Having the best agricultural technology simply means that we can produce food more cheaply and in larger quantities than just about anyone. That said, if you want to eat healthy food here in the US, you’ve got plenty of choices. Of course this is a free country, so if you want to eat unhealthy food, that’s your call too. I’m not a big fan of mass-produced US beef, but it is cheap and there’s something to be said for a country of 300 million (!) people where almost everyone can eat a hamburger whenever they want. Not that eating hamburgers is good for you, I’m just saying we’ve made them really, really cheap, so I wouldn’t worry about losing our food supply to foreign imports.