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United States Department of Agriculture

Agricultural Research Service

A Lesson in Nutrition from the Three Little Pigs
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Fariba K. Roughead

From the story—"The Three Little Pigs"—we learn at an early age that building a sturdy house requires a good foundation and the right combination of materials. The same is true with strong bones. The foundation of healthy bones is the protein matrix, which is about 90 percent collagen and a mixture of noncollagenous proteins.

This protein matrix is a highly organized lattice upon which calcium phosphate crystals are formed. Some of the noncollagenous proteins help bind the protein matrix to the mineral components, just as the mortar used in building a house binds the bricks to each other and to the foundation. Several enzymes that contain trace minerals like zinc and copper are like the masons necessary for getting the job done.

While flimsy houses are not a major problem in this country, osteoporosis, a disease of fragile bone, is a national epidemic! Currently, 10 million individuals suffer from osteoporosis. Another 18 million have low bone mass and are at risk of developing the disease. And these statistics are predicted to increase as the baby boomers age.

There is no cure for osteoporosis, so the adage that an ounce of prevention is worth a pound of cure is especially true. Because women lose a lot of bone in the years surrounding menopause, one of the preventive tools has been hormone replacement therapy. However, because of unpleasant side effects or fear of certain types of cancer, only 12-20 percent of postmenopausal women take hormones.

The National Osteoporosis Foundation ( recommends a balanced diet rich in calcium and vitamin D, weight-bearing exercises, and a healthy lifestyle which includes no smoking or excessive alcohol use.

But calcium is not the only mineral needed for strong bones. In fact, at the Grand Forks Human Nutrition Research Center, when we feed experimental animals diets containing plenty of calcium, but limited in other minerals—such as copper, zinc, magnesium, manganese, iron—they develop weak bones. Again, using the house analogy, this is like having plenty of bricks but not enough mortar or masons to build the house properly.

We think that there is more to the osteoporosis prevention story than just getting enough calcium and vitamin D in your diet. So, we have designed a large, carefully controlled study to test whether supplementation with calcium plus copper and zinc is better than calcium alone in slowing down the bone loss associated with menopause.

We are currently recruiting 220 healthy postmenopausal women from the community. The women will be assigned to two groups. For two years, one group will take a daily calcium supplement and a placebo, while the other group will take daily supplements of calcium plus copper and zinc.

Every six months, we will measure changes in the spine and hip bones using dual energy x-ray absorptiometry (or DXA) in our new, state-of-the art mobile nutrition research laboratory. Periodically, we will also make some blood and urine measurements. One year after the study has ended, we will invite everyone back to see if any benefits to the bone were permanent.

So, stay tuned for the results of this important study. In the mean time, keep moving and eat well.

Last Modified: 10/23/2006