What is Calcium?

Calcium is an important mineral for bone and tooth structure, blood clotting, and nerve transmission; it has a DRI of 1,000 milligrams per day for adult men and women. Calcium as a mineral is most often associated with healthy bones and teeth but as we see it has many more important roles such as in blood clotting, helping muscles to contract, and regulating normal heart rhythms and nerve functions.

Where does Calcium come from?

Calcium is an alkaline Earth mineral. It is naturally found in bones, teeth, shells, rocks, and minerals. Calcium carbonate is a naturally occurring compound that is the basis for limestone, marble, and chalk. Stalagmites and stalactites in caves form from calcium carbonate precipitating out of solution.

Food sources of calcium include: dairy products (milk, cheese, yogurt), dark green vegetables (collards, spinach, chard, mustard greens, broccoli, green peppers), and dried beans and peas (lentils, navy beans, soy beans, and split peas). Calcium and several other minerals (especially iron, magnesium, and zinc) are easily bound to the oxalic acid in dark green vegetables, making the minerals unavailable for absorption. A quick blanching in hot boiling water will remover over 90% of the Oxalic Acid and make the calcium much more available.

Who needs it and what are some symptoms of deficiency?

Your body needs calcium for muscles to move and for nerves to carry messages between your brain and every part of your body. Calcium also helps blood vessels move blood throughout your body and helps release hormones that affect many functions in your body.

The relationships among calcium intake, physical activity, and bone density is very important to athletes. Athletes most often take calcium supplements to reduce the risk of fracture (i.e., by improving bone density), not for the purpose of improving physical performance. Physical activity is known to enhance bone density, just as physical inactivity is known to lower bone density.

How much should be taken? Are there side effects?

Calcium is likely safe when used in recommended amounts of about 1000-1200 mg daily. Calcium can cause some minor side effects such as belching or gas. But calcium is possibly unsafe when taken in doses above the daily tolerable upper intake level (UL).

Recent Calcium Studies

• Fractures: As with the evidence on the link between increased calcium intakes and reductions in BMD loss, the findings of research on the use of calcium supplementation to prevent fractures in older adults are mixed. [1}
• Colorectal Cancer: A substantial body of evidence has addressed the role of calcium in preventing colorectal cancer or its precursor, adenomas. [1}
• Cardiovascular Disease: Calcium binds fatty acids, so it can reduce lipid absorption and might therefore lower CVD risk [1,4]. However, the findings from research on the role of dietary calcium and calcium supplements in reducing CVD have been mixed, and some evidence indicates that calcium supplements might even increase CVD risk. [1}
• Preeclampsia: Calcium supplementation during pregnancy might reduce the risk of preeclampsia, but the benefits might apply only to women with inadequate calcium intakes, and much of this evidence comes from studies with methodological weaknesses. [1]

References:

1. 1. NIH - Office of Dietary Supplements - Calcium