The United States dietary guidelines, based on the 2005 Institute of Medicine report, recommend that the general population aim for sodium levels of 1,500 to 2,300 milligrams a day because those levels will not raise blood pressure.
One of the symptoms of the plague was coughing and sneezing, and it is believed that Pope Gregory VII suggested saying âGod bless youâ after a person sneezed in hopes that this prayer would protect them from an otherwise certain death. The expression may have also originated from superstition.
Another is that people thought that sneezing could open you up to losing your soul or being invaded by the Devil or evil spirits and saying it was supposed to protect you from that. Another possibility is that people just didn't understand sneezing and so saying it was just a response to something worrisome. A couple other possibilities are mentioned in the source but those are the main ones imo. Source(s): http://en.wikipedia.org/wiki/Bless_you.