Saturday, June 9, 2012

Medical Magical Thinking: The Salt Lie

What if salt isn't so bad for you? What if reducing your salt intake isn't good for your heart and blood pressure? What if it's actually BAD for your heart? What if people who control their salt intake are at higher risk for heart failure? What if reducing your salt intake to the levels recommended by the CDC and USDA actually puts you at a higher risk of premature death?

I love going to the movies. And for me, going to the movies means a large popcorn liberally bathed in salt. I love salty popcorn so much that you will find in each of my purses a snack-size zip lock bag with little packages of salt with the Regal logo on them so that when I get to the middle of the large popcorn I can re-salt as necessary. Over the years I've been admonished by many for my salty ways, but I have continued guilt free. In graduate school my husband Stuart studied the salt issue in a cardio-respiratory physiology class and learned that salt actually has little to do with your blood pressure, heart function or over-all health - except when your electrolytes get out of whack - i.e. when you have too little salt in your system.

I have done my best to follow the many, many salt studies since. Only one small study somewhere along the way showed that if you lowered salt intake to a level that is almost unsustainable (and not really possible outside of a clinical setting) you might, for a person or two, lower their blood pressure a point or two. I'm talking from a systolic (upper number) reading of 130 to say 128 - in only a few people - most in the study had no change in blood pressure at all. Furthermore, this small reduction was never shown to impact hypertension, heart disease or make anyone live longer. All the research since then has shown the same results - reducing salt does little to affect blood pressure. (see Gary Taube's book "Good Calories, Bad Calories" pg 146-148).

However, "in an abundance of caution" that is so prevalent in medicine - that Medical Magical Thinking - we've been hounded for decades to deny ourselves salt for very little, if any gain - just in case. Well, guess what, when you base medical advice on bad science, bad things can happen. Doctors have begun to see seniors with thyroid problems because they've restricted their salt intake so much that they're not getting enough iodine (that's why we have iodized salt!). Worse yet, research over the past few years has shown that lower salt intake puts you at greater risk of heart failure and death.

I had intended to cover this is a future blog post, but my science crush Gary Taubes beat me to it in last Sunday's NY Times. Given that he's a better writer than me - go read his article - (and please share this post or that article if someone you know is limiting their salt intake in the hopes of being healthier!)

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