Taking vitamins/pills with and without food

How big of a difference does it make when you take supplements with food rather then without food. I have heard that when taken with food it helps absorption but why is that?

I've heard that too, I also am curious of the science behind it.

However, when I take anything on an empty stomach I get horrible stomach cramping and sometimes nausea...I take everything with food, especially my daily multi-vitamin, and only take it in the evening after I've been able to eat a very full meal.

^That's why food is advised.