Food Inc and Freedom of Speech

I'm really shocked to see that people cannot express their opinions about the food we eat openly without being prosecuted or sued, well at least a public figure like celebrities, and in one case Oprah. What happened to the first amendment, and freedom of speech? I understand public figures and celebrities easily influence the public and common people to follow them, but they should still be allowed to express their opinions. I also understand that food laws are especially strict and must be adhered by, but I think our health is more important than protecting the meat packing industry. I think it was absolutely ridiculous to sure Oprah for loss of sales, when really it's their own fault people aren't buying meat due to sanitation and disease infesting the plants and animals which continue to spread. Why should they even want people to keep buying their meat knowing it's infected? Obviously all they care about is money, and unfortunately I'm sure their are more examples like this one. I think our government needs to redirect their priorities from protecting food industries, to protecting the health and first amendment of it's citizens. After all our government is "supposed" to be for the people.