Why is it every time i try to eat healthy i am told its not?

i start eating fish to get high levels of heart healthy omega fatty acids and i am told i shouldn't because fish contains poisonous levels of Mercury. i try to eat lots of fruit and veg and told to be careful as they can contain lots of chemicals. Really wtf is going on with food its getting to the point were junk food is less harmful. i heard ages ago about secret society's and the illuminatti conspiracy's about them supposedly putting poisonous stuff in food i thought it was a load of drivle but now i am not sure any more. food that is supposed to be nutritious and 100% healthy is now getting to the point were your safer eating a Bigmac