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Calcium and Vitamin D Strong Bones for Life




Excerpted from
Strong Women Eat Well: Nutritional Strategies for a Healthy Body and Mind
By Miriam E. Nelson, Ph.D.

Every time I walk down the street and see a woman hunched over from spinal fractures, every time I get a call from a woman who is suffering from osteoporosis, my resolve to help women-and to look after my own bones-becomes stronger.

I began researching exercise, nutrition, and bone health in women at Tufts when I was 23 years old. Since that time, a new world has opened up. We now know that we can strengthen our bones, whatever our age. We have learned that osteoporosis is a preventable disease, and that if you already have it, you can treat it. The most important thing you can do is to start right now-whatever your age-to make sure that your bones last a lifetime.

Osteoporosis is a devastating disease that can leave a person frail, deformed, depressed, disabled, and in pain. Osteoporosis is characterized by loss of bone density, which leads to fragile bones that are susceptible to fracture. One in three women can expect to suffer from the disease in her lifetime. In fact, one in two women and one in eight men over 50 will have an osteoporosis-related fracture in their lifetimes.

In the United States today, 10 million people already have osteoporosis, and 18 million more have low bone mass, putting them at risk for osteoporosis. A woman's risk of dying from the complications of a hip fracture are greater than her risk of developing breast, cervical, and uterine cancer combined.

Osteoporosis is a completely silent disease. You cannot feel yourself losing bone. Only after you have suffered from a fracture are you aware that the disease has crept up on you. Hip, spine, and wrist are the bones most susceptible to fracture, although any bone can fracture from the disease. Wrist fractures in women in their mid-fifties have recently been noted as an early sign of osteoporosis.

By about age 20, the average woman has accumulated 98 percent of her skeletal mass. Building strong bones during childhood and adolescence and maintaining those bones into later life is the best defense against developing osteoporosis.

A comprehensive program that can help prevent this disease includes a diet that is rich in calcium and vitamin D, plenty of exercise-especially weight-bearing and strengthening exercises-and a way of life that excludes smoking and excessive use of alcohol. Some women may need to take medication to prevent or treat osteoporosis.

Strong Women, Strong Bones, my previous book, presents all the latest information about osteoporosis. If you are at risk for the disease, I encourage you to read the book and to use the Resources at the back of this book.

Vitamin D and our bones

Vitamin D acts to strengthen our bones and teeth by increasing the absorption of calcium in the gut and by assisting with the mineralization of calcium in bone. When vitamin D is insufficient in the body, calcium absorption is also sub-optimal, and the symptoms of vitamin D deficiency are similar to those of calcium deficiency: rickets in children, whose weakened bones and muscles cause bowed legs and a protruding abdomen; osteomalacia, or adult rickets, which affects young adult women; and, of course, osteoporosis, or extreme loss of calcium from the bones. Rickets and osteomalacia are relatively rare in the United States, but osteoporosis is on the rise, due to longer life expectancy, sedentary habits, poor nutrition, and detrimental lifestyle factors that harm bone, such as smoking and disordered eating.

What the research shows

The importance of vitamin D in preventing bone loss was shown definitively in a seminal study of calcium supplements undertaken at Tufts University in the late 1980s through the early 1990s by Bess Dawson-Hughes, M.D., and colleagues. The subjects were a group of 389 men and women volunteers (mostly women) over 65, about half of whom were given daily calcium supplements that contained a significant amount of vitamin D, with the control subjects being given placebos.

In following these men and women over the course of three years, the scientists discovered that the volunteers receiving the calcium supplement with vitamin D, which contained 500 mg of calcium and 700 IU of vitamin D, had half the number of fractures as those taking the placebo.

There have been no studies showing that calcium supplementation alone can reduce fractures. Vitamin D is the critical addition to calcium that makes the difference.

How much vitamin D do I need?

The following chart shows your vitamin D requirements. The DRIs are the same for women and men.

Supplements Are Not a Last Resort

In the best of all possible worlds, we would all eat so perfectly that each of us would be in complete nutritional balance ... unfortunately, this is not a reality. Many of us do get the nutrients our bodies need from the food we eat and, perhaps, from one multivitamin pill a day. For us, most vitamin- or mineral-specific supplements are superfluous, or at best, icing on the cake. But in the case of calcium supplements, there are many people, especially women, whose need for calcium and vitamin D is not being met by food alone, even when augmented by a daily multivitamin pill. For them, supplements may make the difference between a steady loss of bone density and maintaining healthy bones for life. There are a bewildering number of calcium supplements from which to choose. Here are some of the issues you should consider.

How to decide if you need to take
a calcium/vitamin D supplement

1. Estimate how much calcium you get in your daily diet, using the table beginning on page 89.

2. Look at your age category and the DRI on pages 87 and 91.

3. Calculate the difference and make that up either by adding more calcium-rich foods to your diet or by taking supplements.

If you take a supplement, which type should it be?

There are two main formulations of calcium supplements: calcium citrate and calcium carbonate. Calcium citrate is more easily absorbed than calcium carbonate, but both types have been shown to be effective in improving bone health, when combined with vitamin D.

Rule of thumb: Try calcium citrate first. It can be taken after eating or on an empty stomach. If possible, take your supplement later in the day as calcium is better absorbed when taken without the presence of other food. If you don't tolerate calcium citrate (which most people do), switch to calcium carbonate. Calcium carbonate should be taken with a meal. It can give you gas, and some people become constipated, so take it in small doses.

A third supplement formulation is made up of powdered or crushed materials such as oyster shell, bone meal or dolomite, which are rich in calcium. Use caution in taking these supplements. Some of them are not well absorbed because they don't dissolve easily in the stomach, and some of the sources for the supplements can be contaminated with trace compounds that are toxic.

Be sure that whatever supplement you take contains vitamin D or, if not, that you are receiving vitamin D from another multivitamin supplement.

Do not take more calcium or vitamin D than you need

Supplements are a form of medication-remember that you are also getting these nutrients from foods. Excessive dosages of calcium (more than 1,000 milligrams, or 1 gram, a day from supplementation) or vitamin D (2,000 IU a day from all sources) can be dangerous and can actually reverse the beneficial effects of sufficient amounts of these nutrients.

At the moment, there is no evidence that calcium supplements containing such trace minerals as magnesium, copper, and other nutrients are more effective. Although these minerals may in themselves help promote healthy bones, they have not been shown to be of any additional help when taken supplementally.

I believe that eating food that promotes strong bones for life promotes overall health and longevity. We should be careful not to fall into an "eat for the disease of the month" syndrome. When I eat well, which is most of the time, I feel great, and I know that I'm helping to strengthen my bones as well as my heart, skin, eyes-in fact my whole body. This is a goal I hope all of us can work toward.

But nutrition is only a piece of the puzzle for achieving and maintaining strong bones. Genetics, sex, race, exercise, and lifestyle are also determinants, as they are for every other aspect of our health, and some of these factors are beyond our control at present.

I am sure that within the next five to ten years, enormous progress will be made in finding ways to reverse or cure osteoporosis, through medications and through better understanding of nutrition. Until then, your understanding of your own nutritional goals and your awareness of what you eat are the best ways to control many aspects of your good health. In terms of strong bones, those goals should include adequate amounts of calcium and vitamin D as well as plenty of exercise, all of which have been shown overwhelmingly to promote good bone health.



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