Do You Really Need To Reduce Salt Intake?
When a new Institute of Medicine (IOM) report entitled "Sodium Intake in Populations: Assessment of Evidence" came out in May, many in the media spun a story that was far different from what the report actually said. From the doctors and dietitians at the Pritikin Longevity Center, here are the facts.
Our doctors and dietitians do not have a problem with the report. They have a problem with the media’s interpretation of the report.
Many media headlines and spins were not only sloppy, they were shameful. They could lead people to believe that reducing sodium intake doesn’t matter, which is the exact opposite of what the Institute of Medicine (IOM) stated. In the first paragraph of its 4-page summary report, the IOM asserted: “Evidence has shown that reducing sodium intake reduces blood pressure and the risk for cardiovascular disease (CVD) and stroke.”
Below are more messages rolled out by many in the media, followed by what the IOM report really said.
What many in the media reported…
“Low sodium intake can be harmful.”
What the IOM report really said…
Low sodium intake may be harmful, not for the general population, but for a subgroup of people, namely, “patients who have a diagnosis of moderate or severe congestive heart failure and are receiving certain aggressive therapeutic treatments.”
And even among this group of very sick individuals, it’s highly questionable if it’s the low sodium intake that is causing the harm, or the fact that these patients are on powerful salt-depleting diuretics and struggling with a life-threatening chronic disease. As the IOM report stated:
“Specifically, in some studies, low sodium intakes apparently appeared to show an association with risk of disease, when, in fact, the relationship may have been that the disease itself led to low or incomplete measures of sodium among those with pre-existing disease.”
And let’s not forget that most people develop heart failure in the first place because they have typically spent decades eating far too much sodium (and saturated fat, calories, sugars, and refined carbohydrates), which led to hypertension and hardening of the arteries, and ultimately, heart failure.
The last thing most Americans need to worry about is going too low in their intake of sodium.
As the IOM report pointed out, “Adults still consume an average of 3,400 mg of sodium a day, well above the current federal guidelines of less than 2,300 mg a day.”
Inferring, as the media did, that Americans might be harmed if they didn’t eat enough salty food is, unfortunately, “like telling older overweight Americans that they might be harmed if they lost excess body fat. Yes, some data have found that lower weight in later years was linked with an increased risk of dying. But let’s examine that link. The fact is, older people who are very ill with chronic disease often have poor appetites, and so they eat less and become thin and then die,” points out Dr. Jay Kenney, Nutrition Research Specialist at the Pritikin Longevity Center.
“No doubt older Americans with chronic illnesses like heart failure are consuming less salt because they are eating less food.
“Scientists have a name for this phenomenon. It’s called ‘reverse causation.’ It means that things like being thin or eating less salt are not causing illness but in fact are the result of serious illness. The IOM report pointed this out, but news reports generally missed this important fact.”
What many in the media reported…
“There is no good evidence that restricting sodium to 1,500 mg a day is beneficial.”
What the IOM report really said…
There is a “substantial body of research that links excessive sodium intake to high blood pressure, a widely accepted biological predictor of risk for cardiovascular disease and stroke.” And, “based on this research,” the Department of Health and Human Services and USDA recommend reducing sodium intake to less than 2,300 mg/day for the general population and 1,500 mg/day among groups at higher risk: African Americans, everyone 51 years and older, and people with hypertension, diabetes, or chronic kidney disease.
But for this particular 2013 report on sodium intake, the IOM had been commissioned by the Centers for Disease Control to focus its review solely on studies that looked at direct outcomes, such as heart attacks and strokes, not risk factors like hypertension.
But these studies were so few – and so flawed in their methodologies (“the range of limitations included over- or under-reporting intake levels and incomplete collection of urine samples”) – that the data were not “strong enough,” stated the IOM, to derive any definitive conclusions.
Put simply, the IOM was not saying (as many in the media reported), that the evidence indicates that consuming 1,500 mg/day of sodium has no benefits. Rather, the IOM was saying that the evidence we currently have on direct outcomes is insufficient and “less-than-optimal” to make recommendations.
The good news: We do have strong evidence that reducing sodium intake to 1,500mg/day is very beneficial for reducing blood pressure in the short term and preventing the development of hypertension over a lifetime.
For example, the DASH-Sodium Trial1 showed a greater fall in blood pressure when sodium intake was reduced from 2,300mg/day to 1,500mg/day than when it was reduced from 3,100mg/day to 2,300mg/day. “This was true both on a typical American diet and on a healthier DASH-diet, which is similar to the Pritikin Eating Plan,” notes Dr. Kenney.
The current media focus on “no good evidence” reminds us of the 1960s and 70s, when the Tobacco Institute kept telling us to: “Keep smoking, because there’s no good evidence that cigarette smoking directly causes lung cancer, emphysema, heart disease, and death.” At that time, the Tobacco Institute even suggested that encouraging older smokers to quit could be dangerous to their well-being.
“Similarly,” observes Dr. Kenney, “we now have the Salt Institute claiming that salt has been given an unfair shake by U.S. health agencies who are currently advising Americans that excess salt is a key contributor to hypertension and cardiovascular disease.”
It’s interesting to note that when it comes to smoking, randomized clinical trials were never done because, well, just think about it: Who is going to randomly assign teenagers to either smoking or nonsmoking for decades?
“However, the preponderance of credible research continues to show just how dangerous tobacco smoke is to health, and no one today questions the life-saving benefits of quitting smoking,” points out Dr. Kenney.
We may never see randomized clinical trials on sodium consumption and direct outcomes. It would be very costly, requiring hundreds of people, perhaps thousands, to stay on their randomly assigned diets for many years. “And it would be considered medically unethical to study people with hypertension and not control their blood pressure with medications for many years,” notes Dr. Kenney.
“But as we’ve seen with tobacco, one does not need a randomized, controlled clinical trial to make a strong scientific case against smoking, and the case against salt is nearly as strong.”
The preponderance of credible research shows how important it is to cut back on salt to combat the global epidemic of high blood pressure. According to the World Health Organization, elevated blood pressure causes more preventable deaths worldwide than tobacco, obesity, alcohol, or any other cause.
Reduce sodium intake, reduce hypertension
We have proof that reducing sodium from 2,300mg/day to 1,500mg/day lowers blood pressure, especially in those with hypertension.
And we have overwhelming data showing that hypertension is the #1 cause of strokes as well as a major cause of heart attacks, congestive heart failure, and kidney disease.
To be sure, scientific analyses in the past few years have predicted life-saving and disease prevention outcomes. Earlier this year, for example, scientists at the University of California, San Francisco, using mathematical models, determined that immediately reducing people’s salt consumption from 3,500 mg/day to 1,500 mg/day would save up to 1.2 million lives over the next decade.3 1.2 million lives.
Health authorities like the American Heart Association and Centers for Disease Control have rightly relied on the mountain of evidence that higher sodium intake raises blood pressure, and that high blood pressure, or hypertension, raises the risk of stroke and coronary heart disease.
These health authorities have also rightly recommended, as the Pritikin Program has done for the past 50+ years, that reducing sodium intake to 1,500 mg/day or less does the best job of lowering blood pressure into healthy normal ranges.
We see the results of lowering sodium and living well every day here at the Pritikin Longevity Center.
We see people who, before coming to Pritikin, could not get their blood pressures below 140/90, even though they were taking multiple blood pressure medications. But within just three to five days of arriving here, their blood pressures are plummeting to 120/80, or lower.
We see reductions in blood pressure that are so fast and furious that our physicians must closely monitor our guests, reducing or eliminating medications before blood pressures go too low.
Most importantly, we see people who couldn’t be happier with the results.
We see success.
In the future, more data will likely continue to confirm this success. But today, right now, we see success we couldn’t be prouder of. We see people who are living longer, better quality lives.
1 New England Journal of Medicine, 2001; 344 (1): 3.
2 World Health Organization, 2009; Global Health Risks: Mortality and burden of disease attributable to selected major risks.
3 Hypertension, published online February 11, 2013