Why is Google.co.uk showing so many US retailers on search queries?

[predatornutrition]

Over the last couple of years Google seems to be showing more and more irrelevant search results in the field I am based in (dietary supplements) with searches for products coming back with results which highlight US vendors. Given I am in google.co.uk and actually logged in as well, why is Google so far off with their results lately?

[predatornutrition]

Bump.