What's better for an 18 month old pasteurized or unpasteurized?

Pasturized: Pasturized milk is healthy fir you. There is little risk of infection as with unpasturized milk.

Pasteurized: Pasteurization kills germs! Some nutrients can be reduced or lost but some awfully nasty germs are killed too. See http://en.wikipedia.org/wiki/Pasteurization When you do research check both sides of the issue. Consider the source! It the page is ad-free good. When checking studies, sometimes the ones they say support a view turn out to have only a few subjects which is not enough.