Sugar and fat have been put through the regulatory wringer, but salt hasn’t been, argues Michael Jacobson, PhD, in his latest book, Salt Wars: The Battle Over the Biggest Killer in the American Diet.
Although salt is a ubiquitous ingredient in the American diet — present in processed foods and meals at chain restaurants — little regulation has been imposed on the food industry. That’s despite the known harms of high salt intake, including cardiovascular disease, writes Jacobson, co-founder and former director of the Center for Science in the Public Interest (CSPI).
MedPage Today spoke to Jacobson about his latest book and his hopes for the stalled 2016 voluntary guidelines from the FDA on reducing salt intake.
This interview has been edited and condensed for clarity.
MedPage Today: What drove you to publish Salt Wars?
Jacobson: I’ve been working on salt since 1977, and the absence of progress has been very frustrating. Companies haven’t done anything to reduce salt in their products. The FDA has done a little, but what they did was ineffective. I wanted to bring these different threads together, and try to give this issue — which is not the most prominent issue in public health — a push in the right direction.
MPT: Where has there been an absence of progress?
Jacobson: CSPI first petitioned the FDA to set limits on sodium content in 1978. The petition sat around for a few years, and the FDA commissioner stated in the early 1980s that the agency would urge the food industry to lower sodium content, but would not impose regulations. When things did not change, CSPI petitioned the FDA again in 2005.
Finally in 2010, the Institute of Medicine [now the National Academies of Science, Engineering, and Medicine] issued a report stating that high-sodium diets were harmful. It recommended that FDA should set mandatory limits on sodium for different foods, with those limits gradually declining over the years.
After that report came out, the FDA stated that it would not develop mandatory limits, but voluntary guidelines. It took six years, but the FDA finally proposed voluntary guidelines in 2016.
That was at the end of the Obama administration. The Trump administration has done nothing on the issue. Four and a half years later, those proposed guidelines are still sitting there, yet to be finalized — maintaining the longstanding lack of progress.
MPT: Some research around the health effects of salt consumption is contradictory, particularly the Mente et al. study published in JAMA about a decade ago. What is the current consensus in the scientific community?
Jacobson: There are a bunch of studies indicating that lowering salt intake might actually be dangerous. They are all observational studies that look at salt intake in a large number of people and rates of heart disease and stroke.
Those studies indicate a J-shaped curve, where the lowest risk is at consumption of about what we are consuming now: 3,000-3,500 mg per day. They found a higher risk of cardiovascular disease at lower sodium levels — levels recommended by the WHO, the American Heart Association (AHA), and the U.S. government — as well as at much higher levels of sodium intake, around 5,000 mg per day.
When a novice looks at those studies, they look very impressive. They are generally not sponsored by industry and the research is funded by government agencies.
But those studies have just been ripped to pieces by the AHA, many individual researchers, and most recently in 2019 by the National Academy of Medicine. They didn’t take those studies seriously for a couple of reasons. Probably the most important reason is that the researchers only looked at sodium intake on one day, at the beginning of the study. One day may not be representative of what a person is going to eat over the next five, ten, or twenty years.
Critics of the studies also noticed that a disproportionate number of people who consumed lower amounts of sodium had diseases like cancer or heart disease. Those people may have intentionally lowered their sodium intake, so it wasn’t that low sodium was causing disease, but that the disease was spurring people to consume less sodium.
Then there were some other follow-up studies. In the TOHP trial, some people were put on low sodium diets and others stuck to higher sodium diets. The people who consumed under 2,300 mg a day (in other words, those who were meeting the government’s recommendation for sodium intake) had lower risk of heart attacks and strokes. So it wasn’t a J-shaped curve; it was a more linear relationship.
One of my intentions of the book is to lay to rest the notion that lowering sodium could actually be dangerous.
MPT: How do the health impacts of a high-sodium diet affect the U.S. healthcare system?
Jacobson: Health economists have asked, “well, what is the harm?” What if people were eating a diet of 2,300 mg of sodium a day, instead of the 3,400 mg that we’ve been consuming?
They’ve estimated that a high sodium consumption could be linked to up to 100,000 premature deaths a year. It really has been a silent pandemic that we’ve just grown to tolerate. Hypertension drugs have not solved the problem, and the medical costs are also huge, with estimates ranging on the order of $10 to $20 billion in unnecessary costs, because people are consuming high-sodium diets.
The Department of Health and Human Services conducted a study that was written in 2013, and those economists estimated that higher sodium diets are causing a loss of productive life — either morbidity or mortality — that amounts to $3.5 trillion.
MPT: You mentioned that salt and sodium don’t get nearly as much public attention as sugar or fat intake. Why do you think that is?
Jacobson: With sugar there was a burst of research around 10-15 years ago that connected high sugar, and especially high soda pop consumption, with obesity. Considering the obesity epidemic, that was kind of a bombshell. That stimulated more research, and it got the public’s attention.
With trans fat, which was banned about five years ago, there was just huge activism. It was really in public attention — everything from the New York Times to late-night comedy shows.
In salt, the arguments have been around for a long time. Many journalists think “that story has been done already.” Except for the contrarians that look for the “man bites dog stories,” that say cutting salt should be dangerous. That has made a lot of headlines over the years, and really confused the public and stunted progress.
MPT: What does the political agenda have to do with regulations around salt?
Jacobson: The food industry has been behind a lot of the publicity. The industry didn’t sponsor the research, but boy did they play it up. And they go to town with lobbying.
Congress has stepped in with the Republicans and Trump loosening the sodium limits in school foods. And that was such a natural place to get kids accustomed to less salty foods.
Industry’s fingerprints are all over this. They say “we don’t mind voluntary reductions.” I think they fear that voluntary reductions will turn into mandatory restrictions. They are just so instinctively opposed to regulation.
MPT: What do you hope readers can take away from your book?
Jacobson: Readers should know that things are not going to change instantly. They can either wait for industry to lower the salt levels in their food, or they can do it themselves. By eating more natural foods, by eating out less often, and by reading nutrition labels carefully, it is possible to get a lower sodium diet. But it takes an effort. It may take cooking our own meals.
I’m hoping the readers understand the politics and understand the science. But I also hope they make an effort to change the sodium content in their own diets.