Calcium function in the body: What does it do?

Your body needs vitamins and minerals, including calcium, to stay healthy and function at its best. Calcium is found in nearly every cell of the human body and is a key player in many of the processes involved in daily bodily functions.

Calcium is important for many reasons, including:

• Keeping bones strong
• Maintaining heart function
• Sending and receiving nerve signals
• Maintaining healthy blood pressure
• Regulating blood clotting
• Releasing hormones and enzymes necessary for a variety of bodily functions

Calcium is known for its role in bone health, and understandably so. Most of the calcium in the body—a remarkable 99%—is found in bones and teeth, while the rest circulates through blood, muscles and other tissues. The large amount of calcium in bone tissue is what gives bones and teeth their strong, hard structure.

Calcium is important for building and repairing bones. Throughout your lifetime, bones are constantly under a state of repair, a process called bone remodeling. This is needed for bone growth during the developmental years and for repairing old and damaged bone regularly. Calcium, as a crucial component of bone tissue, is incorporated into this recurring process. In fact, virtually all of the adult human skeleton is remodeled over 10 years.

Beyond giving your skeleton its framework, the calcium within your bones is a reservoir of the mineral for when it's needed elsewhere. If calcium levels drop too low in the blood, your bones will release stored calcium into the bloodstream to help return levels to normal. It works the other way too. When you have extra calcium circulating in the blood, your bones can absorb more of the mineral and put it into storage until you need it again.

Perhaps overshadowed by its role in bone health is the vital role calcium plays in heart function. Calcium is also an electrolyte, meaning that it's an electrically charged mineral. Calcium and other electrolytes are needed for many functions in the body, including muscle contraction.

The heart is arguably the most important muscle we have, and it needs calcium to function properly. The movement of calcium in and out of heart cells triggers the contraction and relaxation of the heart muscle. Without calcium, your heart would not beat. Calcium also supports the mechanism controlling the rhythm and strength of your heartbeat.

Similar to how calcium enables our heart to beat, the presence of calcium also causes contraction and relaxation of the smooth muscles in the walls of our blood vessels. The contraction and relaxation of the small muscles lining the vessels causes narrowing and widening of the blood vessels themselves. This is also known as vasoconstriction and vasodilation.

When our blood vessels constrict during vasoconstriction, our arteries get narrower, leaving less room for blood to flow. This added resistance causes blood pressure to rise. Conversely, when our blood vessels dilate, our arterial walls widen and blood flows more easily, causing our blood pressure to lower. Because of calcium's role in causing the narrowing and widening of our blood vessels, it helps regulate our blood pressure.

Our nervous system is responsible for detecting impulses from our surrounding environment and within our bodies, and transmitting the messages so that we can react accordingly. The nervous system works through a complex network of nerve cells, called neurons, that can communicate with each other at rapid speed with the help of calcium.

When an impulse reaches the end of one neuron, the presence of calcium triggers the release of neurotransmitters, which share the message from that neuron to the next, enabling the chain reaction of communication to continue. Without calcium, our nerves wouldn't be able to function properly.

Blood clotting is the process that heals our damaged blood vessels and stops bleeding. This process happens through a cascade of events that help platelets accumulate at the sites of wounds and form a clot. Calcium is a key regulator of this process by activating several proteins that are important in the actual coagulation of blood platelets. By controlling the activation of these important factors in the blood-clotting process, calcium can initiate and halt the coagulation cascade. Therefore, calcium helps the body heal wounds and prevents excessive bleeding when a blood vessel is injured.

Enzymes are proteins in the body that accelerate just about every chemical reaction in our body. They're important components to regulating many biological processes. In order for enzymes to do their jobs, they need to be activated by a substance such as calcium. Calcium is an example of an enzyme activator. Calcium binds to specific sites on the protein, which changes the structure of the enzyme. This change in physical structure leads to increased activity. Calcium is therefore very important in ensuring that many essential processes in our body can happen.

Despite the many important functions of calcium, most people do not get enough from their diet. Close to 30% of men and 60% of women over 19 do not consume enough calcium. Fortunately, calcium is found in a wide variety of foods and is available in the form of dietary supplements. If you're concerned that you might not be getting enough calcium from foods in your diet, check with your healthcare provider before adding supplements to your daily routine.

Updated October 2024.