I want to start a health site and obviously I am not a health expert, I just have a lot of interest in the topic. I have purchased numerous books over the years on various health topics and am wondering if it's legal for me to use the content in the books as a source for my web content? I am talking along the lines of majorly rewriting or summing up content that I read on particular topics.

Of course I understand that you can't steal someone's concept or republish content taken from somewhere but aren't facts just facts, can't we "rephrase" them in our own words? When I write about calories and antioxidants I am not reinventing the wheel here so I don't see an issue. Am I missing something?