Sunday, February 19, 2006

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.

14 Comments:

At 2:52 PM, February 19, 2006, Blogger Dr. Sanity said...

I have a family history of osteoporosis and every time I try to take calcium, within a month or so I have a kidney stone. This is extreme negative reinforcement for taking the supplement and I finally stopped a year ago and decided to stay on estrogen therapy instead. Turns out that probably works better, except that women have been scared out of their wits by all the latest brouhaha about the evils of estrogen. The truth is that all such decisions have to be a cost/benefit analysis done by the individual woman (and this holds true for any medication for any illness, male or female). There is no such thing as a drug without side effects.

 
At 5:41 PM, February 19, 2006, Blogger Joan said...

ITA with the good Dr. Sanity.

About calcium supplements: to get the most out of them, they have to be taken with an acid, and so typically you'd want to take them with vitamin C or with your morning orange juice or something.

Another little-publicized fact is that calcium and iron will bind to each other, so if you take a calcium supplement with an iron supplement at the same time, much of both of them will be prevented from getting into your system.

Calcium on it's own isn't going to do everything you need for your bones, either. You need magnesium, zinc, and vitamin D, too. I've finally settled on a regimen of which includes a combined calcium/magnesium/zinc supplement taken with vitamin D and vitamin C.

(I've heard some advertising insisting that we also need phosphorous, but none of my doctors ever mentions it, so, I dunno know.)

As for this study, what is up with these long, expensive, poorly designed studies? Could we please stop throwing money at research that isn't going to do any good at all? I know it's hard to collect good data, but bad data isn't useful. All these studies are doing is muddying the waters.

 
At 7:52 PM, February 19, 2006, Anonymous Anonymous said...

I feel for ya, but it's fear, not reason that makes you call yourself a neo-neocon

 
At 8:01 PM, February 19, 2006, Anonymous Anonymous said...

Both this and the low-fat diet study were part of the huge Women's Health Initiative study, which, whatever its flaws, is most certainly not a sloppy or poorly designed study. Its size and length have allowed it to provide unprecedented amounts of prospective, longitudinal data on aspects of women's health that had not previously been systematically studied. One of its triumphs has been its ability to provide rational information on therapies that had been assumed to be beneficial without being properly studied. Some of the flaws in the calcium study design, however, may have been due to the fact that the study was initially designed primarily to study the effects hormone replacement therapy and diet on cancer. It's true that results like this can be confusing, but the confusion reflects the reality that the area is not perfectly understood. Despite complaints from the public about conflicting data, I don't see how it would be better to conceal confusing results from an unequivocal answer is reached.

 
At 8:23 PM, February 19, 2006, Blogger neo-neocon said...

Anon at 7:52 PM: Your comment is either a joke, or the newly-popular fear meme de jour rearing its tiresome head again (and when one least expects it--on a post about calcium supplements, of all things!) If the latter, so much for the straw man accusation (see this, especially this comment).

 
At 11:42 PM, February 19, 2006, Blogger ligneus said...

And nowhere on this post and comments does anyone mention the importance of exercise in keeping bones strong. Walking a mile or two a day might do more good than a complicated regimen of supplements.

 
At 7:25 AM, February 20, 2006, Blogger AmericanWoman said...

Thank for post this. As a woman who is soon facing menopause, I am overwhelmed by the 'choices' we have.

You either have to put up with hot flashes, osteoporosis, increase risk in heart disease OR increased chance of breast cancer.

This plus the low fat/low carb/low whatever diet debacle is confusing enough.

I think the best you can do is go with the flow. Get a BD test, as you have, then you know if you should worry or not.

Also, it can never hurt to eat health and stay active. I think that is the key.

 
At 2:17 PM, February 20, 2006, Blogger Ymarsakar said...

Using fractures as the variable criteria, is a very bad decision. It does not truly tell how strong a bone is, through the statistics.

I feel for ya, but it's fear, not reason that makes you call yourself a neo-neocon

I don't get this. It is Republicans with the guns and the buried M60s, M82 sniper rifles, and bombs. Why aren't the Democrats afraid? They're not that courageous.

What made you dislike milk in the first place? Did you drink it while you were young? Cause I always hated vegetables cause they were hard to chew on.

 
At 3:30 PM, February 20, 2006, Blogger Wacky Hermit said...

I had read somewhere (don't remember where at the moment, I'm suffering from pregnancy-induced amnesia) that the amount of calcium recommended in the diet is more or less a "best guess" since it's not known how much of the calcium is actually absorbed. I also remember reading somewhere that the amount of calcium you need is in direct proportion to the amount of protein you eat, so if you're eating not a lot of protein, you don't need a lot of calcium.

 
At 7:18 AM, February 22, 2006, Anonymous Ben-David said...

It's likely your healthy bones come from those years spent dancing, as you described in your other post.

The other part of the healthy bones prescription was "load bearing exercise" - but human nature being what it is, most folks just pop the supplement.

The body responds not just to what's loaded into it, but also to the demands made upon it.

 
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