True or False? Salt restriction lowers blood pressure.
According to the CDC, at least 75 million Americans have high blood pressure. Whether you fall into that category or not, it’s common knowledge that the instruction to restrict dietary salt follows the diagnosis of hypertension.
Dietary salt is an absolute necessity. Like most species, humans have evolved upon the very dependence of it. However, the avoidance of salt has become a societal cliche at this point— but why?
Where salt goes, water follows. Give yourself a minute to think about that sentence. We’ll come back to it shortly.
Your blood consists of red and white blood cells, platelets, and plasma. Plasma is the “liquid” portion of the blood that serves as the major means of transportation for almost everything throughout the body. The maintenance of optimal plasma osmolality, the electrolyte to water balance within the blood, is of utmost importance. Plasma can be affected by the movement of materials in and out of the body (ingestion/digestion/urination) as well as movement of materials between different compartments in the body (into and out of cells).
The body is always reacting, adapting, and functioning to reach a state of homeostasis or balance. Where salt goes, water goes. Let’s say you restrict your dietary salt intake. Now what? Serum sodium levels are low, and the body follows suit by lowering the amount of water in the bloodstream to get back to the right electrolyte-to-water ratio. Think about a garden hose. When there is little water flowing through it, the pressure is low and flows at a slowed rate. Similarly, your blood pressure drops from this cascade of events, the body perceives this as a problem, and acts accordingly. Blood vessels serve as paths or roadways for your blood to travel through. Have you ever gotten a blood test done or seen the results of a blood test? The amount of information that can be obtained from this “lab-drawn snapshot” is incredible. You are already more than aware of the importance of blood, and the extensiveness of a blood test further allows you to deduce the potential implications than can result if things aren’t properly flowing.
The Renin-Angiotensin-Aldosterone System, or RAAS, works in response to low blood pressure or low serum sodium. The ultimate goal is to raise blood pressure. When the kidneys detect a decline in blood flow due to ineffective blood pressure, they release renin into the bloodstream. Angiotensinogen is released from the liver, and acts with renin to form angiotensin I. The lungs then release what is called angiotensin converting enzyme (ACE) into the blood to react with angiotensin I, forming angiotensin II. Angiotensin II is a powerful vasoconstrictor, which means it acts to narrow the blood vessels, causing an increase in blood pressure. Angiotensin II also stimulates the release of aldosterone from the adrenal glands. Aldosterone is the end product of the RAAS. Aldosterone acts on the renal tubules (inside of your kidneys) to reabsorb sodium and water back into the bloodstream AND to excrete potassium to balance out electrolytes. With this water and salt retention, circulating volume increases and the body signals for the end of renin release. Optimal blood pressure is restored.
If you are someone who tightly restricts sodium intake, it’s very likely that you are causing the RAAS system to be in constant activation. An over-activated RAAS stimulates the Sympathetic Nervous System, your “fight-or-flight” response, which is a system meant for times of STRESS. With stress comes an increase in inflammation and aging and a decrease in thyroid and metabolism. Additionally, you can see how this habit would exhaust the system and perpetuate improper responses in the future. Count me out.
Renin, angiotensin, and aldosterone all contribute to inflammation and are increased with sodium deficiency. High levels of aldosterone are associated with chronic kidney disease, thickening of the heart valves, oxidative stress, and accelerated aging.
Blood pressure lowering medications act to inhibit specific steps in the RAAS system, such as ACE inhibitors, which block angiotensin converting enzyme from being released. Therefore, angiotensin II cannot be formed, blood pressure stays as it is, and blood flow remains LOW. The pharmaceutical industry has become one of our most remarkable feats to this day and this is absolutely no attempt to discredit that. Let’s be real about this though. Working with an individual to better his/her health for the long-term takes time. It’s easier/faster to prescribe a daily medication to treat a symptom instead of correcting or eradicating the underlying issue.
Are all salts the same?
No-- Your options are almost unlimited as different salt sources, such as seas and mines, contain various, naturally-occurring elements such as magnesium or iron. That choice is up to you. However, I would make a point to avoid bleached table salt, which is more than likely what you’re accustomed to using. I skip the preservatives/additives and opt for Morton’s pickling salt. Look at the ingredients and make sure "salt" is the only one.
Thanks for sticking it out through this lengthy post!
My goal is to educate YOU on how to sift out the nutritional truths from the many misconceptions in regards to the human physiology. Things don’t really make sense when you compare diet and pharmaceutical trends. We fail to give our body credit and ignore the symptoms as anything but what they are-- an attempt to communicate that something is OFF. As you read above, the body works very hard to conserve sodium when intake is low. I think that it’s important to ask yourself if what you are doing is working. By no means am I encouraging you to load up on salt, but instead slowly start to find out what works best for your body. The right amount of salt will create the ideal environment for proper hydration and proper cell function. When it comes to nutrition, it’s all about finding the ratios and amounts that work best for you. That ALSO requires you to be more in tune with your body, and I think that we could all use a little more of that. Trust in your own process and allow yourself to discover what true health feels like.