Best, most effective, preferred...

Marketing and advertising are about images and words, how a product is described is meant to draw your interest and appeal to you. If you read "least effective diet pill" or "completely untested wrinkle cream" you'd probably not be at all interested. However if you read, most effective diet pill or four out of five dentists prefer (fill in name) then you'd be more inclined to give a product a look. It's up to you as a consumer to do your homework and my standard advice before taking any diet or health supplement, check with your health care professional first.