We who are concerned about osteoporosis wonder what is the best source of calcium. Some people advise dairy products daily – not a possibility for those of us who are avoiding a monotonous diet and a major problem for those of us with milk sensitivities. Other people advise us to take a particular calcium supplement, saying that it is absorbed much better than other calcium supplements. In an interesting study, Sheikh and colleagues from the Baylor University Medical Center in Dallas, Texas,* cleared the gastrointestinal tracts of eight healthy, young volunteers both before and after testing with whole milk, calcium acetate, calcium lactate, calcium gluconate, calcium citrate, calcium carbonate, and a placebo. Thus they were able to calculate precisely the amount of calcium absorbed from each of the test materials, taken while fasting. The calcium salts were carefully given in gelatin capsules with water. Though the calcium supplements had very different degrees of solubility in water, all five dissolved completely dissolved completely in one hour in an acid solution comparable to that in our stomachs. Blood levels of a vitamin D metabolite, which enhances the absorption of calcium, were tested and found to be practically the same on all the test days.

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. . . there were no differences in levels of absorption between the milk and any of the five different calcium salts. . . . Thus, on the basis of this research, we have six equally appropriate choices . . .

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Their surprising results showed that there were no differences in levels of absorption between the milk and any of the five different calcium salts. In all cases, about "32 percent of the ingested calcium was absorbed from the various sources." Thus, on the basis of this research, we have six equally appropriate choices for our daily source of calcium.

The authors mention three particular aspects of their study: first, the calcium source was ingested while fasting; second, 500 mg of calcium was supplied by each source; and third, the volunteers were young and healthy. The results might have been different with a higher intake, with older people, and, of course, with ingestion during a meal.

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*Sheilh, M. S., et al, "Gastrointestinal Absorption of Calcium from Milk and Calcium Salts," The New England Journal of Medicine, 317(9):532-36, April 27, 1987.