Aluminun is actually used in the vaccines specifically because it illicits a response from the immune system. This is done so that the vaccine can contain less virii (whatever the plural of virus cells is). The idea is to get the immune system into gear so it'll bother fighting the relatively tiny amount of virus that is injected and create antibodies so you have long term immunity.
So Aluminum is harmful and too much of it can be bad for you. Vaccines are usually tested by themselves, which makes sense because they are looking for problems with that specific vaccine. However that is not how vaccines are ordinarily given in practice. Doctors and hospitals usually bundle the vaccines in an atempt to make sure that kids get all of them because they can't be sure when a kid will show up next if at all. I don't believe that even with 3 or 4 vaccines at once you are likely to cause real harm to a kid but by doing so many vaccinations at once the amount of aluminum being injected is far higher than it needs to be for the desired affect and if for whatever reason a child is more sensitive to the aluminum they are more likely to suffer ill affects from having such a large dose all at once.
So I'm very glad that we were able to find a pediatrician who is willing to see my kids more frequently and split the vaccines up between visits. This way our children are still vaccinated in time for school and day care but we've spread whatever risk there might be. As a side benefit my youngest seems to almost expect a shot each doctors visit and doesn't even tear up anymore when he gets one. The only vaccine we've waived is Chicken Pox, because, seriously it's the fucking chicken pox. The vaccine is hardly worthy of the name, it produces a very weak immunity, is manadatory so that insurance companies have to cover it, and requires contant boosters to have any affect at all. Meaning we are nearing the point that a whole generation will mature to adulthood without a real immunity to chickenpox, won't that be fun.
So far as aluminum in food goes I'm not sure how well it is absorbed by the digestive track. So it may be that you could consume aluminum without risk. Injecting it into the blood stream though is a completely different matter.