Calcium and Bone Mass
Bones may seem like hard and lifeless structures, but they are, in fact, living tissue. Old bone is constantly broken down (through a process called resorption) by our bodies, and new bone is deposited. Anytime bone is broken down faster than it is deposited, bone weakness and osteoporosis can occur.
Bones are made from collagen and non-collagen proteins, and
they are fortified with calcium. If a person does not take in enough calcium from their diet, the body extracts calcium from the bones, resulting in loss of bone strength and mass. This can ultimately lead to thin, fragile bones and osteoporosis.
More than 90% of a person's bone mass develops before 20 years of age, and half of that bone mass develops from 11-15 years of age. To have strong bones, children and adolescents need to consume enough calcium to build up the bone mass that they will need throughout their lives.
Even after age 20, a person can help protect his or her bones. Bone mass can still be built up until the early 30s. After that, protecting the amount of bone that already exists comes from consuming enough calcium because calcium is essential in maintaining bone mass.
Calcium works like this:
- After calcium is consumed, several nutrients, especially vitamin D, help the body absorb the calcium.
- The blood transports the calcium that is not needed for other body processes to the bones where it adds to the bone mass and is stored for when it is needed in the rest of the body.
- Sometimes a lack of calcium comes from not consuming enough in the diet or because the body is not absorbing enough into the blood. When this happens, calcium is removed from the bones into the blood to keep a constant level of calcium in the blood.
Adequate calcium intake is important to keep a normal amount of calcium in the blood and to protect the bones from calcium loss. If enough calcium is not regularly consumed and the calcium continues to be taken from the bones, a person's bone mass decreases. Decreased bone mass can lead to osteoporosis, fractures, and disability.
Adequate calcium intake is also important because the body cannot produce calcium on its own. Every day, the body loses calcium through shedding hair, skin, and nails and through sweat, urine, and feces. Every day, this lost calcium must be replaced by what a person eats.