Of course, this is not meant to be taken literally, in the sense that if you eat a pig, you are a pig. However, what was meant was that the food that we eat has a direct influence on our mind and our body.
It goes without saying that when the food we consume is laden with pesticides or toxic chemicals, we will ingest these things. Researchers at Johns Hopkins Center for a Livable Future set out to prove just this with regards to chicken.

Chicken Study

In the years 2010 and 2011, researchers collected chicken samples from grocers in ten major cities in the United States. Some of these samples were conventional chicken, some were antibiotic-free chicken, and some were USDA Certified Organic chicken.