And they also come with some unpleasant side-effects: a much higher incidence of skin cancer and all the risks that come with being immunosuppressed. (Plus the disadvantages - if you like soft cheese and deli meats, being on an anti-TNF drug will suck.)
Having a depressed immune system means you're more likely to contract things like listeria or toxo plasmosis which are commonly found in cured meats and soft cheeses. This is also the reason why pregnant women are advised against eating them.
They're also very, very expensive.