The FDA [Federal Department of Agriculture] in America has set a recommended sodium intake of 2300 mg per day. A lawsuit against the FDA by the Centre for Science in the Public Interest [CSPI] is currently in progress to force the FDA to list sodium as a 'food additive' so that it's use in all foods can be regulated. The reason for this is that the average sodium intake for an adult American is 4000 to 6000 mg per day.
Some people are more susceptible to the effects of sodium than others, and sodium sensitivity appears to increase with age but there is no test, currently, to determine this and that is why a diet low in sodium is advised.