As physicians who treat women over 40, we’ve always assumed that estrogen is great for our bones. Studies have shown that there is rapid bone loss (as much as 10% in the first three years) after menopause! And even if estrogen is given initially, once it is discontinued, rapid bone loss occurs, again as much as 5 to 6% after one year. But it is not the loss seen on bone mineral density scans that worries us, it’s the increase in fracture rates. In the Million Woman Study in England (Guess how many women participated?), those on estrogen or estrogen and progestin had a 30% reduction in fractures; among those who discontinued their hormones, the fracture rate was similar to that of the untreated population within one year. In a study of a large group in California, the number of women taking estrogen declined from 85% to 18% between 2002 and 2007 as a result of the publication of the initial data from the Women’s Health Initiative (WHI) which scared women and their physicians with evidence that in older women Premarin and Provera increased breast cancer risk. And lo and behold, fracture rates in this population increased by 50%. With all this in mind I was somewhat surprised by a recent article in the journal Menopause published by the North American Menopause Society.
The authors again used the WHI study to look at the impact of hormones as well as calcium and vitamin D on osteoporosis. Several years after starting hormone therapy, half the women in the study who were on Premarin alone or Premarin and Provera were randomized to either a group that took 1200 mg of elemental calcium and 400 units of vitamin D daily or a group that did not. Bone status was then followed for the women on hormones taking no supplements, women taking supplements but no hormones and women in the control group who took neither. A total of 16,089 women participated in this arm of the study.
The researchers looked at the fracture rates and bone density in all of the groups. They found that the effect of hormone therapy on hip fracture was significantly stronger among women who were assigned to also take calcium and vitamin D. In short, calcium and vitamin D supplementation significantly reduced the incidence of hip fractures beyond hormone therapy alone. The beneficial effect of hormone therapy on the bones was evident at a level of 1200 mg of calcium use and continued to increase at even higher doses. Similarly, the benefit of hormone therapy continued to increase at levels higher than 400 units of vitamin D. But the supplements alone were not effective…this study and others that were published based on WHI data have shown no overall significant fracture prevention when calcium and vitamin D supplements were taken alone. The conclusion: although taking calcium and vitamin D may not be statistically effective for fracture prevention but they may have a significant effect when used with hormone therapy. And for hormone therapy to “work” to prevent fracture, these supplements should be added.
In an accompanying editorial, the authors suggest that 1200 mg calcium (by diet and/or supplements) and 600 to 800 units of vitamin D be taken with hormone therapy in order to achieve the hormonal benefit of reduction in risk of osteoporotic fractures.
Bottom line: Hormone therapy alone is not enough for osteoporosis prevention, nor are supplements… But together they are effective. So if you use hormone therapy make sure to add calcium and vitamin D.