Pressure is building on food producers to cut back on salt in processed foods. But the question for many salt lovers is: Just how bad for your health are those tasty, flavor-enhancing crystals? A study published this month in the Journal of the American Medical Association came to the surprising conclusion that too much salt might not raise the risk of cardiovascular disease complications after all. Making matters even more confusing, death rates appeared to be higher in those with lower sodium levels.
The study instantly ignited debate over population-wide efforts to get folks to put down their shakers and cut back on hidden sources of salt.
To put the issue in perspective msnbc.com talked to Dr. David Heber, a professor and director of the Center for Human Nutrition at the University of California, Los Angeles.
Q: First things first. Why is there so much salt in processed foods?
A: Salt is a taste enhancer. Truly low-salt stuff is not edible. It tastes like dishwater.
Q: I can see why that would make food producers hesitant to cut back on salt. Do the health benefits of making food low salt override any loss in flavor?
A: For the most part, the problem with salt is the setting in which you find it. The vast majority of “processed” or convenience foods are high in both fat and salt. It’s the fat that’s the big problem. As for the benefits of reducing salt, only about 5 percent of people have a salt sensitivity that is the primary cause of their hypertension. The major contributors to hypertension are obesity and diabetes. Studies have shown that when people are put on a diet rich in vegetables and fruit, their blood pressure comes down. If you then lower salt, it comes down a little bit more.
Q: Is salt actually bad for you?
A: Salt by itself is not bad. For people at a healthy weight, without illnesses like heart failure, there’s a big zone of safe salt intake. But remember that 65 percent of the American public is overweight and 32 percent are obese. And about 50 percent of those aged 45 to 65 have metabolic syndrome.
Q: It sounds like you weren’t surprised by the results of the JAMA article? It would seem to suggest that salt is unimportant when it comes to complications of hypertension and heart disease.
A: If you make an effort to reduce salt without paying attention to other factors, such as body fat and physical activity, it’s not going to have much effect. The big public health problem in America is obesity.
Q: The JAMA article did find that high salt was linked to an increase in systolic blood pressure. Isn’t that bad?
A: Salt affects the volume of blood in our bodies and that impacts systolic blood pressure. Normally we carry about 5 quarts of blood in our bodies. When we take in salt the volume can go up by half a quart to a quart.
Think of the blood vessels as a balloon. Systolic blood pressure is a measure of the pressure against the sides of the balloon. It goes up when the blood volume goes up.
Q: What about the other measurement, diastolic blood pressure. Isn’t that affected by salt?
A. No. That’s affected by our weight. As it turns out, a fat cell is more than just a bag of fat. It also makes hormones and when these substances are released into the blood stream they can raise blood pressure in a different way — by tightening the blood vessels. Think about that balloon again. Now imagine someone has their hands around the balloon and is squeezing it tight from the outside. Now you’ve got the diastolic measurement, which is the more important one.
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Q: Does that mean that efforts to improve health through lowering salt in processed foods are futile?
A: Public health agencies are looking for things that they can solve easily. People will think, “Oh yeah, I can control salt. But I can’t stop eating ice cream.” And people’s taste for salt will adjust after three to five months from now. Then, they’ll feel things are too salty.
But don’t get me wrong. I’m not against these maneuvers to reduce salt. But I think it’s just the tip of the iceberg. We need to make a lot more difficult changes.
Linda Carroll is a health and science writer living in New Jersey. Her work has appeared in The New York Times, Newsday, Health magazine and SmartMoney. She is co-author of the forthcoming book, "The Concussion Crisis: Anatomy of a Silent Epidemic."
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