I heard the safest thing u can do is to eat ass on the regular. The human ass alone houses over a thousand different types of bacteria and fungi. Having your body exposed to that on the consistent basis will help get your white blood molecules in fighting shape.
Think of this as a MMA or boxing match with your body and germs squaring off in a fight. You have to train your body consistently to stand a chance. Eating ass will expose you to the latest viruses and ultimately make you immune to a lot of shyt that drugs won't even heal.