What exactly is the relationship between sodium and potassium?

Browsing some of the threads, I’ve noticed something common. Some Soylent drinkers have been reporting that without supplementing additional sodium into their diet, they feel lightheaded or have headaches.

Soylent provides 100% of the required potassium and around 60% of the sodium (depending on the version). I’ve read that most Americans only get 20% of their daily potassium needs while having a > 150% intake of sodium. It’s speculated that this along with high salt intake, is why so many people suffer from hypertension, since apparently potassium counteracts the effect of sodium on blood pressure.

I have two questions relating to this:

1.) Do sodium and potassium interact with eachother in the same way as, say insulin and glucose (for example, does raising one lower the other?.) If Soylent is optimal in potassium but low in sodium this could explain why people have symptoms of hyponatremia.

2.) Is there any evidence that either lowering your sodium or raising your potassium can cause some short term effects (i.e. sodium/potassium tolerance in the body or withdrawal issues?) This may explain why people switching to 100% Soylent tend to feel achy and lightheaded within first week or so.

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It’s complicated.



it’s complicated, but yes, sodium & potassium interact. raising one doesn’t directly lower the other, but having a strong imbalance either way can cause health problems, and where the balance point is & how sensitive a person is to an imbalance depends on lots of things (such as whether they have diabetes).

low sodium is associated with hypotension, which symptoms include lightheadedness.

This is something that so many people get wrong because the way they handle this on food labels is counter-intuitive and weird.

The percentage of potassium on food labels is the percentage of the recommended MINIMUM intake.

The percentage of sodium on food labels is the percentage of the recommended MAXIMUM intake.

Recommended MINIMUM sodium intake (which is considered the ideal intake level by many doctors) is 1500mg. 2000 calories of Soylent 2.0, 1.5, or 1.6 all add up to about 1500mg of sodium, so saying that a 100% Soylent diet doesn’t have enough sodium are flat-out wrong for the majority of people.

I really with food labels would have separate “% of minimum” and “% of maximum” columns, maybe even have a “% of ideal” in between them. Having minimums and maximums mixed together is super weird.


Yes, but in a different way than the other examples you cite. There is something called the sodium-potassium pump:

The other factor to bear in mind is that water tends to flow towards salts (sodium chloride and potassium chloride are both salts). This is why high-salt diets cause us to retain water.

Water flows (slowly) through cell membranes to whichever side has higher overall concentrations of sodium or potassium ions… so if the sodium/potassium balance changes, cellular pressure will change, until the body can compensate.

A sudden decrease in sodium can cause more fluid to move from the outside of the cell into the cell. (There’s more sodium outside the cell than inside, because of the sodium/potassium pump… and a decrease in sodium means the water will flow towards the potassium inside the cell.)

Alternately, a sudden increase in potassium will get into the cell, and once there, it will draw water to itself, inside the cell.

In both situations, the cell will tend to swell slightly. So if you rapidly go from a high-sodium, low-potassium diet (typical) to a low-sodium, high-potassium diet (like Soylent), you get a double-whammy. In sensitive tissues, it may be that this cellular swelling may result in a bit of pain similar to a dehydration headache. It just takes the body a little bit of time to adjust to the new (healthier) salt ratios, and for water pressures to rebalance.

Alternately, the problem may be more directly related to cellular signalling; cells have a resting “potential” or electrical gradient, and the sodium/potassium balance is important to the resting potential and therefore signalling. Again, the change in sodium/potassium balance may cause disturbances or pain sensations as the body adjusts.

Regardless the cause, it doesn’t last more than a few hours, and doesn’t seem to happen if you don’t have a very high ratio of sodium to potassium in you when you start on soylent. It’s possible that tapering into Soylent will avoid the problem entirely, even for those who are prone to it. By tapering, I don’t mean one meal per day of Soylent, which can still cause a headache after that meal. I mean having a bit of Soylent with one or two regular meals, as part of the meal - this will start getting your potassium up gradually before you start having meals consisting exclusively of Soylent.

After the first couple of meals, it doesn’t seem to happen any more (in my experience.)


Simailry there are also many doctors who dont consider 1500 the ideal intake. Also saying that a 100% soylent diet has enough sodium is flat out wrong for the majority of people.


The large majority of people do not need more than 1500mg of sodium per day. 2000 calories of any recent Soylent version provides 1500mg (older versions had less). 2300mg is the MAXIMUM per day. You should NOT be consuming the maximum on a regular basis (if ever).

Similar to saturated fat – if you’re adding up percentages try to reach/exceed 100% saturated fat, you’re doing it wrong: that’s the MAXIMUM, not the minimum.

Again, I blame the stupid way that the food label system requirse some nutrients to be labeled based on “percentage of minimum” and others to be labeled “percentage of maximum”, no telling how many health problems and deaths are caused because of misunderstanding like this.

Tark may not be wrong. I have at least heard of studies that suggest that the 2.3g limit might actually be the lower limit and that 1.5g might be too low. I haven’t actually read any of these studies so I don’t know how good they were.


When they say “salt” they mean “sodium”.