Regarding @Nullo‘s first post- that is spamming.
We get dozens of such users daily paid to become members, participate some then drop a link. I should know. I have banned 984 users for spamming on Fluther in the last 17 months.
To join a web site with the sole purpose of dropping a link to promote your web site is spamming. It does not matter if you find a place to put it where you think it will not be noticed or how innocent you want it to look. Bottom line is that you would not have joined had you not been waiting for the chance to drop that link to serve your ratings.
On the bright side we DO allow you to place a link in your profile. However if you place a link in your profile and then stop being a contributing member we will remove it as spam.
My advice is to put your link in legitimate venues as you have done- to create podcasts or continue to create great articles and your site will build naturally. See if other sites will cross-link with you.
To find people to rate supplements I think asking for honest reviews is a legit thing- provided you are not trying to sell supplements and remove unfavorable ones.
So suggestions:
Begin having podcasts on topics related to your blog.
Create newsletters
Link on your profile here- but continue to be a productive member.
Write articles for magazines and ezines where they allow authors a promotional linkback.
Set up an email list to send out new articles and keep users from forgetting you.
Be a guest on other people’s podcasts.
Take any chance you can get to discuss your passion, supplements, and people who share your passion will follow.
All these things will help you gain- and keep- users and get better search engine ratings.