The scientific community, including the National Research Council (NRC) and U.S. Surgeon Gen. C. Everett Koop, has a bone to pick with women who regularly fail to meet the Recommended Dietary Allowance of 800 milligrams of calcium or who do so by swallowing calcium tablets in lieu of low-fat foods. There is concern that the importance of continuously replenishing the body’s supply of the mineral through dietary sources has been under-evaluated and overshadowed by the fear of fat in the diet.
A report released earlier this month by the NRC stressed the need for young and adolescent women to increase their intake of dietary calcium. The Surgeon General’s Report on Nutrition and Health, published last year, also addressed this topic.
“Calcium is an essential nutrient,” the NRC report stated. “It is necessary for adequate growth and skeletal development. Certain segments of the population, especially women and adolescents, need to make careful food choices to obtain adequate calcium from the food supply. The committee recommends that consumption of low- and nonfat dairy products and dark green vegetables, which are rich sources of calcium, can assist in maintaining calcium intake at approximately the RDA levels.”
Furthermore, the report continues, “the potential benefits of calcium intake above the RDAs to prevent osteoporosis or hypertension are not well-documented and do not justify the use of calcium supplements.”
Figures taken from the USDA’s nationwide food consumption survey found that in 1985 women between the ages of 19 and 34 managed to achieve only about 80% of the RDA of calcium from food sources. Calcium intake for women in the 35- to 50-year-old age range, dropped to as low as 68% of the RDA--which is itself under scrutiny for being too low.
And since 1984, when a National Institutes of Health panel concluded that post-menopausal women needed twice the RDA of calcium and pre-menopausal women needed 1 1/2 times the RDA, supplement sales have “skyrocketed,” USDA reports.
To improve consumer intake of dietary calcium, researchers have launched a triple attack. They are re-emphasizing the importance of building bone during the formative years, noting that older women consuming less than half the calcium needed over a prolonged period can suffer a loss of nearly 5% of spinal bone per year. They are stressing that the female hormone estrogen has a significant role in bone loss. And they are citing the negative effects of meeting the recommended goal through supplementation.
Research data indicates that taking extra calcium after menopause probably doesn’t slow bone loss and building additional bone during youth--when the soft tissue inside the bones is in a continuous state of development--is the best insurance against osteoporosis later in life.
This was underscored most recently when studies of high calcium intake in older rats were completed. The research was directed by Dr. James C. Smith, head of the Vitamin and Mineral Nutrition Laboratory at Beltsville, Md., part of the government’s Agricultural Research Service.
“I think there’s a body of evidence that the best way is to build up the bones before menopause,” Smith said in an interview, adding, “but I haven’t worked with women.”
His investigation was conducted at the Beltsville lab by University of Maryland graduate students under the direction of Joseph H. Soares, nutrition professor.
It is scientific fact that the body’s ability to absorb calcium is variable with age. During typical periods of growth, intestinal absorption of calcium increases, with infants and children absorbing up to 60% of the calcium they ingest. Pregnant women use about 50% and other adults only retain about 30%. Calcium available from supplements is often even less, depending upon the binders used in the product, which can hold onto the calcium and prevent the body from using it. The ability of an individual’s stomach acid to dissolve the supplements also is associated with malabsorption.
And there are other factors: bone loss accelerates naturally after age 35 and becomes more and more difficult to retard with age; after menopause a steady decline of estrogen--an important component in bone mineralization--is observed, and the process of bone development appears to slow down as an animal ages, making the bones solid, more brittle and thus less efficient at storing calcium.
(Ninety-nine percent of the body’s calcium is stored in the bones and teeth. But it is used for various bodily functions. These include: regulating cell and nerve functions, maintaining normal blood pressure, muscle contraction capabilities including maintaining heartbeat, clotting of blood and preserving the material that holds cells together.)
“The high calcium intake did not affect bone dynamics in the aged female rats but increased bone formation in the young rats,” said Rashmi Sinha, the nutritionist who conducted the study. “Just taking a lot of calcium later in life, without replacing the female hormones, is not going to increase bone formation as it does earlier in life.”
Risk of Cancer
But estrogen replacement therapy is associated with an increased risk for endometrial cancer and requires ongoing medical follow-up, according to Dr. Bess Dawson Hughes, director of the Calcium and Bone Research Laboratory at the USDA Human Nutrition Research Center on Aging at Tufts University. She is currently conducting a five-year study of 360 post-menopausal women to determine the benefit of taking calcium, how much is necessary to minimize bone loss and the potential hazards associated with calcium supplementation. Preliminary results indicate that with extremely low intakes of calcium--below the current U.S. intake level of 600 milligrams--there is some benefit, even without estrogen replacement therapy.
“The study suggests that postmenopausal women most likely to benefit from increased calcium are those who consume less than 400 milligrams a day, the equivalent of 1 1/3 glasses of milk,” she said.
“If our research shows calcium can retard bone loss in some women regardless of estrogen, that’s good news, because estrogen replacement therapy isn’t for everybody.”
Osteoporosis is the gradual loss of bone mineral from the skeleton, occuring in millions of American women (and some men), and it “goes on for many, many years,” she said. It starts as early as age 20 and continues at a rate of 1% a year in women throughout their lives. The rate in men is about .25% per year.
This deterioration typically starts out in the spine, and manifests itself as a compression fracture. It is a very common disorder, according to Dawson Hughes, who estimated that one out of every four white women over the age of 60 will be afflicted with the ailment. There are a number of factors that increase risk.
Since women have less bone to start with and tend to lose it at a greater rate from their spines, being a female is the primary factor, said Dawson Hughes. Being either Asian or Caucasian is another. Family history has a role, as does a lifetime of low calcium intake. Early menopause, low body weight, sedentary life style, bearing no children, alcohol abuse, high sodium intake, cigarette smoking, high caffeine intake, high protein intake and high phosphorus intake are others.
One conclusion that can be drawn is that younger women, who typically are deficient in calcium as well as iron, should adjust their diets to include at least three servings of dairy products and other calcium-rich foods per day, instead of relying on supplements.
According to the National Dairy Board, a serving size is: 1 cup milk, 8 ounces yogurt, 1 1/2 ounces natural cheese or 2 ounces processed cheese.
Drinking nonfat or low-fat milk is the most efficient way to accomplish this. One (8-ounce) serving of fluid nonfat milk provides about 90 calories, less than a gram of fat and 300 milligrams of calcium. The same size serving of 1% low-fat milk offers 102 calories, 3 grams fat and 300 milligrams calcium. One-cup of whole milk provides the most calories and fat for its calcium benefit--150 calories, 8 grams fat and 291 grams calcium--while 2% low fat has just slightly less calories and fat: 121 and 5 grams fat for its 297 grams calcium.
Meeting Dairy Requirement
If drinking milk is not an option, here are some dairy and non-dairy foods which in combination can help meet the daily requirement: 1 ounce of low-fat cheese, such as part-skim mozzarella adds 200 milligrams calcium; 1 cup low-fat cottage cheese offers about 140 milligrams calcium, 1 cup low-fat fruit-added yogurt, 345; 3 ounces canned salmon with bones, 180, and 3 ounces sardines, 300 milligrams.
Dark leafy vegetables, in general, are rich in calcium, but some, such as kale, broccoli and beet greens, are the best absorbed. Other types, such as spinach and turnip greens, contain a naturally occuring calcium binder, which tends to hold on to the calcium.
Some processed foods, because of fortification or a calcium-salt additive used in the manufacturing process, are also good sources of dietary calcium. These include tofu (bean curd), canned tomatoes, stone-ground or self-rising flour and blackstrap molasses.
In addition to increasing low-fat sources of calcium in the diet, women are encouraged to develop a regular routine of exercise. This helps maintain bone mass and stimulates new bone formation. Although Dawson Hughes admits that the exact role of exercise in the maintenance of bone mass remains a little unclear, it appears that it is “very, very important.”
She said it apparently increased bone density in a studied population representing a cross section of women of all ages--particularly those who previously were extremely sedentary.
In another study, women who exercised for one hour, three times a week increased their bone mineral content by 1% over a one-year period. Those, who did not decreased their bone mineral content by the same amount.
“If you took the balance on a daily basis,” she explained, “the exercisers were gaining 42 milligrams of calcium for their bodies. You have about 100,000 milligrams in your body, so that doesn’t sound like much. But every day, day in, day out, that adds up . . . . It’s a very effective means of impact on your bones.”
To help in designing a calcium-conscious life style, consider some of the following recipes, which are based upon a popular Oriental cooking ingredient and non-dairy substitute, bean curd.
SIMPLY SUPER SUKIYAKI
1/2 cup soy sauce
2 tablespoons sugar
3/4 pound ground beef
1 medium onion, thinly sliced
1 pound spinach, washed and drained
1 bunch green onions, cut into 2-inch lengths
1/4 pound mushrooms, sliced
1 (10.5-ounce) package firm tofu, cut into 1-inch cubes and well-drained
Combine soy sauce, sugar and 1/2 cup water. Set aside.
Brown beef in Dutch oven or large skillet over medium heat, stirring to break beef into large chunks. Add onion and cook 1 minute. Add spinach, white parts of green onions, mushrooms and soy sauce mixture and cook until spinach is limp, stirring constantly. Gently stir in tofu and green onion tops. Cook about 5 to 7 minutes or until vegetables are tender and tofu is seasoned with sauce. Makes 4 to 6 servings.
1 (0.6-ounce) package sugar-free lemon gelatin
2 cups boiling water
1 1/2 cups cold water
1 (14.2-ounce) package soft tofu
3 tablespoons lemon juice
2 teaspoons grated lemon zest
1 (9-inch) graham cracker crust
Dissolve gelatin in boiling water. Add cold water and chill until consistency of egg whites. Place in blender with tofu and lemon juice. Quickly blend until well mixed. Stir in lemon peel, then pour into pie crust. Chill until firm. Serve topped with strawberries or other fresh fruit. Makes 8 servings.
3/4 cup chopped onion
2 tablespoons oil
1 (28-ounce) can tomatoes
1 (1 1/4-ounce) package taco seasoning mix
1/2 teaspoon salt
1 (4-ounce) can chopped green chiles
1 (7 1/2-ounce) package tortilla chips
1/4 pound Jack cheese, shredded
1/4 pound Cheddar cheese, shredded
1 (14.2-ounce) package regular tofu, crumbled
Saute onion in oil until tender. Add tomatoes, taco seasoning, salt and green chiles. Simmer, uncovered, 10 to 15 minutes. In lightly greased 2-quart casserole, arrange 1/2 of tortilla chips, sauce, cheese and tofu. Repeat layers, reserving small amount cheese. Bake at 350 degrees 25 minutes. Sprinkle with reserved cheese and continue baking 10 minutes longer. Let stand 10 minutes before cutting. Makes 6 to 8 servings.
BLUE CHEESE DIP
1 (14.2-ounce) package soft tofu, drained
1 (1.1-ounce) package blue cheese salad dressing mix
Fresh vegetables or chips
Place tofu on paper towel and gently squeeze out excess moisture. Crumble and place in blender along with packaged mix. Whirl until dip is well blended. Serve with fresh vegetables or chips. Makes 1 1/2 cups.
1 (14.2-ounce) package regular tofu, drained well
1 (10-ounce) package frozen, chopped broccoli, thawed
1 (17-ounce) can cream-style corn
2 egg whites, lightly beaten
1/2 cup cornmeal
1 teaspoon salt
1/8 teaspoon black pepper
1/4 cup bread crumbs
2 tablespoons butter or margarine
Crumble tofu to consistency of cottage cheese. Carefully blend together broccoli, corn, egg whites, cornmeal, butter, salt and pepper. Fold in crumbled tofu. Pour into greased 2-quart casserole sprayed with non-stick vegetable coating spray. Sprinkle with bread crumbs and dot with butter. Bake at 350 degrees 45 minutes or until set. Makes 6 to 8 servings.
1 cup prepared pizza sauce
1 (12-inch) frozen pizza crust
1/2 pound turkey sausage, cooked and drained
1 (10.5-ounce) package firm tofu, drained and crumbled
2 tablespoons black olives, sliced
2 tablespoons sliced mushrooms
2 tablespoons diced green peppers
1/2 teaspoon dried oregano
1 cup shredded part-skim mozzarella cheese
2 tablespoons grated Parmesan cheese
Spread half of pizza sauce on crust. Sprinkle with sausage. Drain tofu on paper towels. Gently squeeze out as much moisture as possible, then squeeze again. Crumble tofu to consistency of cottage cheese. Sprinkle over sausage, then top with olives, mushrooms, green peppers, oregano and cheeses. Bake at 450 degrees 15 to 20 minutes. Makes 1 pizza.
1 (15 1/2-ounce) can red salmon, flaked
1 (10 1/2-ounce) can cream of celery soup
1 (14.2-ounce) package firm tofu, crumbled
2 tablespoons minced onion
2 eggs, lightly beaten
1 tablespoon lemon juice
1/2 teaspoon salt
1/8 teaspoon black pepper
1/2 teaspoon dried dill weed
1/2 cup saltine crackers, crushed
Blend together salmon and soup in large bowl. Drain tofu on paper towel. Gently squeeze out moisture and crumble to consistency of cottage cheese. Add to salmon mixture along with onion, eggs, lemon juice, salt, pepper, dill and cracker crumbs. Blend together lightly. Shape into loaf and place in non-stick 9x5-inch loaf pan. Bake at 350 degrees 1 hour. Let stand 10 minutes before unmolding. Makes 6 to 8 servings.
1 cup soft tofu, drained
1 banana, sliced
1/4 cup egg substitute
1/2 cup low-fat milk
2 tablespoons honey
1/2 teaspoon banana extract
1 teaspoon coconut extract
Place tofu on paper towel and squeeze out excess moisture. Place in blender container along with banana, egg substitute, milk, honey and extracts. Whirl until blended and smooth. Serve over ice. Sprinkle with cinnamon-sugar. Makes about 3 cups.