Adding minerals to heavily filtered water actually increases cell uptake. I don't have the study to hand but you need to drink somewhere around 1.7x the amount to achieve the same hydration. The body has no need to retain water void of nutrients.
A pinch or flake of salt is hardly going to spike sodium levels to instigate such drastric water retention, nor will it have an effect on your blood pressure.
The body is self-regulating and protocols like sodium or water loading are outdated, fruitless and dangerous.
Okay, so you're sort of right and wrong at the same time.
Yea, adding minerals (ie, electrolyes) to water will make it be more easily taken up into cells (why you think this is a good idea, I'm not sure). You're increasing the osmolality of the fluid and this helps it move between fluid compartments. It's the same process that will help it move into your blood vessels though, as I mentioned earlier. One doesn't happen without the other. This is why in hospital patients are given saline to help maintain (and sometimes increase) blood pressure. Critically though: we're talking about fluids given intravenously here.
Fluids taken orally although "void of nutrients" initially, will go into your stomach where they mix with your gastric contents, then flush out into your duodenum where your pancreas will dump some sodium in it to help it be absorbed. Then obviously as it travels along your gut it'll further mix with partially digested food. This idea that some of you have that it somehow goes from mouth to toilet bowl untouched is oversimplification. Even if you ingested some ultra-pure distilled water, by the time it was absorbed in the gut it would be part of the same foul smelling, nutrient rich sludge that anything else that passes your lips would be. Try to appreciate here that a pinch of salt is going to make absolutely no difference to this. I don't know where this idea has come from but it has no foundation in science, even if it is
himalayan salt.
The reason I'm stressing it is a bad idea is that if we're talking about adding a pinch of salt to each pint, and someone is consuming 3ish litres, we're potentially talking about a couple of extra grams of salt here for no real reason. I'm not saying don't consume salt, because like most things it's fine in moderation. But honestly, use that moderate amount for something useful like making your food taste delicious.
There was a really great article in the BMJ in 2012 that goes over a lot of these concepts. It's titled "the truth about sports drinks" but it goes over a lot more than that. It talks about a lot of myths about hydration (and dehydration) that were started by companies like GSK trying to sell sports drinks. It's got good videos (great for me) and good references (great for serious people).
The take home point here is what you talk about in the last line: "the body is self-regulating". It's got systems for fluid balance that have been developed over a few hundred thousand years. They're pretty complex and very sensitive and it do all the work so you don't have to. You don't need to sprinkle salt in your drink or drink litres and litres a day. Drink when you're thirsty. It's worked fine for humans up until now and still works fine for the vast majority of the planet. Fuss over something else.
