Monday, July 11, 2011

The War on Sodium

I came across an article on Scientific American about the "war on salt" and why it needs to end. After reading through the article and finding it challenged most of my knowledge and opinions on the topic, I decided it might be an interesting exercise to craft a response.

Hey, I've got a blog. That's a handy place for a discussion such as that.

This is the challenge: 90 minutes to read and respond to an article. After that, pencils down, no corrections, put it out there for people to read. (Confession: It was going to be 60 minutes, but I realized I'm way out of practice from school to stay under that limit.)

A couple of reasons for doing this:
One, I love to debate things. I hate being wrong, but I do appreciate the opportunity to have to put myself behind what I (think) I know and believe to be true.
Two, I definitely think there's enough debate going on about health and food (goodness gracious, just look at the senate and school lunches), but there's not enough conversation. A good debate makes the best argument (or arguer) quickly rise to the top, but it rarely educates thoroughly and doesn't foster the best environment for meaningful learning. People need to be taught how to help themselves eat better, not just be chastised for doing it wrong.

So, here's attempt number one. My response to Scientific American's "It's Time to End the War on Salt" (original article linked from the title).

The article “It’s Time to End the War on Salt,” published this month in Scientific American, discusses the lack of firm scientific evidence linking excessive sodium intake with negative consequences on cardiovascular health.

Wait, what? You mean, someone is saying that there’s no real proof too much salt is a bad thing? Doesn’t that go against everything we’ve heard in mainstream media for the last decade? And, you know, common sense?

Absolutely. So let’s dig in and see just what they have to say.

The article references two main published scientific studies, one in the American Journal of Hypertension and the other in the Journal of the American Medical Association. They reported the first “found no strong evidence that cutting salt intake reduces the risk for heart attacks, strokes or death in people with normal or high blood pressure.” The second finds “The less sodium that study subjects excreted in their urine…the greater their risk was of dying from heart disease.”

The topic of cardiovascular health is extremely broad. Even the sub-topic of heart disease is quite complex. To examine the issue further, I’m looking at one risk factor, hypertension, within one cardiovascular health issue (heart disease).

Hypertension, or high blood pressure, is believed to be caused by several risk factors, including: smoking, being overweight/obese, sedentary lifestyle, too much salt intake, alcohol consumption, stress, advanced age, genetics, family history, kidney disease and adrenal or thyroid disorders.

About half of those risk factors are (at least to some degree) controllable. The big question that lingers, is how much weight each of those factors have in determining your risk for hypertension. If they were all equally balanced (which science typically ensures never happens), you could, in theory, cut your risk by 50% by eliminating the X-factors that are within your control. We know that’s not how science works and even if it were, 50% of your risk would still be entirely exposed. Let’s take just one of those risk factors, a high sodium intake, the factor that this particular article chooses to focus on, and examine it more closely.

Sodium is a necessary element to supporting human life. We need it in our bodies to maintain a proper balance of fluids and to help nerves and muscles function properly. Your kidneys are in charge of balancing sodium to keep your body working like it should. When there’s too much sodium in the body it builds up in the blood. This causes your blood volume to increase and causes your body to use more pressure to move the blood on its necessary course.

Sodium is taken into our body the same way protein, fats and sugars are – through the foods we eat. As if this issue of cardiovascular health didn’t have enough onion layers to peel, wow we have to add in the explosive topic of the American diet.

To keep the conversation brief and look at a real-life example, let’s take the marinara sauce I had with my lunch today. I ate about a half cup of sauce made from a recipe of canned tomatoes, fresh onion, garlic, red wine, olive oil, and spices/herbs (including added salt and sugar).

See that total compared to what’s available at the store:

Homemade Pasta Sauce (using canned tomatoes)
128 mg sodium per serving
Prego “Healthy Heart” (low-sodium) Traditional Sauce
360 mg sodium per serving
Prego Traditional Sauce
480 mg sodium per serving

The recommended daily value of sodium for the average adult in the US is 2300 mg/day. Just with a half cup of my marinara sauce, I’ve taken in 6% of my daily allowance. Lucky me, I could have taken in 20% if I’d opted for a “more convenient” option with a store bought sauce.

That’s one drill down on one example of one risk factor of one element of cardiovascular disease. That context makes it entirely unsurprising to me that science has been able to solidly attribute high salt intake to poor cardiovascular health in any significant population of patients.

Eating a salty French fry one day isn’t going to give me high blood pressure for life. That’s why I’m less inclined to fully rely on information in studies such as the ones referenced in the Scientific American article where the participants in the study were followed for a relatively short period of time (six months in the AJH study) versus others published that have followed patients for decades (See the JAMA article “Dietary Sodium Intake and Subsequent Risk of Cardiovascular Disease…”)

The way all of these X-factors of cardiovascular health integrate, balance and affect one another is, I’d imagine, a highly complex Rubik’s cube of a puzzle that will take scientists far smarter than me to solve.

Luckily for the proponents of this article, however, it doesn’t seem that kind of research is likely:

Rather than create drastic salt policies based on conflicting data, Alderman and his colleague Hillel Cohen propose that the government sponsor a large, controlled clinical trial to see what happens to people who follow low-salt diets over time. Appel responds that such a trial "cannot and will not be done," in part because it would be so expensive. But unless we have clear data, evangelical antisalt campaigns are not just based on shaky science; they are ultimately unfair. "A great number of promises are being made to the public with regard to this enormous benefit and lives saved," Cohen says. But it is "based on wild extrapolations."

I guess I missed the unfair promise the government made me that if I ate less salt, it would save my life. While the debate to salt or not to salt is hot within the realms of science and Washington, I’ll continue to do what I believe to be in the best interest of my own health – exercise, drink water, and intelligently fuel my body with food I believe to be good.

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