Friday, September 14, 2012

Salt and Hypertension? Don't Blame Your Salt Shaker

High blood pressure is deadly. High blood pressure, or hypertension, is diagnosed when systolic blood pressure (the top number) is measured twice at 140 mmHg or greater, or when diastolic blood pressure (the bottom number) is measured two times at 90 mmHg or greater. How deadly is hypertension? Strokes are more than eight times more likely in people with a systolic blood pressure in the 150s versus people under 112 [1]. The risk of dying from heart disease or a heart attack is also dramatically higher in people at 150 mmHg or greater. Having chronic hypertension causes the following mechanisms that underlie strokes, heart attacks, and kidney failure:

  • Increased arterial stiffness ("hardening of the arteries")
  • An enlargement of the heart
  • Aneurysms in the blood vessels of the brain
  • A narrowing of blood vessels in the kidneys

It's not controversial: being hypertensive puts you closer to the grave.

Salt increases blood pressure. Therefore, we should stop salting our foods and cut down on sodium-containing foods such as red meat and eggs, right?

Wrong. Confused? Keep reading.

A New Perspective on Sodium

In previous posts, I made a few arguments in favor of salt:
  • Cutting a half tablespoon of your salt from your diet makes an average reduction of 6/3 mmHg, which is not a significant change [2]. If you use a salt shaker with lunch and dinner, you may have added a half tablespoon to your daily salt intake. In the same blog, I pointed out a study of congestive heart failure patients which showed salt reduction was associated with an increased rate of hospitalization.
  • Salt's effect of increasing blood pressure may not last long [3]. People with hypertension typically have diabetic signs such as high levels of glucose and insulin in their blood. Changing the lifestyle habits that cause the diabetic problems would likely fix hypertension.

I said my answer is complicated, so here's the complication: I don't think people should cut down on salt shaker use and meat and egg consumption, but I do think people should reduce their salt intakes. People are eating foods that are unnaturally high in salt, foods that contain much more sodium than red meat and eggs can even dream of - processed foods.

Processed foods are dense with salt - it's part of the taste formula that keeps customers coming back. According to the National Institute of Health, about 75% of US salt consumption comes from processed foods such as, "processed meats, sauces, dressings, soups, and breakfast cereals" [4] - yes, even breakfast cereals are high in sodium (calorie-for-calorie, Kellogg's Raisin Bran and Rice Krispies have more sodium than eggs). If you want to see what an abundance of sodium looks like, look at nutrition labels of common condiments: ketchup and sauces such as soy, terriyaki, and barbecue.

If I'm wrong and sodium is a major cause our health troubles, it's an indictment on the amount of processed foods we eat. We shouldn't look at taking salt shakers off the table and meats out of the diet; replacing foodstuffs with natural foods will create a more natural salt intake.

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