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How Does Salt In Diet Cause Hypertension?
Author: Cleaves M. Bennett MD FACP
Monday, January 07, 2008

The biggest single nutritional question that faces the hypertensive person is salt use.

How much salt do you use on your food; that you add at the table with the shaker?

How much salt do you use in your food—salt that's added while the food is being cooked?

And how much salt have the manufacturers added to the food you eat—before you even begin to cook it, while it was being processed, or preserved, or packaged?

Many people with high blood pressure are aware of the effects of salt in their diet and don't add any salt to the food at the table. You may have thrown the salt-shaker out already. I certainly hope so! Some people are already avoiding adding any salt to the food they cook. But that's usually less than half the problem. The real question isn't how much salt you add, its how much salt the food already has in it when you pick it up in the grocery store. Or order at a diner.

Salt isn't added to food only as a seasoning of course, it's also added as a preservative, a mixer, and a stabilizer. Manufacturers don't really know yet what to replace it with in most cases.

Food that spoils on the shelf could cause botulism, and other forms of food poisoning—and the specter of customers dying of food poisoning is something that makes food manufacturers very reluctant to stop using salt as a preservative until they an find a satisfactory substitute.

Some of the substances that have been suggested cause cancer; others don't work well as preservatives; some make the food taste bad; and some turn it a funny color.

We've gotten used to the pink coloration of bacon and ham; in fact now we even think it means the meat's in good condition. But that coloration comes from sodium nitrate and nitrite. You will find nitrates and nitrites in all the pink meats—hot dogs, luncheon meats, bologna, ham, bacon, and so on. And those nitrates and nitrites don't just change the color of the meat. They are sodium based. And there's also some concern that they may cause cancer.

We are so used to manufactured, processed convenience foods (and so dependent on them) that we are buying more and more of them. It's a real advantage to the manufacturers to be able to make food with a long shelf life, and if they don't use salt to preserve these foods, what are they going to do instead? At the moment, salt and other sodium products are the best they've come up with. So even when you don't add salt to the food you eat, the manufacturers has almost certainly added it for you.

Cutting out salt at table and not adding salt while cooking, may be reducing only about 20 to 25 percent of the total salt in your diet. And once you have hypertension that may not be enough to make much of a difference.

What's the problem with salt? As I've said before, our bodies simply weren't designed to cope with the amount of salt that's in our everyday diet. There are now plenty of studies available that show a direct correlation between the amount of salt a society consumes and the amount of hypertension in that society. In the few isolated cultures that still exist where there's virtually no salt in the diet there's also virtually no hypertension.

Our bodies have been around for millions of years, and they are best adapted to an environment in which salt was very hard to come by. Primitive man didn't have salt-shakers or manufacturing companies that preserved his foods for him, and salt occurs naturally in foods only in very small amounts. So we're perfectly adapted to an environment where sodium is rare and the potassium content of food is very high.

What goes wrong today is our kidneys. They simply weren't designed to throw off the quantity of salt that we eat every day, at least not for a lifetime. Oh, they may manage to do it for forty or fifty years before they begin to fail, but sometimes they give out when you're only twenty- nine years old. You suddenly find out from your doctor that you have high blood pressure. Then you really need to go on a low salt diet!

Do you use any canned foods? Do you eat anything that comes from a jar, or a sack, or a box, or a bag, or anything frozen? (If it has been frozen, even if it's a dessert, it likely has salt in it.) What kind of cheese, any baked goods, or restaurant food? There's salt in virtually everything that's prepared by other people and marketed for you to eat.

Salt, of course, is sodium chloride; it's present in soy sauce, tamari, sea salt, garlic salt, seasoned salt… or under a dozen other names. Most kinds of seasonings in shaker bottles have salt in them. It's in most sauces and dressings. Cured and prepared meats are full of it. And the sodium part of sodium chloride is also toxic by itself; it is found in such things as baking powder, baking soda, and Accent (monosodium glutamate).With a high blood pressure problem, you need to watch all this very closely. You'll need to read the labels and know your way around foods. (In the Appendices to this book you'll find the names of some books that list the sodium content of foods.)

If you're on a diuretic and you're eating what you think is a low- sodium diet but you're not responding, it may mean that you're still eating too much salt. The only way to find this out for sure is to have your doctor perform a twenty-four-hour urine sodium test. The amount of sodium you excrete every day is a very accurate indicator of the amount of sodium you're eating. So this test will let you know how low in sodium your "low sodium diet" really is.

The typical American eats about 180 to 200 millimoles of sodium a day (about 4.5 grams of sodium, or 11 grams of salt)—and we want you to try to get down to less than 50 millimoles (a little over I gram of sodium). You can get down to less than 50 millimoles and still enjoy your food, but you'll probably have to be a lot more careful about it than you are at present.

Even then, you'll still be eating four or five times more sodium than the avenge Yanomamo tribesman!

I read in Newsweek that the idea that salt causes hypertension is pretty controversial still, and that not all the experts agree. Apparently some of them feel the evidence isn't strong enough to warrant reducing the salt intake of the average person, or even restricting salt in the diet of everyone with hypertension.

You're right, these are controversial issues. Not as controversial as some of the media would lead you to believe. An article in Nutrition Action, published by the Center for Science in the Public Interest (1982), looked at some of the behind-the-scenes maneuvering that led to stories in both the New York Times and Newsweek. One item they mentioned was that a Dr. David McCarron has been lobbying very hard to promote his own theory that calcium loss is the most important factor in the genesis of human hypertension. (He's been an outspoken critic of the theory that links sodium with hypertension. However, Dr. McCarron has received substantial financial support from the National Dairy Council, who would obviously love to see 60 million hypertensive Americans drinking a lot more milk to obtain extra calcium, while ignoring salt which is in their cheeses and butter!A symposium held in September 1982 led to headlines in some papers such as “Experts Challenge Low Sodium Diet." This symposium and its participating speakers received major support from… the Campbell Soup Company and the International Life Sciences Institute (an organization whose membership includes General Foods, Kellogg, Kraft, Nabisco, ITT-Continental Baking, Procter and Gamble, and others). These organizations would naturally be only too happy to take some of the heat off sodium, which is such an important constituent of many of their products.

There will always be “experts” who disagree—that's just the way we are. We’re an argumentative species. And more than fifty years after the first research showed the link between cigarette smoking and cancer the American Tobacco Institute can still find "experts” who disagree. That's human nature.

But since it affects your health and well being so directly, you shouldn't just throw up your hands as if to say, “Well, if the experts can't agree, I'm not going to change my eating habits." Talk to your doctor and see what she says. Read this book carefully and try out the program. If I'm right, it'll work for you—and that's the true test: what works for you.

The American Society for Clinical Nutrition considered the links between different dietary factors and human disease in 1979. On a scale of 0 to 100, they judged the strength of the relationship between salt and hypertension to be 74, which is especially significant when you consider how many other factors are involved that we already know about. Only two other factors (sugar and tooth decay at 87, and alcohol and liver disease at 84) received higher ratings.

Oh, the evidence is there, all right. Look at the list of scientific papers, most very current, at the end of Chapter 20 entitled “Letter to a Physician”. All of them, without exception, support and/or prove the notion that high dietary salt intake is one of the critical elements that makes hypertension and its crippling vascular consequences epidemic in most of the world.

A very large-scale study of the effects of weight loss and salt restriction on literally thousands of hypertensives conducted at the Universities of Minnesota, Alabama, Mississippi, and California showed that both interventions lowered blood pressure. According to one of the principal scientists involved in this study, Dr. Ronald Prineas, "The best animal, epidemiological (population), human clinical and anthropological evidence says it is reasonable for everyone—even people with normal blood pressure—to cut down on sodium."

Addressing public health policymakers, Dr. Prineas says, "By not taking action, you're actually adopting a conscious policy… to let people at risk go on being at risk. I am not willing, given the current evidence, to make that decision." He says, in effect, that we can and should do something now.

Salt isn't the only factor causing hypertension in humans. But it's probably the most important one. Salt a not as dramatic or as predictable and immediate in its effects as cyanide. But its toxic effects in this country alone are like a mini-holocaust. Well, perhaps actually a maxi-holocaust.

It's a major contributing factor in the more than 800,000 cardiovascular deaths we suffer each year. Without salt, the other factors—obesity, stress, sedentary life style, and other dietary influences such in fat, calcium, potassium, and alcohol--just wouldn't have the same effect, at least not on the grand scale that we see in this country today. In Europe it’s just as bad or worse.

If it weren’t for our excessive salt intake, hypertension would be a relatively rare problem, interesting to a few specialists—about like systemic lupus erythematosis or polycythemia vera--afflicting a few thousand, instead of 65 million Americans! And even hundreds of millions more around the globe.

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