Calcium: after the craze.

"A few years ago, everyone recommended it, but now I've heard you don't need it," says Hilda Flamm, a grandmother from Austerlitz, New York. "Should I take calcium or not?"

It's no surprise that Flamm --and millions like her--are confused. They remember the "Calcium Craze" of 1982 to 1986.

Every time you turned the page of a magazine, there was a calcium supplement ad with the silhouette of a stooped-over woman.

Then the bubble burst.

"The miracle mineral builds up bones, teeth--and perhaps false hopes," voted Newsweek in 1986.

End of craze...at least for the public. Researchers continued to amass evidence that calcium--and vitamin D--strengthens bones. By 1993, their case was so strong that the FDA ruled that food and suplement labels could state that calcium can help prevent osteoporosis, the disease of fragile bones.

Will new claims rekindle the craze? let's hope so...but without the hype that killed the last one. The numbers are downright scary:

* Roughly 25 million Americans have osteoporosis. Four out of five are women. As the population ages, that number is sure to swell.

* Osteoporosis causes 1.5 million fractures a year--mostly of the back, hip, and wrist. The current yearly tab: $10 billion to $12 billion. It's expected to hit $60 billion to $80 billion by the year 2025.

* Fifteen percent of white women 50 or older will fracture a hip sometime in their lifetimes. Among those 75 or older, as many as 20 percent will die within a year after the fracture, due to complications like a blood clot or pneumonia. Half will lose the ability to walk independently. Only one out of five fully recovers.

* Men get osteoporosis less often because their bones are denser and because they die younger. As more men live longer, it should become more of a problem for them.

And then there's the good news: "Osteoporosis is a disease that is preventable," says C. Conrad Johnston, an osteoporosis expert at Indiana University Medical Center and vice president of the National Osteoporosis Foundation in Washington, D.C. "With adequate diet, weight-bearing exercise, and judicious use of hormone replacement therapy, we could make a big impact."

To understand how, you have to know what makes bones strong...and what makes them break.

DEM BONES

Bones don't start breaking as you get older because they've gotten tired of carrying you around for 70-odd years.

"Bone is continually being destroyed and rebuilt to adapt to mechanical strain," explained Gideon Rodan, a bone expert with the drug manufacturer Merck Sharp & Dohme, at a recent conference sponsored by the National Osteoporosis Foundation. Thanks to this "remodeling" process, about a fifth of your skeleton is replaced each year.

But remodeling isn't always a zerosum game. During the first few decades of life, each rebuilding makes the bones denser. They "peak" somewhere between ages 25 and 35. It's not until later that the trouble starts:

* At menopause, women's bodies begin to dissolve old bone at an accelerated rate. This hits the wrist and spine hardest.

* As men and women age, their bodies build new bone at a slower pace. This hits the hip hardest.

That's what happens to everyone. In people whose genes make them prone to osteoporosis, the bone loss is out of control.

BAD GENES

"We now have an osteoporosis gene," says Mona Calvo, a calcium researcher at the Food and Drug Administration, referring to work by Nigel Morrison of the Garvan Institute of Medical Research in Sydney, Australia.

People who have the gene have different vitamin D "receptors" on their cells. The receptors control other genes that determine whether the body absorbs enough calcium.(1)

Scientists don't know if that fully explains why the remodeling process goes haywire. But they know the results: Over time, the classic honeycomb pattern of healthy bone gives way to a series of weakened fragments (see photo).

When bone is that weak, it doesn't even take a fall to fracture it. "Bending over and lifting 30 pounds--like grandma picking up baby--could be enough because it puts a lot of stress on the spine," says Indiana University's C. Conrad Johnston.

Knowing who is genetically predisposed to osteoporosis will someday make a big difference, says the FDA's Mona Calvo. "We'll have a way to pick out who in the crowd needs to build up and maintain their bone mass through diet and exercise."

For now, we're all in that boat. True, scientists have noticed that certain people are at greater risk. But some risks factors, like having small bones and fair skin, you can't change.

One thing you can change--in addition to taking estrogen--is the calcium you consume.

"When you sort out the evidence, it becomes clear that calcium has a positive effect on bone," says Robert Heaney, an osteoporosis expert at Creighton University in Omaha.

HOW MUCH AND WHEN

Exactly how much calcium do you need to protect your bones? Researchers are still unsure about middle-aged and older women. But for men, kids, and twenty-somethings, there is little debate.

* Youth. Everyone loses bone when they're old. It's inevitable. But if you stock up on bone when you're young, you'll have enough left over after those losses to avoid fractures. Denser bones explains why blacks have less osteoporosis than whites. It's not a calcium-rich diet, but good genes, that protect them.

"We tend to think of osteoporosis when menopause rolls around, but we can have the biggest impact between the ages of four and 20," says Charles Slemenda, a bone expert at Indiana University School of Medicine.

In fact, bones gain mass only during the first three decades of life--by age 18 they've reached 95 percent of their maximum density. Once you hit your peak bone mass at between 25 and 35, "that's all you'll ever have," says Slemenda.

Several years ago, he studied 70 pairs of twins aged six to 14 who were getting about 900 mg of calcium a day from food. Among the 22 pairs who had not yet reached puberty when the study begin, he found that an extra 450 mg to 1,000 mg a day raised bone mass by three to five percent over three years.(2)

But, based on only one study, Slemenda is not willing to recommend that all kids get more than the Recommended Dietary Allowance (RDA), which is 800 mg to 1,200 mg a day.

And, he cautions, "if you don't intend to increase your calcium intake for the long term, don't start, because there's a rebound as soon as you go off it." Three years after his twin study ended, the bones of the former calcium-takers were no denser than those of the non-takers.

Rebound aside, extra calcium is "benign" for kids, says Slemenda. Along with milk, he gives his own children calcium-fortified orange juice.

* Middle Age. During menopause, only one thing matters. "If you want to stop menopausal bone loss, taking estrogen is the only way," says Slemenda. "There are no nutritional or exercise replacements for estrogen."

But not all women opt for hormone replacement therapy. Even though it might lower the risk of heart disease, osteoporosis, and maybe Alzheimer's, many are nervous that it might also raise the risk of breast cancer. "Getting their bone mass measured may help women decide whether to take estrogen," says Indiana's Johnston.

That's not to say women can forget about calcium from their thirties to their fifties. "You always need an adequate calcium intake," says the FDA's Calvo. "It may allow you to keep what bone you've got."

What's adequate? The Recommended Dietary Allowance for people between the ages of 25 and 55 is 800 mg a day. The National Osteoporosis Foundation recommends 1,000 mg.

But some researchers think that the difference between 800 mg and 1,000 mg isn't worth arguing over. "Past surveys show that the female population is consuming about half that amount, so the real challenge is to reach 800 to 1,000 milligrams," says Bess Dawson-Hughes, an osteoporosis researcher at the U.S. Department of Agriculture's Human Nutrition Research Center on Aging at Tufts University.

And the Daily Value on food labels is 1,000 mg, notes Calvo. So anyone who uses labels to estimate daily intake will find it easier to shoot for that round number.

* Later Years. Here's where researchers disagree the most. The Recommended Dietary Allowance for people over the age of 55 is 800 mg a day. The Osteoporosis Foundation is pushing for 1,500 mg.

There is good logic behind an increase. "There's a sharp decline in calcium absorption that occurs after the age of 65," says Dawson-Hughes.

Still, she and others want proof that adding calcium to the diet slows bone loss. So far, the only undisputed evidence comes from her 1990 trial of 300 women.

Among women who were at least six years past menopause, an extra 500 mg of calcium a day slowed bone

loss, but only in those who were getting less than 400 mg from their food.(3) "After two years, there was no benefit in taking calcium among women getting between 400 and 650 milligrams a day from their diet," she concludes.

That's not what happened in a 1993 trial led by lan Reid of the University of Auckland in New Zealand. In his study, a calcium supplement of 1,000 mg a day slowed bone loss in late-menopausal women who were already getting about 750 mg of calcium from food.(4)

But after the first year of Reid's study, notes Dawson-Hughes, "there was an increase in calcium in the whole body, not in the spine or hip, so it may going to parts of the skeleton that aren't prone to fracture."

Yet Dawson-Hughes acknowledges that aiming for a higher daily intake--like the Osteoporosis Foundation's 1,500 mg--won't hurt.

"My concerns are the expense, and that we're not swinging the RDAs back and forth every year," she says. "More importantly, I wouldn't want to distract women from using other treatments with well-established benefits, like taking estrogen."

As for men, 800 to 1,000 mg a day is probably adequate.

How much is enough?

Researchers are debating whether to raise the Recommended Dietary Allowance (RDA) for calcium for adults, especially for older people, above the current 800 mg a day. In the meantime, it can't hurt to shoot for the National Osteoporosis Foundation's recommendations.

                                National     Recommended
                              Osteoporosis      Dietary
                               Foundation      Allowance
Age                            (mg/day)        (mg/day)
1-10                               800           800
11-24                            1,200           1,200
25+                              1,000           800
Post-menopausal women
not taking estrogen              1,500            --
Pregnant or lactating women      1,200           1,200

BEYOND CALCIUM

It's important not to oversell calcium. Among the other factors:

* Vitamin D. In 1992, French researchers gave 3,270 healthy women aged 69 to 106 either a placebo or 800 IU of vitamin D plus 1,200 mg of calcium a day. All were able to walk, but they lived in nursing homes or apartment buildings for the elderly, so they didn't get out much.

After a year and a half, the supplement-takers had 43 percent fewer broken hips.(5)

"It may never be too late to prevent hip fractures," condludes Pierre Meunier of the Institut National de la Sante et de la Recherche Medicale in Lyon, France.

The body needs vitamin D to absorb calcium, and many older people get too little from food or from sunshine. Even people who are outside get too little vitamin D in the winter.

"At the latitude of Boston, for example, there's too much atmosphere for the sun's rays to get through to your skin even if you're out skiing every day," saus Creighton's Robert Heaney.

How much vitamin D is enough? "The U.S. recommended Daily Allowance--400 IU--is not an outlandish level," says Heaney. You can get it from four glasses of milk, or almost any multivitamin supplement.

* Exercise. No disagreement here. Any exercise that puts a strain on your bones--just about anything but swimming or cycling--is important from cradle to grave.

"The longer you go without doing it, the harder it becomes," says Indiana University's Charles Slemenda.

Exercise not only builds bone and maintains strength, it also helps older people avoid falling. "People who exercise have greater mobility, better reflexes, and more muscle padding to diffuse the energy if they do fall," he adds. (1)Nature 367: 284, 1994. (2)New England Journal of Medicine 327: 82, 1992. (3)New England Journal of Medicine 323: 878, 1990. (4)New England Journal of Medicine 328: 460, 1993. (5)New England Jurnal of Medicine 327: 1637, 1992.

THE BOTTOM LINE

* White, fair-skinned, small-boned women, especially smokers, have the greatest risk of osteoporosis.

* Getting enough calcium, especially before age 30 and after age 60, can reduce the risk of osteoporosis. (For details, see page 8.)

* Walking and other exercise--almost anything except swimming or cycling--strengthens bones throughout life and helps prevent falls in older people.

* To absorb calcium, you should get about 400 IU a day of vitamin D. You'll find it in four glasses of milk, most ordinary multivitamins, or exposure to the sun. Except in the South or Southwest, the winter sun is too weak to enable your skin to make enough vitamin D.