Do people that live along oceans shores or on islands have higher dietary sodium intakes from eating more saltwater seafood?
No. Supplemental sodium intake from preservation, curing, and seasoning is much higher than the additional sodium that sea salt provides in sea food.
The elements that coastal natives do get more of, due to things like seaweeds, or certain kinds of shellfish and crabs, are potassium and iodine.
In fact, there was an interesting study about iodine released a couple years ago, which described the effects of iodine deprivation.
It seems that young males that are deprived of iodine before and during puberty develop larger testicles, and produce more sperm, but show reduced IQ scores.
Coastal populations, and those where iodized salt is common, show less semen production and smaller testicles, but higher IQ scores.
So – you have a choice, balls or brains!