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Still, if you have congestive heart failure, it might help your management to limit salt intake.
There are countless myths about diet and health. The truth is that most of it is driven by wishful thinking, the wish that we might control our fates as easily as by deciding what to have for supper.
The only dietary-related thing (besides basic sustenance) that probably helps health to some extent is to get your Vitamin D from plenty of natural sunlight (instead of from pills or diet) over much of your body, while avoiding sunburn and avoiding obsessive use of sunblock.
There is a very small population that is sensitive to ingested sodium and will have a spike in blood pressure because of it. This is measurable and the blood pressure returns to normal as the kidneys remove the excess. Otherwise I agree with your wise Dr. friend.
Most (grown-up)people tend to know when they are eating/drinking/etc to an excess. And most people only indulge in excess rarely.
Personally I think the vit D study is hype. It has identified almost everyone as deficient.
There's a difference between eating something (anything) and eating that same thing in excess.
Salt in itself is not a problem (except ruining the taste of almost everything it touches if used in more than miniscule amounts).
But the amount of salt contained in many goods most of us consume on a daily basis is far higher than the human body needs or in some, maybe many, cases higher than is healthy.
The kidneys have trouble getting rid of it, leading to kidney stones (just one reason those form, but a factor).
The problem though with most dietary regimens is that they tend to go for extremes, as do politicians.
So instead of a diet telling you to limit your salt intake, you get diets that tell you to eat no salt at all in any form.
And those diets may well have a point as you're almost certain to get your daily recommended dose just by eating a few slices of bread and having some ready made salad dressing on your letuce at diner. The canned soup as starters and the sauce mix used to create the sauce for your steak only make things worse, as does the prepackaged desert.