An LA Times article announcing “England’s salt-reduction campaign saved lives, researchers say” caught my attention and immediately frustrated me. Years before I became a shiatsuist, I got a degree in environmental science and my thesis was a meta-analysis of medical research studies connecting breast cancer incidence and exposure to certain pesticides. The main thing I learned from writing this thesis is that most news articles wildly interpret scientific studies and contribute to cultural misinformation about health. Now whenever I read a news article about a medical study published, I immediately go to the journal and read the results for myself to see how it stacks up to their summary.
So let’s tackle this salt issue. The LA Times article is quoting the results of a study published in the British Medical Open Journal and you can read the full article here (or even just the abstract, which is still pretty illuminating). First off, the number of people in the study is in the thousands, so we’re off to a good start – some research studies only have a sample size of a few dozen people, which can open the door for more investigation, but it’s rarely a significant enough size to make sweeping conclusions. The news article headline says that England’s salt-reduction campaign saves lives, but look at what the full results say: from 2003-2011, the number of deaths from stroke and heart disease decreased by 42%. In this time frame, there was also a reduction in overall blood pressure, a reduction in cholesterol, a reduction in smoking, an increase in eating fruits and vegetables, an increase in BMI. Oh, and a decrease in salt intake. (It’s fascinating that the BMI went up as stroke deaths went down and the study says we’re supposed to ignore it – which is convenient, since I ALWAYS ignore BMI numbers because they are pointless and unscientific in regards to individual health.)
Several concrete health factors improved in England over the 8 year period, particularly less smoking and eating more fruits and vegetables (as well as advances in medical treatments), but the news article says we should be focused on the salt intake. However, the study itself lists a weakness in their conclusion, saying “the population surveys included different sets of participants. Therefore, the results of our study could possibly be subject to ecological bias.” The sample of people used for blood pressure is not the same sample of people used to measure salt intake, yet they are connecting them and saying that it all must be related and causal. I’m sure the amount of cell phone use went up amongst that population between 2003-2011 as well, so why not write a news article about how increased cell phone use decreases stroke deaths?
The LA Times article goes on to talk about the campaign by the political action group “Action on Salt” to get the amount of salt in processed food reduced. So I did a little research and after googling the name of the doctors of this study, I learned from the bottom paragraph of this article that:
Dr. Feng J. He is a member of Consensus Action on Salt & Health (CASH) and World Action on Salt & Health (WASH) — both of which are non-profit charitable organizations. Dr. He does not receive financial support from either CASH or WASH. Study co-author Graham A. MacGregor is also associated with CASH and WASH, and co-author Sonia Pombo-Rodrigues is an employee of CASH.
Sounds like the doctors are pretty passionate about their cause of salt and health, which seems like a good idea on paper, but it’s based on a fallacy we’ve taken for granted for decades. The LA TImes even states it as simple fact: “Salt consumption increases blood pressure – a risk factor for stroke and heart disease.” But there’s a problem with this statement – we’ve never proven it to be related to a person’s overall health.
“Wait, what?” I can hear you say. For years we’ve been hearing we should lower our sodium intake! How did this happen? I’ll let this article from the American Heart Association’s journal explain:
These two facts—the positive relation of blood pressure to strokes and heat attacks and the positive association of sodium intake to blood pressure—underlie the hypothesis that a reduction in sodium intake, by virtue of its hypotensive effect, might prevent strokes and heart attacks….The problem with this appealing possibility is that a reduction in salt consumption of this magnitude has other—and sometimes adverse—health consequences. The question, therefore, is whether the beneficial hypotensive effects of sodium restriction will outweigh its hazards. Unfortunately, few data link sodium intake to health outcomes, and that which is available is inconsistent. Without knowledge of the sum of the multiple effects of a reduced sodium diet, no single universal prescription for sodium intake can be scientifically justified. [emphasis added]
Let me pause and say, if your doctor has told you to give up salt, believe them! Some people are extremely salt sensitive and it can drastically affect their blood pressure and cause problems….but some people are also salt resistant and their health is not adversely affected by their salt intake. Other people might even need more salt in their diet for good health, so cutting it out would be more of a detriment than a benefit. The short answer to salt intake boils down to: it depends on you and your current personal health. There are no proven generalized guidelines about salt that benefit everyone.
The next time you see a dramatic medical claim in the news, I encourage you to do three things:
- Read the original study (or at least the abstract) to get the full picture
- Consider the affiliations and motivations of the journal and/or researchers (or the news source highlighting the study)
- Don’t assume all the conventional wisdom and assumptions about health mentioned in the article have been scientifically proven.
We are learning and changing all the time in areas about medicine, health, and food, and most often the answers are complicated and individual – that however doesn’t make for exciting and sexy headlines. So the next time you see or hear a health proclamation in the news…..take it with a grain of salt.