Boning Up on Calcium (and Vitamin D)

"I can walk for 12 minutes on the treadmill," boasted Shirley to me when I bumped into her as she emerged from our neighborhood gym. "This is the first time in my 76 years that I have ever exercised. But my doctor told me I had to for my bones. Now I have a trainer and I am even lifting weights." "Are you taking calcium also?" I asked, having just purchased a large bottle of calcium supplements myself. "No, I can't be bothered. I take enough medication for my high blood pressure. My doctor didn't say anything and besides, I drink at least a glass of milk a day."

The sidewalk did not seem to be the place for a short workshop on calcium supplementation but as I walked away, I wondered if Shirley was really doing enough for her bones. I wanted to ask her if she had a bone scan recently to find out if she was developing osteoporosis. Was she getting enough vitamin D? Did she even know calcium would not be absorbed into her body unless her body had enough vitamin D? A glass a milk a day did not seem to be enough to give her the calcium she needed at her age and somehow I doubted she was drinking shots of cod liver oil to get her D vitamin.

Was my interest in Shirley's bones a result of a recent conversion myself on the importance of getting enough calcium and vitamin D? So many people I knew were on medicine to reverse the early signs of bone weakening that it felt like an epidemic. And these were not people in their eighties: one was a competitive athlete in her forties and another was the fifty-something husband of a friend.

What they all had in common was years of avoidance of dairy products, not taking calcium supplements, staying out of the sun to prevent skin cancer and as a result, preventing natural vitamin D from being made in the skin. Additionally, they didn't do enough upper body weight-bearing exercise. According to the National Osteoporosis Foundation, adults under the age of 50 need l000mg of calcium and over 50, 1200 mg daily. Eight-ounce servings of milk, cottage and ricotta cheese and yogurt provide between 25-40% of daily calcium needs. Some orange juices and other foods are fortified with calcium fortified but unless one makes the effort to consume enough of these foods daily, it is very easy for your diet to be deficient in this essential mineral.

Think you are getting enough vitamin D? Think again. The National Osteoporosis Foundation reviewed studies on the intake of this vitamin and found that there is a widespread deficiency in the U.S. among adults. Our bodies make vitamin D naturally through the action of ultraviolet radiation on our skin. So it seems as if we should all have enough. Wrong. Exposure to ultraviolet radiation is also linked to skin cancer so protective skin coverings and sunblock effectively prevent this vitamin from being made. We can't really get enough from food unless we eat a great deal of salmon, tuna and mackerel and drink fish liver oils. Fortunately, our milk has been fortified with this vitamin since the l930's when it was found that vitamin D prevented rickets, a bone disease prevalent among children. And now orange juice, ready to eat breakfast cereals, yogurt and margarine may also be fortified with vitamin D. A National Institute of Health (NIH) fact sheet on adequate intake of this vitamin recommends 200 IU (international units) daily for those 50 and younger. For baby boomers and beyond, ages 51-70, the amount goes up to 400 IU. And people over 70, such as my 76-year-old neighbor, should be getting 600 IU a day.

So for many of us, supplements may be the only reliable way of getting enough of this mineral and vitamin in our diet. A quick check of calcium supplements in my local drug store indicated that most contain vitamin D as well. But not all calcium supplements are equally effective or even safe. Calcium from unrefined oyster shell, bone meal or dolomite may contain lead. Moreover, you won't find calcium in pure form in any supplement. In nature this mineral is always combined with another substance. The most common combinations found in supplements are calcium carbonate, calcium citrate and calcium phosphate. The pills tend to be large, but chewable forms of this supplement are also available. The NIH Bone Health fact sheet suggests not taking all the pills at once but spacing them out throughout the day. This apparently improves their absorption into the body. Calcium carbonate is absorbed best when taken with food but calcium citrate can be taken on an empty stomach. Remember to drink plenty of water as these supplements can be constipating.

And check with your physician about interactions between calcium supplements and other medications you may be taking. If you are post-menopausal ask about having a bone scan to establish your own baseline of bone density. And don't wait until you are 76 to start to exercise.

Judith Wurtman is the author of "The Serotonin Power Diet".