Dear Nutri8
Your question about Google and Facebook have been well answered by my colleagues.
I’d like to suggest that there are other ways to target an audience – specifically public relations, trade shows, podcasts and bloggers.
If you can find groups of consumers who are well suited to your product and then find out
– what magazines they read
– what podcasts they listen to
– what trade shows and exhibitions cater to that audience
– whether bloggers write for this audience

Then you can do some slightly different marketing.

Approach these media owners and seek an product review, an interview with you or offer a competition to win some product in exchange for getting email addresses from interested people. This will help to build your direct marketing database (for newsletters) and that will be a valuable asset in the longer run.