Thanks for joining me for another edition of the SerenityThroughSweat blog. This week, I want to talk about science.
What is science? Why is it important? How do we verify or approve the results? Is all science good science? These are important questions. Questions, which may not have definitive answers. Just like good science, the answers and insights are not fixed, but rather, continuously evolving.
I take in a lot of salt. That might go against some of the established medical advice regarding blood pressure and heart health, but I do so deliberately and with “scientific” justification.
So when I read the following study, I wanted to share it and explain my thoughts and interpretations. You know, for science.
The title of the paper reads, “Middle-age high normal serum sodium as a risk factor for accelerated biological aging, chronic diseases, and premature mortality.”
The study took blood draws of participants in middle age in years one and three. The blood draw was taken after 8-12 hours of fasting. The blood draw was measured for average serum sodium levels.
The thought process behind this methodology is that average serum sodium levels taken two years apart would provide a baseline for hydration.
Your hydration is regulated to a very tight range by two primary mechanisms in the body, thirst and antidiuretic hormone (ADH).
When you lose water through sweat or fail to take in enough water, the concentration of sodium (among other things) increases in your blood. This triggers the release of ADH which results in less volume and more concentrated urine.
This has led to the guidelines from health organizations to check the color of your urine to gauge your hydration status.
The study followed up with participants after 25 years to assess all cause mortality, biological aging, and chronic disease. The participants were broken down into three categories based on their average serum sodium levels, (a proxy for hydration) optimal, high and low.
So far the authors of the study have a solid hypothesis, (based on previous findings done initially in mice) a good methodology, and an easily identifiable and measurable variable to track.
However, the results (raw data) and the interpretation of those results, start to go a little off the rails.
“Lowest mortality rate was among people with 137–142 mmol/l serum sodium (26.2%, n = 8604), with increased mortality in 135–136.5 mmol/l (39.3%, n = 122) and 144.5–146 mmol/l (34.5%, n = 397) groups.”
“Kaplan–Meier survival analysis gave similar results showing increased mortality rates among people with serum sodium less than 137 mmol/l and greater than 142 mmol/l (Fig. 1e). In Cox proportional hazard time-to-event analysis adjusted for age, sex, race and smoking, serum sodium 135–136.5 mmol/l was associated with 71% increased risk of all-cause mortality, and 144.5–146 mmol/l increased risk of premature mortality by 21% in comparison to the 137–142 mmol/l group (Fig. 1f).”
“Interpretation:
People whose middle-age serum sodium exceeds 142 mmol/l have increased risk to be biologically older, develop chronic diseases and die at younger age. Intervention studies are needed to confirm the link between hydration and aging.”
Lets start out by saying that everything they said in their interpretation is factually correct according to their data.
However, the data suggest a higher risk of all cause mortality, in the low sodium when compared to the high sodium group. (39.3% vs. 34.5% and 71% vs. 21% respectively)
71% vs 21% is a huge difference in your likelihood of all cause mortality. Their own data indicate that the low serum sodium group was at significantly higher risk than the high serum sodium group when compared to the optimal range.
Over hydration, or lack of the required sodium intake, seems to be significantly more hazardous than under hydrating or over consumption of salt. Obviously the optimal range is optimal, go figure. The study results focus on the high sodium side, which was more hazardous than the optiMAl range but an order of magnitude less deadly than its lowernsodium counterpart.
I am a heavy sweater, as you may have guessed from the blog title, my closing remarks, and most of the topics covered. I also know that my sweat is very electrolyte heavy. This can be measured in a lab, or anecdotally, by seeing salt crystals on your workout gear after your sweat dries.
Appropriate hydration and electrolyte replacement are essential to everything I do from triathlon and jiu jitsu, to flying and parenting. You aren’t going to get very far physically or mentally if you are dehydrated or your electrolyte balance is off.
Like we mentioned earlier, this study started off with a good hypothesis, methodology, and the right variables. The data set was robust, and the study should be repeatable. These are all hallmarks of “good science”
I would classify the interpretation as somewhat missing the point. Mayne the the reporting omitted the more important or the more significant finding, maybe it was biased toward a specific outcome.
I don’t know the authors. I dont know the editors. I dont know their advisors or bosses. I don’t know their funding, their political leanings, or their personal inclinations. Frankly, none of that matters. Science is not partisan. It is cold, unemotional, and calculating.
While I believe you should “trust the science” (as we have heard so often these past few years) I also believe, in the wise words of President Roosevelt, you should trust but verify.
In this case the science was good, the interpretations less so. Knowledge is power, and sometimes that power needs to be mined with cognitive effort, ingenuity, and a little sweat. (As long as you replenish fluids and sodium 😉
Thanks for joining me, stay safe and stay sweaty my friends.
