrition label. The bioavailability—the proportion of a nutrient that is absorbed and utilized by the body—is the key factor, and it varies significantly among vegetables.

Bioavailability: Why Some Greens Are Better Than Others

Some vegetables, particularly leafy greens, contain compounds called oxalates (or oxalic acid) that bind to calcium during digestion, significantly inhibiting its absorption. Therefore, a vegetable with a seemingly high total calcium content might actually provide less usable calcium than a vegetable with a lower overall amount. Understanding this difference is critical for effective plant-based nutrition.

Vegetables with High Bioavailable Calcium

Collard Greens: Often regarded as a star player, a single cooked cup of collard greens provides a substantial amount of highly absorbable calcium—around 268 mg. Their low oxalate level makes the calcium they contain readily available for your body to use. This makes them a superior choice compared to spinach for bone health.
Kale: This popular leafy green is another excellent source. A cooked cup contains approximately 177 mg of calcium, and its low oxalate content ensures good absorption. Kale is also packed with Vitamin K, which is vital for bone metabolism.
Bok Choy: Also known as Chinese cabbage, bok choy is another great option for calcium. With low levels of oxalates, a cooked cup provides about 185 mg of highly absorbable calcium. It is a versatile vegetable that can be easily incorporated into many dishes.
Turnip Greens: Coming from the turnip plant, these greens offer a good amount of calcium with decent bioavailability. One cooked cup provides nearly 200 mg of calcium.

The Case of Spinach

Spinach presents a classic example of the bioavailability issue. While a cooked cup contains around 245 mg of calcium, its very high oxalate content means that most of this calcium is not absorbed by the body. Studies show that calcium absorption from spinach is dramatically lower compared to milk or other low-oxalate greens. It remains a nutritious food, but should not be relied upon as a primary calcium source.

Other Plant-Based Calcium Options

While leafy greens are standout choices, other vegetables and plant foods also contribute to your daily calcium intake.

Broccoli: A cup of cooked broccoli provides about 60 mg of calcium, and its low oxalate levels ensure good absorption. It also offers other bone-supporting nutrients like Vitamin C and K.
Amaranth Leaves: Cooked amaranth leaves contain a high amount of calcium, with approximately 276 mg per cooked cup. They are a great, though less common, option.
Tofu (Calcium-Set): Tofu that is prepared with calcium sulfate is an exceptional non-dairy source. Half a cup can provide over 430 mg of calcium, making it one of the most reliable vegan sources.
Beans and Legumes: Certain varieties, like white beans, offer moderate amounts of calcium. A cup of cooked white beans provides around 19% of the daily value.

Maximizing Your Calcium Intake

To ensure your body gets the most out of the calcium in your vegetables, consider these tips:

Combine with Vitamin D: Vitamin D is essential for calcium absorption. You can get it from sunlight exposure, fortified foods, or supplements.
Cooking Matters: Boiling vegetables can reduce their oxalate content. For instance, boiling spinach and discarding the water can increase calcium bioavailability.
Strategic Pairing: Consider consuming oxalate-rich vegetables like spinach alongside a low-oxalate, calcium-rich food to help with absorption.

Comparison of Calcium Content and Bioavailability


Food Source	Serving Size	Calcium (mg)	Relative Bioavailability	Notes
Milk	1 cup	~300	High (32%)	A benchmark for comparison.
Collard Greens	1 cooked cup	~268	Very High (54%)	Excellent choice for absorbable calcium.
Kale	1 cooked cup	~177	High (49%)	Another great option with high absorption.
Bok Choy	1 cooked cup	~185	Very High (54%)	Highly absorbable, perfect for stir-fries.
Spinach	1 cooked cup	~245	Very Low (5%)	Total amount is high, but oxalates block most absorption.
Broccoli	1 cooked cup	~60	High (61%)	Lower total calcium, but high absorption rate.

Conclusion: The Best Vegetables for Calcium

In conclusion, while many vegetables contain calcium, it is crucial to focus on bioavailability to maximize your intake. The answer to which vegetable is considered calcium-rich and offers the most absorbable calcium points towards collard greens, kale, and bok choy. These low-oxalate greens provide a significant amount of usable calcium, making them far more effective for promoting bone health than high-oxalate vegetables like spinach. For a balanced diet, including a variety of these low-oxalate vegetables, along with calcium-fortified plant-based products, is the best strategy for meeting your daily calcium needs.

For more detailed nutritional information, consult the Dietary Guidelines for Americans.

Frequently Asked Questions

Collard greens and bok choy are among the vegetables with the highest bioavailable calcium. They have low oxalate levels, allowing the body to absorb a high percentage of their calcium content.

No, despite its high total calcium content, spinach is not a good source of calcium for the body. It contains high levels of oxalates that bind to the calcium, preventing most of it from being absorbed.

Cooking methods like boiling can help reduce the oxalate content in some vegetables. When boiled, the oxalates leach into the water, and discarding that water can increase calcium's bioavailability.

Oxalates are compounds found in plants that can bind to minerals like calcium during digestion. This binding process forms calcium oxalate, which the body cannot absorb, thus reducing the amount of calcium available.

It is challenging but possible for vegans to get sufficient calcium from diet alone. It requires careful planning to focus on high-bioavailability vegetables and often includes calcium-fortified foods like tofu and plant-based milks.

Yes, other vegetables like broccoli, okra, and edamame contain moderate amounts of calcium with good bioavailability. Tofu prepared with calcium sulfate is also a great source.

Vitamin D is a crucial nutrient that helps the body absorb calcium from the food you eat. Combining calcium-rich vegetables with sources of Vitamin D can maximize absorption.