Critique my letter to my congressfolk
Dear (various people):
Two members of congress have now started working to launch a public health initiative to reduce the amount of sodium in the American diet. This is a bad idea, one which is not at present supported by existing scientific research.
I have attached a commentary from the Journal of the American Medical Association which briefly summarizes the reasons why this is a bad idea. In short, there have been no randomized clinical trials that have even attempted to measure the impact of reducing salt on the diet of healthy people. In fact, the only randomized trials that have been performed, which looked at patients with congestive heart failure, showed a drop in blood pressure, but surprisingly, a greatly increased risk of death in the group placed on salt restriction.
The evidence cited by advocates of salt restriction is too weak to support their conclusions -- it takes the form of observational studies, a cheaper but weaker methodology in which people's reports of their diet are compared against rates of illness and death. Even these studies have only shown clearly positive effects in nations like Finland where typical salt consumption is much higher than it is in the United States. Observational studies in countries with more moderate salt consumption showed that decreased salt intake caused worse health outcomes.
The rest of their argument comes from measurement of blood pressure -- but the fact that decreased salt consumption causes blood pressure measurements to fall does not necessarily mean that it has a positive impact on health (as with those congestive heart failure patients.) Furthermore, even this relatively weak evidence from blood pressure is not applicable to everyone -- in fact, only a minority of the population shows this sensitivity to salt.
At best, the scientific data being marshaled to support this effort is equivocal. We just do not know that decreasing the average American's salt intake would improve their health at all. And, in general, the clinical evidence is that even when people are ordered by doctors to decrease their salt intake, they do not comply. At best, this effort may well just cause people to salt their food more. At worst, some experts have suggested that the body naturally regulates its sodium intake, and people may end up unconsciously eating more food in order to consume the amount of sodium we are naturally wired to desire. And that would have a very dangerous impact indeed on Americans' health.
With the science for salt-reduction as weak as it is, it would be irresponsible for the government to attempt to continue research by performing a study on the entire American population. But that is what this amounts to. And the track record of previous attempts to impose a healthier diet on the American population is frightening: concern over dietary cholesterol and saturated fat led the government and public health advocates to recommend the consumption of margarine in place of butter -- not knowing, because the science was incomplete, that the trans-fats in margarine were far more dangerous to health than what they were replacing.
Another example were the 1980 Dietary Guidelines, which encouraged people to consume a low-fat diet. They were effective -- our diets had less fat. But the unfortunate result was that we replaced them with even more carbohydrates -- and many experts have suggested that the enormous increase in obesity (which began right around 1980) is, in part, the result of increasing our intake of carbohydrates and reducing our intake of fats.
Both of those efforts were made in good faith. They made perfect sense, given the state of the science at the time. The intentions were good, the reasoning was sound -- but the evidence was not strong enough to support the conclusions that were drawn. And people died as a consequence.
With sodium, again, we see an effort by the government to improve the nation's health by singling out one nutrient and attempting to reduce our consumption of it. Again, people are acting due to good intentions, and weighing the best evidence that exists. The danger is that once again we just do not know what the results will be. We must not risk people's health based on extrapolations from incomplete data like the alarming figures speculating that some enormous number of people die every year due to sodium intake. We just will not know what the real truth is until there are randomized studies to prove it one way or another.
I urge you not to support attempts to restrict our sodium intake. The science is not strong enough for any of us to know what impact this will have. More research -- that is, large, randomized clinical trials looking at the general population -- will provide the evidence we need to find out what the impact of public efforts to reduce sodium consumption. I hope you will stand up and call for the research to be done in a clinical setting -- rather than by trying it out on the entire American public. The government's track record in tinkering with our diets is dismal. Please do not be a part of the next great failed public health experiment. Lives are at stake.
Sincerely,
Exy
