Madonna,
I just read that eating as little as 2 ounces per day of processed meat can increase your risk of cancer by as much as 50%. I think that's also a good example. Processing damages the food in such a way as to make it dangerous (Sorry, Jared!). I also know that grilling increases the carcinogenic effect of meat. But the good news is marinading reduces the risk tremendously. So, the more natural the state of the food, the better.
Grains that are highly processed lose important elements which are not replaced during the enrichment process. So, if a product says "enriched" nutrients have been removed then replaced but rarely to the extent they should be!
Hope this helps!
Bobbi