Do you think you could clarify your question? The percentage values on your food tell you the percentage of that "thing" that you're supposed to have in a day, underneath it in small print it will usually say what studies or theories they're going off of, which you could look up. Does that answer your question?
One serving of the product represents the % of certain nutrients that is recommended for a person per day. For example, if a serving contains 20% of the recommended vitamin B, then It's suggested that you find the other 80% elsewhere so to speak.