Next Step In My Research Paper

My topic is about the preservatives implemented in our foods and the consequences on consuming them. So far I've read that some preservatives can cause heart problem and even cancer! So far I feel like my research paper is a mess because I’m not sure what to talk about next because I don’t want to get off topic but everything makes a connection towards the end. For my second draft, I’m trying to incorporate more resources and make it less confusing because so far I feel like it doesn’t flow like it should. Also, I want to find out what preservative is in the daily foods we eat. I’m considering on talking about McDonald’s because I saw a video the other day in where this guy had a burger from there that was a month old and it looked brand new. He was explaining that McDonald’s uses many preservatives for that to even happen because it was naturally made it wouldn’t have lasted more than a week. I honestly found that very shocking because it’s a well-known fast food restaurant and I feel like there are many people that don’t know what they’re consuming. I feel like I would want to incorporate a real life story about the negative effects of preservatives but I’m still undecided. I’m considering in quoting doctors and people that are specialized in this topic but I’m not sure if it’s a good idea, what do you guys think? Should I incorporate real life testimonies from people who’ve suffered consequences from these preservatives or incorporate many doctors and specialists? Or maybe even both?