Salt Pills... What do ya know about them?

It's important to understand how sodium and electrolyte supplementation affects the rest of your digestive system.

Using an electolyte supplement like "salt tablets" may help in some environmental conditions depending on your level of acclimation. It may also shunt fluid toward your digestive tract in an attempt to process the sodium making you even more dehydrated.

The only sure way to know if you need sodium and electrolyte supplementation is to be tested for it. Urine and blood analysis while exercising in heat will reveal this. Everything else is either a shoot from the hip experiment or guessing. You can test the affect of sodium supplementation in training on hot days but do so with caution and moderation and carefully monitor your results.

In many cases electrolyte supplementation is fixing a problem that doesn't exist.

I get GI issues EVERY TIME that I try even one.  I take in a ton of electrolytes through sports drinks and my infinit 10x homemade gel.

funny, that was exactly what I thought when I read her post. 

I'd venture to say it's a lot less about the cramps and more about fluid retention.

Ingested water in the body is held there by the salt (osmosis). Your blood plasma is very salty. That's what keeps the water there - water wants to move toward the salt (to 'dilute' it). 

Without salt to match water intake at large volumes (like for long 3=hr efforts) , ingested free water will go to the bladder instead of the blood plasma. The more salt you lose, the less total body water you can maintain. Fortunately, nature has adapted us so that we've got enough salt to go for hours, but if you're going long enough to lose pounds and pounds of water (like those 5+ hrs bike training rides in the heat), ingested salt with water to match is essential to keeping your plasma volume up. 

An extreme example of this gone haywire is in people with poorly functioning kidneys, like advanced diabetics. They have to carefully watch their salt intake, because if they take too much salt in food, they'll get very thirsty and then drink so much water that they can actually overload their heart or even get some severe leg swelling. Healthy people don't have as much an issue with this since our kidneys can dump extra salt, but you can see how the water clearly follows the salt in these people.

Note that for efforts even as long as typical marathons (3-4.5hrs), salt isn't really a performance limiter. Ask this question on an ultramarathoner forum (like 100 mile races), and you'll get a lot more answers as to how essential it is.