Bone Formation and Osteoporosis: The Role of Calcium and Vitamin D

IN MY I talked about a delicate balance maintained between bone formation and bone loss. Throughout our life, this balance between bone formation and bone loss keeps tilting to one side or the other depending on our calcium levels and our age.

When we are young and growing (age 0-25 years) our body makes new bone faster than it breaks down old bone -- this allows us to grow in height, gain strength and increase bone mass. To reach the maximum bone mass and density (around the age of 25), it is important to get adequate amounts of calcium and Vitamin D at this stage.

When we reach adult age (around 25 years), our bones stop growing and enter a phase called bone remodeling, which occurs throughout our adult life. During this phase, old bone is broken down at a faster rate than new bone is formed. Depending on the amount of work/load we put on the bone, new bone portions are formed as old bone portions are being lost. Again, for new bone tissue to form, we need calcium and Vitamin D.  If we don’t work our bones enough or if  we don’t have enough calcium, formation of new bone tissue will be slowed down; but we will continue to lose old bone tissue.

This is the reason for increased calcium requirements at old age. So as we age, with increased bone loss, our bones become weak and fragile. Increase in bone loss is also the reason why our parents/grand parents have become a little short now when compared to their height in their 20s.

The higher the maximum bone mass at age 25, the more bone tissue we have in the 'bank' - though there is a loss in bone tissue as we age, its effect on our bone strength would be lower when compared to its effect if we had a low peak bone mass to start with. One important thing to note here is that once we pass the age for peak bone mass, we cannot increase our bone mass any more. All we can do now is to minimize bone loss and try and keep our bones as strong as possible.

WE CAN see that calcium, and Vitamin D, are important at every stage of life, not only to form new bone tissue but also to prevent bone loss. Inadequate calcium  contributes to diminished bone density, early bone loss, increased fractures and development of osteoporosis.

Osteoporosis is a condition where bones become so weak and brittle that a fall or mild stress like bending over or coughing can cause fractures. Women are at a higher risk for osteoporosis than men. Women have certain female hormones that help preserve the strength of bones and slow down bone loss between the age of 25 and 50. But after menopause, the production of female hormones is decreased and there is a drastic increase in the amount of bone tissue that is lost. So after the age of 50, women lose more bone tissue than do men. This is the primary reason why women are at a greater risk for osteoporosis than men.

Men and women who have small body frames are also at a higher risk because they have less bone mass to draw from as they age. People with a sedentary lifestyle also have a higher risk for osteoporosis when compared to active people.

But not to worry, we can definitely reduce bone loss in a number of ways, preserve the strength of our bones and reduce risk of osteoporosis.

• Any weight bearing exercise is beneficial. This places some load on the bones and reduces bone loss. Activities like walking, jumping, dancing, jogging, stair climbing, skipping rope and weight lifting appear to be particularly helpful for healthy bones. Exercise will benefit your bones no matter when you start, but you will gain the most benefit if you start exercising regularly when you are young and continue to exercise throughout your life.

• Consume recommended levels of calcium so that our body doesn’t use our bones to supply calcium required for other functions. Special attention to dietary calcium is important after the age of 60.

• Maintain Vitamin D levels in the normal range to absorb sufficient amount of calcium from our foods.

• Reduce alcohol consumption to a maximum of one drink per day. Alcohol interferes with the body's ability to absorb calcium. 

Calcium, vitamin D and exercise is the way to go for good bone health!