It isn't hard. Fresh fruit and vegetables don't even have labels because it isn't needed. Meats, and eggs, spices, flour, sugar, oils, and all the other staples might have a label but I don't need to read the fine print to know what is inside because the answer is always the same: whatever is on big print on front.

When buying processed food it is impossible though. Just learn to cook and you will typically have much healthier meals. It takes more time, but there isn't an other reasonable option to be healthy in first world society.