Tuesday, April 27, 2010

The Effect of Salt Intake on Health

While eating breakfast with my father on Sunday morning, he mentioned hearing that excess salt intake increases risk of heart disease-related death by 30%. Others agreed as I was adding salt to my three-egg omelette (yolks included). While watching the news later that day with other members of my family, a health segment featured talk of salt leading to hypertension, one of the major risk factors for heart disease. My first action was stating how typical this was: Media and government agencies always push us away from eating real things (red meat, butter, salt) while telling us to eat processed ones (anything made from grain...look at the bottom of the food pyramid).

Then I figured I might as well review the medical literature again. I mean, I did once believe that stretching is effective and that low fat diets are healthy, so I might as well be thorough in my analysis of salt. Here's what research says about the issue:
  1. In a study of 52 populations, four showed people to have a low sodium intake and low blood pressure. The other 48 found an inverse relationship, showing increased sodium intake and lower blood pressure. This study was actually put together by people who were biased towards proving salt raises blood pressure...oops.
  2. Individuals with congestive heart failure (CHF) had a lower incidence of rehospitalization when consuming normal amounts of sodium as compared to those CHF patients who were on low sodium diets. In addition, low sodium intake also had detrimental effects on kidney and neurohormonal function.
  3. In his article, The (Political) Science of Salt, Gary Taubes states that a study of 7,300 Scottish men found sodium to have no effect on blood pressure while potassium was found to reduce it (before you go eating a bunch of bananas, read this). In addition, he found many of the salt reduction advocates to push their beliefs by misinterpreting the scientific data in their favor.
  4. One meta-analysis (found in Taubes' article) found a six gram reduction in daily salt intake to have a decrease of 5.8 mmHg in systolic blood pressure (the top number) and a 2.5mmHg diastolic decrease for hypertensive individuals. Those with healthy blood pressure levels experience a significantly lower difference. If you are borderline hypertensive with a blood pressure of 140/90 and reduce your salt intake by six grams, your new blood pressure of 134/87 still leaves you as borderline hypertensive. Another meta-analysis found the reduction for hypertensives to be only 3.7 for systolic and 0.9 for diastolic.
Overall, the point is that we should stop looking at small things that may arguably help us (or hurt us, according to the CHF study) in a minor way. If you want to improve your cardiovascular health, I suggest considering significant changes, such as stress reduction, increasing sleep quantity, decreasing alcohol intake, performing intense exercise, and improving diet.


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