Which Plant Has the Highest Calcium?

December 1, 2025 •

3 min read

While many people associate calcium primarily with dairy, several plants offer exceptional amounts of this vital mineral. This article explores which plant has the highest calcium concentration, focusing not only on total content but also on how well the body can absorb it.

Quick Summary

Several leafy greens and seeds are potent sources of calcium for plant-based diets. High total calcium doesn't always mean high absorption, as natural compounds can inhibit uptake. Fortified foods and specific cooking methods can significantly enhance mineral bioavailability. A balanced intake of varied calcium-rich plants is crucial for optimal bone health.

Key Points

Bioavailability Matters: Some plants, like spinach, have high calcium but poor absorption due to oxalates; others, like kale, offer better bioavailability.
Dried Herbs are High in Concentration: Dried basil contains extremely high calcium levels per 100g, but practical serving sizes are small.
Kale and Collard Greens are Excellent Choices: Cooked kale provides superior absorbable calcium per serving compared to many other vegetables.
Fortified Tofu is a Reliable Source: Tofu set with calcium sulfate is a predictable and rich source of dietary calcium.
Seeds are Potent Sources: Sesame seeds, including tahini, are dense with calcium but their absorption can be hindered by phytates.
Cooking Increases Absorption: Boiling certain vegetables can reduce oxalates and increase calcium bioavailability.
Diversify Your Sources: For optimal intake, rely on a variety of plants, not just one, and include fortified foods and vitamin D.

Total Calcium Content vs. Bioavailability

When exploring which plant has the highest calcium, it's crucial to understand the difference between raw calcium content and bioavailability. Some plants, like spinach, contain a large amount of calcium but also have high levels of oxalates, which bind to the calcium and prevent the body from absorbing it effectively. Conversely, plants with lower total calcium but also lower oxalate levels, such as kale and broccoli, can be excellent sources because the body absorbs the mineral more efficiently.

The Contenders for Highest Calcium

While dried herbs like basil and marjoram boast incredibly high calcium concentrations per 100g, their small serving sizes make them less practical for daily needs. For example, 100g of dried basil contains a massive 2,240 mg of calcium, but you would likely use only a teaspoon at a time. For practical, edible portions, the focus shifts to more common foods.

Lambsquarters: Also known as goosefoot, this edible weed offers an impressive 464 mg of calcium per cooked cup.
Nettles: Cooked nettles are another strong contender, providing 428 mg of calcium per cup.
Amaranth Leaves: Cooked amaranth leaves, a popular ingredient in some cuisines, contain 276 mg of calcium per cup.
Collard Greens: These leafy greens offer a solid 268 mg of calcium per cooked cup and have relatively low levels of oxalates.
Sesame Seeds: Though not a leaf, whole sesame seeds are a concentrated source, providing up to 975 mg of calcium per 100g. Tahini, a paste made from sesame seeds, is also a good option.
Fortified Tofu: Tofu made with calcium sulfate as a coagulant can contain up to 861 mg of calcium per 100g, making it a highly reliable source.

Maximizing Plant-Based Calcium Absorption

Beyond choosing the right plants, several strategies can help your body get the most out of the calcium you consume. Soaking and cooking legumes and grains can help reduce anti-nutrients like phytates, which interfere with mineral absorption. Similarly, boiling leafy greens with high oxalate content, like spinach, can reduce oxalate levels, though it's still not the best source for absorbable calcium. Pairing calcium-rich foods with vitamin D, either from sunlight or fortified foods, is also crucial, as vitamin D aids calcium absorption in the gut.

Comparison of High-Calcium Plants (Per 100g)


Plant Source	Raw Calcium (mg/100g)	Bioavailability	Bioaccessible Calcium (mg/serving)*	Notes
Dried Basil	2,240	Low	N/A	High concentration, low volume usage.
Sesame Seeds	975	Moderate	~29 (per 5g)	High concentration, but absorption varies.
Kale (cooked)	177	High (~50%)	328 (per 80g)	Excellent bioavailability, a practical food source.
Collard Greens (cooked)	268	High	134 (per 80g)	Very good absorption, practical portion size.
Tofu (calcium-set)	350-861	Moderate (~31%)	80 (per 126g)	Content depends on coagulant used.
Amaranth Leaves (cooked)	276	Moderate	~138 (per 66g)	Excellent concentration, good absorption.
Spinach (cooked)	245	Very Low (~5%)	6 (per 85g)	High in oxalates, very poor absorption.
White Beans (cooked)	113	Moderate (~22%)	25 (per 110g)	Good source, soak to reduce phytates.

*Bioaccessible Calcium values are estimated based on various serving sizes and absorption rates from referenced studies.

Conclusion

While dried herbs offer the highest total calcium content per 100g, they are not practical for daily intake. For a combination of high concentration and good bioavailability, cooked leafy greens like kale, collard greens, and amaranth leaves stand out as excellent options. Furthermore, calcium-set tofu and sesame seeds provide reliable calcium boosts. The plant with the absolute highest practical amount of bioaccessible calcium per serving size is kale. However, the best approach is to consume a variety of these nutrient-dense plant sources to meet your daily calcium needs, paying attention to preparation methods that enhance absorption. Incorporating a range of foods, from fortified plant milks to low-oxalate greens, ensures a steady and absorbable supply of this critical mineral for bone health.

References

Food Unfolded (2019). "4 Foods That Have More Calcium Than Milk"
The Nutrition Source - Harvard University (2020). "Calcium"
Viva! (2025). "Calcium & Veganism - Everything You Need To Know"
Be Good Organics (2025). "Top 75 Sources of Plant-Based Calcium"
Veggies & More (2025). "Vegan Calcium; How to Get Enough Without Dairy"
Examine.com (2024). "The best plant-based sources of calcium - Study Summary"
ScienceDirect (2023). "A comparison of the bioaccessible calcium supplies of various..."

Frequently Asked Questions

Dried herbs, such as dried basil and marjoram, have the highest calcium content per 100g, with basil containing over 2,240 mg. However, for practical dietary servings, cooked kale offers excellent absorbable calcium levels.

No, despite its high calcium content, spinach also contains a high amount of oxalates, which bind to the calcium and significantly reduce its absorption by the body.

Bioavailability refers to the proportion of a nutrient that is absorbed and utilized by the body. It is crucial for plant-based calcium because compounds like oxalates and phytates can interfere with absorption, making some sources less effective than their raw calcium content suggests.

Other excellent plant-based sources include calcium-set tofu, sesame seeds and tahini, fortified plant milks (such as soy or almond), white beans, and dried figs.

To increase calcium absorption, you can cook plants high in oxalates, soak nuts and seeds to reduce phytates, and pair calcium-rich foods with vitamin D. Choosing low-oxalate greens like kale is also effective.

Yes, many fortified foods like plant-based milks and cereals contain calcium that is specifically added for better absorption. Check the label to ensure the product is fortified.

It is possible to get enough calcium from a well-planned plant-based diet. However, since calcium intake can sometimes be lower than average for vegans, focusing on a variety of high-bioavailability sources and considering fortified foods is recommended.