Faye Flam is a Bloomberg Opinion columnist. She has written for the Economist, the New York Times, the Washington Post, Psychology Today, Science and other publications. She has a degree in geophysics from the California Institute of Technology. Read more opinion LISTEN TO ARTICLE 4:28 SHARE THIS ARTICLE Share Tweet Post Email

Photographer: Cristina Pedreira/EyeEm, via Getty Images Photographer: Cristina Pedreira/EyeEm, via Getty Images

When it comes to public health in the developed world, the perfect can be the enemy of the good.

The American Heart Association urges every American to reduce sodium intake to an “ideal” level of less than 1,500 milligrams of sodium per day — a goal that fewer than 1 percent of the world’s population achieves. No wonder: 1,500 milligrams represents the inescapable amount of sodium that’s embedded in the amount of food we need to avoid starving. Setting that as the “ideal” is really a zero-tolerance policy toward sodium: You can’t add salt when cooking, let alone eat anything from packages or restaurants.

A few years ago the health division of the National Academies commissioned a panel to review all the science to date and concluded that there was no evidence that people would benefit from giving up moderate sodium intake. Some studies suggested that people who consumed very little sodium had a greater risk of dying from stroke or heart disease. At the time, the doctor who led the panel, Brian Strom of Rutgers University, told me the 1,500 milligram goal was derived from a process that was “not entirely rational.”

Instead of a zero-tolerance policy toward sodium, how about zero tolerance toward irrationality in public health? Because there is a serious problem here, and the war on salt won’t solve it.

A new report puts the cost of high blood pressure in the U.S. at $131 billion — about $2,000 per patient. Millions of people are dying prematurely. What we need is further study to uncover the true causes of hypertension. Salt may play a role, but hypertension has also been linked to genes, obesity, heavy drinking, lead exposure, sugar consumption and stress.

Recently, some researchers proposed a controlled experiment done on a prison population. The suggestion raised ethical objections, because people in prison may not be in a good position to give informed consent free of pressure. But the researchers are onto something: We need better data. In the meantime, why not be honest about the limited evidence that we can fix hypertension through extreme dietary sacrifice?

I found an advocate for rationality in Richard Sloan, a professor of behavioral medicine at Columbia University. He said that when it comes to hypertension and other health problems, Americans put too much faith in the power of personal agency. We tend to believe that if we try hard enough, we can accomplish anything. But in reality, he said, some patients can lower their blood pressure to a healthy range by cutting back on salt, and others can make the same lifestyle change with little improvement.

While it's known that salt temporarily causes blood pressure to rise, and that's bad for people who already have hypertension, there's no consensus on the role salt plays in causing chronic hypertension in the first place, or whether people are doing themselves any harm if they consume the American average of 3,400 milligrams of sodium a day.

Sloan said he sees the same sort of magical thinking in the quest to reduce blood pressure by controlling stress. There’s abundant evidence that stress harms people’s health, he said. It’s hard on the body and the mind when people are bullied, or their loved ones die or abandon them, when they lose jobs, run out of money, or sink into debt.

But there’s no credible evidence that people can consistently control the physical toll of stress — whether with positive thinking or meditation or other forms of training. The danger, he said, is not just that these interventions won’t work, but that when they don’t work, they will leave people filled with remorse and a sense of failure.

Sloan tried to puncture the “we can do anything” fantasy in an opinion piece he wrote for The New York Times a few years ago. The notion that power of will can overcome any injury or illness is part of a feel-good story that people like to tell when someone famous recovers from something terrible. The implication, he points out, is that people who don’t survive cancer or gunshot wounds or similar tragedy have failed. “I don’t think this is just a problem in medicine,” he said. “It’s a problem with American culture, which imposes this belief that you are in control.”

We do have some control. Cigarettes turned out to be a major cause of lung cancer, and anti-smoking campaigns have cut the death rate from the disease. There are also pretty compelling studies showing that some people are putting their health in danger by eating more than the American average of 3,400 milligrams of sodium a day.

It couldn’t hurt for restaurants to offer palatable lower-sodium options, or to make it easier for people to get access to fresh produce rather than relying on heavily salted packaged and canned foods. Scientists have yet to figure out what “perfect” would be, but there’s still some progress we can make in the direction of the good.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.