The FDA, acting on a recommendation to be made by a task force of the Institute of Medicine of the National Academy of Sciences, is about to take the unprecedented step of regulating the salt content of processed foods. There actually is a scientific rationale for this. Numerous studies have shown that high sodium chloride (salt) intake is associated with an increased likelihood of hypertension leading to strokes, heart attacks, and congestive heart failure. Of course tobacco isn’t good for you either, but the FDA, which now regulates cigarettes, isn’t talking about reducing the nicotine levels in every pack of cigarettes sold in the United States. The question is, why salt? How dangerous is it?
The risk has mostly been based on the results of so called “observational studies,” where patients are not asked to ingest a given amount of salt but rather are assessed based on their own preferences. In these studies, the effect of dietary salt level on blood pressure is determined. The results generally show that a high salt intake leads to a higher risk of heart and vascular disease because blood pressure is higher with a high salt diet. But you have to take those numbers with a grain of salt. No one has really proven that a low salt diet will reduce heart disease, only that it will lower blood pressure. While it is true that it is likely that higher blood pressure will lead to more heart disease, the proof that removing salt from processed food will improve survival could represent the triumph of hope over reality. Also, high cholesterol levels, untreated hypertension, diabetes, and smoking convey a far higher risk of heart and vascular disease than does a high salt intake.
So, while not all studies support the role of salt intake in cardiac disease, it does appear to be a risk factor in the majority of studies. Salt can slowly raise the blood pressure over several years, and can even result in 5 to 10 point rises in blood pressure, which is known to damage blood vessels and lead to strokes and heart attacks. But the risk is not uniform across all groups. Men, patients with obesity and diabetes, and African Americans are at much greater risk than women. In fact, in some studies, women are not at risk at all. But they may be eating less salt anyway.
The other aspect of the problem is that salt intake doesn’t vary widely. Most people self-select to a level of about 3600 mg/day. This level seems to be the result of a specific “salt taste” that most people possess. It turns out, patients who need to eat a very low salt diet because of underlying heart or kidney disease generally hate that diet – the food just doesn’t taste that good. Salt is added to processed foods because it makes the foods taste better and, also, it is an important preservative. High salt content tends to suppress the growth of harmful bacteria.
Governments have tried before to convince their citizens to eat less salt, but the efforts have almost always failed. In fact, getting anyone to stick to a regulated diet of any kind is almost always a failed effort over the long haul. The current idea to prevent people from eating excess salt by reducing the salt content of processed foods like cereals and breads is a response to that record of failure.
The food industry has been trying to reduce the salt content of various foods for some time, and technology may some day allow them to succeed without compromising the taste of food. But not yet. The FDA’s new policy will make some of your favorite processed foods less tasty.
The issue here is really not one of scientific validity. The FDA generally has science on its side--as least for a generous slice of the population. The question is actually a political and ideological one. Should individuals have the option to eat foods that may add a 5 or 10 percent risk of a cardiovascular complication? Should they have to doctor their foods with extra salt to make it satisfy their tastes, or should manufacturers be able to make foods that satisfy their customers, even with the risks described? And finally, should individuals who are susceptible to the risks of higher salt intake have the right to employ a pill to lower blood pressure without giving up the processed foods they know and love? Because while science cannot yet make an edible salt-free pretzel, it can easily produce a cheap medication to lower blood pressure or elevated cholesterol and make dinner time far more pleasurable.