Calcium is important for bones, which are constantly being broken down and built back up. Vitamin D regulates calcium absorption and excretion, especially when calcium intake is low.
Calcium is a component of bones, but is more immediately needed in the blood to keep muscles, such as the heart, contracting efficiently. The body preserves blood calcium levels at the expense of bone calcium. Calcium alone though is not enough to keep bones healthy. It is combination a of a balanced calcium and Vitamin D intake.
While not found in many foods, vitamin D can be made by the action of sunlight (UV rays) on skin.
If you get exposed to the following amounts of midday sun (10 am to 2 pm), without sunscreen, on a day when sunburn is possible (i.e., not winter or cloudy), then you do not need any dietary vitamin D that day:
Chart below for Calcium content in various vegetarian foods.
- Many non-dairy milks are now fortified with calcium, vitamin D, and/or vitamin B12. Many orange juices are fortified with calcium.
- Shake calcium fortified non-dairy milks before pouring as the calcium can settle to the bottom.
- The calcium in kale, broccoli, collard greens, and soymilk is all absorbed relatively well.
- The calcium in spinach, Swiss chard, and beet greens is not well absorbed, due to their high content of oxalates, which bind calcium.
- Calcium supplements can inhibit iron absorption if eaten at the same time.
- In addition to the calcium in the leafy greens listed on the right, leafy greens also contain vitamin K which is good for bones.
- The Daily Value for calcium on food labels is 1,000 mg. Therefore,if a food label says it has 25% of the daily value, it means it has 250 mg of calcium per serving.