Calcium is an essential mineral that plays a vital role in bone health, muscle function, nerve transmission, and hormone secretion. Many people do not get enough calcium in their diets, putting them at risk for osteoporosis and other health issues. When looking to increase calcium intake, one of the best strategies is to consume calcium-rich vegetables. But what vegetable actually contains the most calcium?
The Importance of Calcium
Calcium is crucial for building and maintaining strong bones and teeth. Over 99% of the calcium in the body is stored in the bones and teeth. Calcium is continuously exchanged between the bones and bloodstream – old bone is broken down and new bone is formed. An adequate calcium intake is necessary to achieve peak bone mass in youth and reduce bone loss later in life.
In addition to bone health, calcium has several other important functions. It helps muscles contract, nerves transmit signals, and blood clot. A few of the hormones secreted by the body also require calcium in order to work properly. Examples include parathyroid hormone, calcitonin, and insulin.
When calcium levels in the blood drop too low, the body will draw calcium from the bones in order to normalize blood calcium levels. Over time, this can lead to brittle bones that are prone to fractures – a condition known as osteoporosis. Getting enough calcium from the diet throughout life can help prevent this bone loss.
Recommended Calcium Intake
The recommended dietary allowance (RDA) for calcium is as follows:
- Infants 0-6 months: 200 mg per day
- Infants 6-12 months: 260 mg per day
- Children 1-3 years: 700 mg per day
- Children 4-8 years: 1000 mg per day
- Children 9-18 years: 1300 mg per day
- Adults 19-50 years: 1000 mg per day
- Women over 50: 1200 mg per day
- Men over 50: 1000 mg per day
- Pregnant/lactating women under 18: 1300 mg per day
- Pregnant/lactating women over 18: 1000 mg per day
These recommendations are set to meet the needs of approximately 97% of healthy individuals in each age group. Some people, such as elite athletes, may need more than the RDA to support bone health.
Top Calcium-Rich Vegetables
Many vegetables contain significant amounts of calcium. Here are some of the top vegetable sources:
Kale
Kale is often hailed as the king of calcium-rich vegetables. One cup of raw kale contains 90-150 mg of calcium, depending on the variety. Even more calcium can be obtained from cooked kale – a cup of cooked kale contains close to 300 mg.
Kale is a leafy green vegetable that belongs to the Brassica family, which also includes broccoli, Brussels sprouts, and cabbage. In addition to calcium, kale provides vitamins K, A, C, B6, manganese, copper, potassium, and magnesium.
Broccoli
Broccoli is another nutritional powerhouse that’s loaded with calcium. One cup of raw broccoli has about 40-50 mg of calcium. When cooked, this amount nearly doubles – a cup of cooked broccoli contains 60-80 mg.
Along with calcium, broccoli is high in vitamins C, K, A, B6, and folate. It also provides fiber, potassium, phosphorus, and phytonutrients with antioxidant effects.
Chinese Cabbage
Chinese cabbage, commonly known as bok choy or pak choi, is a versatile cruciferous vegetable. A cup of cooked bok choy has 105-210 mg of calcium, making it one of the most calcium-dense veggies.
In addition to supplying calcium, bok choy contains antioxidants like beta-carotene and vitamins A, C, and K. It can be enjoyed raw or cooked in soups, stir-fries, and side dishes.
Collard Greens
Like other leafy greens, collard greens provide a considerable calcium punch. One cup of cooked collard greens contains 177-357 mg of calcium.
Collard greens have large, dark green leaves and a mildly bitter flavor. They are a staple vegetable in Southern U.S. cuisine. Beyond calcium, collard greens offer vitamins A, C, and K, fiber, and the antioxidant kaempferol.
Turnip Greens
Turnip greens are the leafy tops of the turnip plant and are another excellent source of calcium and other nutrients. A cup of cooked turnip greens packs about 125-200 mg of calcium.
Turnip greens are more robust in flavor than other greens and have a distinctively bitter taste. They contain high levels of antioxidants like quercetin and glucosinolates and provide vitamins A, C, E, and K.
Spinach
One cup of cooked spinach offers roughly 125 mg of calcium, while a cup of raw spinach has 30-40 mg. Although not the highest vegetable source, spinach still provides a considerable amount.
Spinach is known for being exceptionally nutritious and low in calories. It’s rich in vitamin K, folate, magnesium, iron, potassium, and the antioxidants lutein and zeaxanthin. Eating spinach regularly promotes bone health and reduces risk of age-related eye disorders.
Okra
Okra is more known for being high in vitamin C, vitamin K, and antioxidants. But the green pods also deliver a decent calcium kick. A cup of sliced raw okra has about 80-130 mg of calcium.
Okra has a unique mucilaginous texture and is often used to thicken stews and soups like gumbo. It can also be baked, fried, or pickled. Okra provides magnesium, folate, potassium, and vitamin B6 in addition to its calcium content.
White Beans
Beans aren’t just a protein powerhouse – they can also be a great plant-based source of calcium. White beans, in particular, contain substantial amounts. One cup of cooked white beans has about 100-160 mg of calcium.
Kidney beans, navy beans, Great Northern beans, and cannellini beans are all varieties of white beans. Besides calcium, beans supply plant-based protein, fiber, iron, magnesium, potassium, folate and antioxidants.
Edamame
Edamame are immature soybeans that are harvested while still green. Although soy has become controversial in recent years, edamame remains one of the richest plant calcium sources. One cup of shelled edamame contains about 100-150 mg of calcium.
Edamame can be boiled or steamed and eaten as a snack or protein-packed side dish. In addition to calcium, edamame provides plant-based protein, fiber, vitamin K, folate, iron, and phytoestrogens like isoflavones.
Sea Vegetables
Sea vegetables, also known as seaweed, are renowned for their high calcium content. Different varieties of seaweed contain varying amounts of calcium, but they typically deliver at least 100 mg per cup.
Wakame and hijiki are two sea vegetables that are especially calcium-rich, with over 300 mg per cup of cooked seaweed. Nori, kombu, and dulse also provide substantial calcium along with iodine, fiber, vitamin K, and antioxidants.
Figs
Dried figs are one of the best fruit sources of calcium, containing about 75 mg per fig. That translates to roughly 250 mg of calcium in one cup of dried figs.
Figs have a sweet, honey-like taste and chewy texture. They can be enjoyed whole, chopped up in salads and baked goods, or blended into smoothies. Along with calcium, figs provide antioxidants, magnesium, potassium, vitamin K, and fiber.
Oranges
While not as high in calcium as the other foods on this list, oranges do contain a moderate amount. One large orange offers about 50-60 mg of calcium or 5% of the RDA.
Oranges supply vitamin C, potassium, thiamine, folate, and antioxidants like hesperidin. The whole fruit, juice, zest, and pulp can be consumed to obtain the nutrients and flavor oranges provide.
Highest Calcium Vegetables
To summarize, here are the vegetables with the most calcium per cup:
| Vegetable | Calcium (mg) |
|---|---|
| Kale (cooked) | 299 |
| Chinese cabbage (cooked) | 210 |
| Collard greens (cooked) | 357 |
| Okra (raw) | 130 |
| Broccoli (cooked) | 80 |
| Seaweed (wakame) | 300 |
| White beans (cooked) | 160 |
| Figs (dried) | 250 |
| Edamame (shelled) | 150 |
| Oranges (1 large) | 60 |
As shown, kale tops the list with 299 mg of calcium per cooked cup. Chinese cabbage, collard greens, and seaweed like wakame are also extremely high in calcium.
Increasing Calcium Absorption From Vegetables
Calcium bioavailability refers to how well the calcium in foods can be absorbed and utilized by the body. Certain compounds can either enhance or hinder calcium absorption.
To maximize the amount of calcium absorbed from vegetables:
- Avoid pairing them with foods high in oxalic acid like spinach, rhubarb, sweet potatoes, and beans. Oxalic acid binds to calcium and prevents absorption.
- Increase vitamin D intake from foods, sunlight, or supplements. Vitamin D promotes calcium absorption.
- Include sources of vitamin C like oranges, peppers, and broccoli which can slightly boost absorption.
- Soak and sprout grains, nuts, and seeds before eating them to reduce phytic acid, which lowers absorption.
- Consider cooking vegetables since the process breaks down antinutrients that interfere with absorption.
Role of Other Nutrients for Bone Health
While calcium is extremely important, it’s not the only nutrient required for building and maintaining strong bones. Here are some of the other key nutrients involved:
Vitamin D
Vitamin D improves calcium absorption and plays an essential role in bone metabolism. Low vitamin D levels have been associated with decreased bone mineral density and increased fracture risk.
Vitamin K
Vitamin K is needed for the protein osteocalcin, which binds calcium molecules together in the bone matrix. It also regulates osteoclast and osteoblast activity to control bone turnover.
Magnesium
About 60% of magnesium in the body is stored in the bones. It’s required for the activation of vitamin D and osteocalcin. Magnesium may also directly stimulate osteoblasts.
Phosphorus
Phosphorus combines with calcium to form hydroxyapatite crystals that give bones their rigidity and strength. It makes up about 1% of adult bone composition.
Potassium
Potassium neutralizes acids in the body that can leach calcium from the bones. It also reduces calcium excretion through the urine by promoting its reabsorption in the kidneys.
Omega-3 Fatty Acids
Omega-3s reduce inflammation that can interfere with bone formation. They also seem to enhance calcium absorption and incorporation into bone.
Protein
Consuming adequate protein provides the amino acids needed to build bone matrix proteins like collagen. Very low protein intake is linked to poor bone health.
Other Ways to Support Bone Health
In addition to getting enough calcium and other bone-supporting nutrients, here are some other ways to keep bones strong:
- Perform weight-bearing and resistance exercises like walking, jogging, tennis, and strength training.
- Achieve a healthy body weight since being under or overweight stresses bones.
- Don’t smoke cigarettes or abuse alcohol, as these habits weaken bones.
- Consume less sodium and protein to reduce calcium lost in urine.
- Manage conditions like hyperthyroidism that accelerate bone loss.
- Get enough vitamin D from sun exposure, food, or supplements.
Conclusion
Leafy green vegetables tend to be the highest in calcium due to their low calorie density. Kale reigns supreme when it comes to calcium content, followed by other greens like Chinese cabbage, collard greens, and spinach. Broccoli, okra, sea vegetables, beans, figs, and oranges also contain substantial amounts of calcium. Aim for multiple servings of these vegetables daily as part of a bone-healthy diet.