The Institute of Medicine recently upended the health apple cart with a new study that says we don't need as much calcium or vitamin D as we've been told. In fact, taking the kind of megadose that makes you feel virtuous and keeps the supplement industry healthy can lead to kidney stones in the case of calcium, and kidney or heart damage in the case of vitamin D.

If that sounds alarmist, let me quote directly from the Institute of Medicine's statement, which says that "some signals suggest there are greater risks of death and chronic disease associated with long-term high vitamin D intake."

Suddenly, a distracted, contrarian noncompliant like me no longer feels so guilty for buying supplements and forgetting to take them, or considering gelato a perfectly effective calcium delivery system. After all these years of being chastised for my recalcitrance, I can feel, temporarily, like the smartest girl in the room - simply by continuing to not do what I've always not done.

Temporarily, that is - because I fully expect a new study to contradict the findings before you get to the end of this sentence. Substances go in and out of favor just as hemlines do, and in each case, low-key consistency carries its own occasional rewards: I don't take now-suspect supplements, and I rarely stray from my collection of minimalist jackets, whose descendants happen to be popping up this season in magazines all over town. Every now and then, I intersect with what's "in" by not budging - and at the moment, I seem to be at the height of fashion on all fronts.

Supplements are only one of the categories in which marketing - or desire - seems to outstrip verifiable proof. Hormone-replacement therapy is perhaps the best example of a miracle drug gone south. My mother's generation believed that Premarin was the fountain of youth for postmenopausal women. A couple of decades and several studies later, the rap on hormone-replacement therapy is: Don't do it, and if you must, take the lowest dose possible for the shortest amount of time.

And then there are drugs whose helpful reputation is still intact - if you don't mind the really scary news lurking just outside the halo's circumference. Bone-building drugs do what they say they're going to do, but while they're at it, they increase the risk of esophageal cancer or may cause jawbone necrosis. Some of the drugs that combat gastrointestinal reflux disease can increase your risk of bone fracture.

I know that these side effects are rare, and that many people have no choice because the immediate danger outstrips everything else. Still, a breast-cancer patient I know once put statistics in a sobering light: When you're the 1 percent, she said, it's 100 percent of your life.

But back to choice and fashion, and to being a slave to the style of the moment. We are an irresponsible lot in general, with a fairly juvenile attitude about health: We like the quick-fix idea of pills that counteract our bad habits; "no pain, no gain" doesn't have a lot of traction among the general populace.

In 2009, all 50 states failed to meet the Centers for Disease Control and Prevention's Healthy People 2010 overweight target of no more than 15 percent of the population. And yet we spend billions on supplements designed to keep us healthy in spite of ourselves. We want an effortless fix - longevity in a capsule with a doughnut chaser.

We like enhancement; we like preventives that don't require us to change our ways; and we're disappointed when Toto pulls the curtain back to give us a glimpse of the little guy who isn't really a wizard. The Institute of Medicine report undoubtedly will cause a spike in loudly stated endorsements of calcium, vitamin D, and who knows what else. I choose to remain on the sidelines - watching, waiting, and not hoping for much in terms of resolution, a wary eyebrow cocked.

We are nowhere near definitive answers about what our bodies need, no matter what consumer advertising promises. But in the meantime, there are products to be promoted and money to be made.

Still, the cost-benefit ratio of trend-chasing does not always favor the consumer. If you still have doubts, go try on that blazer whose wingspan is as wide as you are tall - the one you've kept for years because you figured someday big, padded shoulders would be cool again. Now look in the mirror and tell the truth: You look like the wicked witch's sentries in Oz. You got suckered by the sheer momentum of popular style.

Now apply the same dispassionate scrutiny to all those vitamins and pills we take. For some people, medications are a lifeline. The rest of us might be better off with a brisk walk around the block, a piece of fresh fruit, and a calcium-rich glass of nonfat milk.

Karen Stabiner's most recent book is the comic novel "Getting In." This appeared in the Los Angeles Times.