illustration of a salt shaker, shaking out salt


Salt and other wounds

   

That lovin' spoonful
Salt is poison
Salty history
Intersalt assault
Big study. Big problems?
Millimeters of megadeath
Finding common ground

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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salt shaker icon 2

 

 

 

 

   


Can we agree?
Enough of the "salt-in-your-wounds" sniping among the adversaries. What else can we do to reduce blood pressure?

How about eating lots of vegies and going low-fat? According to the Dietary Approaches to Stop Hypertension study (see "A Clinical Trial... " in the bibliography), you can get dramatic reductions without worrying much about sodium.

graph of systolic blood pressure over the course of 8 weeks

"People actually followed the diet, got a blood pressure reduction, it was more significant than sodium reduction," says David Freedman of UC-Berkeley. Indeed, the combination of high-vegies and low fat reduced blood pressure by 5.5/3.0, far more than most non-drug interventions.

However, before we get too carried away, let's remember that this is one study, conducted in an elaborate manner. Meals, for example, were prepared for the subjects.

A follow-up study will compare three levels of sodium intake to the high-vegie, low-fat DASH diet, Whelton says. He cautions that while the DASH improvement does seem impressive, the study has not been repeated yet.
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A second idea is to broaden the focus from sodium to other minerals, primarily potassium. "Everything we are learning about potassium shows that it's the converse of sodium," says Whelton. "It seems to protect blood vessels in animals, and epidemiology shows that a higher intake is associated with a better cardiovascular outcome," meaning fewer heart attacks and strokes.

Lessons
A third focus is to look at how the science develops. In any public health squabble of this magnitude, it helps to ask questions:

What are the preconceptions – are we prisoners of our expectations? Have the anti-salt crusaders exceeded the evidence, forcing them to stick with untenable recommendations?

Who is paying for the research, and where is it published? Despite charges that the Salt Institute, an industry group, was behind the critics, we found some financial support. Alderman says he gave a few talks sponsored by the Institute a few years ago, and attended two meeting at the Institute. Logan says he accepted "a small honorarium from the Salt Institute for my advice to offset the loss of practice income." Davey Smith and Freedman say they've taken no Salt Institute money. McCarron did not answer. Before you jump to the conclusion that Salt Institute funding has biased the results, however, remember that many of the key critiques of the salt hypothesis published by these scientists have appeared in major medical journals.

What's missing? Do the contradictory results mean that we're studying the wrong thing? How, for example, do other minerals and genetics play into the situation?

What is the limit of human endurance: Can people actually make the changes we're asking? How much credibility has been lost in the vendetta against salt?

Is there another way to skin this cat? Could a better diet – with less focus on sodium – achieve the same goal? Should we worry more about the total diet, and less about individual nutrients? Will drugs for controlling blood pressure be more effective in the long run?

How long can we, or should we, wait for a definitive answer before taking action, as individuals or a society?

The evidence in people with normal blood pressure "does not support the current recommendation for a universal dietary sodium restriction," says Logan. But practically speaking, one size may need to fit everybody. If roughly one-third of the population must eat a low-sodium diet to be healthy, and if upwards of 75 percent of sodium is coming from processed foods, then the choices for improving public health are:

Hypertensives and obese people must stop eating processed foods

Food packagers must reduce the amount of sodium in their food

 

Sodium podium

Woman buys leafy greens at a supermarket

A new study indicates that eating a low-fat diet with
plenty of vegies can sharply reduce hypertension,
without worrying about salt.

We promised we'd not be able to sort out the salt. If, as the skeptics contend, the salt bogeyman has been overblown, it's time to back off and issue fewer, and more circumspect recommendations. "This may be a thing in human life where we don't know what to do," says Alderman. "I don't think there's any need or basis for saying that one size of sodium intake will fit the entire U.S. population."

But Rocella and the other anti-salt campaigners observe that while only a minority of the population needs to cut salt, they can't do that given the preponderance of salt in processed foods.

Manufacturers, he says, must start cutting down on sodium in their products, even though only a minority will benefit. Air bags and seat belts offer a comparable public-health benefit: "On the way home from work today, some people will have an accident. We can't predict who...but we ask people as a public-health interest to wear a seat belt anyway."salt shaker icon 2

As we said, when it comes to salt and health, you pays your money and you takes your choice. If you have a medical reason to reduce your blood pressure, it makes a lot of sense to find out whether reducing your salt intake will help. If you have no medical reason to worry about blood pressure, you at least understand why so many people are calling for lower salt in processed foods.

And whether or not you have hypertension, you have a better understanding why, in the world of epidemiology, 2 plus 2 can equal 5.

What's shakin' in the saline science bibliography?

 

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