Kerrygold Butter is considered the staple butter of Paleo / Primal Diet followers. The main reason is that is is 100% grass fed butter, and available year round (I buy mine at Trader’s Joe’s [pic on Amazon]).
I came across a blog post in which a Kerrygold representative clarified the difference between the salted and unsalted versions of their butter. Here’s what they said:
Kerrygold produces two different types of butter for the US: a salted sweet cream butter (gold foil) and unsalted lactic/cultured butter (silver foil). (link)
The bold emphasis is mine because it shows that the unsalted (silver foil) butter is cultured, which means it’ll have healthy bacteria in it.
So my recommendation is to always buy the Unsalted Kerrygold butter and add your own real salt (not processed and from a source with no contaminants) for taste