Imagine Salt is on trial.
The charges? Murder. Assault. It kills. It makes people sick.
The evidence? Well, there’s the rub. If Salt were on trial, it would be easy for the prosecution to pile up mountains of evidence that “proves” salt is dangerous — and conversely, a mine of evidence the defense would argue “proves” salt is not only not dangerous, it’s actually good for us.
The theory that salt is bad for us has roots in the 1970s, and was reinforced by dozens of studies in the years since then, including the 1988 Intersalt study of 10,079 people from 52 countries. The authors of that study argued:
“The INTERSALT results, which agree with findings from other diverse studies, including data from clinical observations, therapeutic interventions, randomized controlled trials, animal experiments, physiologic investigations, evolutionary biology research, anthropologic research, and epidemiologic studies, support the judgment that habitual high salt intake is one of the quantitatively important, preventable mass exposures causing the unfavorable population-wide blood pressure pattern that is a major risk factor for epidemic cardiovascular disease.”
But, some people didn’t think the Intersalt data supported this conclusion, as Gary Taubes noted in his 1998 Science magazine article The Political Science of Salt. (pdf)
“Intersalt had failed to confirm its primary hypothesis, which was the existence of a linear relationship between salt intake and blood pressure. Of the 52 populations, four were primitive societies … with low blood pressure and daily salt intake below 3.5 grams. The remaining 48 revealed no relationship between sodium intake and blood pressure.”
Other studies continued to produce a salt/hypertension connection, including a 1991 study published in the British Medical Journal which looked at data from 78 studies and concluded that salt was even worse for you than previously thought. The Associated Press interviewed the lead researcher who said everyone should cut their salt intake by 30 percent:
“’The bottom line is that everyone, even if their doctor didn’t tell them they were at high risk for heart disease, should reduce the amount of salt in their diets by at least three grams a day,’ or half a teaspoon, said Dr. Malcolm Law… Dr. Law said that in people over 50 years of age, a three-gram reduction in daily salt consumption would cut blood pressure by about five millimeters of mercury in healthy people and by seven millimeters in people with high blood pressure.”
Then, there was a follow-up analysis of a 1997 study of 412 people published in the New England Journal of Medicine published in January 2001, titled the Effects on Blood Pressure of Reduced Dietary Sodium and the Dietary Approaches to Stop Hypertension (DASH) Diet. The goal of the original study was to look at:
“The effect of different levels of dietary sodium, in conjunction with the Dietary Approaches to Stop Hypertension (DASH) diet, which is rich in vegetables, fruits, and low-fat dairy products, in persons with and in those without hypertension.”
That study — of just 412 people, over just 30 days — found that
“The reduction of sodium intake to levels below the current recommendation of 100 mmol per day and the DASH diet both lower blood pressure substantially, with greater effects in combination than singly.”
Not everyone was convinced, though, as Taubes noted. Part of the problem is that people in studies who eat less sodium might also be eating more fruits and vegetables, or doing other, unnoticed things like getting more exercise that are not accounted for.
Researchers continued to look at the issue, with folks on both sides defending their positions with zeal. When hypertension expert Dr. Michael Alderman posited that a low sodium diet might actually cause you to die early, he was attacked in the 1998 issue of the Lancet:
“It does not embellish Alderman and co-workers’ crusade against the worldwide recognition that the present consumption of salt should be reduced, to misrepresent previous work, make misleading statistical claims, and introduce other irrelevant material.”
Since then there have been enough studies connecting higher sodium with higher blood pressure that advocates of salt reduction could easily find research to support their views. But there is also an increasing number of studies, including a May 4, 2011 study of 3,681 people called Fatal and Nonfatal Outcomes Incidence of Hypertension and Blood Pressure Changes in Relation to Urinary Sodium Excretion and published in the Journal of American Medicine, which have found that having lower sodium levels in the body actually increases a person’s likelihood of dying:
“In this population-based cohort, systolic blood pressure, but not diastolic pressure, changes over time aligned with change in sodium excretion, but this association did not translate into a higher risk of hypertension or CVD complications. Lower sodium excretion was associated with higher CVD mortality.”
“In a recent paper based on computer simulations of assumptions on associations between salt intake and BP, and between BP and mortality, it was concluded that a daily teaspoonful of salt (3 g) was a bigger health risk than cigarette smoking… The authors overestimated the assumed linear relationship between salt intake and BP and ignored the possibility that salt reduction may induce adverse effects. The present meta-analysis indicates that the adverse effect on lipids, especially triglyceride, is not just an acute effect as previously assumed, but may be persistent also in longer-term studies. Furthermore, reduced sodium intake seems to harm patients with heart insufficiency and diabetes type 1 and 2. In all three patient groups reduced sodium intake is associated with increased mortality.”
This sort of study makes the salt industry happy, as does this one published just last month in the American Journal of Hypertension, which found that unless you consume very,very little or huge piles of salt, you’ll be just fine:
“Their analysis indicated that this broad, safe range went from 5 grams ( a bit less than a teaspoon) all the way to 15.6 grams ( two and a half teaspoons).”
It’s time to dump the government’s dietary guidelines, Salt Institute President Lori Roman said via her PR person:
“The debate on the right amount of salt people should eat is over. It’s time we base our nutritional recommendations on the actual evidence rather than outdated opinion.”
So, will extra salt kill you early, or will having too little salt kill you early? The jury might be out. Perhaps they are out to lunch having something salty.
But the verdict continues to depend on who you ask, and the federal government continues to recommend that you eat less salt. But that might be an uphill battle in a world that produces more than 200 million metric tons of salt every year.
Melinda Tichelaar is the Community Manager for Food.Farmer.Earth, as well as a reporter for the Kenosha (Wisconsin) News and website/line producer for WFLD in Chicago. Melinda, her husband, and their three sons live happily on Lake Michigan in Kenosha, where they like to sail, bar-b-q, buy interesting eggs at the Farmers Market and sneak whole wheat flour into cookies when no one is looking.