Swedish researchers report that antioxidants make cancers worse in mice. It’s already known that the antioxidant beta-carotene exacerbates lung cancers in humans. Not exactly what you’d expect given the extravagant claims you hear made about antioxidants’ miraculous effects.

In fact, they are either useless or harmful, conclude the editors of the prestigious Annals of Internal Medicine: “Beta-carotene, vitamin E and possibly high doses of vitamin A supplements are harmful.” Moreover, “other antioxidants, folic acid and B vitamins, and multivitamin and mineral supplements are ineffective for preventing mortality or morbidity due to major chronic diseases.”

Such revisionism is a constant in medicine. When I was a child, tonsillectomies were routine. We now know that, except for certain indications, this is grossly unnecessary surgery.

Even the tried-and-true may not be true. Take the average adult temperature. Everyone knows it’s 98.6 F. Except that when some researchers actually did the measurements – rather than rely on the original 19th-century German study – they found that it’s actually 98.2.

But if that’s how dicey biological “facts” can be, imagine how much more problematic are the handed-down verities about our staggeringly complex health care system. Take three recent cases:

• Emergency room usage:

It’s long been assumed that insuring the uninsured would save huge amounts of money because they wouldn’t have to keep using emergency rooms, which is expensive. Indeed, that was one of the prime financial rationales underlying Romneycare and Obamacare.

Well, in a randomized study, Oregon recently found that when the uninsured were put on Medicaid, they increased their ER usage by 40 percent. Perhaps they still preferred the immediacy of the ER to waiting for an appointment. Whatever the reason, this finding contradicted a widely shared assumption about health care behavior.

• Medicaid’s effect on health:

Oregon allocated by lottery scarce Medicaid slots for the uninsured. Comparing those who got Medicaid to those who didn’t yielded the following stunning result, published in the New England Journal of Medicine: “Medicaid coverage generated no significant improvements in measured physical health outcomes in the first two years.”

To be sure, the Medicaid group was more psychologically and financially secure. Which is not unimportant (though for a $425 billion program, you might expect more bang for the buck).

• Electronic records will save zillions:

That’s why the federal government is forcing doctors to convert to electronic health records, threatening penalties for those who don’t by the end of 2014. Yet one of the earliest effects of the electronic record mandate is to create a new category of previously unnecessary health workers. Scribes, as they are called, now trail doctors, room to room, entering data.

Why? Because electronic records are so absurdly complex, detailed, tiresome and wasteful that if doctors fill them out, they can barely talk to and examine patients, let alone make eye contact. Doctors rave about the scribes, reports The New York Times, because otherwise they have to stay up nights endlessly checking off boxes.

This is not to say medical practice should stand still. It is to say we should be a bit more circumspect about having central planners and their assumptions revolutionize by fiat the delicate ecosystem of U.S. health care. In the case of electronic records, for example, doctors were gradually going digital anyway, learning through trial and error what saves time and money. Instead, Washington threw $19 billion and a rigid mandate at the problem and created a sprawling mess.

It’s not surprising that myths about the U.S. health care system tantalize – and confound – policymakers. After all, Americans so believe in their vitamins/supplements that they swallow $28 billion worth a year.

Charles Krauthammer is a columnist for The Washington Post. He can be contacted at:

letters@charleskrauthammer.com