You try to find the most reliable sources you can.

1. Grow your own.

2. Eat the stuff with an "Organic" label. (Yes, they could be lying or just barely following the law. But, its better than the regular stuff.)

3. Buy from companies that are dedicated to healthy food. Yes, you can tell and research. Not everyone is lying.

4. Buy from stores that research and stock good quality organic items. (Yes, they do exist. You can learn to tell who is lying and who is not. You might get duped, sometimes. I have eaten products I thought were good, only to discover I was wrong, and then changed.

5. Buy local. It might not be perfect but it's probably better than the stuff from a factory farm.

6. Try. Trying to find good healthy food, can be fun and the beginning of a new life. It's better than dying from cancer wondering if you could have lived longer if you had just ate better.