Question about Nutritional yeast & Preservatives

Hi. I am wondering if you guys could clear up some confusion for me. I have Multiple sclerosis and from what I have researched food plays a large role in my disease. The long and short of the diet I am to follow/want to follow is that NO DAIRY/NO MEAT/NO GLUTEN/NO REFINED SUGARS/NO PRESERVATIVES/NO SOY. Because of this I am adapting a vegan diet…it’s challenging to find a cookbook that covers all of my restrictions lol - if anyone knows the name of one it would be helpful to me if you’d tell me and the name of the author. My main question is that a lot of he vegan cookbooks have “meat & dairy like” products. I do not want to eat pre-packaged vegan food either. Is it safe for me to consume products like nutritional yeast on this diet?