It's not the food itself that will kill them. Iceberg lettuce, in large quantities, can cause them to have diarrhea, which will kill them if it's not treated. Since Iceberg has no nutritional value, no point in giving it anyways. Small amounts of other lettuce are ok, green leaf and romaine are good choices. I personally stick with parsley & cilantro for the leafy greens. Garlic and onions I believe can also kill them (can cause them to become anemic), and also chocolate. I stick with the basics pretty much. Parsley, a little carrot, bell peppers, orange, sometimes a little kiwi, apples. For his regular food, only use the straight pellets. Don't get the mixes that have pellets and other little things in it. The other items are completely unnecessary and are not good for them at all. For a young pig, under 6 months, use alfalfa hay, and for older pigs, use timothy hay.
Also, for the bedding, avoid Pine & Cedar shavings like the plague. It can cause respiratory damage to both animals and people. Only use aspen shavings or another product called Carefresh. Don't use newspaper unless you know for a fact that your newspaper only uses non-toxic dyes. And if your cage starts looking kind of dingy, use plain white vinegar to clean it. It will break down ammonia build up and is safe for piggies.
