Conservatives, particularly those of libertarian bent, have always bristled at government efforts to do good, believing that the state has no business performing any but essential functions. They’re the ones who, when a government shutdown loomed and it was announced that only “essential” workers should report to work following a budget impasse, asked, “Why the heck to do we have non-essential workers?”

Neoconservatives, at least in their early incarnation in the late ’60s and ’70s, tended to stress that the unintended consequences of government efforts to do good were often more important (and usually more harmful) than the intended consequences.

Writing in City Journal, Steven Malanga reminds us of another reason to resist government-sponsored attempts to improve us — government frequently gets it wrong. They don’t intend to do harm, but through a combination of zeal and haste, they often do.

American life is characterized by pervasive, low-level anxiety about health risks in our air, water, cellphones, power lines, chemicals, prescription drugs, and, most of all, food — punctuated by periodic panics about this or that (avian flu, “flesh-eating” bacteria, H1N1, SARS, and on and on). We are healthier than human beings have ever been in the history of the world, but we are beset by an epidemic of worry.

The federal government both responds to and contributes to this fear. Picking up on the then-fashionable view that dietary cholesterol and saturated fat were responsible for heart disease and other ailments, the Senate Select Committee on Nutrition and Human Needs, chaired by George McGovern, issued food guidelines in 1977. All Americans were urged to reduce the proportion of fat in their diets from 40 percent to 30 percent, and to increase the percentage of carbohydrates to 60 percent of daily calories.

Though some members of the committee, notably Republican Charles Percy, demurred, noting that there was considerable debate within the scientific and medical worlds about the role of dietary fat in disease, the guidelines were embraced by busybodies and earnest improvers of their fellow men.

As Malanga details, when large studies on the effects of low-fat diets were conducted during the 1980s and beyond, researchers found that the link between dietary fat and heart disease was not clear at all. One study found no difference between a group assigned to limit dietary fat and cholesterol and a control group that was simply urged to see the doctor regularly. Further research continued to undermine the government guidelines. One study showed no effect for women who reduced their cholesterol levels. Another found that men with elevated cholesterol were more likely to suffer heart attacks, but that those who reduced their cholesterol to very low levels were more likely to die of all causes.

Malanga writes: “There was little doubt that some public-health researchers wished such research would go away. ‘Some people don’t want to talk about it,’ said Michael Criqui, an epidemiologist at the University of California at San Diego and an associate editor of Circulation . . . ‘They think it is going to impede public-health measures.’”

Arguably, Americans followed the government guidelines first promulgated by McGovern’s committee and later updated with minor changes. Yet, as three prominent physicians concluded in a 2008 article for The American Journal of Preventive Medicine, the government’s guidelines may have harmed public health. During the past three decades, American men, on average, cut their fat intake from 37 percent of calories to 32 percent and increased their consumption of carbohydrates from 42 percent to 49 percent. Over the same 30 years, “the fraction of men who were overweight or obese increased from 53 percent of the population to about 69 percent.” As the doctors concluded in their piece, “it now seems clear that the U.S. guidelines recommending fat restriction may have worsened rather than helped the obesity epidemic and, by so doing, possibly laid the groundwork for a future increase in cardiovascular disease.”

Woody Allen used ever-changing health recommendations to comic effect in Sleeper, when his health-food-store-owning hero wakes up in the 22nd century to find that cigarettes are healthy, but lettuce will kill you.

The lesson of the past few decades of government-issued health guidelines is not that nothing is knowable, but that skepticism, flexibility, and an open mind are required to make sense of constantly shifting information. Those are not the qualities for which government is known.

The feds are moving against salt next. Take it with a grain.

— Mona Charen is a nationally syndicated columnist. © 2011 Creators Syndicate.