There's a common food additive named tert-butylhydroquinone (tBHQ) used to stabilize cooking oils, frozen meat products, crackers, chips, etc. that appears to make flu vaccines less effective.  Vaccinated mice who ate the foods with the additive also took three days longer to recover from the flu when they got it.  Unvaccinated mice who ate the additive, had more virus in their lungs, had inflammation and increased mucus production deeper in their lungs than usual.  We are really killing ourselves with all the additives and products that have ingredients that can't even be pronounced.  There are a lot of foods I can't eat because of an intolerance to them, I think it probably makes me a healthier person.