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Need calcium? Try tofu and tortillas....

Need calcium? Try tofu and tortillas ...

With an eye toward preventing or postponing osteoporosis--calcium loss that can embrittle bones--many people have been trying to increase the level of calcium in their diet. While drinki plenty of skim milk would seem to be an obvious solution, many don't like its taste or can't digest the lactose most dairy products contain. Many who could eat cheese are reluctant to make it their primary calcium source because of the calories, cholesterol and fat it contains. but two alternatives that might warrant consideration include tofu and lime-treated corn tortillas, according to new animal research at the University of Illinois in Urbana-champaign.

The tortilla's main calcium source is the lime--Ca(OH).sub.2.--an alkaline compound added to soften the corn as it's boiled. Not only is the tortilla's calcium "highly bioavailable" -- about equivalent to that in milk -- but te lime treatment enhances protein quality, according to Angela Poneros/Schneier and John Erdman. Their measurements, made from the ashed leg bones of rats sacrificed after 27 days of feeding, show that tortillas can provide up to almost 300 milligrams of calcium per 100 grams (3.5 ounces). The adult recommended daily allowance (RDA) of calcium for humans is 800 mg.

More unexpected, the authors write in the January/February JOURNAL OF FOOD SCIENCE, is a finding that the calcium in the soybean-based tofu they studied was 12.6 percent more bioavailable than that in nonfat milk. It had generally been assumed, they note, that milk products provide a more bioavailable source of this important mineral than do plant products. However, all tofu is not alike. The type the Illinois scientists studied, which uses calcium sulfate (CaSO.sub.4.) to coagulate soybean "milk" during processing, provides roughly 128 mg of the mineral per 100 grams. Tofu made with magnesium chloride instead of CaSO.sub.4 offers only about a tenth as much calcium.

Finally, their study appears to solve a nagging question: whether vitamin C enhances the availability of calcium in the body. In experiments involving nonfat dry milk, mozzarella cheese, tortillas and tofu, the Illinois researchers found no increased calcium bioavailability from adding vitamin C.
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Publication:Science News
Date:Mar 12, 1988
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