The role of calcium in our body is multifunctional: it makes our heart beat, bones and teeth healthy and strong, our muscle function, our nerves transmit signals, and our hormones create.
Our body cannot produce calcium. The only source of this mineral for us is food. The body’s calcium depots are bones and teeth. To maintain constant concentrations of calcium in blood, our body uses bone tissue as a reservoir. So, it’s of vital importance to have enough bioavailable calcium in out diet.
Our bodies have a biological need for about 250-300mg of bioavailable calcium per day, meaning that our bodies can absorb and utilize it.
What is calcium bioavailability?
Many vegetable sources of calcium exist, including seaweeds such as kelp, wakame and hijiki; nuts and seeds like almonds, hazelnuts, sesame, and pistachio; blackstrap molasses; beans (especially soy beans); figs; quinoa; okra; rutabaga; broccoli; leaves; and kale. But here the problem of calcium bioavailability arises.
Bioavailability is the degree to which a nutrient is absorbed and utilized by the body.
The bioavailability of calcium refers to the fraction of dietary calcium that is potentially absorbable and can be incorporated into bones.
So, a variety of vegetables are rich in calcium, but they may also contain different substances (most often – oxalic acid) that bind calcium forming insoluble salt complexes and making only a small fraction of it available for absorption and utilization in our body. For example, spinach has moderate calcium content, but only about 5% of it is bioavailable. In other words, you have to eat tons of spinach to get enough calcium. The same problem may affect the absorption of calcium from amaranth, collard greens, and chicory greens.
10 Vegan sources of bioavailable calcium
1
Seaweed
Do you think that seaweeds have been consumed by coastal people worldwide for nothing? Due to low levels of oxalic acid and phytates, which bind calcium making it not absorbable in the body, seaweed such as kelp, wakame and hijiki is an excellent source of bioavailable calcium. For instance, in Korea, the soup miyeokguk made out of seaweed named wakame is popularly consumed by women during the pregnancy period and after giving birth. Maybe that is why people in Eastern Asia have such a low rate of osteoporosis. Moreover, seaweed is not only rich in bioavailable calcium, but it is also a pot full of other essential minerals, especially: iodine, iron, and magnesium.
Seaweed, wakame
- Serving size: 125 mL (1/2 c)
- Average calcium content (mg): 63
2
Bok choy
- Serving size: 125 mL (1/2 cup)
- Average calcium content (mg): 79
- Bioavailability (%): 54
3
Kale
This dark leafy green from the cabbage family is a great vegan source of calcium. About 3 cups of kale would be good enough to meet your biological calcium needs.
- Serving size: 125 mL (1/2 cup)
- Average calcium content (mg): 61
- Bioavailability (%): 49
4
Collard Greens
Widely considered to be a healthy food, collard greens are excellent sources of calcium. If you ate 2 cups of collard greens, you would be very close to your biological needs for calcium – close but still not enough.
5
Broccoli
Try to include calcium-rich broccoli to your daily menu.
- Serving size: 125 mL (1/2 cup)
- Average calcium content (mg): 35
- Bioavailability (%):61
6
Cabbage, Chinese
- Serving size: 85g
- Average calcium content (mg): 79
- Bioavailability (%): 54
7
Cabbage, green
- Serving size: 75g
- Average calcium content (mg): 25
- Bioavailability (%): 65
8
Cauliflower
- Serving size: 62g
- Average calcium content (mg): 17
- Bioavailability (%): 69
9
Rutabaga
In Sweden and Norway, Finland and Scotland, Holland and England, people cook rutabaga in a variety of ways: roasted, baked, boiled, as a flavor enhancer in soups, uncooked and thinly in a salad. Finns use rutabaga in most dishes that call for any root vegetable. So, go Finnish.
- Serving size: 85g
- Average calcium content (mg): 36
- Bioavailability (%): 61
10
Redish
- Serving size: 50g
- Average calcium content (mg): 14
- Bioavailability (%): 75
