I stick to a very low sodium diet which has helped a lot with Meniere's (severe bouts of vertigo & nausea).  It's difficult trying to learn the correct amount of sodium intake when training in the hot, humid summer weather.  There has to be some other athletes out there who have this problem.  I'd like to hear any suggestions or personal experience regarding sodium intake required during hot weather endurance sports, and signs to watch for that I need more sodium.