[mrtesthah]

The study measured hydration in terms of sodium, but how do we know that the effective age reduction was not (or additionally) due to relatively higher consumption of potassium rich foods (such as fruits & vegetables)? Potassium can reduce sodium via membrane potential.

[Maxburn]

Or even on a more basic level; people that manage their hydration probably overall manage their health better.

For me it's a constant balance that's hard to find, am I thirsty and lips cracked or did I visit the bathroom six times this morning?

[mtlmtlmtlmtl]

We don't. This is why these studies should be taken with a huge grain of salt.

[l33tman]

Very funny :)

[hinkley]

I’m having a Bad Pants day today because we had a big bowl of popcorn with our movie last night and I’m retaining water because of it.

One of the ways I’ve controlled weight, tooth decay and crossing the A1C threshold into prediabetes is to swap sweets for savory snacks, which almost universally come with a higher sodium burden (not just salt but also umami).

Telling people that sodium is bad is part of how we got to overindulgence in sweets. We do not want to go back down that road.

[adrian_b]

I doubt that the there is any way in which a higher potassium intake could reduce the sodium concentration in the blood.

All the living cells in the body pump inside them all the potassium that exists in their environment.

When more potassium is ingested, there is more potassium inside the cells. That draws more water inside the cells, to restore the intracellular concentrations, i.e. the equilibrium between the intracellular and extracellular osmotic pressures.

This leaves less extracellular water, but the same amount of sodium, so the sodium concentration in the blood increases, which causes thirst. After drinking water, both the extracellular sodium concentration and the intracellular potassium concentration are back to normal.

It does not matter whether one eats more sodium or more potassium. The final effect is the same, more water retained in the body, after initially having both a higher extracellular sodium concentration and a higher intracellular potassium concentration.

The difference between sodium and potassium is that when eating more potassium there is more water inside the cells and less outside, while when eating more sodium the reverse relation is true (but the deviations from normal will be corrected when sodium and potassium will be excreted).