ELI5 Fish Oil - if it’s so good for you, why not use it more for cooking?

Does fish oil actually help? What makes it help? What are the specific types of Omega-3 that are good for you? If it’s so good for us why not use it more for cooking? Why are there some eggs that have Omega-3 on the label? ... we explain like I'm five Thank you to the r/explainlikeimfive community and in particular the following users whose questions and comments formed the basis of this discussion: adapid, baggier, dvlpr404, ridcullylivces, siznit, mandolele and scarydare5. To the community that has supported us so far, thanks for all your feedback and comments. Join us on Twitter: https://www.twitter.com/eli5ThePodcast/ or send us an e-mail: ELI5ThePodcast@gmail.com