I think there is evidence that a really low salt diet can cause problems. But then, I've been reading the research papers of Morton Satin of the Salt Institute (totally unbiased, of course).

And is his name really Morton Satin? From the Salt Institute? REALLY? Whoo, that's funny!

Edit:

I guess I didn't really answer your last bit. Yes, sodium is required by the body. No salt, you die. My limited understanding is that the body maintains electrolytes in balance (sodium/potassium) for cells to do their thing.

Getting you to restrict salt is just another way they keep you sick and dependent on western medicine. Most people vastly underestimate there sodium needs imo.

http://raypeat.com/articles/articles/salt.shtml

I avoid refined table salt but see (and feel) no problems with liberal amounts of pink salt or himalyan crystal salt. Refined salt leaves me puffy and thirsty however.

As long as you're getting a bare minimum of salt intake (500mg/day), there's nothing strictly wrong with it.

However...

There's nothing strictly wrong with letting your taste and body decide how much salt it should take in, either.

What I fail to see is what you get out of it, when it makes your food less tasty, and makes it more difficult to get a good amount of water intake (which does have benefits).

I just completed a semester of college biology, and I remember learning about sodium-potassium pumps which are located in virtually all cellular membranes. They're responsible for maintaining cellular potential and cell volume. They're also important for nerve cell signaling.

I am against reducing the amount of salt in our diet because of a study done on mice to see how sodium deficiency affected their mineral metabolism.

http://www.jbc.org/content/133/1/75.full.pdf

One thing that really stuck out was "The amount of food consumed per gm. of body weight was 7.5 gm. [sodium deficient group] and 4.6 gm. [control group] respectively." The sodium deficient mice were definitely eating more than their salted up peers!

And another thing; Japan has one of the most saltiest diet in the world, but one of lowest obesity rates.

http://www.nationmaster.com/graph/hea_obe-health-obesity

I won't be putting down the salt shaker anytime soon.

Adrenal dysfunction and adrenal fatigue may be aleviated by finding the amount of salt intake one should have.

http://www.drkaslow.com/html/adrenal_insufficiency.html

For the person with depleted adrenals sunbathing on the beach can have devastating results. The salt loser that attempts to function on low salt does not understand why he feels faint, or is suddenly unable to function in the heat, or he feels his mind is cloudy and his energy gone. He may become very weak, tired, and depressed. Salt is needed for the electrical function of the heartbeat, to make hydrochloric acid in the stomach, and for the fluid around the cells. Sodium is the principal fluid outside of the cell (extra-cellular fluid) and as a result affects the proper function of all cells. The nerve cells of the brain, and consequently all of our emotions, are affected by the salt levels. Adding enough sodium chloride (salt) to the diet may be all that is needed for some patients.

Even other types of conditions, like kidney disease, need "some" salt and should have a moderate amount. According to Richard H. Ahrens, Ph.D. of the USDA and an Associate Professor of Nutrition at the University of Maryland, salt use does not cause hypertension as is frequently claimed. There should be no salt restrictions during pregnancy and no diuretic use. If there is edema in pregnancy, extra salt brings about diuresis. It can be a serious mistake for an individual to avoid salt for no apparent reason. For any loss of body fluids - excessive perspiration or urination, vomiting or diarrhea - the lost salt must be replaced. A person with undiagnosed adrenal dysfunction (who is therefore a salt loser) on a salt restricted diet may be slowly deteriorating as the result.

There appears to be no food that naturally contains more sodium than potassium and therefore salt must be added to the diet. This is why Gandhi led the revolution in India. Salt is essential to life. In Addison's Disease, where there is a complete non-function (atrophy) of the adrenal cortex, patient's can suffer from prostration, die from excess perspiration or a diet high in potassium or low in sodium.

To find the amount of salt you need, gradually increase your salt intake until you find the amount you feel best on - usually 2 to 10 grams or roughly 1/2 teaspoonful to 1 tablespoonful. After determining the amount, try to cut back and see if that is just as effective. The addition of a small amount of sugar actually helps you absorb salt. In fact this is the basis for many popular electrolyte replacement products like Gatorade. Some individuals may also need potassium.

I read the book, 'the art and science of low carbohydrate living', a few months ago and it covers salt in a good bit of detail. It said that the amount of carbs you eat changes the amount of salt you need to eat. High carbs diets make the kidneys retain salt and low carb diets will make the kidneys excrete salt. If you eat a low carb diet and avoid salt you will end up with symptoms like tiredness, weakness and headaches.

I don't think so, in fact I think it's a good thing for those struggling with obesity. Salt increases palatability of your food (that is why you use salt, think about it) and many whole foods unseasoned become only edible when you're hungry. i.e. plain meat, plain tubers, steamed vegs. A lower salt diet will certainly decrease its food reward, and allow one to become satisfied with less calories from the SAME diet (except salt difference). My 2 cents.