In case you missed it, salt is the new fat.
It seems that everybody from the FDA to Steven Colbert of the Colbert Report has set their sights on limiting our consumption of salt. In the past week, I’ve seen dozens of articles from the blogosphere to the front page of USA Today and a recent edition of Time on reducing our alarming levels of salt consumption.
Many of us are aware that salt is bad for us. What has seemed to kick off this latest salt outcry was a report put forth April 20th by the Institute of Medicine (IOM) calling for the FDA to set new federal regulations on the amount of salt that food manufacturers, food service companies, and restaurants can add to their products.
This has not only reignited (in a good way) public health advocates who have been calling for decreasing levels of salt consumption for years but also (in a bad way) many others who see this as yet another example of big government infringing on our personal lives.
Side-stepping these issues for a moment, what is the evidence behind lowering salt intake? Salt (or sodium) is essential for life, but study after study has demonstrated that excess salt intake is also a major risk factor for hypertension (or high blood pressure). Not surprisingly, many Americans consume more than the recommended amount of sodium. Experts recommend that we consume no more than 2,300 mg of sodium per day (or 1 teaspoon of salt per day); however, the average American consumes about 3,400 mg of sodium per day and some much, much more.
Don’t eat a lot of salt, you say? The problem is that only about one-tenth of the sodium we consume is from salt added at the table. The majority is from salt that is already added to foods during the manufacturing process or at restaurants before it gets to our plates. That’s why after looking at decades of rising salt consumption (see below), despite increasing public awareness of its hazards, the IOM concluded it had to go to the source and recommend limiting the amount of salt food suppliers add to foods.
Simply reducing sodium consumption across the U.S. to the recommended levels would save over 100,000 lives per year. But what does this mean to the individual? Studies show that reducing salt consumption reduces systolic blood pressure by about 5 mmHg in people with hypertension and 2 mmHg in people with normal blood pressures.
As a brief refresher, a healthy blood pressure is one with a systolic (top number) of less than 120 mmHg; between 120-139 mmHg is prehypertension; and above 140 mmHg is hypertension. From this alone, it’s readily apparent that decreasing salt consumption alone won’t cure hypertension. This led Gary Taubes in Good Calories, Bad Calories to remark “…so cutting our salt intake in half and decreasing our systolic blood pressure by 4 to 5 mmHg makes little difference.”
So which is it? Will reducing salt intake save 100,000 lives or does it make “little difference?” The answer oddly is both. On a population level reducing salt intake will have a dramatic effect but to the individual the difference is small. As a doctor, I take Gary Taubes to task for saying it makes “little difference.” I have many patients with borderline hypertension would could get themselves into the prehypertensive range and avoid taking an anti-hypertensive medication if they reduce salt intake, and in fact, many do.
But at the same time, his broader point that salt consumption is not the “cause” of hypertension is valid. Thus reducing salt intake — while it makes a difference and we should definitely do it — will itself not “cure” hypertension.
This brings us back to the most important scientific question of our time — what is the ultimate cause of the metabolic syndrome and the chronic diseases associated with it including obesity, hypertension, and diabetes? Is it, as the medical establishment would say, due to eating too much and exercising too little?
Is it, as Gary Taubes would say, eating too many carbohydrates and particularly refined carbohydrates? Or is it, as Michael Pollan would suggest, eating too many processed foods and not heeding the dictum “eat food; not too much; mostly plants”?
Whatever your view take heart that reducing your salt intake is a good idea. It’s just that — despite what the current media attention might suggest — it probably won’t save your life.
Shantanu Nundy is an internal medicine physician and author of Stay Healthy At Every Age: What Your Doctor Wants You to Know.
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