u/BluRayHiDef

I think that there is a positive correlation between the dosage of Vitaman D+ and the age of memories that it suppresses. So, as long as the Vitamin D+ comprises only a small percentage of the water supply, Silo 18's residents will gradually lose their memories in reverse of the order in which they formed them until the Vitamin D+ is no longer in the water supply.

Therefore, Silo 18's residents will still remember their identities and relationships with other people; however, they will have forgotten events that transpired from the time that Juliette went out to clean and onwards.

The sandwich is the most brilliant food ever invented, because it's comprised of all major food groups except fruit (though fruit can be added but typically is not): protein in the form meat, nutrients and minerals in the form of vegetables, dairy in the form of cheese, and grains in the form of bread. Furthermore, it's versatile and portable, unlike other all-in-one foods (e.g. pizza).