Sodium is a very misunderstood mineral. Some people love it and recommend not limiting your intake and pounding salt/electrolyte powders. Others avoid it like the plague because of blood pressure concerns. As usual, the true optimal approach to sodium lies somewhere in between these extremes. We need sodium. It’s an essential mineral for nourishing our cells, which means we cannot get hormones or nutrients inside our cells without it. We also need enough sodium to support muscle contraction, healthy blood pressure, transmit signals to our nerves, make stomach acid, transport thyroid hormone, and more. The question is do you really need to add more salt in order to optimize your sodium status? The answer might surprise you!
Like most blood levels of minerals, our bodies regulate the amount of sodium in our blood very closely. We can have changes in our sodium intake and stress from day to day, which both impact sodium levels, but we have systems in place that keep the levels in our blood within a tight range.
Our kidneys are the main regulator of sodium (and potassium). When sodium levels decrease (from excessive sweating or low intake or both) the kidneys will respond by conserving sodium. How? Our kidneys have small blood vessels that release a hormone called renin. Once renin is released into the bloodstream, it acts upon enzymes that will eventually make angiotensin. Angiotensin then acts on our adrenal cortex, causing it to make more aldosterone. This aldosterone hormone is what causes sodium to be retained. When sodium levels are low in the body, aldosterone production increases, causing the kidneys to conserve sodium. Aldosterone can also cause a craving for salt or salty foods. Salt cravings can also be caused by ACTH (adrenal corticotrophic hormone), which is secreted by the pituitary gland during the stress response. When sodium levels are normal or high, aldosterone levels decrease, which leads to less sodium being reabsorbed by the kidneys.
Potassium also plays a major role in regulating sodium levels in the body.
Sodium gets all the attention when it comes to things like blood pressure and adrenal health, but we need potassium too. If we are taking in a lot of sodium and not enough potassium, water will get pulled from our cells and pushed into the blood in order to compensate for the increase in sodium. This leads to dehydration of the cells and fluid retention. Potassium intake also impacts sodium loss. The more potassium we eat, the more sodium is excreted in the urine. This is why people that are salt sensitive can typically tolerate salt if they are taking in enough potassium. These two minerals work closely together in the body. Each cell has a sodium-potassium pump. This pump will move sodium out of the cell and potassium into the cell.
The optimal ratio for sodium to potassium is 1:4. 4x as much potassium as sodium. Before you start stressing out about achieving an exact 1:4 ratio, I recommend focusing just on increasing potassium-rich foods. I have also seen a ratio of 1:3 work really well for many people. It will be different for everyone. Experimentation and working with your provider to figure out what is best for you is key.
Our sympathetic or fight-or-flight nervous system plays a major role in our regulation of sodium levels as well. When our bodies are experiencing a stressor and stimulate the sympathetic nervous system, this causes an increase in sodium retention. In fact, when sodium levels are low, our sympathetic nervous system will turn on in order to increase the body’s sodium levels. This shows that low levels of sodium are a stressor on the body. Over time, low sodium levels weaken our adrenal glands and can lead to fatigue. Especially with how low sodium leads to less cell permeability AKA fewer nutrients getting inside our cells.
When it comes to high blood pressure, the automatic recommendation is often to reduce sodium intake. This can work for some (not all, some people experience even higher blood pressure from this, likely related to the stress response happening in the body from too low of sodium) but for many, they do much better with increasing potassium instead. Potassium can help lower blood pressure and excrete more sodium from the body. It also supports healthy blood sugar. Low-sodium diets have been shown to reduce insulin resistance (even in healthy individuals). Insulin resistance is a major driver of what contributes to high blood pressure in the first place, which is why I think we need to take all minerals into consideration when it comes to addressing blood pressure. Potassium matters, but magnesium and calcium do too. High blood pressure is so much more than just lowering sodium intake.
If you are enjoying this deeper look into salt then make sure to listen to my sodium deep dive podcast episode on the are you menstrual? podcast!
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