Figure it all out: Fat's out but calcium is in. On the heels of government reports that urge Americans to cut down on fat, we take a hard look at our butter, milk and cheese consumption. But a National Institutes of Health 1984 consensus conference calls osteoporosis -- a disease causing loss of bone mass -- a major public-health problem that may be reduced in incidence by increased calcium intake in early life. Then comes the dairy industry, spending millions advertising the calcium benefits of its products.

It gets more complex. Drug store shelves are lined with calcium supplements, each boasting the advantages over the next bottle. And there is still debate about just how much calcium we need. Plus, our bodies absorb different amounts of calcium at different times of our lives and under various dietary conditions. And osteoporosis is not solely a calcium problem, according to Henry Kamin, professor of biochemistry at Duke University and chairman of the National Academy of Sciences committee that is presently updating the country's Recommended Dietary Allowances; there are other risk factors involved as well.

Despite the controversies, the bulk of the scientific evidence suggests that many men and women need more calcium, says Dr. William Peck, professor of medicine at the Washington University School of Medicine and chairman of the recent NIH consensus conference on osteoporosis. According to NIH, daily intake of the mineral falls "well below" the recommended dietary allowance.

"People should put their calcium money in the bank," says Kamin, referring to the importance of storing up calcium throughout life.

Now is the time to start. Here are the answers you'll need to find out how.

Q. How does the calcium content of dairy products compare?

A. A diet with dairy products doesn't necessarily mean a diet high in fat. Lowfat dairy products contain just as much if not more calcium than non-skimmed products, not only because the calcium is more concentrated (the calcium is in the milk, not the fat), but because processors often add nonfat milk solids to skim products to thicken them.

As a general rule, hard cheeses contain more calcium than soft cheeses. And butter and cream have little calcium; they are primarily fat.

Q. Are calcium supplements necessary?

A. Most nutrition experts agree that it's preferable to get calcium from the supermarket rather than the drug store -- you get a lot of other valuable nutrients out of food that you don't get from pills. So before considering supplementation, you first need to assess how much calcium you're getting daily in your diet.

Many in the scientific community, including NIH, recommend supplementation for those who are unable to get enough from their diets. And Henry Kamin from Duke University, who agrees that if "you're convinced" that your dietary calcium intake doesn't approach the RDA, supplementation is appropriate, but cautions that you shouldn't overdo it: "Twice as much is not twice as good."

Others, such as Mark Hegsted, professor emeritus of nutrition at Harvard University, who has been studying calcium for 40 years, believes that the evidence is "inadequate" that high calcium diets prevent osteoporosis, rendering supplementation unnecessary. The public posture for calcium should be one of moderation, says Hegsted, not hysteria.

Talk to your doctor about supplementation. For information on the different kinds of supplements and some warnings about them, read on.

Q: Who's at risk for osteoporosis?

A. Since women have less bone mass than men, they are more likely to get osteoporosis than men. White and Oriental women are at a higher risk than black women, white men are at a higher risk than black men. While lifelong low intakes of calcium are considered to be a risk factor, according to Dr. William Peck of the Washington University School of Medicine, others at a higher risk for osteoporosis include those who are: Elderly (advancing age slows down calcium absorption); Post menopausal, particularly after early menopause and surgically induced menopause (estrogen protects bones); Underweight or have a light bone structure; Hereditarily prone; Sedentary (exercise may replace bone calcium); Obsessive female exercisers, such as marathon runners, who may exercise to the point of amenorrhea; Alcoholics, heavy smokers and possibly caffeine abusers

Q. Who's not getting enough calcium?

A. Practically everybody, particularly women.

68 percent of the total U.S. population fails to meet the recommended dietary allowance (RDA) for calcium. Roughly eight out of 10 women don't get enough calcium. The two highest groups are:

87 percent of females between ages 15 and 18 don't meet the RDA.

84 percent of females between ages 35 and 50 don't meet the RDA. Source: USDA Nationwide Food Consumption Survey 1977-78.

Q. What are the best dietary sources of calcium?

A. Dairy products are the most concentrated sources, but sardines and salmon (with bones) and leafy green vegetables such as turnip greens, kale and collards are also good sources.

Whole milk 1 cup = 290 mg.; Lowfat milk 1 cup = 300 mg.; Buttermilk 1 cup = 300 mg.; Lowfat yogurt 1 cup = 415 mg.; Whole milk yogurt 1 cup = 275 mg.; Gruyere 1 ounce = 290 mg.; Parmesan 1 ounce = 340 mg.; Creamed cottage cheese 1 cup = 135 mg.; 2% cottage cheese 1 cup = 155 mg.; Brie 1 ounce = 50 mg.; 3 1/3 glasses of skim milk; 5 Tums tablets; 1 cup lowfat yogurt + 1 ounce cheddar cheese + 4 ounces salmon + 2/3 cup broccoli 68 87 84

Q. How widespread is osteoporosis?

A. According to NIH, osteoporosis affects as many as 15 to 20 million people in the U.S.

1.3 million fractures attributable to osteoporsis occur annually in people age 45 and older. Among those who live to be 90, 32 percent of women and 17 percent of men will suffer a hip fracture, most due to osteoporosis.

Q. What are ways to add calcium to the diet without the fat? And is it possible to get a calcium-rich diet without dairy products?

A. Remember that lowfat dairy products often provide more calcium than their higher fat counterparts -- and often for far less calories. For instance, while providing slightly more calcium, a cup of skim milk is approximately 90 calories; a cup of whole milk is 150. Patricia Hausman, a local nutritionist and author of "The Calcium Bible" (Rawson Associates, 1985, $13.95), makes the following suggestions from her book:

* Make a lowfat, higher-calcium substitute for cream cheese by putting a cup of plain yogurt in a paper coffee filter, covering it with plastic wrap and letting it sit over a mug in the refrigerator for a day, allowing the water to drain out of the yogurt.

* Add nonfat dry milk powder to soups, puddings, pie fillings, dairy drinks and sauces. It will thicken the texture of the food, giving it a higher fat mouth feel and at the same time raise the calcium content. A tablespoon of nonfat dry milk powder contains over 50 mg. of calcium, according to Hausman, and only 15 calories. She suggests combining it with a cold liquid and stirring to dissolve it before adding it to foods, particularly hot ones.

* Don't forget about lowfat yogurt and lower fat cheeses such as parmesan, part-skim ricotta and mozzarella.

As for getting "calcium without the cow," as Hausman puts it, she contends that there is "plenty of evidence that we do not build bone by milk alone" and that dairy-free diets aren't necessarily low in calcium. For those who don't eat dairy products and to balance the diets of those who do, Hausman suggests canned sardines, salmon, herring and smelts and vegetables such as bok choy, collard greens, okra, kale and mustard and turnip greens. Tofu, beans, seeds and grain cereals are also modest sources of calcium. Some nuts, such as almonds, brazil nuts and filberts, although high in fat, are also relatively good sources of calcium, if eaten in large quantities, says Hausman.

Quantity is the important point; the reason some nutrition experts contend that non-dairy products are less valuable sources of calcium than those "from the cow" is that you have to eat more than normal portions of them. For example, to equal the amount of calcium in a serving size of lowfat yogurt (about 400 mg. per cup), a person would have to eat two cups of mustard greens. Standard serving sizes for vegetables are 1/2 cup. Q What about vegetables such as spinach or swiss chard? Don't they contain calcium? A They do, but they also contain oxalic acid, a substance that is believed to hinder calcium absorption. While these are good foods to include in a balanced diet, Dr. William Peck, professor of medicine at the Washington University School of Medicine, advises that you shouldn't depend on just them for your sole source of calcium. (Other oxalates that are believed to hinder calcium absorption include rhubarb, beet greens and sorrel.)

Other regimens such as high-fiber and high-fat diets are believed to impair calcium absorption, but the degree to which they do so is uncertain, according to Peck. The degree to which high-protein diets may promote loss of calcium through the body is unclear as well, Peck added. Practically speaking, though, if calcium intake is liberal from other sources, these components shouldn't interfere substantially, Peck said.

Q. What are the different kinds of calcium supplements, and which are considered better than others?

A. The most frequently sold types of calcium supplements are calcium carbonate (frequently made from oyster shells), calcium phosphate, calcium lactate and calcium gluconate. Peck says there is no data to suggest that any one type of calcium is better absorbed by the body than another.

The difference between them is primarily the amount of elemental calcium they contain, or the amount of total calcium in each pill. So what it comes down to is price per pill and how many pills you end up taking.

Because calcium carbonate contains the most elemental calcium (40 percent), many physicians recommend this variety over others, says Peck. (The calcium percentages of the others are: calcium phosphate, 32 percent; calcium lactate, 13 percent; calcium gluconate, 9 percent.) Be aware, however, that calcium carbonate needs gastric acid for absorption, according to the Tufts University Diet and Nutrition newsletter, and sometimes this may be a problem in older individuals whose stomachs make less acid.

Antacids, such as Tums, Chooz and Alka-2, are all made of calcium carbonate and are cheaper than traditional supplements. Peck cautions, however, that excessive use of chewable antacids that contain sugar may not be the best bet for dental health. And antacids that contain aluminum may have an adverse effect on calcium absorption, according to the Tufts University newsletter. Excessive amounts of aluminum may be bad for your bones, says Robert Heaney, a professor at Creighton University who has been studying osteoporosis since 1955.

Another important warning: Beware of bone meal and dolomite, two calcium supplements that Peck says he does not recommend. These supplements have been under investigation by the Food and Drug Administration, as some products have been shown to contain lead, according to agency spokesman Emil Corwin.

Other tips when buying supplements:

* Make sure to read the fine print on the bottle to determine just how much calcium the product contains. If the label flashes "600 mg.," it may refer to the size of the pill, not the amount of calcium.

* If you have a family history of kidney stones, check with your physician before taking supplements.

* As for supplements that contain Vitamin D, which aids calcium absorption, be aware that in large doses taken over a prolonged period, Vitamin D is toxic. Supplements that contain about 125 IU's (International Units) of Vitamin D, which is about a third of the RDA for the vitamin, are safe, says John Vanderveen, director of the division of nutrition at the FDA, but cautions that no more than 2000 IU's a day are considered safe. Peck says that most people already get enough Vitamin D from sunlight and other food sources.

Q. When is the best time to take a calcium supplement?

A. There is disagreement surrounding this issue. Tufts University reports that spacing supplements between meals results in maximum absorption, although at least one supplement manufacturer recommends taking the tablets with meals to minimize stomach upset. And Heaney of Creighton University says that large amounts of calcium at mealtimes may impair zinc and iron absorption.

Peck says that he recommends that calcium be taken before bedtime since you need acid to absorb calcium and while you sleep, there's acid in your stomach. Heaney says supplements taken at night may protect against bone mass loss during the night, but that there are no definitive studies to suggest this is absolutely the case.

Q. Will calcium cure osteoporosis?

A. Evidence suggests that the disease is not reversable, that the skeleton cannot be rebuilt, but that increased calcium may slow down the rate of bone mass loss.

Q. Should men be concerned about getting more calcium?

A. Kamin says the process of calcium loss in bones is slower for men than women, so that osteoporosis is less of a problem in men, but not "a zero problem." Heaney says that since men generally eat more food than women, they are also apt to get more calcium. Plus, Heaney added, the "whole notion of slimness" hasn't obsessed men yet, so they may be more likely to consume more dairy products as well.

Q. Is calcium more important at certain ages?

A. The mass of women's bones decrease in mid-adulthood, says Kamin, so that the strategy is for women to assure themselves of a good bone density when they approach menopause.

But during adolescence, when bones are rapidly growing, calcium is especially important, agree physicians and nutritionists; and pregnant and lactating women need to ingest more calcium as well.

Here are some low-fat, high-calcium recipes to get you started: BANANA-ORANGE LASSI (1 serving)

1/3 cup plain low-fat yogurt

1/3 cup orange juice

2 tablespoons nonfat dry milk

1 small ripe banana

3 ice cubes

Combine all ingredients in a blender. Process until smooth. This recipe can be adapted by substituting peaches, blueberries or cantaloupe chunks for the banana. From "The Calcium Bible," by Patricia Hausman BAKED MACARONI AND CHEESE WITH SALMON (6 servings)

3 tablespoons butter

1 small onion, diced

1 tablespoon flour

1/4 teaspoon dry mustard

Generous sprinkling freshly ground black pepper

1 1/2 cups skim milk

1 tablespoon minced fresh parsley

1 cup shredded cheddar cheese

2 cups elbow macaroni, cooked and drained

15 1/2-ounce can salmon, drained and broken into chunks

1 cup frozen peas, cooked and drained

3/4 cup fresh bread crumbs

In a large skillet, melt 1 tablespoon butter and saute' onion until limp. Add flour, mustard and pepper; cook for 2 minutes.

Slowly stir in milk and parsley; cook until smooth and thickened. Remove from heat and stir in cheese.

In a bowl, combine cooked macaroni with salmon and peas. Spoon macaroni mixture into a 2 1/2-quart casserole dish. Pour cheese sauce over macaroni.

Melt remaining butter in skillet. Stir in bread crumbs and saute' until well coated. Sprinkle crumbs over top of macaroni mixture. Bake 25 minutes at 350 degrees until bubbly and crumbs are golden. From "The Calcium-Requirement Cookbook," by Joanne Ness and Genell Subak-Sharpe LEMON-LACED SARDINE SANDWICH (2 servings)

3 3/4-ounce can sardines

Hot pepper sauce to taste

1 tablespoon lemon juice

1 tablespoon butter, softened

2 teaspoons lemon rind, grated fine

1/2 teaspoon dijon mustard

Warm french bread, spinach leaves and tomatoes for serving

Drain the sardines. In a small bowl, combine the hot pepper sauce, lemon juice, butter, lemon rind and mustard. Spread over top half of french bread, place spinach leaves and tomatoes on bottom half and sandwich sardines in between. Adapted from "The Calcium Bible," by Patricia Hausman BROCCOLI RICOTTA SOUFFLE (4 servings)

2 tablespoons unsalted butter

1/2 cup finely chopped onion

1 cup chopped cooked broccoli

1 pound part skim milk ricotta

3 large eggs, lightly beaten

1/2 cup freshly grated parmesan

Salt and freshly ground pepper

4 egg whites

1/4 cup bread crumbs

Heat the butter in a skillet, add onion and saute' over moderate heat, stirring until soft. Stir in broccoli and cook 2 minutes longer. Transfer mixture to a large bowl and add ricotta, whole eggs, parmesan and salt and pepper to taste. Mix well.

Beat the egg whites in an electric mixer until they hold soft peaks. Fold 1/3 of the whites into the ricotta mixture, then fold in the remaining whites gently but thoroughly.

Grease a 1 1/2-quart souffle' dish and sprinkle with crumbs, shaking out any excess. Transfer the broccoli mixture to the souffle' dish, running your thumb around the edge to make a groove. Bake in a 375-degree oven for 35 to 40 minutes, or until puffed and golden brown. Serve immediately. Adapted from "Vegetables: The New Main Course Cookbook," by Joe Famularo and Louise Imperiale COOL CUCUMBER SOUP (4 servings)

1 clove garlic

1 tablespoon white wine vinegar

1 large cucumber

16-ounce container plain low-fat yogurt

4 teaspoons fresh dill, chopped, or 2 teaspoons dried dill

2 tablespoons fresh mint, chopped

Salt to taste

Chopped scallions for garnish

Rub a serving bowl with the garlic, then swirl the vinegar in the bowl. Peel and grate the cucumber; add to the bowl. Stir in the yogurt, dill and mint. Salt to taste, if desired, chill and garnish with chopped scallions. Adapted from "The Calcium Bible," by Patricia Hausman