A recent report has suggested that taking calcium supplements has very little impact on the development or progression of osteoporosis. As a result of this report, many women are feeling confused and unsure of how best to prevent this crippling condition.
Should the use of calcium supplements begin earlier in life? Should the daily intake of calcium from foods be increased? Is there any other way to increse the amount of calcium in the bones?
Here, we answer many of the questions that women have regarding their calcium intake and the prevention of osteoporosis.
A report from the Women's Health Initiative - an ongoing U.S. study of more than 35,000 women aged 50 to 79 years of age - found that taking calcium supplements for seven years had little impact on bone density or the incidence of hip fractures. Furthermore, calcium supplement users had a 17 percent increase in the development of kidney stones.
So what does this mean for the woman who is concerned about the very real risk of developing osteoporosis? Should she stop taking calcium supplements? And, if she does, what can be done to ensure that the recommended daily level of calcium is met? (It is important to note that women in the study who exercised and consumed plenty of calcium and vitamin D from food sources, purportedly reduced their risk of hip fracture by 21 percent.)
A Controversial Study
Unfortunately, this much-quoted study is very controversial as it was not well controlled. For example, many of the women in the placebo control group continued to take their own calcium supplements throughout the observation period. (The authors of such health studies do not advise participants to change their behavior when this might be detrimental to their health. Therefore, the women were not asked to stop taking supplements if they were already doing so.)
The researchers also cautioned that the results may have been influenced by previous hormone use.
The double-blind, placebo-controlled study was designed to demonstrate whether postmenopausal women who were given calcium and vitamin D supplements would experience a lower incidence of hip fractures. Study participants were given 1000mg of calcium carbonate and 400IU of vitamin D daily for eight years. The control group was not prescribed calcium or vitamin D.
Although the women receiving calcium and vitamin D showed a greater preservation of hip bone density, over all there was a statistically insignificant 12 percent lower risk of fracture. However, most media reports failed to disclose that, by the end of the study, only 59 percent of the participants taking the prescribed supplements were still doing so. In other words, 41 percent of the study participants stopped taking the prescribed daily dose of calcium and vitamin D or were taking the supplements sporadically. Twenty-four percent were no longer taking any of the supplements - a level of non-compliance that significantly decreased the difference between the two groups. The fact that many of the women in the control group routinely took calcium supplements served to further close this gap.
Previous Studies Show Otherwise
During the past two decades, numerous studies have shown that supplementation with calcium and vitamin D helps build strong bones - a key to reducing the risk of fractures. This applies to all age groups from children to seniors. What is not clear is whether supplementation in addition to an adequate calcium intake of 1000 to 1500mg per day, confers additional benefit.
The mineral calcium plays a significant role in almost all our body functions, even before birth. These include: the development and health of our teeth and bones; assisting blood clotting, muscle contraction and nerve transmission; muscle maintenance and growth, and ensuring rhythmic heart action. Additional demands in any of these areas could put extra demand on calcium reserves - a demand which may not always be supplied by the foods and beverages we consume. Since the bones act as reservoirs for calcium, they are the first to suffer when calcium is required for other vital body functions.
Many people have been hesitant to take calcium supplements as they have been linked to the development of kidney stones. While this is true, it applies only to calcium carbonate supplements. Calcium citrate (available from the pharmacy at your local London Drugs) does not increase the risk of developing kidney stones as it is more soluble within the body.
Other Minerals/Vitamins Important
The depositing of calcium in the bones is dependent on a number of trace minerals and vitamins, in addition to vitamin D. Vitamin D is added to milk in Canada, and also included in many calcium supplements as it is vital to the healthy development of bone. Often called 'the sunshine vitamin', vitamin D is produced in the upper layers of the skin in response to sunlight. (All you require is 15 minutes of UV exposure a day - without a sunscreen - to obtain adequate vitamin D.) Magnesium is also vital to the development and maintenance of bone. This mineral contributes to the fortification of the bone mineral matrix and is essential for the proper function of vitamin D. (Magnesium intake should be about half that of calcium intake.)
The minerals boron, zinc, copper, manganese and silicon also appear to be essential for maintaining healthy bones. You can obtain these from eating a varied diet rich in greens and other fruits and vegetables, and from good quality vitamin/mineral supplements. Please ask your London Drugs pharmacist for advice on choosing a supplement that is appropriate for your needs.
Calcium Needs Throughout Life
In December 2001, the U.S. National Institutes of Health issued the warning that a 'calcium crisis' is affecting American youth: Only 13.5 percent of girls and 36.3 percent of boys aged 12 to 19 in the United States obtains the RDA of calcium from their diets. Canadian youth is not far behind. Recent research shows that, during midlife, a woman's bones are much stronger if her calcium intake was adequate during her teenage years. This is because close to 90 percent of an adult's bone mass is established by the end of the teens.
As a woman ages, her need for adequate calcium continues. In general, a woman begins to lose bone in her late 20s to early 30s. Health professionals agree that, to reduce this loss, a woman should pay close attention to her calcium/magnesium/vitamin D intake.
Calcium requirements increase significantly when a woman is pregnant. The developing baby requires calcium for the development of bones and teeth and this must come from calcium supplies within the mother's body. If adequate calcium is not provided by the diet, calcium will be obtained from the bones and teeth of the mother.
After menopause, when a woman's body produces less estrogen than during her childbearing years, she will lose between two and five percent of bone mass per year for about five years, after which the bone loss continues at a slower pace. When the loss of bone density becomes significant, bones become porous, brittle and fragile - the condition known as osteoporosis.
While women are typically at a greater risk for osteoporosis than men, one in eight Canadian men over the age of 50 also develops this disease. Risk factors for developing osteoporosis include:
- Small/slight build
- Caucasian or Asian ancestry
- Family history of osteoporosis
- Little physical activity/sedentary lifestyle
- No weight-bearing exercise
- Poor calcium intake
- Limited exposure to sunlight or poor dietary intake of vitamin D
- More than three cups daily of coffee, tea, or cola
- More than 2 drinks of alcohol daily
- Use of tobacco
- Prolonged use of thyroid medications, cortisone, prednisone, or anti-convulsant drugs
- Primary hyperparathyroidism
The Importance of Exercise
For the bones to absorb calcium and become stronger, they must continually receive the message that they are needed to support the body. When the body is active, and the muscles placing tension on the bones, calcium is deposited to ensure this force does not result in injury.
To ensure your bones 'recognize' that they must absorb calcium, you should perform weight-bearing and resistance exercises at least three times a week. (Weight bearing exercise includes walking, running, aerobics, hiking, dancing and weight-training.) Although exercise alone cannot prevent osteoporosis, it should be part of your overall program to prevent this very serious condition.
If you are over 40, please be sure to check with your doctor before starting an exercise program.
The Impact of Osteoporosis
Osteoporosis is a debilitating disease that can greatly compromise the quality of life. Bones weakened by th econdition can cause disfigurement, loss of height, reduction of mobility, fractures and pain - leading to increased dependence on others.
One of the problems with osteoporosis is that it produces no symptoms. The disease progresses silently until a fall or other mishap causes a fracture - usually in the hip, spine, ankle or wrist.
The female hormone estrogen is responsible to a degree for keeping the bones strong. This is why post-menopausal women are at particular risk for osteoporosis.
A Little Prevention...
Fractures attributable to osteoporosis are largely preventable when the condition is discovered early and treated appropriately.
If the condition is in its earliest stage, your doctor may recommend increased calcium supplementation combined with a program of weight-bearing exercise to help boost bone mass. If the condition has progressed further, prescription drugs may help arrest further bone loss. Whether or not you have osteoporosis, if you are a pre or post-menopausal woman, you should obtain a minimum 1500mg of calcium on a daily basis. This may be obtained through the diet, supplementation or a combination of the two.