The Daily Dose 2/28/08

I am always amazed at how medicine changes. Treatments that were previously considered to standard of care have come under great scrutiny and some are now recognized as potential harmful. Some issues that immediately come to mind are the controversies surrounding estrogen replacement therapy, and the use of vitamin E as an antioxidant. Even in the short time I have practiced medicine I have been witness to several of these "awakenings". My mentor in residency training (who was in his late 40’s) speculated that 50% of what he had learned was either obsolete or outdated. A recent study by Dr. Bolland and his associates in New Zealand further challenge medical knowledge. In a five-year study of 1471 osteoporosis patients, Bolland has found that calcium supplementation may in fact be harmful and contribute to an increased number of cardiovascular events. In the study, women were randomized to receive calcium at 1000 mg per day or placebo. All women were postmenopausal and over the age of 55. Ten percent were older than 80. Every six months, they evaluated the two groups for death, chest pain and stroke. A total of 21 of the 732 women in the calcium group had heart attacks compared with only 10 of the 739 in the placebo group. This was determined to be statistically significant. The authors suggest therefore that supplementation with calcium may be harmful. Many experts caution that it is too early to recommend that females discontinue this practice, but it certainly does open a lot of eyes. It has been postulated that the amount of calcium in the older female declines in bone but somehow manifests itself within the lining of blood vessels thereby speeding up the process of arteriosclerosis. Additional intake of calcium may hasten the process and increase risk of cardiovascular events.
A study from 1999 revealed a one-third decrease in cardiovascular deaths in those women who had the highest amount of calcium intake. Obviously, this is in complete opposition to the Bolland study. What does all this really mean? My general reaction is that one study is rarely enough to generalize treatment for a whole group. Conflicting results from previous studies only cloud the matter and serve to confuse patient and physician alike. Women may certainly ask me what to do in this case. I think it is premature to suggest they stop their calcium or vitamin D. In fact, until further data proves a definitive link between calcium intake and cardiovascular mortality, I will continue to suggest 1200-1500 mg of calcium and 800 IU of vitamin D per day for most women. In five years, we may laugh at ourselves and ask, "What was I thinking?" This seems to be the trend in medicine, a trend towards humility in the face of an ever-growing body of knowledge and sophistication.

Do you have any medical questions or concerns that you would like addressed? You can contact Dr. Spence by email at panhandledailydose@hotmail.com or by mailing your question to Daily Dose, P.O. Box 6107, Marianna, FL 32446.