A couple of months ago, I met with congressman, Louie Gohmert. Our conversation somehow got around to history, and I admitted to him that I wasn’t much of a history buff. He said something like this, “You have to fall in love with the stories in order to fall in love with history. History is all about the stories!” That comment really stuck with me. I love a good story.
So, how does that lesson tie into my topic about sodium?
A couple of years ago, I put together a lengthy and detailed presentation on sodium. I found the research on sodium much less interesting than what I learned about the researchers. The study of sodium has continued for decades, and surprisingly, it is a very controversial topic! And the researchers are a bunch of passionate people who believe whole-heartedly in what they do. This can put some unexpected personality behind the science - creating a story where you least expect it.
In my research, I read articles where some scientists bashed other scientists. And the scientists who were bashed stood their ground and criticized the former scientists. Arguments happened publicly, even, not just in print! And after preparing for this blog, I see that it still continues!
Limitations of Nutrition Research
You see, when it comes to nutrition research, there are no absolutes. It is rare for us to say X food causes Y disease with absolute certainty and no caveats. The field of nutrition research is complicated. When we study what people are eating, you really can’t put them in a box and control every variable in their lives. And when (or if) you do, you can’t do it for long and you can’t get a large sample size. This is the problem. So, the research that is well controlled is either on animals or on a small sample of humans over a short period. That doesn’t exactly give us data we can extrapolate to the entire population with a lot of certainty. Plus, the results have to be repeated multiple times before we can put our faith in them. More often than not, nutrition research is observational, meaning we watch people’s habits, or more often, have them report to us, and then we document our findings. The biggest problem here is that self-reported data is much less reliable – people can lie about their intake and, more often, people aren’t aware of actual portions and tend to underestimate their intake. Also, we can’t control for all the other variables that can affect an outcome like exercise, stress, sleep, and other foods they eat besides the one we are looking at, etc.
Keep in mind that the amount of time it takes for nutrition to affect ones health is over the course of years, not days or weeks! As a result, observational studies must take place over the course of years and have to include extremely large sample sizes for findings to be reliable.
To illustrate my point, I got this quote out of an online Medscape article: “Mente and others have called for large randomized, controlled trials to compare low vs moderate sodium intake. But Mozaffarian notes that would be a massive undertaking: ‘You'd need 30,000 to 40,000 healthy people followed for 6 to 10 years kept on a low-sodium diet vs a regular-sodium diet. . . . I don't know if that's ever going to happen.’" Keeping that many people on a specific dietary restriction for that amount of time is nearly impossible. There are plenty of large sample size studies over long periods of time, but they don’t have subjects follow set guidelines for the duration of the study in these cases – remember they are simply observational and do not attempt to control subjects behaviors.
The conclusions we make from these observational studies are usually correlations and not causations. In other words, we see a correlation with X food intake and Y disease. For example, repeated studies show a correlation between overweight/obesity and skipping breakfast. But we can’t say for certain that skipping breakfast causes obesity. So, you see, it’s tricky.
With this said, the study of nutrition takes a great investment of the researcher’s time; often her or his lifetime. In fact, many researchers devote their entire lives and livelihood to their hypothesis.
This is most certainly the case with the study of sodium.
The Sodium Controversy
The disagreement related to sodium is over how much sodium is too much and whether this restriction should apply to everyone.
Here’s what that debate looks like right now:
Backed by several studies, Researcher A supports a sodium restriction of 1500 mg (1.5 g) per day.
However, Researcher B finds more cardiovascular incidents and death among those with sodium intake less than 3 grams per day, compared with those between 3-6 g per day. Whereas, those with high intake of greater than 6 grams per day had more increased risk in individuals who were diagnosed with hypertension. Researcher A makes a case to abandon the population wide sodium restriction and come up with a way to identify individuals to whom the restriction applies, i.e. those with hypertension.
Researcher A expressed concern that adopting the authors' recommendation "may reverse the progress that has occurred in modifying dietary sodium intake and reducing the risk of high blood pressure and its effect on heart disease and stroke." This researcher is supported by another researcher who dismissed the findings saying that it was a flawed study.
Researcher B stands by the research he conducted and says it used industry standards and denies it being flawed.
And we are at a standstill.
The Dietary Guidelines are set by a committee that heeds the recommendations of the professionals in light of the most recent research as well as the long-term findings. Currently, The 2015-2020 Dietary Guidelines recommendation is to limit sodium to 2300 mg per day for all people over the age of 14. They add that individuals with hypertension and pre-hypertension would benefit from reducing sodium intake to less than 1500 mg per day. The current recommendation by the American Heart Association (AHA) is for 1500 mg sodium per day based on large amounts of data that support this restriction.
At present, the average American is consuming 3,440 mg per day; specifically adult men average 4,240 mg, while adult women average 2,980 mg per day.
The following graph shows our current consumption compared with the recommendation:
Whenever I bring up the subject of sodium in any talk or presentation, a common response I hear is “I never add salt to my food.” It may surprise you to learn that added salt (whether during or after cooking) only contributes a small percent of the sodium in our diets! More than 75% of the sodium Americans consume comes from processed and restaurant foods.
So what is the take away?
I realize this blog doesn’t exactly tell you what you should do about your sodium intake. I just expose the surprising controversy of sodium. So to give you some guidance, here is my advice:
1. All of us: Do what you can to limit sodium, particularly from processed foods. Eat more fresh fruits and vegetables, more whole grains, more whole meat. Eat less processed meat and packaged food. Cook and eat at home more, as opposed to going to restaurants.
2. Those who have ever had high blood pressure (even if it’s controlled by medication), resolve to do the above. Take every measure in your power to make it happen. Realize that the more sodium you take in (which mostly comes from processed foods and restaurant foods) the greater chance you have for a cardiovascular event.
3. For those that have never been told they have high blood pressure, do the above anyway because there are enormous benefits to eating more fruits and vegetables, more whole grains and less processed meats and processed food, in general. But realize you have more flexibility when it comes to how much sodium (which, in our culture, mostly comes from processed and restaurants) you take in. There is more room for the convenience of pre-packaged, processed foods without real worry about cardiovascular events.
As for amount of sodium daily? Well, who can keep track of that anyway? Eat the right foods and feel good about any change you make in the right direction!
If you have high blood pressure that is uncontrolled, see a doctor!!