Those calcium pills--Emily Litella again?
First it was low fat diets. Now it's calcium supplements that have been tested and found somewhat wanting, according to the Washington Post and many other newspapers reporting on a recent study. What's a woman to do?
First, a personal note. I've been taking those things for at least twenty years. And, you know what? I'll continue to take them.
I've always detested milk, and couldn't even drink it while pregnant, relying instead on those horse-pill-sized supplements. I've never had a kidney stone (the study reports that supplements slightly increase the risk of one); and, although there's always a first time, I'll take my chances on one. I try to eat other foods high in calcium, but there's just no substitute for milk products in that respect. I'm part of a subgroup of women who probably get less calcium in the diet than is the norm.
And so far (although I don't have a clone and therefore there's no control subject in my own little study) those calcium pills appear to have done right by me. Or at least, something has. A year or two ago I had my first bone density test. Given my history with milk, I wasn't looking forward to getting the results. So I was stunned when I was told the test showed that I had the bones of a healthy eighteen-year-old.
Now, that may just be the first time since--well, since about twenty-two--that I've been told I had the anything of a healthy eighteen-year old. Granted, there might be a few characteristics that would be higher on my list of coveted eighteen-year-old traits than bone density--but I'll take it, I'll take it.
However, I strongly suspect that I have the something else of an eighteen-year-old--namely, her bone density test results, which I suspect accidentally got switched with mine. Somewhere in my town there may be a terrified eighteen-year-old taking tons of (worthless?) calcium supplements because she's been told she's sporting the bones of a creaky fifty-something-year-old.
But I digress; back to that research. It was undertaken by the federally-funded Women's Health Initiative, which found indications in the seven-year study of about 36,000 women aged 50-79 that calcium supplementation doesn't appear to do all that much, except lead to a few extra kidney stones. There was a small increase in bone density at the hip, it's true, and a significant reduction in hip fractures for the oldest group of women who took the full complement of supplements. But no significant reduction in fractures or in colorectal cancer was found for the group as a whole.
It wasn't discussed in most of the newspaper reports, but if you go to the NIH website for a fuller report of the study, you'll find that it had some very strong limitations in design, according to a Dr. Rebecca D. Jackson, who was in charge of the research:
The low rates [of fractures or change in their incidence] could be due to a number of factors, such as the high body mass index of participants (heavier people have stronger bones), the inclusion of relatively few women over age 70 years, and the fact that many participants were already using calcium and vitamin D supplements, or were on hormone therapy.
I find it quite astounding that a large and well-funded seven-year study of the benefits of calcium supplementation in reducing bone fractures could be conducted without including many women over seventy. That group is, after all, the population in which almost all such fractures occur.
I assume there are reasons for this lack--for example, it may be more difficult to recruit women of that age, more of them would be expected to die over the course of the study, and an intervention at that late stage might be considered too late to afford measurable benefit. Such long-term lifestyle/diet intervention studies are notoriously difficult to design, and therefore the results are often subject to criticism. But the relative lack of inclusion of such women makes the study almost worthless in studying the phenomenon, I'm afraid.
The cumulative effect of these "on again, off again" dietary recommendations and their Emily Litella-like findings can only be confusion and skepticism about all medical studies of this sort--and depression on the part of those who make and market low-fat food products and calcium supplements.